Sun VirtualBox
User Manual
Version 3.1.0_BETA2
c
2004-2009 Sun Microsystems, Inc.
http://www.virtualbox.org
R
Contents
1 First steps 9
1.1 Why is virtualization useful? . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2 Some terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3 Features overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4 Supported host operating systems . . . . . . . . . . . . . . . . . . . . . 14
1.5 Installing and starting VirtualBox . . . . . . . . . . . . . . . . . . . . . . 15
1.6 Creating your first virtual machine . . . . . . . . . . . . . . . . . . . . . 17
1.7 Running your virtual machine . . . . . . . . . . . . . . . . . . . . . . . . 21
1.7.1 Keyboard and mouse support in virtual machines . . . . . . . . . 21
1.7.2 Changing removable media . . . . . . . . . . . . . . . . . . . . . 23
1.7.3 Saving the state of the machine . . . . . . . . . . . . . . . . . . 24
1.8 Snapshots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.9 Virtual machine configuration . . . . . . . . . . . . . . . . . . . . . . . . 27
1.10 Deleting virtual machines . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.11 Importing and exporting virtual machines . . . . . . . . . . . . . . . . . 29
2 Installation details 32
2.1 Installing on Windows hosts . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.1.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.1.2 Performing the installation . . . . . . . . . . . . . . . . . . . . . 32
2.1.3 Uninstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.1.4 Unattended installation . . . . . . . . . . . . . . . . . . . . . . . 33
2.2 Installing on Mac OS X hosts . . . . . . . . . . . . . . . . . . . . . . . . 33
2.2.1 Performing the installation . . . . . . . . . . . . . . . . . . . . . 33
2.2.2 Uninstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.2.3 Unattended installation . . . . . . . . . . . . . . . . . . . . . . . 34
2.3 Installing on Linux hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.3.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.3.2 The VirtualBox kernel module . . . . . . . . . . . . . . . . . . . 34
2.3.3 USB and advanced networking support . . . . . . . . . . . . . . 36
2.3.4 Performing the installation . . . . . . . . . . . . . . . . . . . . . 36
2.3.5 Starting VirtualBox on Linux . . . . . . . . . . . . . . . . . . . . 41
2.4 Installing on Solaris hosts . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.4.1 Performing the installation . . . . . . . . . . . . . . . . . . . . . 41
2.4.2 Starting VirtualBox on Solaris . . . . . . . . . . . . . . . . . . . 42
2.4.3 Uninstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.4.4 Unattended installation . . . . . . . . . . . . . . . . . . . . . . . 42
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2.4.5 Configuring a zone for running VirtualBox . . . . . . . . . . . . 43
3 Configuring virtual machines 44
3.1 Supported guest operating systems . . . . . . . . . . . . . . . . . . . . . 44
3.2 64-bit guests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.3 General settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3.1 “Basic” tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3.2 “Advanced” tab . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3.3 “Description” tab . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.4 System settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.4.1 “Motherboard” tab . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.4.2 “Processor” tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.4.3 “Acceleration” tab: hardware vs. software virtualization . . . . . 49
3.5 Display settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.6 Storage settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.7 Audio settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.8 Network settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.9 Serial ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.10 USB support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.10.1 USB settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.10.2 Implementation notes for Windows and Linux hosts . . . . . . . 58
3.11 Shared folders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.12 Alternative firmware (EFI) . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 Guest Additions 60
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.2 Versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.3 Windows Guest Additions . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.3.1 Installing the Windows Guest Additions . . . . . . . . . . . . . . 62
4.3.2 Updating the Windows Guest Additions . . . . . . . . . . . . . . 63
4.3.3 Unattended Installation . . . . . . . . . . . . . . . . . . . . . . . 64
4.3.4 Manual file extraction . . . . . . . . . . . . . . . . . . . . . . . . 64
4.3.5 Windows Vista networking . . . . . . . . . . . . . . . . . . . . . 64
4.4 Linux Guest Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.4.1 Installing the Linux Guest Additions . . . . . . . . . . . . . . . . 65
4.4.2 Video acceleration and high resolution graphics modes . . . . . 66
4.4.3 Updating the Linux Guest Additions . . . . . . . . . . . . . . . . 67
4.5 Solaris Guest Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.5.1 Installing the Solaris Guest Additions . . . . . . . . . . . . . . . 67
4.5.2 Uninstalling the Solaris Guest Additions . . . . . . . . . . . . . . 68
4.5.3 Updating the Solaris Guest Additions . . . . . . . . . . . . . . . 68
4.6 OS/2 Guest Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.7 Folder sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.8 Seamless windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.9 Hardware 3D acceleration (OpenGL and Direct3D 8/9) . . . . . . . . . 72
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4.10 Hardware 2D video acceleration for Windows guests . . . . . . . . . . . 73
4.11 Guest properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5 Virtual storage 76
5.1 Hard disk controllers: IDE, SATA (AHCI), SCSI . . . . . . . . . . . . . . 76
5.2 Disk image files (VDI, VMDK, VHD, HDD) . . . . . . . . . . . . . . . . . 79
5.3 The Virtual Media Manager . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.4 Special image write modes . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.5 Differencing images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.6 Cloning disk images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.7 Writing CDs and DVDs using the host drive . . . . . . . . . . . . . . . . 85
5.8 iSCSI servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
5.8.1 Access iSCSI targets via Internal Networking . . . . . . . . . . . 86
6 Virtual networking 88
6.1 Virtual networking hardware . . . . . . . . . . . . . . . . . . . . . . . . 88
6.2 Introduction to networking modes . . . . . . . . . . . . . . . . . . . . . 89
6.3 Network Address Translation (NAT) . . . . . . . . . . . . . . . . . . . . 90
6.3.1 Configuring port forwarding with NAT . . . . . . . . . . . . . . . 90
6.3.2 PXE booting with NAT . . . . . . . . . . . . . . . . . . . . . . . . 91
6.3.3 NAT limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.4 Bridged networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.5 Internal networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.6 Host-only networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
7 Alternative front-ends; remote virtual machines 96
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.2 Using VBoxManage to control virtual machines . . . . . . . . . . . . . . 97
7.3 VBoxSDL, the simplified VM displayer . . . . . . . . . . . . . . . . . . . 98
7.4 Remote virtual machines (VRDP support) . . . . . . . . . . . . . . . . . 99
7.4.1 Common third-party RDP viewers . . . . . . . . . . . . . . . . . 100
7.4.2 VBoxHeadless, the VRDP-only server . . . . . . . . . . . . . . . . 101
7.4.3 Step by step: creating a virtual machine on a headless server . . 102
7.4.4 Remote USB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
7.4.5 RDP authentication . . . . . . . . . . . . . . . . . . . . . . . . . 104
7.4.6 RDP encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.4.7 VRDP multiple connections . . . . . . . . . . . . . . . . . . . . . 105
8 VBoxManage reference 106
8.1 VBoxManage list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.2 VBoxManage showvminfo . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.3 VBoxManage registervm / unregistervm . . . . . . . . . . . . . . . . . . 113
8.4 VBoxManage createvm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.5 VBoxManage modifyvm . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
8.5.1 General settings . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
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8.5.2 Networking settings . . . . . . . . . . . . . . . . . . . . . . . . . 116
8.5.3 Serial port, audio, clipboard, VRDP and USB settings . . . . . . 117
8.6 VBoxManage import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
8.7 VBoxManage export . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8.8 VBoxManage startvm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8.9 VBoxManage controlvm . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
8.10 VBoxManage discardstate . . . . . . . . . . . . . . . . . . . . . . . . . . 122
8.11 VBoxManage snapshot . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
8.12 VBoxManage openmedium / closemedium . . . . . . . . . . . . . . . . . 123
8.13 VBoxManage storagectl / storageattach . . . . . . . . . . . . . . . . . . 123
8.13.1 VBoxManage storagectl . . . . . . . . . . . . . . . . . . . . . . . 124
8.13.2 VBoxManage storageattach . . . . . . . . . . . . . . . . . . . . . 124
8.14 VBoxManage showhdinfo . . . . . . . . . . . . . . . . . . . . . . . . . . 125
8.15 VBoxManage createhd . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
8.16 VBoxManage modifyhd . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
8.17 VBoxManage clonehd . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8.18 VBoxManage convertfromraw . . . . . . . . . . . . . . . . . . . . . . . . 127
8.19 VBoxManage addiscsidisk . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.20 VBoxManage getextradata/setextradata . . . . . . . . . . . . . . . . . . 129
8.21 VBoxManage setproperty . . . . . . . . . . . . . . . . . . . . . . . . . . 130
8.22 VBoxManage usbfilter add/modify/remove . . . . . . . . . . . . . . . . 130
8.23 VBoxManage sharedfolder add/remove . . . . . . . . . . . . . . . . . . 131
8.24 VBoxManage metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
8.25 VBoxManage guestproperty . . . . . . . . . . . . . . . . . . . . . . . . . 132
8.26 VBoxManage dhcpserver . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
9 Advanced topics 135
9.1 VirtualBox configuration data . . . . . . . . . . . . . . . . . . . . . . . . 135
9.2 Automated Windows guest logons . . . . . . . . . . . . . . . . . . . . . 137
9.3 Automated Windows system preparation . . . . . . . . . . . . . . . . . . 138
9.4 Custom external VRDP authentication . . . . . . . . . . . . . . . . . . . 139
9.5 Secure labeling with VBoxSDL . . . . . . . . . . . . . . . . . . . . . . . 141
9.6 Custom VESA resolutions . . . . . . . . . . . . . . . . . . . . . . . . . . 142
9.7 Multiple monitors for the guest . . . . . . . . . . . . . . . . . . . . . . . 143
9.8 Releasing modifiers with VBoxSDL on Linux . . . . . . . . . . . . . . . . 143
9.9 Launching more than 120 VMs on Solaris hosts . . . . . . . . . . . . . . 144
9.10 Using serial ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
9.11 Using a raw host hard disk from a guest . . . . . . . . . . . . . . . . . . 145
9.11.1 Access to entire physical hard disk . . . . . . . . . . . . . . . . . 145
9.11.2 Access to individual physical hard disk partitions . . . . . . . . . 146
9.12 Allowing a virtual machine to start even with unavailable CD/DVD/floppy
devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
9.13 Fine-tuning the VirtualBox NAT engine . . . . . . . . . . . . . . . . . . . 148
9.13.1 Configuring the address of a NAT network interface . . . . . . . 148
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9.13.2 Configuring the boot server (next server) of a NAT network in-
terface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
9.13.3 Tuning TCP/IP buffers for NAT . . . . . . . . . . . . . . . . . . . 149
9.13.4 Binding NAT sockets to a specific interface . . . . . . . . . . . . 149
9.13.5 Enabling DNS proxy in NAT mode . . . . . . . . . . . . . . . . . 150
9.13.6 Using the host’s resolver as a DNS proxy in NAT mode . . . . . . 150
9.14 Configuring the maximum resolution of guests when using the graphi-
cal frontend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.15 Configuring the BIOS DMI information . . . . . . . . . . . . . . . . . . . 151
9.16 Configuring the guest time stamp counter (TSC) to reflect guest execution152
9.17 Configuring the hard disk vendor product data (VPD) . . . . . . . . . . 152
10 VirtualBox programming interfaces 154
11 Troubleshooting 155
11.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
11.1.1 Collecting debugging information . . . . . . . . . . . . . . . . . 155
11.1.2 Guest shows IDE/SATA errors for file-based images on slow host
file system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
11.1.3 Responding to guest IDE/SATA flush requests . . . . . . . . . . . 156
11.2 Windows guests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
11.2.1 Windows bluescreens after changing VM configuration . . . . . 157
11.2.2 Windows 0x101 bluescreens with SMP enabled (IPI timeout) . . 157
11.2.3 Windows 2000 installation failures . . . . . . . . . . . . . . . . 157
11.2.4 How to record bluescreen information from Windows guests . . 158
11.2.5 No networking in Windows Vista guests . . . . . . . . . . . . . . 158
11.2.6 Windows guests may cause a high CPU load . . . . . . . . . . . 158
11.3 Linux and X11 guests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
11.3.1 Linux guests may cause a high CPU load . . . . . . . . . . . . . 159
11.3.2 AMD Barcelona CPUs . . . . . . . . . . . . . . . . . . . . . . . . 159
11.3.3 Buggy Linux 2.6 kernel versions . . . . . . . . . . . . . . . . . . 159
11.3.4 Shared clipboard, auto-resizing and seamless desktop in X11
guests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
11.4 Windows hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
11.4.1 VBoxSVC out-of-process COM server issues . . . . . . . . . . . . 160
11.4.2 CD/DVD changes not recognized . . . . . . . . . . . . . . . . . . 160
11.4.3 Sluggish response when using Microsoft RDP client . . . . . . . 161
11.4.4 Running an iSCSI initiator and target on a single system . . . . . 161
11.5 Linux hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
11.5.1 Linux kernel module refuses to load . . . . . . . . . . . . . . . . 162
11.5.2 Linux host CD/DVD drive not found . . . . . . . . . . . . . . . . 162
11.5.3 Linux host CD/DVD drive not found (older distributions) . . . . 162
11.5.4 Linux host floppy not found . . . . . . . . . . . . . . . . . . . . 163
11.5.5 Strange guest IDE error messages when writing to CD/DVD . . . 163
11.5.6 VBoxSVC IPC issues . . . . . . . . . . . . . . . . . . . . . . . . . 163
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11.5.7 USB not working . . . . . . . . . . . . . . . . . . . . . . . . . . 164
11.5.8 PAX/grsec kernels . . . . . . . . . . . . . . . . . . . . . . . . . . 165
11.5.9 Linux kernel vmalloc pool exhausted . . . . . . . . . . . . . . . 165
11.6 Solaris hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
11.6.1 Cannot start VM, not enough contiguous memory . . . . . . . . 165
11.6.2 VM aborts with out of memory errors on Solaris 10 hosts . . . . 166
12 Change log 167
12.1 Version 3.1.0 Beta 2 (2009-11-19) . . . . . . . . . . . . . . . . . . . . . 167
12.2 Version 3.0.12 (2009-11-10) . . . . . . . . . . . . . . . . . . . . . . . . 169
12.3 Version 3.0.10 (2009-10-29) . . . . . . . . . . . . . . . . . . . . . . . . 170
12.4 Version 3.0.8 (2009-10-02) . . . . . . . . . . . . . . . . . . . . . . . . . 171
12.5 Version 3.0.6 (2009-09-09) . . . . . . . . . . . . . . . . . . . . . . . . . 173
12.6 Version 3.0.4 (2009-08-04) . . . . . . . . . . . . . . . . . . . . . . . . . 176
12.7 Version 3.0.2 (2009-07-10) . . . . . . . . . . . . . . . . . . . . . . . . . 177
12.8 Version 3.0.0 (2009-06-30) . . . . . . . . . . . . . . . . . . . . . . . . . 179
12.9 Version 2.2.4 (2009-05-29) . . . . . . . . . . . . . . . . . . . . . . . . . 182
12.10Version 2.2.2 (2009-04-27) . . . . . . . . . . . . . . . . . . . . . . . . . 183
12.11Version 2.2.0 (2009-04-08) . . . . . . . . . . . . . . . . . . . . . . . . . 185
12.12Version 2.1.4 (2009-02-16) . . . . . . . . . . . . . . . . . . . . . . . . . 188
12.13Version 2.1.2 (2009-01-21) . . . . . . . . . . . . . . . . . . . . . . . . . 190
12.14Version 2.1.0 (2008-12-17) . . . . . . . . . . . . . . . . . . . . . . . . . 194
12.15Version 2.0.8 (2009-03-10) . . . . . . . . . . . . . . . . . . . . . . . . . 196
12.16Version 2.0.6 (2008-11-21) . . . . . . . . . . . . . . . . . . . . . . . . . 197
12.17Version 2.0.4 (2008-10-24) . . . . . . . . . . . . . . . . . . . . . . . . . 198
12.18Version 2.0.2 (2008-09-12) . . . . . . . . . . . . . . . . . . . . . . . . . 199
12.19Version 2.0.0 (2008-09-04) . . . . . . . . . . . . . . . . . . . . . . . . . 201
12.20Version 1.6.6 (2008-08-26) . . . . . . . . . . . . . . . . . . . . . . . . . 202
12.21Version 1.6.4 (2008-07-30) . . . . . . . . . . . . . . . . . . . . . . . . . 204
12.22Version 1.6.2 (2008-05-28) . . . . . . . . . . . . . . . . . . . . . . . . . 205
12.23Version 1.6.0 (2008-04-30) . . . . . . . . . . . . . . . . . . . . . . . . . 207
12.24Version 1.5.6 (2008-02-19) . . . . . . . . . . . . . . . . . . . . . . . . . 209
12.25Version 1.5.4 (2007-12-29) . . . . . . . . . . . . . . . . . . . . . . . . . 211
12.26Version 1.5.2 (2007-10-18) . . . . . . . . . . . . . . . . . . . . . . . . . 213
12.27Version 1.5.0 (2007-08-31) . . . . . . . . . . . . . . . . . . . . . . . . . 215
12.28Version 1.4.0 (2007-06-06) . . . . . . . . . . . . . . . . . . . . . . . . . 218
12.29Version 1.3.8 (2007-03-14) . . . . . . . . . . . . . . . . . . . . . . . . . 221
12.30Version 1.3.6 (2007-02-20) . . . . . . . . . . . . . . . . . . . . . . . . . 222
12.31Version 1.3.4 (2007-02-12) . . . . . . . . . . . . . . . . . . . . . . . . . 223
12.32Version 1.3.2 (2007-01-15) . . . . . . . . . . . . . . . . . . . . . . . . . 224
12.33Version 1.2.4 (2006-11-16) . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.34Version 1.2.2 (2006-11-14) . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.35Version 1.1.12 (2006-11-14) . . . . . . . . . . . . . . . . . . . . . . . . 226
12.36Version 1.1.10 (2006-07-28) . . . . . . . . . . . . . . . . . . . . . . . . 227
12.37Version 1.1.8 (2006-07-17) . . . . . . . . . . . . . . . . . . . . . . . . . 227
7
Contents
12.38Version 1.1.6 (2006-04-18) . . . . . . . . . . . . . . . . . . . . . . . . . 228
12.39Version 1.1.4 (2006-03-09) . . . . . . . . . . . . . . . . . . . . . . . . . 228
12.40Version 1.1.2 (2006-02-03) . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.41Version 1.0.50 (2005-12-16) . . . . . . . . . . . . . . . . . . . . . . . . 231
12.42Version 1.0.48 (2005-11-23) . . . . . . . . . . . . . . . . . . . . . . . . 231
12.43Version 1.0.46 (2005-11-04) . . . . . . . . . . . . . . . . . . . . . . . . 232
12.44Version 1.0.44 (2005-10-25) . . . . . . . . . . . . . . . . . . . . . . . . 232
12.45Version 1.0.42 (2005-08-30) . . . . . . . . . . . . . . . . . . . . . . . . 233
12.46Version 1.0.40 (2005-06-17) . . . . . . . . . . . . . . . . . . . . . . . . 234
12.47Version 1.0.39 (2005-05-05) . . . . . . . . . . . . . . . . . . . . . . . . 235
12.48Version 1.0.38 (2005-04-27) . . . . . . . . . . . . . . . . . . . . . . . . 235
12.49Version 1.0.37 (2005-04-12) . . . . . . . . . . . . . . . . . . . . . . . . 236
13 Known limitations 237
14 Third-party licenses 240
14.1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
14.2 Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
14.2.1 GNU General Public License (GPL) . . . . . . . . . . . . . . . . . 242
14.2.2 GNU Lesser General Public License (LGPL) . . . . . . . . . . . . 247
14.2.3 Mozilla Public License (MPL) . . . . . . . . . . . . . . . . . . . . 254
14.2.4 MIT License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
14.2.5 X Consortium License (X11) . . . . . . . . . . . . . . . . . . . . 262
14.2.6 zlib license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
14.2.7 OpenSSL license . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
14.2.8 Slirp license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
14.2.9 liblzf license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
14.2.10libpng license . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
14.2.11lwIP license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
14.2.12libxml license . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
14.2.13libxslt licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
14.2.14gSOAP Public License Version 1.3a . . . . . . . . . . . . . . . . . 267
14.2.15Chromium licenses . . . . . . . . . . . . . . . . . . . . . . . . . 273
14.2.16curl license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
15 VirtualBox privacy policy 277
Glossary 279
8
1 First steps
Welcome to Sun VirtualBox!
VirtualBox is a cross-platform virtualization application. What does that mean? For
one thing, it installs on your existing Intel or AMD-based computers, whether they are
running Windows, Mac, Linux or Solaris operating systems. Secondly, it extends the
capabilities of your existing computer so that it can run multiple operating systems
(inside multiple virtual machines) at the same time. So, for example, you can run
Windows and Linux on your Mac, run Windows Server 2008 on your Linux server, run
Linux on your Windows PC, and so on, all alongside your existing applications. You
can install and run as many virtual machines as you like – the only practical limits are
disk space and memory.
VirtualBox is deceptively simple yet also very powerful. It can run everywhere from
small embedded systems or desktop class machines all the way up to datacenter deployments and even Cloud environments.
The following screenshot shows you how VirtualBox, installed on a Linux machine,
is running Windows 7 in a virtual machine window:
In this User Manual, we’ll begin simply with a quick introduction to virtualization
and how to get your first virtual machine running with the easy-to-use VirtualBox
graphical user interface. Subsequent chapters will go into much more detail covering
more powerful tools and features, but fortunately, it is not necessary to read the entire
User Manual before you can use VirtualBox.
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1 First steps
You can find a summary of VirtualBox’s capabilities in chapter 1.3, Features overview,
page 12. For existing VirtualBox users who just want to see what’s new in this release,
there is a detailed list in chapter 12, Change log, page 167.
1.1 Why is virtualization useful?
The techniques and features that VirtualBox provides are useful for several scenarios:
• Operating system support. With VirtualBox, one can run software written for
one operating system on another (for example, Windows software on Linux or
a Mac) without having to reboot to use it. Since you can configure what kinds
of hardware should be presented to each virtual machine, you can even install
an old operating system such as DOS or OS/2 in a virtual machine if your real
computer’s hardware is no longer supported by that operating system.
• Testing and disaster recovery. Once installed, a virtual machine and its virtual
hard disks can be considered a “container” that can be arbitrarily frozen, woken
up, copied, backed up, and transported between hosts.
On top of that, with the use of another VirtualBox feature called “snapshots”,
one can save a particular state of a virtual machine and revert back to that state,
if necessary. This way, one can freely experiment with a computing environment.
If something goes wrong (e.g. after installing misbehaving software or infecting
the guest with a virus), one can easily switch back to a previous snapshot and
avoid the need of frequent backups and restores.
Any number of snapshots can be created, allowing you to travel back and forward in virtual machine time.
• Infrastructure consolidation. Virtualization can significantly reduce hardware
and electricity costs. Servers today typically run with fairly average low system
loads and are rarely used to their full potential. A lot of hardware potential as
well as electricity is thereby wasted. So, instead of running many such physical
computers that are only partially used, one can pack many virtual machines onto
a few powerful hosts and balance the loads between them.
With VirtualBox, you can even run virtual machines as mere servers for the
VirtualBox Remote Desktop Protocol (VRDP), with full client USB support. This
allows for consolidating the desktop machines in an enterprise on just a few RDP
servers, while the actual clients only have to be capable of displaying VRDP data.
• Easier software installations. Virtual machines can be used by software ven-
dors to ship entire software configurations. For example, installing a complete
mail server solution on a real machine can be a tedious task. With virtualization
it becomes possible to ship an entire software solution, possibly consisting of
many different components, in a virtual machine, which is then often called an
“appliance”. Installing and running a mail server becomes as easy as importing
such an appliance into VirtualBox.
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1 First steps
1.2 Some terminology
When dealing with virtualization (and also for understanding the following chapters
of this documentation), it helps to acquaint oneself with a bit of crucial terminology,
especially the following terms:
Host operating system (host OS): the operating system of the physical computer
on which VirtualBox was installed. There are versions of VirtualBox for Windows, Mac OS X, Linux and Solaris hosts; for details, please see chapter 1.4,
Supported host operating systems, page 14. While the various VirtualBox versions
are usually discussed together in this document, there may be platform-specific
differences which we will point out where appropriate.
Guest operating system (guest OS): the operating system that is running inside
the virtual machine. Theoretically, VirtualBox can run any x86 operating system (DOS, Windows, OS/2, FreeBSD, OpenBSD), but to achieve near-native
performance of the guest code on your machine, we had to go through a lot
of optimizations that are specific to certain operating systems. So while your
favorite operating system may run as a guest, we officially support and optimize
for a select few (which, however, include the most common ones).
See chapter 3.1, Supported guest operating systems, page 44 for details.
Virtual machine (VM). When running, a VM is the special environment that
VirtualBox creates for your guest operating system. So, in other words, you
run your guest operating system “in” a VM. Normally, a VM will be shown as
a window on your computer’s desktop, but depending on which of the various frontends of VirtualBox you use, it can be displayed in full-screen mode or
remotely by use of the VirtualBox Remote Desktop Protocol (VRDP).
Sometimes we also use the term “virtual machine” in a more abstract way. Internally, VirtualBox thinks of a VM as a set of parameters that determine its behavior. They include hardware settings (how much memory the VM should have,
what hard disks VirtualBox should virtualize through which container files, what
CD-ROMs are mounted etc.) as well as state information (whether the VM is
currently running, saved, its snapshots etc.).
These settings are mirrored in the VirtualBox graphical user interface as well as
the VBoxManage command line program; see chapter 8, VBoxManage reference,
page 106. In other words, a VM is also what you can see in its settings dialog.
Guest Additions. With “Guest Additions”, we refer to special software packages that
are shipped with VirtualBox. Even though they are part of VirtualBox, they are
designed to be installed inside a VM to improve performance of the guest OS and
to add extra features. This is described in detail in chapter 4, Guest Additions,
page 60.
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1 First steps
1.3 Features overview
Here’s a brief outline of VirtualBox’s main features:
• Portability. VirtualBox runs on a large number of 32-bit and 64-bit host oper-
ating systems (again, see chapter 1.4, Supported host operating systems, page 14
for details).
To a very large degree, VirtualBox is functionally identical on all of the host
platforms, and the same file and image formats are used. This allows you to
run virtual machines created on one host on another host with a different host
operating system; for example, you can create a virtual machine on Windows
and then run it under Linux.
In addition, virtual machines can easily be imported and exported using the
Open Virtualization Format (OVF, see chapter 1.11, Importing and exporting vir-
tual machines, page 29), an industry standard created for this purpose. You can
even import OVFs that were created with a different virtualization software.
• No hardware virtualization required. For many scenarios, VirtualBox does
not require the processor features built into newer hardware like Intel VT-x or
AMD-V. As opposed to many other virtualization solutions, you can therefore use
VirtualBox even on older hardware where these features are not present. More
details can be found in chapter 3.4.3, “Acceleration” tab: hardware vs. software
virtualization, page 49.
• Guest Additions: shared folders, seamless windows, 3D virtualization. The
VirtualBox Guest Additions are software packages which can be installed inside
of supported guest systems to improve their performance and to provide additional integration and communication with the host system. After installing the
Guest Additions, a virtual machine will support automatic adjustment of video
resolutions, seamless windows, accelerated 3D graphics and more. The Guest
Additions are described in detail in chapter 4, Guest Additions, page 60.
In particular, Guest Additions provide for “shared folders”, which let you access
files from the host system from within a guest machine. Shared folders are
described in chapter 4.7, Folder sharing, page 68.
• Great hardware support. Among others, VirtualBox supports:
– Guest multiprocessing (SMP). VirtualBox can present up to 32 virtual
CPUs to a virtual machine, irrespective of how many CPU cores are actually
present in your host.
– USB 2.0 device support. VirtualBox implements a virtual USB controller
and allows you to connect arbitrary USB devices to your virtual machines
without having to install device-specific drivers on the host. USB support
is not limited to certain device categories. For details, see chapter 3.10.1,
USB settings, page 56.
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1 First steps
– Hardware compatibility. VirtualBox virtualizes a vast array of virtual de-
vices, among them many devices that are typically provided by other virtualization platforms. That includes IDE, SCSI and SATA hard disk controllers,
several virtual network cards and sound cards, virtual serial and parallel
ports and an Input/Output Advanced Programmable Interrupt Controller
(I/O APIC), which is found in many modern PC systems. This eases cloning
of PC images from real machines and importing of third-party virtual machines into VirtualBox.
– Full ACPI support. The Advanced Configuration and Power Interface
(ACPI) is fully supported by VirtualBox. This eases cloning of PC images
from real machines or third-party virtual machines into VirtualBox. With its
unique ACPI power status support, VirtualBox can even report to ACPIaware guest operating systems the power status of the host. For mobile
systems running on battery, the guest can thus enable energy saving and
notify the user of the remaining power (e.g. in fullscreen modes).
– Multiscreen resolutions. VirtualBox virtual machines support screen res-
olutions many times that of a physical screen, allowing them to be spread
over a large number of screens attached to the host system.
– Built-in iSCSI support. This unique feature allows you to connect a vir-
tual machine directly to an iSCSI storage server without going through the
host system. The VM accesses the iSCSI target directly without the extra
overhead that is required for virtualizing hard disks in container files. For
details, see chapter 5.8, iSCSI servers, page 86.
– PXE Network boot. The integrated virtual network cards of VirtualBox
fully support remote booting via the Preboot Execution Environment (PXE).
• Multigeneration branched snapshots. VirtualBox can save arbitrary snapshots
of the state of the virtual machine. You can go back in time and revert the virtual
machine to any such snapshot and start an alternative VM configuration from
there, effectively creating a whole snapshot tree. For details, see chapter 1.8,
Snapshots, page 25.
• Clean architecture; unprecedented modularity. VirtualBox has an extremely
modular design with well-defined internal programming interfaces and a clean
separation of client and server code. This makes it easy to control it from several
interfaces at once: for example, you can start a VM simply by clicking on a
button in the VirtualBox graphical user interface and then control that machine
from the command line, or even remotely. See chapter 7, Alternative front-ends;
remote virtual machines, page 96 for details.
Due to its modular architecture, VirtualBox can also expose its full functionality
and configurability through a comprehensive software development kit (SDK),
which allows for integrating every aspect of VirtualBox with other software systems. Please see chapter 10, VirtualBox programming interfaces, page 154 for
details.
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1 First steps
• Remote machine display. You can run any virtual machine in a special
VirtualBox program that acts as a server for the VirtualBox Remote Desktop Protocol (VRDP), a backward-compatible extension of the standard Remote Desktop Protocol. With this unique feature, VirtualBox provides high-performance
remote access to any virtual machine.
VirtualBox’s VRDP support does not rely on the RDP server that is built into
Microsoft Windows. Instead, a custom VRDP server has been built directly into
the virtualization layer. As a result, it works with any operating system (even
in text mode) and does not require application support in the virtual machine
either.
VRDP support is described in detail in chapter 7.4, Remote virtual machines
(VRDP support), page 99.
On top of this special capacity, VirtualBox offers you more unique features:
– Extensible RDP authentication. VirtualBox already supports Winlogon
on Windows and PAM on Linux for RDP authentication. In addition, it
includes an easy-to-use SDK which allows you to create arbitrary interfaces
for other methods of authentication; see chapter 9.4, Custom external VRDP
authentication, page 139 for details.
– USB over RDP. Via RDP virtual channel support, VirtualBox also allows
you to connect arbitrary USB devices locally to a virtual machine which is
running remotely on a VirtualBox RDP server; see chapter 7.4.4, Remote
USB, page 103 for details.
1.4 Supported host operating systems
Currently, VirtualBox runs on the following host operating systems:
• Windows hosts:
– Windows XP, all service packs (32-bit)
– Windows Server 2003 (32-bit)
– Windows Vista (32-bit and 64-bit1).
– Windows Server 2008 (32-bit and 64-bit)
– Windows 7 (32-bit and 64-bit)
• Mac OS X hosts:
– 10.5 (Leopard, 32-bit)
1
Support for 64-bit Windows was added with VirtualBox 1.5.
2
Preliminary Mac OS X support (beta stage) was added with VirtualBox 1.4, full support with 1.6. Mac OS
X 10.4 (Tiger) support was removed with VirtualBox 3.1.
2
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1 First steps
– 10.6 (Snow Leopard, 32-bit and 64-bit)
Intel hardware is required; please see chapter 13, Known limitations, page 237
also.
• Linux hosts (32-bit and 64-bit3). Among others, this includes:
– Debian GNU/Linux 3.1 (“sarge”), 4.0 (“etch”) and 5.0 (“lenny”)
– Fedora Core 4 to 11
– Gentoo Linux
– Redhat Enterprise Linux 4 and 5
– SUSE Linux 9 and 10, openSUSE 10.3, 11.0 and 11.1
– Ubuntu 6.06 (“Dapper Drake”), 6.10 (“Edgy Eft”), 7.04 (“Feisty Fawn”),
7.10 (“Gutsy Gibbon”), 8.04 (“Hardy Heron”), 8.10 (“Intrepid Ibex”), 9.04
(“Jaunty Jackalope”).
– Mandriva 2007.1, 2008.0 and 2009.1
It should be possible to use VirtualBox on most systems based on Linux kernel
2.6 using either the VirtualBox installer or by doing a manual installation; see
chapter 2.3, Installing on Linux hosts, page 34.
Note that starting with VirtualBox 2.1, Linux 2.4-based host operating systems
are no longer supported.
• Solaris hosts (32-bit and 64-bit4) are supported with the restrictions listed in
chapter 13, Known limitations, page 237:
– OpenSolaris (2008.05 and higher, “Nevada” build 86 and higher)
– Solaris 10 (u5 and higher)
1.5 Installing and starting VirtualBox
VirtualBox comes in many different packages, and installation depends on your host
platform. If you have installed software before, installation should be straightforward
as on each host platform, VirtualBox uses the installation method that is most common
and easy to use. If you run into trouble or have special requirements, please refer
to chapter 2, Installation details, page 32 for details about the various installation
methods.
After installation, you can start VirtualBox as follows:
• On a Windows host, in the standard “Programs” menu, click on the item in the
“VirtualBox” group. On Vista or Windows 7, you can also type “VirtualBox” in
the search box of the “Start” menu.
3
Support for 64-bit Linux was added with VirtualBox 1.4.
4
Support for OpenSolaris was added with VirtualBox 1.6.
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1 First steps
• On a Mac OS X host, in the Finder, double-click on the “VirtualBox” item in the
“Applications” folder. (You may want to drag this item onto your Dock.)
• On a Linux or Solaris host, depending on your desktop environment, a
“VirtualBox” item may have been placed in either the “System” or “System Tools”
group of your “Applications” menu. Alternatively, you can type VirtualBox in
a terminal.
When you start VirtualBox for the first time, a window like the following should
come up:
On the left, you can see a pane that will later list all your virtual machines. Since
you have not created any, the list is empty. A row of buttons above it allows you to
create new VMs and work on existing VMs, once you have some. The pane on the
right displays the properties of the virtual machine currently selected, if any. Again,
since you don’t have any machines yet, the pane displays a welcome message.
To give you an idea what VirtualBox might look like later, after you have created
many machines, here’s another example:
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1 First steps
1.6 Creating your first virtual machine
Click on the “New” button at the top of the VirtualBox window. A wizard will pop up
to guide you through setting up a new virtual machine (VM):
17
1 First steps
On the following pages, the wizard will ask you for the bare minimum of information
that is needed to create a VM, in particular:
1. A name for your VM, and the type of operating system (OS) you want to install.
The name is what you will later see in the VirtualBox main window, and what
your settings will be stored under. It is purely informational, but once you have
created a few VMs, you will appreciate if you have given your VMs informative
names. “My VM” probably is therefore not as useful as “Windows XP SP2”.
For “Operating System Type”, select the operating system that you want to install
later. Depending on your selection, VirtualBox will enable or disable certain VM
settings that your guest operating system may require. This is particularly important for 64-bit guests (see chapter 3.2, 64-bit guests, page 45). It is therefore
recommended to always set it to the correct value.
2. The amount of memory (RAM) that the virtual machine should have for itself.
Every time a virtual machine is started, VirtualBox will allocate this much memory from your host machine and present it to the guest operating system, which
will report this size as the (virtual) computer’s installed RAM.
Note: Choose this setting carefully! The memory you give to the VM will
not be available to your host OS while the VM is running, so do not specify
more than you can spare. For example, if your host machine has 1 GB of
RAM and you enter 512 MB as the amount of RAM for a particular virtual
machine, while that VM is running, you will only have 512 MB left for all the
other software on your host. If you run two VMs at the same time, even more
memory will be allocated for the second VM (which may not even be able to
start if that memory is not available). On the other hand, you should specify
as much as your guest OS (and your applications) will require to run properly.
A Windows XP guest will require at least a few hundred MB RAM to run properly,
and Windows Vista will even refuse to install with less than 512 MB. Of course,
if you want to run graphics-intensive applications in your VM, you may require
even more RAM.
So, as a rule of thumb, if you have 1 GB of RAM or more in your host computer,
it is usually safe to allocate 512 MB to each VM. But, in any case, make sure you
always have at least 256 to 512 MB of RAM left on your host operating system.
Otherwise you may cause your host OS to excessively swap out memory to your
hard disk, effectively bringing your host system to a standstill.
As with the other settings, you can change this setting later, after you have created the VM.
3. Next, you must specify a virtual hard disk for your VM.
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1 First steps
There are many and potentially complicated ways in which VirtualBox can provide hard disk space to a VM (see chapter 5, Virtual storage, page 76 for details),
but the most common way is to use a large image file on your “real” hard disk,
whose contents VirtualBox presents to your VM as if it were a complete hard
disk.
The wizard shows you the following window:
The wizard allows you to create an image file or use an existing one. Note also
that the disk images can be separated from a particular VM, so even if you delete
a VM, you can keep the image, or copy it to another host and create a new VM
for it there.
In the wizard, you have the following options:
• If you have previously created any virtual hard disks which have not been
attached to other virtual machines, you can select those from the dropdown list in the wizard window.
• Otherwise, to create a new virtual hard disk, press the “New” button.
• Finally, for more complicated operations with virtual disks, the “Existing...“
button will bring up the Virtual Disk Manager, which is described in more
detail in chapter 5.3, The Virtual Media Manager, page 80.
Most probably, if you are using VirtualBox for the first time, you will want to
create a new disk image. Hence, press the “New” button.
This brings up another window, the “Create New Virtual Disk Wizard”.
VirtualBox supports two types of image files:
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1 First steps
• A dynamically expanding file will only grow in size when the guest actu-
ally stores data on its virtual hard disk. It will therefore initially be small
on the host hard drive and only later grow to the size specified as it is filled
with data.
• A fixed-size file will immediately occupy the file specified, even if only a
fraction of the virtual hard disk space is actually in use. While occupying
much more space, a fixed-size file incurs less overhead and is therefore
slightly faster than a dynamically expanding file.
For details about the differences, please refer to chapter 5.2, Disk image files
(VDI, VMDK, VHD, HDD), page 79.
To prevent your physical hard disk from running full, VirtualBox limits the size
of the image file. Still, it needs to be large enough to hold the contents of
your operating system and the applications you want to install – for a modern
Windows or Linux guest, you will probably need several gigabytes for any serious
use:
After having selected or created your image file, again press “Next” to go to the
next page.
4. After clicking on “Finish”, your new virtual machine will be created. You will
then see it in the list on the left side of the main window, with the name you
have entered.
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1 First steps
1.7 Running your virtual machine
You will now see your new virtual machine in the list of virtual machines, at the left of
the VirtualBox main window. To start the virtual machine, simply double-click on it,
or select it and press the “Start” button at the top.
This opens up a new window, and the virtual machine which you selected will boot
up. Everything which would normally be seen on the virtual system’s monitor is shown
in the window, as can be seen with the image in chapter 1.2, Some terminology, page
11.
Since this is the first time you are running this VM, another wizard will show up
to help you select an installation medium. Since the VM is created empty, it would
otherwise behave just like a real computer with no operating system installed: it will
do nothing and display an error message that it cannot boot an operating system.
For this reason, the “First Start Wizard” helps you select an operating system
medium to install an operating system from. In most cases, this will either be a real
CD-ROM or DVD (VirtualBox can then configure the virtual machine to use your host’s
drive), or you might have an ISO image of a CD-ROM or DVD handy, which VirtualBox
can then present to the virtual machine.
In both cases, after making the choices in the wizard, you will be able to install your
operating system.
In general, you can use the virtual machine much like you would use a real computer. There are couple of points worth mentioning however.
1.7.1 Keyboard and mouse support in virtual machines
1.7.1.1 Capturing and releasing keyboard and mouse
Since the operating system in the virtual machine does not “know” that it is not running on a real computer, it expects to have exclusive control over your keyboard and
mouse. This is, however, not the case since, unless you are running the VM in fullscreen mode, your VM needs to share keyboard and mouse with other applications
and possibly other VMs on your host.
As a result, initially after installing a host operating system and before you install
the guest additions (we will explain this in a minute), only one of the two – your VM
or the rest of your computer – can “own” the keyboard and the mouse. You will see a
second mouse pointer which will always be confined to the limits of the VM window.
Basically, you activate the VM by clicking inside it.
To return ownership of keyboard and mouse to your host operating system,
VirtualBox reserves a special key on your keyboard for itself: the “host key”. By
default, this is the right Control key on your keyboard; on a Mac host, the default host
key is the left Command key. You can change this default in the VirtualBox Global
Settings. In any case, the current setting for the host key is always displayed at the
bottom right of your VM window, should you have forgotten about it:
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1 First steps
In detail, all this translates into the following:
• Your keyboard is owned by the VM if the VM window on your host desktop
has the keyboard focus (and then, if you have many windows open in your guest
operating system as well, the window that has the focus in your VM). This means
that if you want to type within your VM, click on the title bar of your VM window
first.
To release keyboard ownership, press the Host key (as explained above, typically
the right Control key).
Note that while the VM owns the keyboard, some key sequences (like Alt-Tab for
example) will no longer be seen by the host, but will go to the guest instead.
After you press the host key to re-enable the host keyboard, all key presses will
go through the host again, so that sequences like Alt-Tab will no longer reach the
guest.
• Your mouse is owned by the VM only after you have clicked in the VM window.
The host mouse pointer will disappear, and your mouse will drive the guest’s
pointer instead of your normal mouse pointer.
Note that mouse ownership is independent of that of the keyboard: even after
you have clicked on a titlebar to be able to type into the VM window, your mouse
is not necessarily owned by the VM yet.
To release ownership of your mouse by the VM, also press the Host key.
As this behavior can be inconvenient, VirtualBox provides a set of tools and device
drivers for guest systems called the “VirtualBox Guest Additions” which make VM keyboard and mouse operation a lot more seamless. Most importantly, the Additions will
get rid of the second “guest” mouse pointer and make your host mouse pointer work
directly in the guest.
This will be described later in chapter 4, Guest Additions, page 60.
1.7.1.2 Typing special characters
Operating systems expect certain key combinations to initiate certain procedures.
Some of these key combinations may be difficult to enter into a virtual machine, as
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1 First steps
there are three candidates as to who receives keyboard input: the host operating system, VirtualBox, or the guest operating system. Who of these three receives keypresses
depends on a number of factors, including the key itself.
• Host operating systems reserve certain key combinations for themselves. For
example, it is impossible to enter the Ctrl+Alt+Delete combination if you want
to reboot the guest operating system in your virtual machine, because this key
combination is usually hard-wired into the host OS (both Windows and Linux
intercept this), and pressing this key combination will therefore reboot your host.
Also, on Linux and Solairs hosts, which use the X Window System, the key combination Ctrl+Alt+Backspace normally resets the X server (to restart the entire
graphical user interface in case it got stuck). As the X server intercepts this combination, pressing it will usually restart your host graphical user interface (and
kill all running programs, including VirtualBox, in the process).
Third, on Linux hosts supporting virtual terminals, the key combination
Ctrl+Alt+Fx (where Fx is one of the function keys from F1 to F12) normally
allows to switch between virtual terminals. As with Ctrl+Alt+Delete, these
combinations are intercepted by the host operating system and therefore always
switch terminals on the host.
If, instead, you want to send these key combinations to the guest operating system in the virtual machine, you will need to use one of the following methods:
– Use the items in the “Machine” menu of the virtual machine window. There
you will find “Insert Ctrl+Alt+Delete” and “Ctrl+Alt+Backspace”; the latter will only have an effect with Linux or Solaris guests, however.
– Press special key combinations with the Host key (normally the right Con-
trol key), which VirtualBox will then translate for the virtual machine:
∗ Host key + Del to send Ctrl+Alt+Del (to reboot the guest);
∗ Host key + Backspace to send Ctrl+Alt+Backspace (to restart the
graphical user interface of a Linux or Solaris guest);
∗ Host key + F1 (or other function keys) to simulate Ctrl+Alt+F1 (or
other function keys, i.e. to switch between virtual terminals in a Linux
guest).
• For some other keyboard combinations such as Alt-Tab (to switch between open
windows), VirtualBox allows you to configure whether these combinations will
affect the host or the guest, if a virtual machine currently has the focus. This
is a global setting for all virtual machines and can be found under “File” ->
“Preferences” -> “Input” -> “Auto-capture keyboard”.
1.7.2 Changing removable media
While a virtual machine is running, you can change removable media in the “Devices”
menu of the VM’s window. Here you can select in detail what VirtualBox presents to
your VM as a CD, DVD, or floppy.
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1 First steps
The settings are the same as would be available for the VM in the “Settings” dialog
of the VirtualBox main window, but since that dialog is disabled while the VM is in the
“running” or “saved” state, this extra menu saves you from having to shut down and
restart the VM every time you want to change media.
Hence, in the “Devices” menu, VirtualBox allows you to attach the host drive to the
guest or select a floppy or DVD image using the Disk Image Manager, all as described
in chapter 1.9, Virtual machine configuration, page 27.
1.7.3 Saving the state of the machine
When you click on the “Close” button of your virtual machine window (at the top right
of the window, just like you would close any other window on your system) (or press
the Host key together with “Q”), VirtualBox asks you whether you want to “save” or
“power off” the VM.
The difference between these three options is crucial. They mean:
• Save the machine state: With this option, VirtualBox “freezes” the virtual ma-
chine by completely saving its state to your local disk. When you later resume the
VM (by again clicking the “Start” button in the VirtualBox main window), you
will find that the VM continues exactly where it was left off. All your programs
will still be open, and your computer resumes operation.
Saving the state of a virtual machine is thus in some ways similar to suspending
a laptop computer (e.g. by closing its lid).
• Send the shutdown signal. This will send an ACPI shutdown signal to the vir-
tual machine, which has the same effect as if you had pressed the power button
on a real computer. So long as a fairly modern operating system is installed and
running in the VM, this should trigger a proper shutdown mechanism in the VM.
• Power off the machine: With this option, VirtualBox also stops running the
virtual machine, but without saving its state.
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1 First steps
This is equivalent to pulling the power plug on a real computer without shutting
it down properly. If you start the machine again after powering it off, your
operating system will have to reboot completely and may begin a lengthy check
of its (virtual) system disks.
As a result, this should not normally be done, since it can potentially cause data
loss or an inconsistent state of the guest system on disk.
As an exception, if your virtual machine has any snapshots (see the next chapter),
you can use this option to quickly restore the current snapshot of the virtual
machine. Only in that case, powering off the machine is not harmful.
The “Discard” button in the main VirtualBox window discards a virtual machine’s
saved state. This has the same effect as powering it off, and the same warnings apply.
1.8 Snapshots
With snapshots, you can save a particular state of a virtual machine for later use. At
any later time, you can revert to that state, even though you may have changed the
VM considerably since then.
You can see the snapshots of a virtual machine by first selecting a machine from
the list on the left of the VirtualBox main window and then selecting the “Snapshots”
tab on the right. Initially, until you take a snapshot of the machine, that list is empty
except for the “Current state” item, which represents the “Now” point in the lifetime
of the virtual machine.
There are three operations related to snapshots:
1. You can take a snapshot.
• If your VM is currently running, select “Take snapshot” from the “Machine”
pull-down menu of the VM window.
• If your VM is currently in either the “saved” or the “powered off ” state (as
displayed next to the VM in the VirtualBox main window), click on the
“Snapshots” tab on the top right of the main window, and then
– either on the small camera icon (for “Take snapshot”) or
– right-click on the “Current State” item in the list and select “Take snap-
shot” from the menu.
In any case, a window will pop up and ask you for a snapshot name. This
name is purely for reference purposes to help you remember the state of the
snapshot. For example, a useful name would be “Fresh installation from scratch,
no external drivers”. You can also add a longer text in the “Description” field if
you want.
Your new snapshot will then appear in the list of snapshots under the “Snapshots”
tab. Underneath, you will see an item called “Current state”, signifying that the
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1 First steps
current state of your VM is a variation based on the snapshot you took earlier.
If you later take another snapshot, you will see that they will be displayed in
sequence, and each subsequent snapshot is a derivation of the earlier one:
VirtualBox allows you to take an unlimited number of snapshots – the only limitation is the size of your disks. Keep in mind that each snapshot stores the state
of the virtual machine and thus takes some disk space.
2. You can restore a snapshot by right-clicking on any snapshot you have taken in
the list of snapshots. By restoring a snapshot, you go back (or forward) in time:
the current state of the machine is lost, and the machine is restored to exactly
the same state as it was when then snapshot was taken.
5
Note: Restoring a snapshot will affect the virtual hard drives that are connected to your VM, as the entire state of the virtual hard drive will be reverted
as well. This means also that all files that have been created since the snapshot and all other file changes will be lost. In order to prevent such data loss
while still making use of the snapshot feature, it is possible to add a second
hard drive in “write-through” mode using the VBoxManage interface and use
it to store your data. As write-through hard drives are not included in snapshots, they remain unaltered when a machine is reverted. See chapter 5.4,
Special image write modes, page 81 for details.
5
Both the terminology and the functionality of restoring snapshots has changed with VirtualBox 3.1. Before
that version, it was only possible to go back to the very last snapshot taken – not earlier ones, and the
operation was called “Discard current state” instead of “Restore last snapshot”. The limitation has been
lifted with version 3.1. It is now possible to restore any snapshot, going backward and forward in time.
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1 First steps
By restoring an earlier snapshot and taking more snapshots from there, it is even
possible to create a kind of alternate reality and to switch between these different
histories of the virtual machine. This can result in a whole tree of virtual machine
snapshots, as shown in the screenshot above.
3. You can also delete a snapshot, which will not affect the state of the virtual
machine, but only release the files on disk that VirtualBox used to store the
snapshot data, thus freeing disk space.
Think of a snapshot as a point in time that you have preserved. More formally, a
snapshot consists of three things:
• It contains a complete copy of the VM settings, so that when you restore a snapshot, the VM settings are restored as well. (For example, if you changed the hard
disk configuration, that change is undone when you restore the snapshot.)
• The state of all the virtual disks attached to the machine is preserved. Going
back to a snapshot means that all changes, bit by bit, that had been made to the
machine’s disks will be undone as well.
(Strictly speaking, this is only true for virtual hard disks in “normal” mode. As
mentioned above, you can configure disks to behave differently with snapshots;
see chapter 5.4, Special image write modes, page 81. Even more formally and
technically correct, it is not the virtual disk itself that is restored when a snapshot
is restored. Instead, when a snapshot is taken, VirtualBox creates differencing
images which contain only the changes since the snapshot were taken, and when
the snapshot is restored, VirtualBox throws away that differencing image, thus
going back to the previous state. This is both faster and uses less disk space. For
the details, which can be complex, please see chapter 5.5, Differencing images,
page 83.)
• Finally, if you took a snapshot while the machine was running, the memory state
of the machine is also saved in the snapshot (the same way the memory can be
saved when you close the VM window) so that when you restore the snapshot,
execution resumes at exactly the point when the snapshot was taken.
1.9 Virtual machine configuration
When you select a virtual machine from the list in the main VirtualBox window, you
will see a summary of that machine’s settings on the right of the window, under the
“Details” tab.
Clicking on the “Settings” button in the toolbar at the top of VirtualBox main window
brings up a detailed window where you can configure many of the properties of the
VM that is currently selected. But be careful: even though it is possible to change all
VM settings after installing a guest operating system, certain changes might prevent a
guest operating system from functioning correctly if done after installation.
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1 First steps
Note: The “Settings” button is disabled while a VM is either in the “running”
or “saved” state. This is simply because the settings dialog allows you to
change fundamental characteristics of the virtual computer that is created for
your guest operating system, and this operating system may not take it well
when, for example, half of its memory is taken away from under its feet. As a
result, if the “Settings” button is disabled, shut down the current VM first.
VirtualBox provides a plethora of parameters that can be changed for a virtual machine. The various settings that can be changed in the “Settings” window are described
in detail in chapter 3, Configuring virtual machines, page 44. Even more parameters
are available with the command line interface; see chapter 8, VBoxManage reference,
page 106.
For now, if you have just created an empty VM, you will probably be most interested
in the settings presented by the “CD/DVD-ROM” section if you want to make a CDROM or a DVD-ROM available the first time you start it, in order to install your guest
operating system.
For this, you have two options:
• If you have actual CD or DVD media from which you want to install your guest
operating system (e.g. in the case of a Windows installation CD or DVD), put the
media into your host’s CD or DVD drive.
Then, in the settings dialog, go to the “CD/DVD-ROM” section and select “Host
drive” with the correct drive letter (or, in the case of a Linux host, device file).
This will allow your VM to access the media in your host drive, and you can
proceed to install from there.
• If you have downloaded installation media from the Internet in the form of an
ISO image file (most probably in the case of a Linux distribution), you would
normally burn this file to an empty CD or DVD and proceed as just described.
With VirtualBox however, you can skip this step and mount the ISO file directly.
VirtualBox will then present this file as a CD or DVD-ROM drive to the virtual
machine, much like it does with virtual hard disk images.
In this case, in the settings dialog, go to the “CD/DVD-ROM” section and select
“ISO image file”. This brings up the Virtual Disk Image Manager, where you
perform the following steps:
1. Press the “Add” button to add your ISO file to the list of registered images.
This will present an ordinary file dialog that allows you to find your ISO file
on your host machine.
2. Back to the manager window, select the ISO file that you just added and
press the “Select” button. This selects the ISO file for your VM.
The Virtual Disk Image Manager is described in detail in chapter 5.3, The Virtual
Media Manager, page 80.
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1 First steps
1.10 Deleting virtual machines
To remove a virtual machine which you no longer need, right-click on it in the list of
virtual machines in the main window and select “Delete” from the context menu that
comes up. All settings for that machine will be lost.
The “Delete” menu item is disabled while a machine is in “Saved” state. To delete
such a machine, discard the saved state first by pressing on the “Discard” button.
However, any hard disk images attached to the machine will be kept; you can delete
those separately using the Virtual Disk Manager; see chapter 5.3, The Virtual Media
Manager, page 80.
You cannot delete a machine which has snapshots or is in a saved state, so you must
discard these first.
1.11 Importing and exporting virtual machines
Starting with version 2.2, VirtualBox can import and export virtual machines in the
industry-standard Open Virtualization Format (OVF).
OVF is a cross-platform standard supported by many virtualization products which
allows for creating ready-made virtual machines that can then be imported into a
virtualizer such as VirtualBox. As opposed to other virtualization products, VirtualBox
now supports OVF with an easy-to-use graphical user interface as well as using the
command line. This allows for packaging so-called virtual appliances: disk images
together with configuration settings that can be distributed easily. This way one can
offer complete ready-to-use software packages (operating systems with applications)
that need no configuration or installation except for importing into VirtualBox.
Note: The OVF standard is complex, and support in VirtualBox is an ongoing
process. In particular, no guarantee is made that VirtualBox supports all appliances created by other virtualization software. For a list of know limitations,
please see chapter 13, Known limitations, page 237.
An appliance in OVF format will typically consist of several files:
1. one or several disk images, typically in the widely-used VMDK format (see chapter 5.2, Disk image files (VDI, VMDK, VHD, HDD), page 79) and
2. a textual description file in an XML dialect with an .ovf extension.
These files must reside in the same directory for VirtualBox to be able to import
them.
A future version of VirtualBox will also support packages that include the OVF XML
file and the disk images packed together in a single archive.
To import an appliance in OVF format, select “File” -> “Import appliance” from the
main window of the VirtualBox graphical user interface. Then open the file dialog and
navigate to the OVF text file with the .ovf file extension.
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1 First steps
If VirtualBox can handle the file, a dialog similar to the following will appear:
This presents the virtual machines described in the OVF file and allows you to change
the virtual machine settings by double-clicking on the description items. Once you
click on “Import”, VirtualBox will copy the disk images and create local virtual machines with the settings described in the dialog. These will then show up in the list of
virtual machines.
Note that since disk images tend to be big, and VMDK images that come with virtual
appliances are typically shipped in a special compressed format that is unsuitable for
being used by virtual machines directly, the images will need to be unpacked and
copied first, which can take a few minutes.
For how to import an image at the command line, please see chapter 8.6, VBoxMan-
age import, page 118.
Conversely, to export virtual machines that you already have in VirtualBox, select
the machines and “File” -> “Export appliance”. A different dialog window shows up
that allows you to combine several virtual machines into an OVF appliance. Then, you
select the target location where the OVF and VMDK files should be stored, and the
conversion process begins. This can again take a while.
For how to export an image at the command line, please see chapter 8.7, VBoxMan-
age export, page 120.
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1 First steps
Note: OVF cannot describe every feature that VirtualBox provides for virtual
machines. For example, snapshot information gets lost on export; the disk
images will have a “flattened” state identical to the current state of the virtual
machine, but any snapshots that were defined for the machine will have been
merged.
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2 Installation details
As installation of VirtualBox varies depending on your host operating system, we provide installation instructions in four separate chapters for Windows, Mac OS X, Linux
and Solaris, respectively.
2.1 Installing on Windows hosts
2.1.1 Prerequisites
For the various versions of Windows that we support as host operating systems, please
refer to chapter 1.4, Supported host operating systems, page 14.
In addition, Windows Installer 1.1 or higher must be present on your system. This
should be the case if you have all recent Windows updates installed.
2.1.2 Performing the installation
The VirtualBox installation can be started
• either by double-clicking on its executable file (contains both 32- and 64-bit
architectures)
• or by entering
VirtualBox.exe -extract
on the command line. This will extract both installers into a temporary directory
in which you’ll then find the usual .MSI files. Then you can do a
msiexec /i VirtualBox-<version>-MultiArch_<x86|amd64>.msi
to perform the installation.
In either case, this will display the installation welcome dialog and allow you to
choose where to install VirtualBox to and which components to install. In addition to
the VirtualBox application, the following components are available:
USB support This package contains special drivers for your Windows host that
VirtualBox requires to fully support USB devices inside your virtual machines.
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Networking This package contains extra networking drivers for your Windows host
that VirtualBox needs to support Host Interface Networking (to make your VM’s
virtual network cards accessible from other machines on your physical network).
Depending on your Windows configuration, you may see warnings about “unsigned
drivers” or similar. Please select “Continue” on these warnings as otherwise VirtualBox
might not function correctly after installation.
The installer will create a “VirtualBox” group in the programs startup folder which
allows you to launch the application and access its documentation.
With standard settings, VirtualBox will be installed for all users on the local system.
In case this is not wanted, you have to invoke the installer by first extracting it by using
VirtualBox.exe -extract
and then do as follows:
VirtualBox.exe -msiparams ALLUSERS=2
or
msiexec /i VirtualBox-<version>-MultiArch_<x86|amd64>.msi ALLUSERS=2
on the extracted .MSI files. This will install VirtualBox only for the current user.
2.1.3 Uninstallation
As we use the Microsoft Installer, VirtualBox can be safely uninstalled at any time by
choosing the program entry in the “Add/Remove Programs” applet in the Windows
Control Panel.
2.1.4 Unattended installation
Unattended installations can be performed using the standard MSI support.
2.2 Installing on Mac OS X hosts
2.2.1 Performing the installation
For Mac OS X hosts, VirtualBox ships in a disk image (dmg) file. Perform the following
steps:
1. Double-click on that file to have its contents mounted.
2. A window will open telling you to double click on the VirtualBox.mpkg installer file displayed in that window.
3. This will start the installer, which will allow you to select where to install
VirtualBox to.
After installation, you can find a VirtualBox icon in the “Applications” folder in the
Finder.
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2 Installation details
2.2.2 Uninstallation
To uninstall VirtualBox, open the disk image (dmg) file again and double-click on the
uninstall icon contained therein.
2.2.3 Unattended installation
To perform a non-interactive installation of VirtualBox you can use the command line
version of the installer application.
Mount the disk image (dmg) file as described in the normal installation. Then open
a terminal session and execute:
sudo installer -pkg /Volumes/VirtualBox/VirtualBox.mpkg \
-target /Volumes/Macintosh\ HD
2.3 Installing on Linux hosts
2.3.1 Prerequisites
For the various versions of Linux that we support as host operating systems, please
refer to chapter 1.4, Supported host operating systems, page 14.
You will need to install the following packages on your Linux system before starting
the installation (some systems will do this for you automatically when you install
VirtualBox):
• Qt 4.4.0 or higher;
• SDL 1.2.7 or higher (this graphics library is typically called libsdl or similar).
Note: To be precise, these packages are only required if you want to run the
VirtualBox graphical user interfaces. In particular, VirtualBox, our main
graphical user interface, requires both Qt and SDL; VBoxSDL, our simplified
GUI, requires only SDL. By contrast, if you only want to run the headless
VRDP server that comes with VirtualBox, neither Qt nor SDL are required.
2.3.2 The VirtualBox kernel module
VirtualBox uses a special kernel module to perform physical memory allocation and to
gain control of the processor for guest system execution. Without this kernel module,
you will still be able to work with virtual machines in the configuration interface, but
you will not be able to start any virtual machines.
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2 Installation details
The VirtualBox kernel module is automatically installed on your system when you
install VirtualBox. To maintain it with future kernel updates, for recent Linux distributions – for example Fedora Core 5 and later, Ubuntu 7.10 (Gutsy) and later and Mandriva 2007.1 and later –, generally we recommend installing Dynamic Kernel Module
Support (DKMS)1. This framework helps to build kernel modules and to deal with
kernel upgrades.
If DKMS is not already installed, execute one of the following:
• On an Ubuntu system:
sudo apt-get install dkms
• On a Fedora system:
yum install dkms
• On a Mandriva system:
urpmi dkms
If DKMS is available and installed, the VirtualBox kernel module should always work
automatically, and it will be automatically rebuilt if your host kernel is updated.
Otherwise, there are only two situations in which you will need to worry about the
kernel module:
1. The original installation fails. This probably means that your Linux system is not
prepared for building external kernel modules.
Most Linux distributions can be set up simply by installing the right packages normally, these will be the GNU compiler (GCC), GNU Make (make) and packages containing header files for your kernel - and making sure that all system
updates are installed and that the system is running the most up-to-date kernel
included in the distribution. The version numbers of the header file packages must
be the same as that of the kernel you are using.
• With Debian and Ubuntu releases, you must install the right version of the
linux-headers and if it exists the linux-kbuild package. Current
Ubuntu releases should have the right packages installed by default.
• In even older Debian and Ubuntu releases, you must install the right version
of the kernel-headers package.
• On Fedora and Redhat systems, the package is kernel-devel.
• On SUSE and openSUSE Linux, you must install the right versions of the
kernel-source and kernel-syms packages.
• Alternatively, if you have built your own kernel, /usr/src/linux should
point to your kernel sources. If you have not removed the files created
during the build process, then your system will already be set up correctly.
1
See http://en.wikipedia.org/wiki/Dynamic_Kernel_Module_Support for an introduction.
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2 Installation details
2. The kernel of your Linux host got updated. In that case, the kernel module will
need to be reinstalled by executing (as root):
/etc/init.d/vboxdrv setup
2.3.3 USB and advanced networking support
In order to use VirtualBox’s USB support, the user account under which you intend to
run VirtualBox must have read and write access to the USB filesystem (usbfs).
In addition, access to /dev/net/tun will be required if you want to use Host
Interface Networking, which is described in detail in chapter 6.4, Bridged networking,
page 92.
2.3.4 Performing the installation
VirtualBox is available in a number of package formats native to various common Linux
distributions (see chapter 1.4, Supported host operating systems, page 14 for details).
In addition, there is an alternative generic installer (.run) which should work on most
Linux distributions.
2.3.4.1 Installing VirtualBox from a Debian/Ubuntu package
First, download the appropriate package for your distribution. The following examples
assume that you are installing to an Ubuntu Edgy system. Use dpkg to install the
Debian package:
sudo dpkg -i VirtualBox_3.1.0_BETA2_Ubuntu_edgy.deb
You will be asked to accept the VirtualBox Personal Use and Evaluation License.
Unless you answer “yes” here, the installation will be aborted.
The group vboxusers will be created during installation. Note that a user who is
going to run VirtualBox must be member of that group. A user can be made member of
the group vboxusers through the GUI user/group management or at the command
line with
sudo usermod -a -G vboxusers username
Also note that adding an active user to that group will require that user to log out
and back in again. This should be done manually after successful installation of the
package.
The installer will also search for a VirtualBox kernel module suitable for your
kernel. The package includes pre-compiled modules for the most common kernel configurations. If no suitable kernel module is found, the installation script
tries to build a module itself. If the build process is not successful you will be
shown a warning and the package will be left unconfigured. Please have a look at
/var/log/vbox-install.log to find out why the compilation failed. You may
have to install the appropriate Linux kernel headers (see chapter 2.3.2, The VirtualBox
kernel module, page 34). After correcting any problems, do
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2 Installation details
sudo /etc/init.d/vboxdrv setup
This will start a second attempt to build the module.
If a suitable kernel module was found in the package or the module was successfully
built, the installation script will attempt to load that module. If this fails, please see
chapter 11.5.1, Linux kernel module refuses to load, page 162 for further information.
Once VirtualBox has been successfully installed and configured, you can start it by
selecting “VirtualBox” in your start menu or from the command line (see chapter 2.3.5,
Starting VirtualBox on Linux, page 41).
2.3.4.2 Using the alternative installer (VirtualBox.run)
The alternative installer performs the following steps:
• It unpacks the application files to a target directory of choice. By default,
/opt/VirtualBox/
will be used.
• It builds the VirtualBox kernel module (vboxdrv) and installs it.
• It creates /etc/init.d/vboxdrv, an init script to start the VirtualBox kernel
module.
• It creates a new system group called vboxusers.
• It creates symbolic links to VirtualBox, VBoxSDL, VBoxVRDP, VBoxHeadless
and VBoxManage in /usr/bin.
• It creates /etc/udev/60-vboxdrv.rules, a description file for udev, if
that is present, which makes the module accessible to anyone in the group
vboxusers.
• It writes the installation directory to /etc/vbox/vbox.cfg.
The installer must be executed as root with either install or uninstall as the
first parameter. If you do not want the installer to ask you whether you wish to accept
the license agreement (for example, for performing unattended installations), you can
add the parameter license_accepted_unconditionally. Finally, if you want
to use a directory other than the default installation directory, add the desired path as
an extra parameter.
sudo ./VirtualBox.run install /opt/VirtualBox
Or if you do not have the “sudo” command available, run the following as root
instead:
./VirtualBox.run install /opt/VirtualBox
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After that you need to put every user which should be able to use VirtualBox in the
group vboxusers, either through the GUI user management tools or by running the
following command as root:
sudo usermod -a -G vboxusers username
Note: The usermod command of some older Linux distributions does not
support the -a option (which adds the user to the given group without
affecting membership of other groups). In this case, find out the current
group memberships with the groups command and add all these groups in a
comma-separated list to the command line after the -G option, e.g. like this:
usermod -G group1,group2,vboxusers username.
If any users on your system should be able to access host USB devices from within
VirtualBox guests, you should also add them to the appropriate user group that your
distribution uses for USB access, e.g. usb or usbusers.
2.3.4.3 Performing a manual installation
If, for any reason, you cannot use the shell script installer described previously, you
can also perform a manual installation. Invoke the installer like this:
./VirtualBox.run --keep --noexec
This will unpack all the files needed for installation in the directory install
under the current directory. The VirtualBox application files are contained in
VirtualBox.tar.bz2 which you can unpack to any directory on your system. For
example:
sudo mkdir /opt/VirtualBox
sudo tar jxf ./install/VirtualBox.tar.bz2 -C /opt/VirtualBox
or as root:
mkdir /opt/VirtualBox
tar jxf ./install/VirtualBox.tar.bz2 -C /opt/VirtualBox
The sources for VirtualBox’s kernel module are provided in the src directory. To
build the module, change to the directory and issue
make
If everything builds correctly, issue the following command to install the module to
the appropriate module directory:
sudo make install
In case you do not have sudo, switch the user account to root and perform
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2 Installation details
make install
The VirtualBox kernel module needs a device node to operate. The above make
command will tell you how to create the device node, depending on your Linux system.
The procedure is slightly different for a classical Linux setup with a /dev directory, a
system with the now deprecated devfs and a modern Linux system with udev.
On certain Linux distributions, you might experience difficulties building the module. You will have to analyze the error messages from the build system to diagnose the
cause of the problems. In general, make sure that the correct Linux kernel sources are
used for the build process.
Note that the user who is going to run VirtualBox needs read and write permission
on the VirtualBox kernel module device node /dev/vboxdrv. You can either define
a vboxusers group by entering
groupadd vboxusers
chgrp vboxusers /dev/vboxdrv
chmod 660 /dev/vboxdrv
or, alternatively, simply give all users access (insecure, not recommended!)
chmod 666 /dev/vboxdrv
You should also add any users who will be allowed to use host USB devices in
VirtualBox guests to the appropriate USB users group for your distribution. This group
is often called usb or usbusers.
Next, you will have to install the system initialization script for the kernel module:
cp /opt/VirtualBox/vboxdrv.sh /etc/init.d/vboxdrv
(assuming you installed VirtualBox to the /opt/VirtualBox directory) and activate
the initialization script using the right method for your distribution. You should create
VirtualBox’s configuration file:
mkdir /etc/vbox
echo INSTALL_DIR=/opt/VirtualBox > /etc/vbox/vbox.cfg
and, for convenience, create the following symbolic links:
ln -sf /opt/VirtualBox/VBox.sh /usr/bin/VirtualBox
ln -sf /opt/VirtualBox/VBox.sh /usr/bin/VBoxSVC
ln -sf /opt/VirtualBox/VBox.sh /usr/bin/VBoxManage
ln -sf /opt/VirtualBox/VBox.sh /usr/bin/VBoxHeadless
ln -sf /opt/VirtualBox/VBox.sh /usr/bin/VBoxSDL
2.3.4.4 Updating and uninstalling VirtualBox
Before updating or uninstalling VirtualBox, you must terminate any virtual machines
which are currently running and exit the VirtualBox or VBoxSVC applications. To
update VirtualBox, simply run the installer of the updated version. To uninstall
VirtualBox, invoke the installer like this:
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2 Installation details
sudo ./VirtualBox.run uninstall
or as root
./VirtualBox.run uninstall
. Starting with version 2.2.2, you can uninstall the .run package by invoking
/opt/VirtualBox/uninstall.sh
To manually uninstall VirtualBox, simply undo the steps in the manual installation in
reverse order.
2.3.4.5 Automatic installation of Debian packages
The Debian packages will request some user feedback when installed for the first time.
The debconf system is used to perform this task. To prevent any user interaction during
installation, default values can be defined. A file vboxconf can contain the following
debconf settings:
virtualbox virtualbox/module-compilation-allowed boolean true
virtualbox virtualbox/delete-old-modules boolean true
The first line allows compilation of the vboxdrv kernel module if no module was found
for the current kernel. The second line allows the package to delete any old vboxdrv
kernel modules compiled by previous installations.
These default settings can be applied with
debconf-set-selections vboxconf
prior to the installation of the VirtualBox Debian package.
2.3.4.6 Automatic installation of .rpm packages
The .rpm format does not provide a configuration system comparable to the debconf system. To configure the installation process of our .rpm packages, a file
/etc/default/virtualbox is interpreted. The automatic generation of the udev
rule can be prevented by the following setting:
INSTALL_NO_UDEV=1
The creation of the group vboxusers can be prevented by
INSTALL_NO_GROUP=1
If the line
INSTALL_NO_VBOXDRV=1
is specified, the package installer will not try to build the vboxdrv kernel module if
no module according to the current kernel was found.
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2 Installation details
2.3.5 Starting VirtualBox on Linux
The easiest way to start a VirtualBox program is by running the program of your choice
(VirtualBox, VBoxManage, VBoxSDL or VBoxHeadless) from a terminal. These
are symbolic links to VBox.sh that start the required program for you.
The following detailed instructions should only be of interest if you wish to execute VirtualBox without installing it first. You should start by compiling the vboxdrv
kernel module (see above) and inserting it into the Linux kernel. VirtualBox consists
of a service daemon (VBoxSVC) and several application programs. The daemon is
automatically started if necessary. All VirtualBox applications will communicate with
the daemon through Unix local domain sockets. There can be multiple daemon instances under different user accounts and applications can only communicate with
the daemon running under the user account as the application. The local domain
socket resides in a subdirectory of your system’s directory for temporary files called
.vbox-<username>-ipc. In case of communication problems or server startup
problems, you may try to remove this directory.
All VirtualBox applications (VirtualBox, VBoxSDL, VBoxManage and VBoxHeadless)
require the VirtualBox directory to be in the library path:
LD_LIBRARY_PATH=. ./VBoxManage showvminfo "Windows XP"
2.4 Installing on Solaris hosts
For the various versions of Solaris that we support as host operating systems, please
refer to chapter 1.4, Supported host operating systems, page 14.
If you have a previously installed instance of VirtualBox on your Solaris host, please
uninstall it first before installing a new instance. Refer to chapter 2.4.3, Uninstallation,
page 42 for uninstall instructions.
2.4.1 Performing the installation
VirtualBox is available as a standard Solaris package. Download the VirtualBox SunOS
package which includes both the 32-bit and 64-bit versions of VirtualBox. The installa-
tion must be performed as root and from the global zone as the VirtualBox installer loads
kernel drivers which cannot be done from non-global zones. To verify which zone you
are currently in, execute the zonename command. Execute the following commands:
gunzip -cd VirtualBox-3.1.0_BETA2-SunOS.tar.gz | tar xvf -
Starting with VirtualBox 3.1 the VirtualBox kernel package is no longer a separate
package and has been integrated into the main package. Install the VirtualBox package
using:
pkgadd -d VirtualBox-3.1.0_BETA2-SunOS.pkg
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2 Installation details
Note: If you are using Solaris Zones, to install VirtualBox only into the current
zone and not into any other zone, use pkgadd -G. For more information
refer to the pkgadd manual; see also chapter 2.4.5, Configuring a zone for
running VirtualBox, page 43.
The installer will then prompt you to enter the package you wish to install. Choose
“1” or “all” and proceed. Next the installer will ask you if you want to allow the
postinstall script to be executed. Choose “y” and proceed as it is essential to execute
this script which installs the VirtualBox kernel module. Following this confirmation
the installer will install VirtualBox and execute the postinstall setup script.
Once the postinstall script has been executed your installation is now complete. You
may now safely delete the uncompressed package and autoresponse files from your
system. VirtualBox would be installed in /opt/VirtualBox.
2.4.2 Starting VirtualBox on Solaris
The easiest way to start a VirtualBox program is by running the program of your choice
(VirtualBox, VBoxManage, VBoxSDL or VBoxHeadless) from a terminal. These
are symbolic links to VBox.sh that start the required program for you.
Alternatively, you can directly invoke the required programs from /opt/VirtualBox.
Using the links provided is easier as you do not have to type the full path.
You can configure some elements of the VirtualBox Qt GUI such as fonts and
colours by executing VBoxQtconfig from the terminal.
2.4.3 Uninstallation
Uninstallation of VirtualBox on Solaris requires root permissions. To perform the uninstallation, start a root terminal session and execute:
pkgrm SUNWvbox
After confirmation, this will remove VirtualBox from your system.
If you are uninstalling VirtualBox version 3.0 or lower, you need to remove the
VirtualBox kernel interface package, execute:
pkgrm SUNWvboxkern
2.4.4 Unattended installation
To perform a non-interactive installation of VirtualBox we have provided a response
file named autoresponse that the installer will use for responses to inputs rather
than ask them from you.
Extract the tar.gz package as described in the normal installation. Then open a root
terminal session and execute:
pkgadd -d VirtualBox-3.1.0_BETA2-SunOS-x86 -n -a autoresponse SUNWvbox
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2 Installation details
To perform a non-interactive uninstallation, open a root terminal session and execute:
pkgrm -n -a /opt/VirtualBox/autoresponse SUNWvbox
2.4.5 Configuring a zone for running VirtualBox
Starting with VirtualBox 1.6 it is possible to run VirtualBox from within Solaris
zones. For an introduction of Solaris zones, please refer to http://www.sun.com/
bigadmin/features/articles/solaris_zones.jsp.
Assuming that VirtualBox has already been installed into your zone, you need to give
the zone access to VirtualBox’s device node. This is done by performing the following
steps. Start a root terminal and execute:
zonecfg -z vboxzone
Inside the zonecfg prompt add the device resource and match properties to the
zone. Here’s how it can be done:
zonecfg:vboxzone>add device
zonecfg:vboxzone:device>set match=/dev/vboxdrv
zonecfg:vboxzone:device>end
zonecfg:vboxzone>verify
zonecfg:vboxzone>exit
If you are running VirtualBox 2.2.0 or above on OpenSolaris or Nevada hosts, you
should add a device for /dev/vboxusbmon too, similar to what was shown above.
This does not apply to Solaris 10 hosts due to lack of USB support.
Replace “vboxzone” with the name of the zone in which you intend to run
VirtualBox. Next reboot the zone using zoneadm and you should be able to run
VirtualBox from within the configured zone.
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3 Configuring virtual machines
Whereas chapter 1, First steps, page 9 gave you a quick introduction to VirtualBox and
how to get your first virtual machine running, the following chapter describe in detail
how to configure virtual machines.
You have considerable latitude in deciding what virtual hardware will be provided to
the guest. The virtual hardware can be used for communicating with the host system
or with other guests. For instance, if you provide VirtualBox with the image of a CDROM in an ISO file, VirtualBox can present this image to a guest system as if it were
a physical CD-ROM. Similarly, you can give a guest system access to the real network
via its virtual network card, and, if you choose, give the host system, other guests, or
computers on the Internet access to the guest system.
3.1 Supported guest operating systems
Since VirtualBox is designed to provide a generic virtualization environment for x86
systems, it may run operating systems of any kind, even those that are not officially
supported by Sun Microsystems. However, our focus is to optimize the product’s performance for a select list of guest systems:
Windows NT 4.0 All versions/editions and service packs are fully supported; how-
ever, there are some issues with older service packs. We recommend to install
service pack 6a. Guest Additions are available with a limited feature set.
Windows 2000 / XP / Server 2003 / Vista / Server 2008 / Windows 7 beta All ver-
sions/editions and service packs are fully supported (including 64-bit versions,
under the preconditions listed below). Guest Additions are available.
DOS / Windows 3.x / 95 / 98 / ME Limited testing has been performed. Use beyond
legacy installation mechanisms not recommended. No Guest Additions available.
Linux 2.4 Limited support.
Linux 2.6 All versions/editions are fully supported (32 bits and 64 bits). Guest Addi-
tions are available.
We strongly recommend using a Linux kernel version 2.6.13 or higher for better
performance.
Note: Certain Linux kernel releases have bugs that prevent them from executing in a virtual environment; please see chapter 11.3.3, Buggy Linux 2.6
kernel versions, page 159 for details.
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3 Configuring virtual machines
Solaris 10, OpenSolaris Fully supported (32 bits and 64 bits). Guest Additions are
available.
FreeBSD Limited support. Guest Additions are not available yet.
OpenBSD Versions 3.7 and later are supported. Guest Additions are not available
yet.
OS/2 Warp 4.5 Requires hardware virtualization to be enabled. We officially support
MCP2 only; other OS/2 versions may or may not work. Guest Additions are
available with a limited feature set.
1
3.2 64-bit guests
Starting with version 2.0, VirtualBox supports 64-bit guest operating systems. Starting
with version 2.1, you can even run 64-bit guests on a 32-bit host operating system.
The hardware prerequisites are identical for both cases.
In particular, 64-bit guests are supported under the following conditions:
1. You need a 64-bit processor with hardware virtualization support (see chapter
3.4.3, “Acceleration” tab: hardware vs. software virtualization, page 49).
2. You must enable hardware virtualization for the particular VM for which you
want 64-bit support; software virtualization is not supported for 64-bit VMs.
3. If you want to use 64-bit guest support on a 32-bit host operating system, you
must also select a 64-bit operating system for the particular VM. Since supporting
64 bits on 32-bit hosts incurs additional overhead, VirtualBox only enables this
support upon explicit request.
On 64-bit hosts, 64-bit guest support is always enabled, so you can simply install
a 64-bit operating system in the guest.
Warning: On any host, you should enable the I/O APIC for virtual machines
that you intend to use in 64-bit mode. This is especially true for 64-bit Windows VMs. See chapter 3.3.2, “Advanced” tab, page 46. In addition, for 64-bit
Windows guests, you should make sure that the VM uses the Intel network-
ing device, since there is no 64-bit driver support for the AMD PCNet card;
see chapter 6.1, Virtual networking hardware, page 88.
If you use the “Create VM” wizard of the VirtualBox graphical user interface (see
chapter 1.6, Creating your first virtual machine, page 17), VirtualBox will automatically
use the correct settings for each selected 64-bit operating system type.
1
See chapter 13, Known limitations, page 237.
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3 Configuring virtual machines
3.3 General settings
In the Settings window, under “General”, you can configure the most fundamental
aspects of the virtual machine such as memory and essential hardware. There are
three tabs, “Basic”, “Advanced” and “Description”.
3.3.1 “Basic” tab
Under the “Basic” tab of the “General” settings category, you can find these settings:
Name The name under which the VM is shown in the list of VMs in the main window.
Under this name, VirtualBox also saves the VM’s configuration files. By changing
the name, VirtualBox renames these files as well. As a result, you can only use
characters which are allowed in your host operating system’s file names.
Note that internally, VirtualBox uses unique identifiers (UUIDs) to identify virtual
machines. You can display these with VBoxManage.
Operating System / Version The type of the guest operating system that is (or will
be) installed in the VM. This is the same setting that was specified in the “New
Virtual Machine” wizard, as described with chapter 1.6, Creating your first virtual
machine, page 17 above.
3.3.2 “Advanced” tab
Snapshot folder By default, VirtualBox saves snapshot data together with your other
VirtualBox configuration data; see chapter 9.1, VirtualBox configuration data,
page 135. With this setting, you can specify any other folder for each VM.
Shared Clipboard If the virtual machine has Guest Additions installed, you can select
here whether the clipboard of the guest operating system should be shared with
that of your host. If you select “Bidirectional”, then VirtualBox will always make
sure that both clipboards contain the same data. If you select “Host to guest”
or “Guest to host”, then VirtualBox will only ever copy clipboard data in one
direction.
Removable Media: Remember Runtime Changes If this is checked, VirtualBox
will save the state of what media has been mounted between several runs of
a virtual machine.
Mini Toolbar In full screen or seamless mode, VirtualBox can display a small toolbar
that contains some of the items that are normally available from the virtual machine’s menu bar. This toolbar reduces itself to a small gray line unless you move
the mouse over it. With the toolbar, you can return from full screen or seamless
mode, control machine execution or enable certain devices. If you don’t want to
see the toolbar, disable this setting.
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3 Configuring virtual machines
3.3.3 “Description” tab
Here you can enter any description for your virtual machine, if you want. This has no
effect of the functionality of the machine, but you may find this space useful to note
down things like the configuration of a virtual machine and the software that has been
installed into it.
3.4 System settings
The “System” category groups various settings that are related to the basic hardware
that is presented to the virtual machine.
Note: As the activation mechanism of Microsoft Windows is sensitive to hardware changes, if you are changing hardware settings for a Windows guest,
some of these changes may trigger a request for another activation with Microsoft.
3.4.1 “Motherboard” tab
On the “Motherboard” tab, you can influence virtual hardware that would normally be
on the motherboard of a real computer.
Base memory This sets the amount of RAM that is allocated and given to the VM
when it is running. The specified amount of memory will be requested from the
host operating system, so it must be available or made available as free memory
on the host when attempting to start the VM and will not be available to the
host while the VM is running. This is the same setting that was specified in the
“New Virtual Machine” wizard, as described with guidelines under chapter 1.6,
Creating your first virtual machine, page 17 above.
Generally, it is possible to change the memory size after installing the guest
operating system (provided you do not reduce the memory to an amount where
the operating system would no longer boot).
Boot order This setting determines the order in which the guest operating system
will attempt to boot from the various virtual boot devices. Analogous to a real
PC’s BIOS setting, VirtualBox can tell a guest OS to start from the virtual floppy,
the virtual CD/DVD drive, the virtual hard drive (each of these as defined by the
other VM settings), the network, or none of these.
If you select “Network”, the VM will attempt to boot from a network via the PXE
mechanism. This needs to be configured in detail on the command line; please
see chapter 8.5, VBoxManage modifyvm, page 114.
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3 Configuring virtual machines
Enable I/O APIC Advanced Programmable Interrupt Controllers (APICs) are a newer
x86 hardware feature that have replaced old-style Programmable Interrupt Controllers (PICs) in recent years. With an I/O APIC, operating systems can use more
than 16 interrupt requests (IRQs) and therefore avoid IRQ sharing for improved
reliability.
Note: Enabling the I/O APIC is required for 64-bit guest operating systems,
especially Windows Vista; it is also required if you want to use more than one
virtual CPU in a virtual machine.
However, software support for I/O APICs has been unreliable with some operating systems other than Windows. Also, the use of an I/O APIC slightly increases
the overhead of virtualization and therefore slows down the guest OS a little.
Warning: All Windows operating systems starting with Windows 2000 install
different kernels depending on whether an I/O APIC is available. As with
ACPI, the I/O APIC therefore must not be turned off after installation of a
Windows guest OS. Turning it on after installation will have no effect however.
In addition, you can turn off the Advanced Configuration and Power Interface
(ACPI) which VirtualBox presents to the guest operating system by default. ACPI is the
current industry standard to allow operating systems to recognize hardware, configure
motherboards and other devices and manage power. As all modern PCs contain this
feature and Windows and Linux have been supporting it for years, it is also enabled
by default in VirtualBox. It can be turned off on the command line; e see chapter 8.5,
VBoxManage modifyvm, page 114.
Warning: All Windows operating systems starting with Windows 2000 install
different kernels depending on whether ACPI is available, so ACPI must not
be turned off after installation of a Windows guest OS. Turning it on after
installation will have no effect however.
3.4.2 “Processor” tab
On the “Processor” tab, you can set how many virtual CPU cores the guest operating
systems should see. Starting with version 3.0, VirtualBox supports symmetrical multiprocessing (SMP) and can present up to 32 virtual CPU cores to each virtual machine.
You should not, however, configure virtual machines to use more CPU cores than
you have available physically.
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3 Configuring virtual machines
In addition, the “Enable PAE/NX” setting determines whether the PAE and NX capa-
bilities of the host CPU will be exposed to the virtual machine. PAE stands for “Physical
Address Extension”. Normally, if enabled and supported by the operating system, then
even a 32-bit x86 CPU can access more than 4 GB of RAM. This is made possible by
adding another 4 bits to memory addresses, so that with 36 bits, up to 64 GB can be
addressed. Some operating systems (such as Ubuntu Server) require PAE support from
the CPU and cannot be run in a virtual machine without it.
3.4.3 “Acceleration” tab: hardware vs. software virtualization
On this page, you can determine whether and how VirtualBox should use hardware
virtualization extensions that your host CPU may support.
In most cases, the default settings will be fine; VirtualBox will have picked sensible defaults depending on the operating system that you selected when you created
the virtual machine. In certain situations, however, you may want to change these
preconfigured defaults.
As a general introduction, VirtualBox allows software in the virtual machine to run
directly on the processor of the host, but an array of complex techniques is employed to
intercept operations that would interfere with your host. Whenever the guest attempts
to do something that could be harmful to your computer and its data, VirtualBox steps
in and takes action. In particular, for lots of hardware that the guest believes to be
accessing, VirtualBox simulates a certain “virtual” environment according to how you
have configured a virtual machine. For example, if the guest attempts to access a hard
disk, VirtualBox redirects these requests to whatever you have configured to be the
virtual machine’s virtual hard disk – normally, an image file on your host.
There are two ways in which VirtualBox can achieve virtualization: either entirely
in software or, with newer processors, using certain hardware features.
• For some years, Intel and AMD processors have had support for so-called “hard-
ware virtualization”. This means that these processors aid virtualization soft-
ware such as VirtualBox in intercepting potentially dangerous operations that a
guest operating system may be attempting and in presenting virtual hardware to
a virtual machine.
These hardware features differ between Intel and AMD processors. Intel named
its technology VT-x; AMD calls theirs AMD-V.
Note: On many systems, the hardware virtualization features first need to be
enabled in the BIOS before VirtualBox can use them.
• As opposed to other virtualization software, for many usage scenarios,
VirtualBox does not require hardware virtualization features to be present.
Through sophisticated techniques, VirtualBox virtualizes many guest operating
systems entirely in software. This means that you can run virtual machines even
on older processors which do not support hardware virtualization.
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3 Configuring virtual machines
You can select for each virtual machine individually whether VirtualBox should use
software or hardware virtualization. Prior to VirtualBox version 2.2, software virtualization was the default; starting with version 2.2, VirtualBox will enable hardware
virtualization by default for new virtual machines that you create. (Existing virtual
machines are not automatically changed for compatibility reasons, and the default can
of course be changed for each virtual machine.)
Even though VirtualBox does not always require hardware virtualization, enabling
it is required in the following scenarios:
• Certain rare guest operating systems like OS/2 make use of very esoteric processor instructions that are not supported with our software virtualization. For
virtual machines that are configured to contain such an operating system, hardware virtualization is enabled automatically.
• VirtualBox’s 64-bit guest support (added with version 2.0) and multiprocessing
(SMP, added with version 3.0) both require hardware virtualization to be enabled. (This is not much of a limitation since the vast majority of today’s 64-bit
and multicore CPUs ship with hardware virtualization anyway; the exceptions to
this rule are e.g. older Intel Celeron and AMD Opteron CPUs.)
The reason for changing the default with version 2.2 is that the hardware has significantly improved with the latest Intel and AMD processors, and VirtualBox has also
fine-tuned its hardware virtualization support to a degree that it is now faster than
software virtualization in many situations.
Warning: Do not run other hypervisors (open-source or commercial virtualization products) together with VirtualBox! While several hypervisors can
normally be installed in parallel, do not attempt to run several virtual machines from competing hypervisors at the same time. VirtualBox cannot track
what another hypervisor is currently attempting to do on the same host, and
especially if several products attempt to use hardware virtualization features
such as VT-x, this can crash the entire host. Also, within VirtualBox, you can
mix software and hardware virtualization when running multiple VMs. In certain cases a small performance penalty will be unavoidable when mixing VT-x
and software virtualization VMs. We recommend not mixing virtualization
modes if maximum performance and low overhead are essential. This does
not apply to AMD-V.
In addition to “plain” hardware virtualization, your processor may also support additional sophisticated techniques:
2
• A newer feature called “nested paging” implements some memory management
in hardware, which can greatly accelerate hardware virtualization since these
tasks no longer need to be performed by the virtualization software.
2
VirtualBox 2.0 added support for AMD’s nested paging; support for Intel’s EPT and VPIDs was added with
version 2.1.
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3 Configuring virtual machines
On AMD processors, nested paging has been available starting with the
Barcelona (K10) architecture; Intel added support for nested paging, which
they call “extended page tables” (EPT), with their Core i7 (Nehalem) processors.
Nested paging is still disabled by default even for new machines, but it can be
enabled for each virtual machine individually in the machine settings.
If your system supports nested paging (AMD-V) or EPT (VT-x), then you can
expect a significant performance increase by enabling hardware virtualization
and the nested paging feature
• On Intel CPUs, another hardware feature called “Virtual Processor Identifiers”
(VPIDs) can greatly accelerate context switching by reducing the need for expen-
sive flushing of the processor’s Translation Lookaside Buffers (TLBs). To enable
this feature for a VM, you need to use the command line; see chapter 8.5, VBox-
Manage modifyvm, page 114.
3.5 Display settings
Video memory size This sets the size of the memory provided by the virtual graph-
ics card available to the guest, in MB. As with the main memory, the specified
amount will be allocated from the host’s resident memory. Based on the amount
of video memory, higher resolutions and color depths may be available.
Enable 3D acceleration If a virtual machine has Guest Additions installed, you can
select here whether the guest should support accelerated 3D graphics. Please
refer to chapter 4.9, Hardware 3D acceleration (OpenGL and Direct3D 8/9), page
72 for details.
Enable 2D video acceleration If a virtual machine with Microsoft Windows has
Guest Additions installed, you can select here whether the guest should support accelerated 2D video graphics. Please refer to chapter 4.10, Hardware 2D
video acceleration for Windows guests, page 73 for details.
Remote display Under the “Remote display” tab, you can enable the VRDP server
that is built into VirtualBox to allow you to connect to the virtual machine remotely. For this, you can use any standard RDP viewer, such as mstsc.exe that
comes with Microsoft Windows or, on Linux systems, the standard open-source
rdesktop program. These features are described in detail in chapter 7.4, Re-
mote virtual machines (VRDP support), page 99.
3.6 Storage settings
In the VM Settings window, the “Storage” section allows you to connect virtual hard
disk, CD-ROM/DVD and floppy images and drives to your virtual machine:
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3 Configuring virtual machines
In a real PC, so-called “storage controllers” connect physical disk drives to the rest
of the computer. Similarly, VirtualBox presents virtual storage controllers to a virtual
machine. Under each controller, the virtual devices (hard disks, CD/DVD or floppy
drives) are shown that are attached to the controller.
If you have used the “Create VM” wizard to create a machine, you will normally see
the following devices:
• You will see an IDE controller, under which there are two devices:
– one virtual hard disk connected to the IDE slot called “primary master”; this
is represented by the disk images that you created with the machine;
– one virtual CD/DVD drive connected to the “secondary master”.
• In addition, there is a floppy controller to which a virtual floppy drive is attached.
You can modify these media attachments freely. For example, if you wish to copy
some files from another virtual disk that you created, you can connect that disk as a
second hard disk. You could also add a second virtual CD/DVD drive, or change where
these items are attached.
In addition to the IDE controller, VirtualBox can also present an SATA controller and
a SCSI controller to the guest, which gives you 30 or 16 additional slots to attach
devices to, respectively. This, however, may require that you run a modern guest
operating system. See chapter 5.1, Hard disk controllers: IDE, SATA (AHCI), SCSI,
page 76 for details.
To add another virtual hard disk or CD/DVD drive, select the storage controller to
which it should be added (IDE, SATA or SCSI) and then click on the “add disk” button
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3 Configuring virtual machines
below the tree. You can then either select “Add CD/DVD device” or “Add Hard Disk”.
Alternatively, right-click on the storage controller and select a menu item there.
On the right part of the window, you can then select where the virtual disk should
be connected to on the controller and which image file to use.
• For virtual hard disks, a drop-down list appears on the right, listing all the hard
disk images that VirtualBox currently knows about. If you click on the “Open
Virtual Media Manager” icon to the right, this will bring up a window in which
you can select or create a different hard disk image (see chapter 5.3, The Virtual
Media Manager, page 80 for details).
• For virtual CD/DVD drives. there are two kinds of options in the drop-down list.
– If you select “Empty”, then VirtualBox will present a virtual CD/DVD drive
to the guest which has no media inserted.
– If you select “Host drive” from the list, then the physical device of the host
computer is connected to the VM, so that the guest operating system can
read from and write to your physical device. This is, for instance, useful if
you want to install Windows from a real installation CD. In this case, select
your host drive from the drop-down list presented.
Note: If you want to write CDs or DVDs using the host drive, you need to
enable a special setting first; see chapter 5.7, Writing CDs and DVDs using the
host drive, page 85.
– The other items in the list, like virtual hard disk images, will be image files
on your host. The file format here is the ISO format. Most commonly,
you will select this option when installing an operating system from an ISO
file that you have obtained from the Internet. For example, most Linux
distributions are available in this way.
Note: The identification string of the drive provided to the guest (which, in
the guest, would be displayed by configuration tools such as the Windows
Device Manager) is always “VBOX CD-ROM”, irrespective of the current configuration of the virtual drive. This is to prevent hardware detection from
being triggered in the guest operating system every time the configuration is
changed.
Note that the floppy controller is special: you cannot add devices other than floppy
drives to it. Virtual floppy drives, like virtual CD/DVD drives, can be connected to
either a host floppy drive (if you have one) or a disk image, which in this case must be
in RAW format.
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3 Configuring virtual machines
To remove a virtual disk or drive, select it and click on the “remove” icon at the
bottom (or right-click on it and select the menu item).
Removable media (CD/DVDs and floppies) can be changed while the guest is running. Since the “Settings” dialog is not available at that time, you can also access these
settings from the “Devices” menu of your virtual machine window.
We have dedicated an entire chapter of this User Manual to virtual storage: please
see chapter 5, Virtual storage, page 76 for every single detail about storage configuration.
3.7 Audio settings
The “Audio” section in a virtual machine’s Settings window determines whether the
VM will see a sound card connected, and whether the audio output should be heard
on the host system.
If audio is enabled for a guest, you can choose between the emulation of an Intel
AC’97 controller or a SoundBlaster 16 card. In any case, you can select what audio
driver VirtualBox will use on the host.
On a Linux host, depending on your host configuration, you can also select between
the OSS, ALSA or the PulseAudio subsystem. On newer Linux distributions (Fedora 8
and above, Ubuntu 8.04 and above) the PulseAudio subsystem should be preferred.
3.8 Network settings
The “Network” section in a virtual machine’s Settings window allows you to configure
how VirtualBox presents virtual network cards to your VM, and how they operate.
When you first create a virtual machine, VirtualBox by default enables one virtual
network card and selects the “Network Address Translation” (NAT) mode for it. This
way the guest can connect to the outside world using the host’s networking and the
outside world can connect to services on the guest which you choose to make visible
outside of the virtual machine.
Note: If you are installing Windows Vista in a virtual machine, you will probably have no networking initially. See chapter 4.3.5, Windows Vista networking,
page 64 for instructions how to solve this problem.
In most cases, this default setup will work fine for you.
However, VirtualBox is extremely flexible in how it can virtualize networking. It
supports up to eight virtual network cards per virtual machine, the first four of which
can be configured in detail in the graphical user interface. All eight network cards
can be configured on the command line with VBoxManage. Because of this, we have
dedicated an entire chapter of this manual to discussing networking configuration;
please see chapter 6, Virtual networking, page 88.
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3.9 Serial ports
3 Configuring virtual machines
VirtualBox fully supports virtual serial ports in a virtual machine in an easy-to-use
manner.
3
Ever since the original IBM PC, personal computers have been equipped with one
or two serial ports (also called COM ports by DOS and Windows). While these are no
longer as important as they were until a few years ago (especially since mice are no
longer connected to serial ports these days), there are still some important uses left for
them. For example, serial ports can be used to set up a primitive network over a nullmodem cable, in case Ethernet is not available. Also, serial ports are indispensable for
system programmers needing to do kernel debugging, since kernel debugging software
usually interacts with developers over a serial port. In other words, with virtual serial
ports, system programmers can do kernel debugging on a virtual machine instead of
needing a real computer to connect to.
If a virtual serial port is enabled, the guest operating system sees it a standard
16450-type serial port. Both receiving and transmitting data is supported. How this
virtual serial port is then connected to the host is configurable, and details depend on
your host operating system.
You can use either the graphical user interface or the command-line VBoxManage
tool to set up virtual serial ports. For the latter, please refer to chapter
8.5, VBoxManage
modifyvm, page 114; in that section, look for the --uart and --uartmode options.
In either case, you can configure up to two virtual serial ports simultaneously. For
each such device, you will need to determine
1. what kind of serial port the virtual machine should see by selecting an I/O base
address and interrupt (IRQ). For these, we recommend to use the traditional
values4, which are:
a) COM1: I/O base 0x3F8, IRQ 4
b) COM2: I/O base 0x2F8, IRQ 3
c) COM3: I/O base 0x3E8, IRQ 4
d) COM4: I/O base 0x2E8, IRQ 3
2. Then, you will need to determine what this virtual port should be connected to.
For each virtual serial port, you have the following options:
• You can elect to have the virtual serial port “disconnected”, which means
that the guest will see it as hardware, but it will behave as if no cable had
been connected to it.
• You can connect the virtual serial port to a physical serial port on your
host. (On a Windows host, this will be a name like COM1; on Linux or
OpenSolaris hosts, it will be a device node like /dev/ttyS0). VirtualBox
3
Serial port support was added with VirtualBox 1.5.
4
See, for example, http://en.wikipedia.org/wiki/COM_(hardware_interface).
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3 Configuring virtual machines
will then simply redirect all data received from and sent to the virtual serial
port to the physical device.
• You can tell VirtualBox to connect the virtual serial port to a software pipe
on the host. This depends on your host operating system:
– On a Windows host, data will be sent and received through a named
pipe. You can use a helper program called VMware Serial Line Gateway, available for download at http://www.l4ka.org/tools/
vmwaregateway.php. This tool provides a fixed server mode named
pipe at \\.\pipe\vmwaredebug and connects incoming TCP connections on port 567 with the named pipe.
– On a Mac, Linux or OpenSolaris host, a local domain socket is used
instead. On Linux there are various tools which can connect to a local
domain socket or create one in server mode. The most flexible tool is
socat and is available as part of many distributions.
In this case, you can configure whether VirtualBox should create the named
pipe (or, on non-Windows hosts, the local domain socket) itself or whether
VirtualBox should assume that the pipe (or socket) exists already. With
the VBoxManage command-line options, this is referred to as “server” or
“client” mode, respectively.
Up to two serial ports can be configured simultaneously per virtual machine, but you
can pick any port numbers out of the above. For example, you can configure two serial
ports to be able to work with COM2 and COM4 in the guest.
3.10 USB support
3.10.1 USB settings
The “USB” section in a virtual machine’s Settings window allows you to configure
VirtualBox’s sophisticated USB support.
VirtualBox can allow virtual machines to access the USB devices on your host directly. To achieve this, VirtualBox presents the guest operating system with a virtual
USB controller. As soon as the guest system starts using a USB device, it will appear as
unavailable on the host.
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3 Configuring virtual machines
Note:
1. Be careful with USB devices that are currently in use on the host! For
example, if you allow your guest to connect to your USB hard disk that
is currently mounted on the host, when the guest is activated, it will be
disconnected from the host without a proper shutdown. This may cause
data loss.
2. Solaris hosts have a few known limitations regarding USB support;
please see chapter 13, Known limitations, page 237.
In addition to allowing a guest access to your local USB devices, VirtualBox even
allows your guests to connect to remote USB devices by use of the VRDP protocol. For
details about this, see chapter 7.4.4, Remote USB, page 103.
In the Settings dialog, you can first configure whether USB is available in the guest
at all, and in addition also optionally enable the USB 2.0 (EHCI) controller for the
guest. If so, you can determine in detail which devices are available. For this, you
must create so-called “filters” by specifying certain properties of the USB device.
Clicking on the “+“ button to the right of the “USB Device Filters” window creates a
new filter. You can give the filter a name (for referencing it later) and specify the filter
criteria. The more criteria you specify, the more precisely devices will be selected. For
instance, if you specify only a vendor ID of 046d, all devices produced by Logitech
will be available to the guest. If you fill in all fields, on the other hand, the filter will
only apply to a particular device model from a particular vendor, and not even to other
devices of the same type with a different revision and serial number.
In detail, the following criteria are available:
1. Vendor and product ID. With USB, each vendor of USB products carries an
identification number that is unique world-wide, the “vendor ID”. Similarly, each
line of products is assigned a “product ID” number. Both numbers are commonly
written in hexadecimal (that is, they are composed of the numbers 0-9 and the
letters A-F), and a colon separates the vendor from the product ID. For example,
046d:c016 stands for Logitech as a vendor, and the “M-UV69a Optical Wheel
Mouse” product.
Alternatively, you can also specify “Manufacturer” and “Product” by name.
To list all the USB devices that are connected to your host machine with their
respective vendor and product IDs, you can use the following command (see
chapter 8, VBoxManage reference, page 106):
VBoxManage list usbhost
On Windows, you can also see all USB devices that are attached to your system
in the Device Manager. On Linux, you can use the lsusb command.
2. Serial number. While vendor and product ID are already quite specific to iden-
tify USB devices, if you have two identical devices of the same brand and product
line, you will also need their serial numbers to filter them out correctly.
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3. Remote. This setting specifies whether the device will be local only, or remote
only (over VRDP), or either.
On a Windows host, you will need to unplug and reconnect a USB device to use it
after creating a filter for it.
As an example, you could create a new USB filter and specify a vendor ID of 046d
(Logitech, Inc), a manufacturer index of 1, and “not remote”. Then any USB devices
on the host system produced by Logitech, Inc with a manufacturer index of 1 will be
visible to the guest system.
Several filters can select a single device – for example, a filter which selects all
Logitech devices, and one which selects a particular webcam.
You can deactivate filters without deleting them by clicking in the checkbox next to
the filter name.
3.10.2 Implementation notes for Windows and Linux hosts
On Windows hosts, a kernel mode device driver provides USB proxy support. It implements both a USB monitor, which allows VirtualBox to capture devices when they are
plugged in, and a USB device driver to claim USB devices for a particular virtual machine. As opposed to VirtualBox versions before 1.4.0, system reboots are no longer
necessary after installing the driver. Also, you no longer need to replug devices for
VirtualBox to claim them.
On newer Linux hosts, VirtualBox accesses USB devices through special files in the
file system. When VirtualBox is installed, these are made available to all users in the
vboxusers system group. In order to be able to access USB from guest systems, make
sure that you are a member of this group.
On older Linux hosts, USB devices are accessed using the usbfs file system. Therefore, the user executing VirtualBox needs read and write permission to the USB file
system. Most distributions provide a group (e.g. usbusers) which the VirtualBox
user needs to be added to. Also, VirtualBox can only proxy to virtual machines
USB devices which are not claimed by a Linux host USB driver. The Driver= entry in /proc/bus/usb/devices will show you which devices are currently claimed.
Please refer to chapter 11.5.7, USB not working, page 164 also for details about usbfs.
3.11 Shared folders
Shared folders allow you to easily exchange data between a virtual machine and your
host. This feature requires that the VirtualBox Guest Additions be installed in a virtual
machine and is described in detail in chapter 4.7, Folder sharing, page 68.
3.12 Alternative firmware (EFI)
Starting with release 3.1, VirtualBox includes experimental support for the Extensible
Firmware Interface (EFI), which is a new industry standard intended to eventually
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3 Configuring virtual machines
replace the legacy BIOS as the primary interface for bootstrapping computers and
certain system services later.
By default, VirtualBox uses the BIOS firmware for virtual machines. To use EFI for a
given virtual machine, use the VBoxManage command line interface like this:
VBoxManage modifyvm <vmname> --firmware efi
To switch back to using the BIOS, use:
VBoxManage modifyvm <vmname> --firmware bios
One notable user of EFI is Apple’s Mac OS X, but recent Linuxes (such as Fedora 11)
and Windows (starting with Vista) can be booted using EFI as well.
Note that EFI is experimental and work in progress. Please do not enable it in a
production environment.
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4 Guest Additions
The previous chapter covered getting started with VirtualBox and installing operating
systems in a virtual machine. For any serious and interactive use, the VirtualBox Guest
Additions will make your life much easier by providing closer integration between host
and guest and improving the interactive performance of guest systems. This chapter
describes the Guest Additions in detail.
4.1 Introduction
As said in chapter 1.2, Some terminology, page 11, the Guest Additions are designed
to be installed inside a virtual machine after the guest operating system has been
installed. They consist of device drivers and system applications that optimize the
guest operating system for better performance and usability. Please see chapter 3.1,
Supported guest operating systems, page 44 for details on what guest operating systems
are fully supported with Guest Additions by VirtualBox.
The VirtualBox Guest Additions for all supported guest operating systems are provided as a single CD-ROM image file which is called VBoxGuestAdditions.iso.
This image file is located in the installation directory of VirtualBox. To install the
Guest Additions for a particular VM, you mount this ISO file in your VM as a virtual
CD-ROM and install from there.
The Guest Additions offer the following features:
Mouse pointer integration To overcome the limitations for mouse support that were
described in chapter 1.7.1.1, Capturing and releasing keyboard and mouse, page
21, this provides you with seamless mouse support. You will only have one
mouse pointer and pressing the Host key is no longer required to “free” the
mouse from being captured by the guest OS. To make this work, a special mouse
driver is installed in the guest that communicates with the “real” mouse driver
on your host and moves the guest mouse pointer accordingly.
Better video support While the virtual graphics card which VirtualBox emulates for
any guest operating system provides all the basic features, the custom video
drivers that are installed with the Guest Additions provide you with extra high
and non-standard video modes as well as accelerated video performance.
In addition, with Windows and recent Linux, Solaris and OpenSolaris guests, if
the Guest Additions are installed, you can resize the virtual machine’s window,
and the video resolution in the guest will be automatically adjusted (as if you
had manually entered an arbitrary resolution in the guest’s display settings).
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4 Guest Additions
For Linux and Solaris guests, the Xorg server version 1.3 or later is required for
automatic resizing (the feature has been disabled on Fedora 9 guests due to a
bug in the X server they supply). The server version can be checked with Xorg
-version.
Finally, if the Guest Additions are installed, 3D graphics for guest applications
can be accelerated; see chapter 4.9, Hardware 3D acceleration (OpenGL and Di-
rect3D 8/9), page 72.
Time synchronization With the Guest Additions installed, VirtualBox can ensure that
the guest’s system time is better synchronized. This fixes the problem that an
operating system normally expects to have 100% of a computer’s time for itself
without interference, which is no longer the case when your VM runs together
with your host operating system and possibly other applications on your host. As
a result, your guest operating system’s timing will soon be off significantly. The
Guest Additions will re-synchronize the time regularly.
Shared folders These provide an easy way to exchange files between the host and
the guest. Much like ordinary Windows network shares, you can tell VirtualBox
to treat a certain host directory as a shared folder, and VirtualBox will make it
available to the guest operating system as a network share. For details, please
refer to chapter 4.7, Folder sharing, page 68.
Seamless windows With this feature, the individual windows that are displayed on
the desktop of the virtual machine can be mapped on the host’s desktop, as if
the underlying application was actually running on the host. See chapter 4.8,
Seamless windows, page 71 for details.
Shared clipboard With the Guest Additions installed, the clipboard of the guest op-
erating system can optionally be shared with your host operating system; see
chapter 3.3, General settings, page 46.
Automated Windows logons (Credentials passing; Windows guests only) For de-
tails, please see chapter 9.2, Automated Windows guest logons, page 137.
4.2 Versions
Each version of VirtualBox, even minor releases, ship with their own version of the
Guest Additions. While the interfaces through which the VirtualBox core communicates with the Guest Additions are kept stable so that Guest Additions already installed
in a VM should continue to work when VirtualBox is upgraded on the host, for best
results, it is recommended to keep the Guest Additions at the same version.
Starting with VirtualBox 3.1, the Windows and Linux Guest Additions therefore
check automatically whether they have to be updated. If the host is running a newer
VirtualBox version than the Guest Additions, a notification with with further instructions is displayed in the guest.
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4 Guest Additions
To disable this update check for the Guest Additions of a given virtual machine, set
the value of its /VirtualBox/GuestAdd/CheckHostVersion guest property to
0; see chapter 4.11, Guest properties, page 73 for details.
4.3 Windows Guest Additions
The VirtualBox Windows Guest Additions are designed to be installed in a virtual
machine running a Windows operating system. The following versions of Windows
guests are supported:
• Microsoft Windows NT 4.0 (any service pack)
• Microsoft Windows 2000 (any service pack)
• Microsoft Windows XP (any service pack)
• Microsoft Windows Server 2003 (any service pack)
• Microsoft Windows Server 2008
• Microsoft Windows Vista (all editions)
• Microsoft Windows 7 (all editions)
4.3.1 Installing the Windows Guest Additions
After mounting the Guest Additions ISO file, the Windows guest should automatically
start the Guest Additions installer, which installs the Guest Additions into your Windows guest.
Note: For Direct 3D acceleration to work in a Windows Guest, you must install
the Guest Additions in “Safe Mode”; see chapter 13, Known limitations, page
237 for details.
4.3.1.1 Mounting the Additions ISO file
In the “Devices” menu in the virtual machine’s menu bar, VirtualBox has a handy menu
item named “Install guest additions”, which will automatically bring up the Additions
in your VM window.
If you prefer to mount the additions manually, you can perform the following steps:
1. Start the virtual machine in which you have installed Windows.
2. Select “Mount CD/DVD-ROM” from the “Devices” menu in the virtual machine’s
menu bar and then “CD/DVD-ROM image”. This brings up the Virtual Disk Manager described in chapter 5.3, The Virtual Media Manager, page 80.
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3. In the Virtual Disk Manager, press the “Add” button and browse your host file
system for the VBoxGuestAdditions.iso file:
• On a Windows host, you can find this file in the VirtualBox installation
directory (usually under C:\Program files\Sun\xVM VirtualBox).
• On Mac OS X hosts, you can find this file in the application bundle of
VirtualBox. (Right click on the VirtualBox icon in Finder and choose Show
Package Contents. There it is located in the Contents/MacOS folder.)
• On a Linux host, you can find this file in the additions folder under where
you installed VirtualBox (normally /opt/VirtualBox/).
• On Solaris hosts, you can find this file in the additions folder under
where you installed VirtualBox (normally /opt/VirtualBox).
4. Back in the Virtual Disk Manager, select that ISO file and press the “Select” button. This will mount the ISO file and present it to your Windows guest as a
CD-ROM.
4.3.1.2 Running the installer
Unless you have the Autostart feature disabled in your Windows guest, Windows will now autostart the VirtualBox Guest Additions installation program
from the Additions ISO. If the Autostart feature has been turned off, choose
VBoxWindowsAdditions.exe from the CD/DVD drive inside the guest to start
the installer.
The installer will add several device drivers to the Windows driver database and
then invoke the hardware detection wizard.
Depending on your configuration, it might display warnings that the drivers are
not digitally signed. You must confirm these in order to continue the installation and
properly install the Additions.
After installation, reboot your guest operating system to activate the Additions.
4.3.2 Updating the Windows Guest Additions
Windows Guest Additions can be updated by running the installation program again,
as previously described. This will then replace the previous Additions drivers with
updated versions.
Alternatively, you may also open the Windows Device Manager and select “Update
driver...“ for two devices:
1. the VirtualBox Graphics Adapter and
2. the VirtualBox System Device.
For each, choose to provide your own driver and use “Have Disk” to point the wizard
to the CD -ROM drive with the Guest Additions.
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4.3.3 Unattended Installation
In order to allow for completely unattended guest installations, you can specify a
command line parameter to the install launcher:
VBoxWindowsAdditions.exe /S
This automatically installs the right files and drivers for the corresponding platform
(32- or 64-bit).
Note: Because of the drivers are not yet WHQL certified, you still might get
some driver installation popups, depending on the Windows guest version.
For more options regarding unattended guest installations, consult the command
line help by using the command:
VBoxWindowsAdditions.exe /?
4.3.4 Manual file extraction
If you would like to install the files and drivers manually, you can extract the files from
the Windows Guest Additions setup by typing:
VBoxWindowsAdditions.exe /extract
To explicitly extract the Windows Guest Additions for another platform than
the current running one (e.g. 64-bit files on a 32-bit system), you have to execute the appropriate platform installer (VBoxWindowsAdditions-x86.exe or
VBoxWindowsAdditions-amd64.exe) with the /extract parameter.
4.3.5 Windows Vista networking
Earlier versions of VirtualBox provided a virtual AMD PCNet Ethernet card to guests by
default. Since Microsoft no longer ships a driver for that card with Windows (starting
with Windows Vista), if you select Windows Vista or newer as the guest operating
system for a virtual machine, VirtualBox will instead present a virtual Intel network
controller to the guest (see chapter 6.1, Virtual networking hardware, page 88).
However, if for any reason you have a 32-bit Windows Vista VM that is configured
to use an AMD PCNet card, you will have no networking in the guest initially.
As a convenience, VirtualBox ships with a 32-bit driver for the AMD PCNet card,
which comes with the Windows Guest Additions. If you install these in a 32-bit Vista
guest, the driver will automatically be installed as well. If, for some reason, you
would like to install the driver manually, you can extract the required files from the
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4 Guest Additions
Windows Guest Additions setup. Please consult chapter 4.3.4, Manual file extraction,
page 64 on how to achieve this. You will then find the AMD PCNet driver files in the
x86\Network\AMD\netamd.inf subdirectory of the default install directory.
Alternatively, change the Vista guest’s VM settings to use an Intel networking card
instead of the default AMD PCNet card; see chapter 3.8, Network settings, page 54 for
details.
Unfortunately, there is no 64-bit driver available for the AMD PCNet card. So for
64-bit Windows VMs, you should always use the Intel networking devices.
4.4 Linux Guest Additions
Like the Windows Guest Additions, the VirtualBox Guest Additions for Linux take the
form of a set of device drivers and system applications which may be installed in the
guest operating system.
The following Linux distributions are officially supported:
• Fedora Core 4, 5, 6, 7, 8, 9 and 11;
• Redhat Enterprise Linux 3, 4 and 5;
• SUSE and openSUSE Linux 9, 10.0, 10.1, 10.2, 10.3, 11.0 and 11.1;
• Ubuntu 5.10, 6.06, 7.04, 7.10, 8.04, 8.10 and 9.04.
Other distributions may work if they are based on comparable software releases.
The version of the Linux kernel supplied by default in SUSE and openSUSE 10.2,
Ubuntu 6.10 (all versions) and Ubuntu 6.06 (server edition) contains a bug which
can cause it to crash during startup when it is run in a virtual machine. The Guest
Additions work in those distributions.
4.4.1 Installing the Linux Guest Additions
The VirtualBox Guest Additions for Linux are provided on the same ISO CD-ROM
as the Additions for Windows described above. They also come with an installation
program guiding you through the setup process, although, due to the significant differences between Linux distributions, installation may be slightly more complex.
Installation involves the following steps:
1. Before installing the Guest Additions, you will have to prepare your guest system
for building external kernel modules. This works similarly as described in chapter 2.3.2, The VirtualBox kernel module, page 34, except that this step must now
be performed in your Linux guest instead of on a Linux host system, as described
there.
Again, as with Linux hosts, we recommend using DKMS for Linux guests as well.
If it is not installed, use this command:
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4 Guest Additions
sudo apt-get install dkms
Install DKMS before installing the Linux Guest Additions.
2. Mount the VBoxGuestAdditions.iso file as your Linux guest’s virtual CDROM drive, exactly the same way as described for a Windows guest in chapter
4.3.1.1, Mounting the Additions ISO file, page 62.
3. Change to the directory where your CD-ROM drive is mounted and execute as
root:
sh ./VBoxLinuxAdditions-x86.run
In a 64-bit Linux guest, use VBoxLinuxAdditions-amd64.run instead.
The VirtualBox Guest Additions contain several different drivers. If for any reason
you do not wish to install them all, you can specify the ones which you wish on the
command line - for example
sh ./VBoxAdditions.run x11
to install the X Window graphic drivers. Type in the command
sh ./VBoxAdditions.run help
for more information.
To recompile the guest kernel modules, use this command:
/etc/init.d/vboxadd setup
After compilation you should reboot your guest to ensure that the new modules are
actually used.
4.4.2 Video acceleration and high resolution graphics modes
In Linux guests, VirtualBox video acceleration is available through the X Window System. Typically, in today’s Linux distributions, this will be the X.Org server. During the
installation process, X will be set up to use the VirtualBox video driver. On recent Linux
guests (that is, guests running X.Org server version 1.3 or later with the exception of
Fedora 9), graphics modes can be selected by resizing the VirtualBox window using
the mouse, or sending video mode hints using the VBoxManage tool.
If you are only using recent Linux guests systems, you can skip the rest of this
section. On older guest systems, whatever graphics modes were set up before the
installation will be used. If these modes do not suit your requirements, you can
change your setup by editing the configuration file of the X server, usually found in
/etc/X11/xorg.conf.
VirtualBox can use any default X graphics mode which fits into the virtual video
memory allocated to the virtual machine, as described in chapter 3.3, General settings,
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page 46. You can also add your own modes to the X server configuration file. You
simply need to add them to the “Modes” list in the “Display” subsection of the “Screen”
section. For example, the section shown here has a custom 2048x800 resolution mode
added:
Section "Screen"
EndSection
Identifier "Default Screen"
Device "VirtualBox graphics card"
Monitor "Generic Monitor"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "2048x800" "800x600" "640x480"
EndSubSection
4.4.3 Updating the Linux Guest Additions
The Guest Additions can simply be updated by going through the installation procedure again with an updated CD-ROM image. This will replace the drivers with updated
versions. You should reboot after updating the Guest Additions.
4.5 Solaris Guest Additions
Like the Windows Guest Additions, the VirtualBox Guest Additions for Solaris take the
form of a set of device drivers and system applications which may be installed in the
guest operating system.
The following Solaris distributions are officially supported:
• OpenSolaris Nevada (Build 82 and higher; this includes OpenSolaris 2008.05,
2008.11 and 2009.06);
• OpenSolaris Indiana (Developer Preview 2 and higher);
• Solaris 10 (u5 and higher).
Other distributions may work if they are based on comparable software releases.
4.5.1 Installing the Solaris Guest Additions
The VirtualBox Guest Additions for Solaris are provided on the same ISO CD-ROM
as the Additions for Windows and Linux described above. They also come with an
installation program guiding you through the setup process.
Installation involves the following steps:
1. Mount the VBoxGuestAdditions.iso file as your Solaris guest’s virtual CDROM drive, exactly the same way as described for a Windows guest in chapter
4.3.1.1, Mounting the Additions ISO file, page 62.
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If in case the CD-ROM drive on the guest doesn’t get mounted (observed on
some versions of Solaris 10), execute as root:
svcadm restart volfs
2. Change to the directory where your CD-ROM drive is mounted and execute as
root:
pkgadd -G -d ./VBoxSolarisAdditions.pkg
3. Choose “1” and confirm installation of the guest additions package. After the
installation is complete, re-login to X server on your guest to activate the X11
Guest Additions.
4.5.2 Uninstalling the Solaris Guest Additions
The Solaris Guest Additions can be safely removed by removing the package from the
guest. Open a root terminal session and execute:
pkgrm SUNWvboxguest
4.5.3 Updating the Solaris Guest Additions
The Guest Additions should be updated by first uninstalling the existing Guest Additions and then installing the new ones. Attempting to install new Guest Additions
without removing the existing ones is not possible.
4.6 OS/2 Guest Additions
VirtualBox also ships with a set of drivers that improve running OS/2 in a virtual
machine. Due to restrictions of OS/2 itself, this variant of the Guest Additions has a
limited feature set; see chapter 13, Known limitations, page 237 for details.
The OS/2 Guest Additions are provided on the same ISO CD-ROM as those for the
other platforms. As a result, mount the ISO in OS/2 as described previously. The OS/2
Guest Additions are located in the directory \32bit\OS2.
As we do not provide an automatic installer at this time, please refer to the
readme.txt file in that directory, which describes how to install the OS/2 Guest
Additions manually.
4.7 Folder sharing
Shared folders allow you to access files of your host system from within the guest
system, much like ordinary shares on Windows networks would – except that shared
folders do not need require networking. Shared folders must physically reside on
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the host and are then shared with the guest; sharing is accomplished using a special
service on the host and a file system driver for the guest, both of which are provided
by VirtualBox.
In order to use this feature, the VirtualBox Guest Additions have to be installed.
Note however that Shared Folders are only supported with Windows (2000 or newer),
Linux and Solaris guests.
To share a host folder with a virtual machine in VirtualBox, you must specify the
path of that folder and choose for it a “share name” that the guest can use to access it.
Hence, first create the shared folder on the host; then, within the guest, connect to it.
There are several ways in which shared folders can be set up for a particular virtual
machine:
• In the graphical user interface of a running virtual machine, you can select
“Shared folders” from the “Devices” menu, or click on the folder icon on the
status bar in the bottom right corner of the virtual machine window.
• If a virtual machine is not currently running, you can configure shared folders in
each virtual machine’s “Settings” dialog.
• From the command line, you can create shared folders using the VBoxManage
command line interface; see chapter 8, VBoxManage reference, page 106. The
command is as follows:
VBoxManage sharedfolder add "VM name"
--name "sharename" --hostpath "C:\test"
There are two types of shares:
1. VM shares which are only available to the VM for which they have been defined;
2. transient VM shares, which can be added and removed at runtime and do not
persist after a VM has stopped; for these, add the --transient option to the
above command line.
Shared folders have read/write access to the files at the host path by default. To
restrict the guest to have read-only access, create a read-only shared folder. This can
either be achieved using the GUI or by appending the parameter --readonly when
creating the shared folder with VBoxManage.
Then, you can mount the shared folder from inside a VM the same way as you would
mount an ordinary network share:
• In a Windows guest, starting with VirtualBox 1.5.0, shared folders are
browseable and are therefore visible in Windows Explorer. So, to attach the
host’s shared folder to your Windows guest, open Windows Explorer and look
for it under “My Networking Places” -> “Entire Network” -> “VirtualBox Shared
Folders”. By right-clicking on a shared folder and selecting “Map network drive”
from the menu that pops up, you can assign a drive letter to that shared folder.
Alternatively, on the Windows command line, use the following:
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4 Guest Additions
net use x: \\vboxsvr\sharename
While vboxsvr is a fixed name (note that vboxsrv would also work), replace
“x:“ with the drive letter that you want to use for the share, and sharename
with the share name specified with VBoxManage.
• In a Linux guest, use the following command:
mount -t vboxsf [-o OPTIONS] sharename mountpoint
• In a Solaris guest, use the following command:
mount -F vboxfs [-o OPTIONS] sharename mountpoint
Replace sharename (use lowercase) with the share name specified with
VBoxManage or the GUI, and mountpoint with the path where you want the
share to be mounted on the guest (e.g. /mnt/share). The usual mount rules
apply, that is, create this directory first if it does not exist yet.
Here is an example of mounting the shared folder for the user “jack” on OpenSolaris:
$id
uid=5000(jack) gid=1(other)
$mkdir /export/home/jack/mount
$pfexec mount -F vboxfs -o uid=5000,gid=1 jackshare /export/home/jack/mount
$cd ~/mount
$ls
sharedfile1.mp3 sharedfile2.txt
$
Beyond the standard options supplied by the mount command, the following are
available:
iocharset CHARSET
to set the character set used for I/O operations (utf8 by default) and
convertcp CHARSET
to specify the character set used for the shared folder name (utf8 by default).
The generic mount options (documented in the mount manual page) apply also.
Especially useful are the options uid, gid and mode, as they allow access by
normal users (in read/write mode, depending on the settings) even if root has
mounted the filesystem.
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4.8 Seamless windows
With the “seamless windows” feature of VirtualBox, you can have the windows that are
displayed within a virtual machine appear side by side next to the windows of your
host. This feature is supported for the following guest operating systems (provided
that the Guest Additions are installed):
• Windows guests (support added with VirtualBox 1.5);
• Linux or Solaris/OpenSolaris guests with an X.org server version 1.3 or higher
(support added with VirtualBox 1.6). The exception is Fedora 9, due to a bug in
its X server.
After seamless windows are enabled (see below), VirtualBox suppresses the display
of the Desktop background of your guest, allowing you to run the windows of your
guest operating system seamlessly next to the windows of your host:
1
To enable seamless mode, after starting the virtual machine, press the Host key (normally the right control key) together with “L”. This will enlarge the size of the VM’s
display to the size of your host screen and mask out the guest operating system’s background. To go back to the “normal” VM display (i.e. to disable seamless windows),
press the Host key and “L” again.
1
The X server version is not the same as the version of the entire X.org suite. You can type X -version
in a terminal to find out about the X.org server version level that is currently installed.
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4.9 Hardware 3D acceleration (OpenGL and Direct3D
8/9)
The VirtualBox Guest Additions contain experimental hardware 3D support for Windows, Linux and Solaris guests.
2
With this feature, if an application inside your virtual machine uses 3D features
through the OpenGL or Direct3D 8/9 programming interfaces, instead of emulating
them in software (which would be slow), VirtualBox will attempt to use your host’s
3D hardware. This works for all supported host platforms (Windows, Mac, Linux,
Solaris), provided that your host operating system can make use of your accelerated
3D hardware in the first place.
The 3D acceleration currently has the following preconditions:
1. It is only available for certain Windows, Linux and Solaris guests. In particular:
• For Windows guests, support is restricted to 32-bit versions of XP and Vista.
Both OpenGL and Direct3D 8/9 are supported (experimental).
• OpenGL on Linux requires kernel 2.6.27 and higher as well as X.org server
version 1.5 and higher. Ubuntu 8.10 and Fedora 10 have been tested and
confirmed as working.
• OpenGL on Solaris guests requires X.org server version 1.5 and higher.
2. The Guest Additions must be installed.
Note: For Direct 3D acceleration to work in a Windows Guest, VirtualBox
needs to replace Windows system files in the virtual machine. As a result, the
Guest Additions installation program offers Direct 3D acceleration as an option that must be explicitly enabled.Also, you must install the Guest Additions
in “Safe Mode”; see chapter 13, Known limitations, page 237 for details.
3. Because 3D support is still experimental at this time, it is disabled by default and
must be manually enabled in the VM settings (see chapter 3.3, General settings,
page 46).
Note: Enabling 3D acceleration may expose security holes to malicious software running the guest. The third-party code that VirtualBox uses for this
purpose (Chromium) is not hardened enough to prevent every risky 3D operation on the host.
2
OpenGL support for Windows guests was added with VirtualBox 2.1; support for Linux and Solaris fol-
lowed with version 2.2. With version 3, Direct3D 8/9 support was added for Windows guests. OpenGL
2.0 is now supported as well.
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4 Guest Additions
Technically, VirtualBox implements this by installing an additional hardware 3D
driver inside your guest when the Guest Additions are installed. This driver acts as
a hardware 3D driver and reports to the guest operating system that the (virtual)
hardware is capable of 3D hardware acceleration. When an application in the guest
then requests hardware acceleration through the OpenGL or Direct3D programming
interfaces, these are sent to the host through a special communication tunnel implemented by VirtualBox, and then the host performs the requested 3D operation via the
host’s programming interfaces.
4.10 Hardware 2D video acceleration for Windows
guests
Starting with version 3.1, the VirtualBox Guest Additions contain experimental hardware 2D video acceleration support for Windows guests.
With this feature, if an application (e.g. a video player) inside your VM uses 2D
video overlays to play a movie clip, then VirtualBox will attempt to use your host’s
video acceleration hardware instead of performing overlay stretching and color conversion in software (which would be slow). This currently works for Windows, Linux
and Mac host platforms, provided that your host operating system can make use of 2D
video acceleration in the first place.
The 2D video acceleration currently has the following preconditions:
1. It is only available for Windows guests (XP or later).
2. The Guest Additions must be installed.
3. Because 2D support is still experimental at this time, it is disabled by default and
must be manually enabled in the VM settings (see chapter 3.3, General settings,
page 46).
Technically, VirtualBox implements this by exposing video overlay DirectDraw capabilities in the guest video driver. The driver sends all overlay commands to the host
through a special communication tunnel implemented by VirtualBox, in order for the
host to perform the requested 2D operations via the host’s programming interfaces.
4.11 Guest properties
Starting with version 2.1, VirtualBox allows for requesting certain properties from a
running guest, provided that the VirtualBox Guest Additions are installed and the VM
is running. This is good for two things:
1. A number of predefined VM characteristics are automatically maintained by
VirtualBox and can be retrieved on the host, e.g. to monitor VM performance
and statistics.
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2. In addition, arbitrary string data can be exchanged between guest and host, and
in both directions.
To accomplish this, VirtualBox establishes a private communication channel between the VirtualBox Guest Additions and the host, and software on both sides can
use this channel to exchange string data for arbitrary purposes. Guest properties are
simply string keys to which a value is attached. They can be set (written to) by either
the host and the guest, and they can also be read from both sides.
In addition to establishing the general mechanism of reading and writing values, a
set of predefined guest properties is automatically maintained by the VirtualBox Guest
Additions to allow for retrieving interesting guest data such as the guest’s exact operating system and service pack level, the installed version of the Guest Additions,
users that are currently logged into the guest OS, network statistics and more. These
predefined properties are all prefixed with /VirtualBox/ and organized into a hierarchical tree of keys.
Some of this runtime information is shown when you select “Session Information
Dialog” from a virtual machine’s “Machine” menu.
A more flexible way to use this channel is via the VBoxManage guestproperty
command set; see chapter
8.25, VBoxManage guestproperty, page 132 for details. For
example, to have all the available guest properties for a given running VM listed with
their respective values, use this:
$ VBoxManage guestproperty enumerate "Windows Vista III"
VirtualBox Command Line Management Interface Version 3.1.0
(C) 2005-2009 Sun Microsystems, Inc.
All rights reserved.
Name: /VirtualBox/GuestInfo/OS/Product, value: Windows Vista Business Edition,
timestamp: 1229098278843087000, flags:
Name: /VirtualBox/GuestInfo/OS/Release, value: 6.0.6001,
timestamp: 1229098278950553000, flags:
Name: /VirtualBox/GuestInfo/OS/ServicePack, value: 1,
timestamp: 1229098279122627000, flags:
Name: /VirtualBox/GuestAdd/InstallDir,
value: C:/Program Files/Sun/xVM VirtualBox
Guest Additions, timestamp: 1229098279269739000, flags:
Name: /VirtualBox/GuestAdd/Revision, value: 40720,
timestamp: 1229098279345664000, flags:
Name: /VirtualBox/GuestAdd/Version, value: 3.1.0,
timestamp: 1229098279479515000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxControl.exe, value: 3.1.0r40720,
timestamp: 1229098279651731000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxHook.dll, value: 3.1.0r40720,
timestamp: 1229098279804835000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxDisp.dll, value: 3.1.0r40720,
timestamp: 1229098279880611000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxMRXNP.dll, value: 3.1.0r40720,
timestamp: 1229098279882618000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxService.exe, value: 3.1.0r40720,
timestamp: 1229098279883195000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxTray.exe, value: 3.1.0r40720,
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timestamp: 1229098279885027000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxGuest.sys, value: 3.1.0r40720,
timestamp: 1229098279886838000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxMouse.sys, value: 3.1.0r40720,
timestamp: 1229098279890600000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxSF.sys, value: 3.1.0r40720,
timestamp: 1229098279893056000, flags:
Name: /VirtualBox/GuestAdd/Components/VBoxVideo.sys, value: 3.1.0r40720,
timestamp: 1229098279895767000, flags:
Name: /VirtualBox/GuestInfo/OS/LoggedInUsers, value: 1,
timestamp: 1229099826317660000, flags:
Name: /VirtualBox/GuestInfo/OS/NoLoggedInUsers, value: false,
timestamp: 1229098455580553000, flags:
Name: /VirtualBox/GuestInfo/Net/Count, value: 1,
timestamp: 1229099826299785000, flags:
Name: /VirtualBox/HostInfo/GUI/LanguageID, value: C,
timestamp: 1229098151272771000, flags:
Name: /VirtualBox/GuestInfo/Net/0/V4/IP, value: 192.168.2.102,
timestamp: 1229099826300088000, flags:
Name: /VirtualBox/GuestInfo/Net/0/V4/Broadcast, value: 255.255.255.255,
timestamp: 1229099826300220000, flags:
Name: /VirtualBox/GuestInfo/Net/0/V4/Netmask, value: 255.255.255.0,
timestamp: 1229099826300350000, flags:
Name: /VirtualBox/GuestInfo/Net/0/Status, value: Up,
timestamp: 1229099826300524000, flags:
Name: /VirtualBox/GuestInfo/OS/LoggedInUsersList, value: username,
timestamp: 1229099826317386000, flags:
To query the value of a single property, use the “get” subcommand like this:
$ VBoxManage guestproperty get "Windows Vista III"
VirtualBox Command Line Management Interface Version 3.1.0
(C) 2005-2009 Sun Microsystems, Inc.
All rights reserved.
Value: Windows Vista Business Edition
"/VirtualBox/GuestInfo/OS/Product"
For more complex needs, you can use the VirtualBox programming interfaces; see
chapter 10, VirtualBox programming interfaces, page 154.
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5 Virtual storage
As the virtual machine will most probably expect to see a hard disk built into its virtual
computer, VirtualBox must be able to present “real” storage to the guest as a virtual
hard disk. There are presently three methods in which to achieve this:
1. Most commonly, VirtualBox will use large image files on a real hard disk and
present them to a guest as a virtual hard disk. This is described in chapter 5.2,
Disk image files (VDI, VMDK, VHD, HDD), page 79.
2. Alternatively, if you have iSCSI storage servers, you can attach such a server to
VirtualBox as well; this is described in chapter 5.8, iSCSI servers, page 86.
3. Finally, as an experimental feature, you can allow a virtual machine to access
one of your host disks directly; this advanced feature is described in chapter
9.11, Using a raw host hard disk from a guest, page 145.
Each such virtual storage device (image file, iSCSI target or physical hard disk) will
need to be connected to the virtual hard disk controller that VirtualBox presents to a
virtual machine. This is explained in the next section.
5.1 Hard disk controllers: IDE, SATA (AHCI), SCSI
In a real PC, hard disks and CD-ROM/DVD drives are connected to a device called
hard disk controller which drives hard disk operation and data transfers. VirtualBox
can emulate the three most common types of hard disk controllers typically found in
today’s PCs: IDE, SATA (AHCI) and SCSI.
1
• IDE (ATA) controllers have been in use since the 1980s. Initially, this type of
interface worked only with hard disks, but was later extended to also support
CD-ROM drives and other types of removable media. In physical PCs, this standard uses flat ribbon parallel cables with 40 or 80 wires. Each such cable can
connect two devices to a controller, which have traditionally been called “master”
and “slave”. Typical hard disk controllers have two connectors for such cables;
as a result, most PCs support up to four devices.
In VirtualBox, each virtual machine has one IDE controller enabled by default,
which gives you up to four virtual storage devices that you can attach to the
1
SATA support was added with VirtualBox 1.6; experimental SCSI support was added with 2.1 and fully
implemented with 2.2. Generally, storage attachments were made much more flexible with VirtualBox
3.1; see below.
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machine. (By default, one of these four – the secondary master – is preconfigured
to be the machine’s virtual CD-ROM/DVD drive, but this can be changed.2)
So even if your guest operating system has no support for SCSI or SATA devices,
it should always be able to see the default IDE controller that is enabled by
default.
You can also select which exact type of IDE controller hardware VirtualBox
should present to the virtual machine (PIIX3, PIIX4 or ICH6). This makes no
difference in terms of performance, but if you import a virtual machine from
another virtualization product, the operating system in that machine may expect
a particular controller and crash if it isn’t found.
After you have created a new virtual machine with the “New Virtual Machine”
wizard of the graphical user interface, you will typically see one IDE controller
in the machine’s “Storage” settings. Of the four slots of this controller, one will
be used by the hard disk that you probably created when you set up the VM, and
another one will be the machine’s virtual CD-ROM/DVD drive.
• Serial ATA (SATA) is a newer standard introduced in 2003. Compared to IDE,
it supports both much higher speeds and more devices per hard disk controller.
Also, with physical hardware, devices can be added and removed while the system is running. The standard interface for SATA controllers is called Advanced
Host Controller Interface (AHCI).
For compatibility reasons, AHCI controllers by default operate the disks attached
to it in a so-called “IDE compatibility mode”, unless SATA support is explicitly
requested. “IDE compatibility mode” only means that the drives can be seen and
operated by the computer’s BIOS. Still, disks assigned to those slots will operate
in full-speed AHCI mode once the guest operating system has loaded its AHCI
device driver.
Like a real SATA controller, VirtualBox’s virtual SATA controller operates faster
and also consumes less CPU resources than the virtual IDE controller. Also, this
allows you to connect up to 30 virtual hard disks to one machine instead of just
three, as with IDE. Of these, the first four (numbered 0-3 in the graphical user
interface) are operated in IDE compatibility mode by default.
To enable the SATA controller, on the “Storage” page of a virtual machine’s settings dialog, click on the “Add Controller” button under the “Storage Tree” box
and then select “Add SATA Controller”. After this, the additional controller will
appear as a separate PCI device in the virtual machine.
2
The assignment of the machine’s CD-ROM/DVD drive to the secondary master was fixed before VirtualBox
3.1; it is now changeable, and the drive can be at other slots of the IDE controller or at other storage
controller such as the SATA controller, and there can be more than one such drive.
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Warning: The entire SATA controller and the virtual disks attached to it (including those in IDE compatibility mode) will not be seen by operating systems that do not have device support for AHCI. In particular, there is no support for AHCI in Windows before Windows Vista, so Windows XP (even SP2)
will not see such disks unless you install additional drivers. We therefore do
not recommend installing operating systems on SATA disks at this time.
To change the IDE compatibility mode settings for the SATA controller, please see
chapter 8.13, VBoxManage storagectl / storageattach, page 123.
• SCSI is another established industry standard, standing for “Small Computer
System Interface”. This was established as early as 1986 as a generic interface for
data transfer between all kinds of devices, including storage devices. Today SCSI
is still used for connecting hard disks and tape devices, but it has mostly been
displaced in commodity hardware. It is still in common use in high-performance
workstations and servers.
Primarily for compatibility with other virtualization software, VirtualBox optionally supports LsiLogic and BusLogic SCSI controllers, to each of which up to 16
virtual hard disks can be attached.
To enable a SCSI controller, on the “Storage” page of a virtual machine’s settings dialog, click on the “Add Controller” button under the “Storage Tree” box
and then select “Add SCSI Controller”. After this, the additional controller will
appear as a separate PCI device in the virtual machine.
Warning: There are limitations with the default SCSI drivers shipped with
some operating systems: the standard Windows XP driver for the LsiLogic
controller does not detect a hard disk attached to the controller’s first port,
and the BusLogic controller does not work with Windows NT4 guests.
In summary, VirtualBox gives you the following categories of virtual storage slots:
1. three slots attached to the traditional IDE controller, which are always present
(plus one for the virtual CD-ROM device);
2. 30 slots attached to the SATA controller, if enabled and provided that your guest
operating system can see it; these slots can either be
a) in IDE compatibility mode (by default, slots 0-3) or
b) in SATA mode;
3. 16 slots attached to the SCSI controller, if enabled and supported by the guest
operating system.
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5.2 Disk image files (VDI, VMDK, VHD, HDD)
Disk image files reside on the host system and are seen by the guest systems as hard
disks of a certain geometry. When a guest operating system reads from or writes to a
hard disk, VirtualBox redirects the request to the image file.
Note that when you create an image file, its size needs to be specified, which represents a fixed geometry of the virtual disk. It is therefore not possible to change the
size of the virtual hard disk later.
VirtualBox supports four variants of disk image files:
• Normally, VirtualBox uses its own container format for guest hard disks – Virtual
Disk Image (VDI) files. In particular, this format will be used when you create a
new virtual machine with a new disk.
• VirtualBox also fully supports the popular and open VMDK container format that
is used by many other virtualization products, in particular, by VMware.
3
• VirtualBox also fully supports the VHD format used by Microsoft.
• Image files of Parallels version 2 (HDD format) are also supported.4For lack of
documentation of the format, newer formats (3 and 4) are not supported. You
can however convert such image files to version 2 format using tools provided
by Parallels.
Irrespective of the disk format, as briefly mentioned in chapter 1.6, Creating your
first virtual machine, page 17, there are two options of how to create a disk image:
fixed-size or dynamically expanding.
• If you create a fixed-size image of e.g. 10 GB, an image file of roughly the same
size will be created on your host system. Note that the creation of a fixed-size
image can take a long time depending on the size of the image and the write
performance of your hard disk.
• For more flexible storage management, use a dynamically expanding image.
This will initially be very small and not occupy any space for unused virtual disk
sectors, but the image file will grow every time a disk sector is written to for the
first time. While this format takes less space initially, the fact that VirtualBox
needs to constantly expand the image file consumes additional computing resources, so until the disk has fully expanded, write operations are slower than
with fixed size disks. However, after a dynamic disk has fully expanded, the
performance penalty for read and write operations is negligible.
3
Initial support for VMDK was added with VirtualBox 1.4; since version 2.1, VirtualBox supports VMDK
fully, meaning that you can create snapshots and use all the other advanced features described above for
VDI images with VMDK also.
4
Support was added with VirtualBox 3.1.
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5.3 The Virtual Media Manager
VirtualBox keeps an internal registry of all available hard disk, CD/DVD-ROM and
floppy disk images. This registry can be viewed and changed in the Virtual Media
Manager, which you can access from the “File” menu in the VirtualBox main window:
The window shows you all images that are currently registered with VirtualBox, conveniently grouped in three tabs for the three possible formats. These formats are:
• Hard disk images, either in VirtualBox’s own Virtual Disk Image (VDI) format or
in the third-party formats listed above;
• CD/DVD images in standard ISO format;
• floppy images in standard RAW format.
As you can see in the screenshot above, for each image, the Virtual Media Manager
shows you the full path of the image file and other information, such as the virtual
machine the image is currently attached to, if any.
The Virtual Media Manager allows you to
• create new hard disk images using the “New” button; this will bring up the
“Create Disk Image” wizard already described in chapter 1.6, Creating your first
virtual machine, page 17;
• import existing image files from your hard drive into VirtualBox using the “Add”
button;
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• remove an image from the registry (and optionally delete the image file when
doing so);
• “release” an image, that is, detach it from a virtual machine if it is currently
attached to one as a virtual hard disk.
We recommend that you maintain two special folders on your system for keeping
images: one for hard disk image files (which can, in the case of dynamically expanding images, grow to considerable sizes), and one for ISO files (which were probably
downloaded from the Internet).
Hard disk image files can be copied onto other host systems and imported into
virtual machines there, although certain guest systems (notably Windows 2000 and
XP) will require that the new virtual machine be set up in a similar way to the old one.
Note: Do not simply make copies of virtual disk images. If you import such
a second copy into a virtual machine, VirtualBox will complain with an error, since VirtualBox assigns a unique identifier (UUID) to each disk image to
make sure it is only used once. See chapter 5.6, Cloning disk images, page 85
for instructions on this matter. Also, if you want to copy a virtual machine to
another system, VirtualBox has an import/export facility that might be better suited for your needs; see chapter 1.11, Importing and exporting virtual
machines, page 29.
5.4 Special image write modes
For each virtual disk image supported by VirtualBox, you can use special commands
how write operations from the virtual machine should affect the image and how snapshots should affect it. This applies to all of the aforementioned image formats (VDI,
VMDK, VHD or HDD) and irrespective of whether an image is fixed-size or dynamically
expanding.
1. With normal images (the default setting), there are no restrictions on how
guests can read from and write to the disk.
When you take a snapshot of your virtual machine as described in chapter 1.8,
Snapshots, page 25, the state of such a “normal hard disk” will be recorded
together with the snapshot, and when reverting to the snapshot, its state will be
fully reset.
(Technically, strictly speaking, the image file is not “reset”. Instead, when a
snapshot is taken, VirtualBox “freezes” the image file and no longer writes to
it. For the write operations from the VM, a second, “differencing” image file is
created which receives only the changes to the original image; see below for
details.)
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While you can attach the same “normal” image to more than one virtual machine, only one of these virtual machines attached to the same image file can
be executed simultaneously, as otherwise there would be conflicts if several machines write to the same image file.
5
2. By contrast, immutable images only remember write accesses temporarily while
the virtual machine is running; all changes are lost when the virtual machine is
restarted. As a result, as opposed to “normal” images, the same immutable image
can be used with several virtual machines without restrictions.
(Again, technically, VirtualBox never writes to an immutable image directly at
all. All write operations from the machine will be directed to a differencing
image; the next time the VM is started, the differencing image is reset so that
every time the VM starts, its immutable images have exactly the same content.6)
If the automatic discarding of the differencing image on VM startup does not fit
your needs, you can turn it off using the autoreset parameter of VBoxManage
modifyhd; see chapter 8.16, VBoxManage modifyhd, page 126 for details.
With respect to snapshots, the behavior of immutable images is identical to that
of “normal” images. When reverting to a snapshot taken of an immutable image,
its state will be fully reset to that of the snapshot.
Creating an immutable image makes little sense since it would be initially empty
and lose its contents with every machine restart (unless you really want to have
a disk that is always unformatted when the machine starts up). As a result,
normally, you would first create a “normal” image and then, when you deem its
contents useful, later mark it immutable using VBoxManage modifyhd; again,
please see chapter 8.16, VBoxManage modifyhd, page 126. Alternatively, open
an existing image in “immutable” mode using VBoxManage openmedium; see
chapter 8.12, VBoxManage openmedium / closemedium, page 123.
3. Finally, write-through hard disks are like normal hard disks in that they fully
support read and write operations. However, such images are completely unaffected by snapshots: their state is not saved when a snapshot is taken, and not
restored when a snapshot is restored.
To create a disk image in VDI format as “write-through”, use the VBoxManage
createhd command; see chapter 8.15, VBoxManage createhd, page 125. To
mark an existing image as write-through, use VBoxManage modifyhd; see
chapter 8.16, VBoxManage modifyhd, page 126.
To illustrate the differences between the various types with respect to snapshots:
Assume you have installed your guest operating system in your VM, and you have
5
This restriction is more lenient now than it was before VirtualBox 2.2. Previously, each “normal” disk
image could only be attached to one single machine. Now it can be attached to more than one machine
so long as only one of these machines is running.
6
This behavior also changed with VirtualBox 2.2. Previously, the differencing images were discarded when
the VM session ended; now they are discarded every time the VM starts.
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taken a snapshot. Imagine you have accidentally infected your VM with a virus and
would like to go back to the snapshot. With a normal hard disk image, you simply
revert the state of the VM, and the earlier state of your hard disk image will be restored
as well (and your virus infection will be undone). With an immutable hard disk,
irrespective of the snapshot, all it takes is to shut down and restart your VM, and the
virus infection will be discarded. With a write-through image however, you cannot
easily undo the virus infection by means of virtualization, but will have to disinfect
your virtual machine like a real computer.
Still, you might find write-though images useful if you want to preserve critical data
irrespective of snapshots, and since you can attach more than one image to a VM, you
may want to have one immutable for the operating system and one write-through for
your data files.
5.5 Differencing images
The previous section hinted at differencing images and how they are used with snapshots, immutable images and multiple disk attachments. For the inquisitive VirtualBox
user, this section describes in more detail how they work.
A differencing image is a special disk image that only holds the differences to another image. A differencing image by itself is useless, it must always refer to another
image. The differencing image is then typically referred to as a “child”, which holds
the differences to its “parent”.
When a differencing image is active, it receives all write operations from the virtual
machine instead of its parent. The differencing image only contains the sectors of the
virtual hard disk that have changed since the differencing image was created. When
the machine reads a sector from such a virtual hard disk, it looks into the differencing
image first. If the sector is present, it is returned from there; if not, VirtualBox looks
into the parent. In other words, the parent becomes “read-only”; it is never written to
again, but it is read from if a sector has not changed.
Differencing images can be chained. If another differencing image is created for a
virtual disk that already has a differencing image, then it becomes a “grandchild” of
the original parent. The first differencing image then becomes read-only as well, and
write operations only go to the second-level differencing image. When reading from
the virtual disk, VirtualBox needs to look into the second differencing image first, then
into the first if the sector was not found, and then into the original image.
There can be an unlimited number of differencing images, and each image can
have more than one child. As a result, the differencing images can form a complex
tree with parents, “siblings” and children, depending on how complex your machine
configuration is. Write operations always go to the one active differencing image, and
for read operations, VirtualBox may need to look up all the parents in the chain until
the sector in question is found. You can look at such a tree in the Virtual Disk Manager.
In all of these situations, to the virtual machine, the virtual hard disk behaves like
any other disk. While the virtual machine is running, there is a slight run-time I/O
overhead because VirtualBox might need to look up sectors several times. This is not
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noticeable however since the tables with sector information are always kept in memory
and can be looked up quickly.
Differencing images are used in the following situations:
1. Snapshots. When you create a snapshot, as explained in the previous section,
VirtualBox “freezes” the images of the virtual machine and creates differencing
images for each of them (to be precise: for those images which are not in “writethrough” mode). From the point of view of the virtual machine, the virtual
disks continue to operate before, but all write operations go into the differencing
images. Each time you create another snapshot, more differencing images are
created and attached forming a chain or tree.
If you now restore a snapshot – that is, if you want to go back to the exact
machine state that was stored in the snapshot –, the following happens:
a) VirtualBox copies the virtual machine settings that were copied into the
snapshot back to the virtual machine. As a result, if you have made changes
to the machine configuration since taking the snapshot, they are undone.
b) If the snapshot was taken while the machine was running, it contains a
saved machine state, and that state is restored as well; after restoring the
snapshot, the machine will then be in “Saved” state and resume execution
from there when it is next started. Otherwise it will be in “Powered Off”
state and do a full boot.
c) The differencing images holding all the write operations since the snapshot
was taken are thrown away, and the original parent images are made active
again. (If you restored the “root” snapshot, then this will be the root disk
images; otherwise, some other differencing image descended from it.) This
effectively restores the old machine state.
If you later delete a snapshot in order to free disk space, one of the differencing
images becomes obsolete. In this case, the differencing images cannot simply be
deleted. Instead, VirtualBox needs to look at each sector of the differencing image and needs to copy it back into the parent; this is called “merging” images and
can be a potentially lengthy process, depending on how large the differencing
image is.
2. Immutable images. When an image is switched to “immutable” mode, a dif-
ferencing image is created as well. As with snapshots, the parent image then
becomes read-only, and the differencing image receives all the write operations.
Every time the virtual machine is started, all the immutable images which are
attached to it have their differencing images thrown away, effectively resetting
the virtual machine’s virtual disk with every restart.
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5.6 Cloning disk images
You can duplicate hard disk image files on the same host to quickly produce a second
virtual machine with the same operating system setup. However, you should only make
copies of virtual disk images using the utility supplied with VirtualBox; see chapter
8.17, VBoxManage clonehd, page 127. This is because VirtualBox assigns a unique
identity number (UUID) to each disk image, which is also stored inside the image, and
VirtualBox will refuse to work with two images that use the same number. If you do
accidentally try to reimport a disk image which you copied normally, you can make a
second copy using VirtualBox’s utility and import that instead.
Note that newer Linux distributions identify the boot hard disk from the ID of the
drive. The ID VirtualBox reports for a drive is determined from the UUID of the
virtual disk image. So if you clone a disk image and try to boot the copied image
the guest might not be able to determine its own boot disk as the UUID changed.
In this case you have to adapt the disk ID in your boot loader script (for example
/boot/grub/menu.lst). The disk ID looks like this:
scsi-SATA_VBOX_HARDDISK_VB5cfdb1e2-c251e503
The ID for the copied image can be determined with
hdparm -i /dev/sda
5.7 Writing CDs and DVDs using the host drive
When you attach your host’s CD/DVD drive to a virtual machine (see chapter 3.6,
Storage settings, page 51), this normally gives the machine read-only access to the
host drive. This prevents the guest from writing to the host drive. In particular, you
cannot burn CDs and DVDs from the guest this way.
As an experimental feature (which currently works for data only, audio is not supported), it is possible to give the guest access to the CD/DVD writing features of the
host drive (if available):
VBoxManage storageattach <uuid|vmname>
See also chapter 8.13, VBoxManage storagectl / storageattach, page 123.
Even if pass-through is enabled, unsafe commands, such as updating the drive
firmware, will be blocked.
--storagectl <name>
--port <number>
--device <number>
[--type <dvddrive|hdd|fdd>
--medium <none|emptydrive|uuid|filename|host:<drive>>]
[--passthrough <on|off>]
[--forceunmount]
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5.8 iSCSI servers
iSCSI stands for “Internet SCSI” and is a standard that allows for using the SCSI protocol over Internet (TCP/IP) connections. Especially with the advent of Gigabit Ethernet,
it has become affordable to attach iSCSI storage servers simply as remote hard disks
to a computer network. In iSCSI terminology, the server providing storage resources
is called an “iSCSI target”, while the client connecting to the server and accessing its
resources is called “iSCSI initiator”.
VirtualBox can transparently present iSCSI remote storage to a virtual machine as
a virtual hard disk. The guest operating system will not see any difference between a
virtual disk image (VDI file) and an iSCSI target. To achieve this, VirtualBox has an
integrated iSCSI initiator.
VirtualBox’s iSCSI support has been developed according to the iSCSI standard and
should work with all standard-conforming iSCSI targets. To use an iSCSI target with
VirtualBox, you must first register it as a virtual hard disk with VBoxManage; see
chapter 8.19, VBoxManage addiscsidisk, page 128. The target will show up in the list
of disk images, as described in chapter 5.3, The Virtual Media Manager, page 80, and
can thus be attached to one of the VM’s three hard disk slots the usual way.
5.8.1 Access iSCSI targets via Internal Networking
As an experimental feature, VirtualBox allows for accessing an iSCSI target running
in a virtual machine which is configured for using Internal Networking mode (as described in chapter 6.5, Internal networking, page 93). The setup of the virtual machine
which uses such an iSCSI target is done as described above. The only difference is that
the IP address of the target must be specified as a numeric IP address.
The IP stack accessing Internal Networking must be configured in the virtual machine which accesses the iSCSI target. A free static IP and a MAC address not used by
other virtual machines must be chosen. In the example below, adapt the name of the
virtual machine, the MAC address, the IP configuration and the Internal Networking
name (“MyIntNet”) according to your needs. The following seven commands must be
issued:
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/Trusted 1
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/Config/MAC 08:00:27:01:02:0f
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/Config/IP 10.0.9.1
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/Config/Netmask 255.255.255.0
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/LUN#0/Driver IntNet
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/LUN#0/Config/Network MyIntNet
VBoxManage setextradata VMNAME
VBoxInternal/Devices/IntNetIP/0/LUN#0/Config/IsService 1
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Finally the iSCSI disk must be registered with the -intnet option to tell the iSCSI
initiator to use internal networking:
VBoxManage addiscsidisk --server 10.0.9.30
--target iqn.2008-12.com.sun:sampletarget --intnet
The target address must be specified as a numeric IP address, as there is no DNS
resolver for internal networking.
The virtual machine with the iSCSI target should be started before the VM using it
is powered on. If a virtual machine using an iSCSI disk is started without having the
iSCSI target powered up, it can take up to 200 seconds to detect this situation. The
VM will fail to power up.
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As briefly mentioned in chapter 3.8, Network settings, page 54, VirtualBox provides up
to eight virtual PCI Ethernet cards for each virtual machine. For each such card, you
can individually select
1. the hardware that will be virtualized as well as
2. the virtualization mode that the virtual card will be operating in with respect to
your physical networking hardware on the host.
Four of the network cards can be configured in the “Network” section of the settings
dialog in the graphical user interface of VirtualBox. You can configure all eight network
cards on the command line via VBoxManage modifyvm; see chapter 8.5, VBoxManage
modifyvm, page 114.
This chapter explains the various networking settings in more detail.
6.1 Virtual networking hardware
For each card, you can individually select what kind of hardware will be presented to
the virtual machine. VirtualBox can virtualize the following five types of networking
hardware:
• AMD PCNet PCI II;
• AMD PCNet FAST III (the default);
• Intel PRO/1000 MT Desktop;
• Intel PRO/1000 T Server;
• Intel PRO/1000 MT Server.
The PCNet FAST III is the default because it is supported by nearly all operating
systems out of the box, as well as the GNU GRUB boot manager. As an exception,
the Intel PRO/1000 family adapters are chosen for some guest operating system types
that no longer ship with drivers for the PCNet card, such as Windows Vista; see chapter
4.3.5, Windows Vista networking, page 64 for details.
1
Support for the Intel PRO/1000 MT Desktop type was added with VirtualBox 1.6. The T Server variant
of the Intel PRO/1000 card was added with VirtualBox 1.6.2 because this one is recognized by Windows
XP guests without additional driver installation. The MT Server variant was added with VirtualBox 2.2
to facilitate OVF imports from other platforms.
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VirtualBox has limited support for so-called jumbo frames, i.e. networking packets
with more than 1500 bytes of data, provided that you use the Intel card virtualization and bridged networking. In other words, jumbo frames are not supported in NAT
mode or with the AMD networking devices; in those cases, jumbo packets will silently
be dropped for both the transmit and the receive direction. Guest operating systems
trying to use this feature will observe this as a packet loss, which may lead to unexpected application behavior in the guest. This does not cause problems with guest
operating systems in their default configuration, as jumbo frames need to be explicitly
enabled.
6.2 Introduction to networking modes
Each of the eight networking adapters can be separately configured to operate in one
of the following five modes:
Not attached In this mode, VirtualBox reports to the guest that a network card is
present, but that there is no connection – as if no Ethernet cable was plugged
into the card. This way it is possible to “pull” the virtual Ethernet cable and
disrupt the connection, which can be useful to inform a guest operating system
that no network connection is available and enforce a reconfiguration.
Network Address Translation (NAT) If all you want is to browse the Web, download
files and view e-mail inside the guest, then this default mode should be sufficient
for you, and you can safely skip the rest of this section. Please note that the ping
utility does not work over NAT, and that there are certain limitations when using
Windows file sharing (see chapter 6.3.3, NAT limitations, page 91 for details).
Bridged networking This is for more advanced networking needs such as network
simulations and running servers in a guest. When enabled, VirtualBox sets up
an additional, software-based network interface on the host to which the virtual
machine is connected.
Internal networking This can be used to create a different kind of software-based
network which is visible to selected virtual machines, but not to applications
running on the host or to the outside world.
Host-only networking This can be used to create a network containing the host and
a set of virtual machines, without the need for the host’s physical network interface. Instead, a virtual network interface (similar to a loopback interface) is
created on the host, providing connectivity among virtual machines and the host.
The following sections describe the available network modes in more detail.
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6.3 Network Address Translation (NAT)
Network Address Translation (NAT) is the simplest way of accessing an external network from a virtual machine. Usually, it does not require any configuration on the
host network and guest system. For this reason, it is the default networking mode in
VirtualBox.
A virtual machine with NAT enabled acts much like a real computer that connects
to the Internet through a router. The “router”, in this case, is the VirtualBox networking engine, which maps traffic from and to the virtual machine transparently. The
disadvantage of NAT mode is that, much like a private network behind a router, the
virtual machine is invisible and unreachable from the outside internet; you cannot run
a server this way unless you set up port forwarding (described below).
The virtual machine receives its network address and configuration on the private
network from a DHCP server integrated into VirtualBox. The IP address thus assigned
to the virtual machine is usually on a completely different network than the host. As
more than one card of a virtual machine can be set up to use NAT, the first card is
connected to the private network 10.0.2.0, the second card to the network 10.0.3.0
and so on. If you need to change the guest-assigned IP range for some reason, please
refer to chapter 9.13, Fine-tuning the VirtualBox NAT engine, page 148.
The network frames sent out by the guest operating system are received by
VirtualBox’s NAT engine, which extracts the TCP/IP data and resends it using the host
operating system. To an application on the host, or to another computer on the same
network as the host, it looks like the data was sent by the VirtualBox application on
the host, using an IP address belonging to the host. VirtualBox listens for replies to
the packages sent, and repacks and resends them to the guest machine on its private
network.
6.3.1 Configuring port forwarding with NAT
As the virtual machine is connected to a private network internal to VirtualBox and
invisible to the host, network services on the guest are not accessible to the host machine or to other computers on the same network. However, VirtualBox can make
selected services available outside of the guest by using port forwarding. This means
that VirtualBox listens to certain ports on the host and resends all packets which arrive
on them to the guest on the ports used by the services being forwarded.
To an application on the host or other physical (or virtual) machines on the network,
it looks as though the service being proxied is actually running on the host (note that
this also means that you cannot run the same service on the same ports on the host).
However, you still gain the advantages of running the service in a virtual machine
– for example, services on the host machine or on other virtual machines cannot be
compromised or crashed by a vulnerability or a bug in the service, and the service can
run in a different operating system than the host system.
You can set up a guest service which you wish to proxy using the command line
tool VBoxManage. You will need to know which ports on the guest the service uses
and to decide which ports to use on the host (often but not always you will want to
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use the same ports on the guest and on the host). You can use any ports on the host
which are not already in use by a service. An example of how to set up incoming NAT
connections to an ssh server on the guest requires the following three commands:
VBoxManage setextradata "Linux Guest"
"VBoxInternal/Devices/pcnet/0/LUN#0/Config/guestssh/Protocol" TCP
VBoxManage setextradata "Linux Guest"
"VBoxInternal/Devices/pcnet/0/LUN#0/Config/guestssh/GuestPort" 22
VBoxManage setextradata "Linux Guest"
"VBoxInternal/Devices/pcnet/0/LUN#0/Config/guestssh/HostPort" 2222
The above example assumes a PCNet virtual network card; if you have configured
the guest to use the Intel PRO/1000, replace “pcnet” with “e1000” in the above commands. Similarly, if you want to configure a different interface instance replace the
/0/ with the appropriate index. pcnet and e1000 are counted separately in this
respect, and counting starts at 0 for both types.
The name guestssh is an arbitrary one chosen for this particular forwarding configuration. With that configuration in place, all TCP connections to port 2222 on the
host will be forwarded to port 22 on the guest. Protocol can be either of TCP or UDP
(these are case insensitive). To remove a mapping again, use the same commands, but
leaving out the values (in this case TCP, 22 and 2222).
It is not possible to configure incoming NAT connections while the VM is running.
However you can change the settings for a VM which is currently saved (or powered
off at a snapshot).
6.3.2 PXE booting with NAT
PXE booting is now supported in NAT mode. The NAT DHCP server provides a boot
file name of the form vmname.pxe if the directory TFTP exists in the directory where
the user’s VirtualBox.xml file is kept. It is the responsibility of the user to provide
vmname.pxe.
6.3.3 NAT limitations
There are four limitations of NAT mode which users should be aware of:
ICMP protocol limitations: Some frequently used network debugging tools (e.g.
ping or tracerouting) rely on the ICMP protocol for sending/receiving messages.
While ICMP support has been improved with VirtualBox 2.1 (ping should now
work), some other tools may not work reliably.
Receiving of UDP broadcasts is not reliable: The guest does not reliably receive
broadcasts, since, in order to save resources, it only listens for a certain amount
of time after the guest has sent UDP data on a particular port. As a consequence,
NetBios name resolution based on broadcasts does not always work (but WINS
always works). As a workaround, you can use the numeric IP of the desired
server in the \\server\share notation.
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Protocols such as GRE are unsupported: Protocols other than TCP and UDP are
not supported. This means some VPN products (e.g. PPTP from Microsoft) cannot be used. There are other VPN products which use simply TCP and UDP.
Forwarding host ports < 1024 impossible: On Unix-based hosts (e.g. Linux, So-
laris, Mac OS X) it is not possible to bind to ports below 1024 from applications
that are not run by root. As a result, if you try to configure such a port forwarding, the VM will refuse to start.
These limitations normally don’t affect standard network use. But the presence of
NAT has also subtle effects that may interfere with protocols that are normally working. One example is NFS, where the server is often configured to refuse connections
from non-privileged ports (i.e. ports not below 1024).
6.4 Bridged networking
With bridged networking, VirtualBox uses a device driver on your host system that
filters data from your physical network adapter. This driver is therefore called a “net
filter” driver. This allows VirtualBox to intercept data from the physical network and
inject data into it, effectively creating a new network interface in software. When a
guest is using such a new software interface, it looks to the host system as though the
guest were physically connected to the interface using a network cable: the host can
send data to the guest through that interface and receive data from it. This means that
you can set up routing or bridging between the guest and the rest of your network.
For this to work, VirtualBox needs a device driver on your host system. The way
bridged networking works has been completely rewritten with VirtualBox 2.0 and 2.1,
depending on the host operating system. From the user perspective, the main difference is that complex configuration is no longer necessary on any of the supported host
operating systems.
2
Note: Even though TAP is no longer necessary on Linux with bridged networking, you can still use TAP interfaces for certain advanced setups, since you can
connect a VM to any host interface – which could also be a TAP interface.
To enable bridged networking, all you need to do is to open the Settings dialog of
a virtual machine, go to the “Network” page and select “Bridged network” in the drop
down list for the “Attached to” field. Finally, select desired host interface from the
2
For Mac OS X and Solaris hosts, net filter drivers were already added in VirtualBox 2.0 (as initial support
for Host Interface Networking on these platforms). With VirtualBox 2.1, net filter drivers were also
added for the Windows and Linux hosts, replacing the mechanisms previously present in VirtualBox for
those platforms; especially on Linux, the earlier method required creating TAP interfaces and bridges,
which was complex and varied from one distribution to the next. None of this is necessary anymore.
Bridged network was formerly called “Host Interface Networking” and has been renamed with version
2.2 without any change in functionality.
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list at the bottom of the page, which contains the physical network interfaces of your
systems. On a typical MacBook, for example, this will allow you to select between
“en1: AirPort” (which is the wireless interface) and “en0: Ethernet”, which represents
the interface with a network cable.
Depending on your host operating system, the following limitations should be kept
in mind:
• On Macintosh hosts, functionality is limited when using AirPort (the Mac’s wire-
less networking) for bridged networking. Currently, VirtualBox supports only
IPv4 over AirPort. For other protocols such as IPv6 and IPX, you must choose a
wired interface.
• On Linux hosts, functionality is limited when using wireless interfaces for
bridged networking. Currently, VirtualBox supports only IPv4 over wireless. For
other protocols such as IPv6 and IPX, you must choose a wired interface.
Also, setting the MTU to less than 1500 bytes on wired interfaces provided by
the sky2 driver on the Marvell Yukon II EC Ultra Ethernet NIC is known to cause
packet losses under certain conditions.
• On Solaris hosts, there is no support for using wireless interfaces. Filtering guest
traffic using IPFilter is also not completely supported due to technical restrictions
of the Solaris networking subsystem. These issues would be addressed in a future
release of OpenSolaris.
With VirtualBox 2.0.4 and above, it is possible to use Crossbow Virtual Network
Interfaces (VNICs) with bridged networking, but with the following caveats:
– A VNIC cannot be shared between multiple guest network interfaces, i.e.
each guest network interface must have its own, exclusive VNIC.
– The VNIC and the guest network interface that uses the VNIC must be as-
signed identical MAC addresses.
6.5 Internal networking
Internal Networking is similar to bridged networking in that the VM can directly communicate with the outside world. However, the “outside world” is limited to other VMs
which connect to the same internal network.
Even though technically, everything that can be done using internal networking can
also be done using bridged networking, there are two good reasons why this additional
mode was implemented:
1. Security. In bridged networking mode, all traffic goes through a physical inter-
face of the host system. It is therefore possible to attach a packet sniffer (such
as Wireshark) to the host interface and log all traffic that goes over it. If, for
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any reason, you prefer two or more VMs on the same machine to communicate privately, hiding their data from both the host system and the user, bridged
networking therefore is not an option.
2. Speed. Internal networking is more efficient than bridged networking, as
VirtualBox can directly transmit the data without having to send it through the
host operating system’s networking stack.
Internal networks are created automatically as needed, i.e. there is no central configuration. Every internal network is identified simply by its name. Once there is more
than one active virtual network card with the same internal network ID, the VirtualBox
support driver will automatically “wire” the cards and act as a network switch. The
VirtualBox support driver implements a complete Ethernet switch and supports both
broadcast/multicast frames and promiscuous mode.
In order to attach a VM’s network card to an internal network, set its networking
mode to “internal networking”. There are two ways to accomplish this:
• You can use a VM’s “Settings” dialog in the VirtualBox graphical user interface.
In the “Networking” category of the settings dialog, select “Internal Networking”
from the drop-down list of networking modes. Now select the name of an existing internal network from the drop-down below or enter a new name into the
entry field.
• You can use VBoxManage modifyvm <VM name> --nic<x> intnet. Op-
tionally, you can specify a network name with the command VBoxManage
modifyvm <VM name> --intnet<x> <network name>. If you do not
specify a network name, the network card will be attached to the network
intnet by default.
Unless you configure the (virtual) network cards in the guest operating systems that
are participating in the internal network to use static IP addresses, you may want to use
the DHCP server that is built into VirtualBox to manage IP addresses for the internal
network. Please see chapter 8.26, VBoxManage dhcpserver, page 133 for details.
As a security measure, the Linux implementation of internal networking only allows
VMs running under the same user ID to establish an internal network.
6.6 Host-only networking
Host-only networking is another networking mode that was added with version 2.2
of VirtualBox. It can be thought of as a hybrid between the bridged and internal networking modes: as with bridged networking, the virtual machines can talk to each
other and the host as if they were connected through a physical ethernet switch. Similarly, as with internal networking however, a physical networking interface need not
be present, and the virtual machines cannot talk to the world outside the host since
they are not connected to a physical networking interface.
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Instead, when host-only networking is used, VirtualBox creates a new software interface on the host which then appears next to your existing network interfaces. In
other words, whereas with bridged networking an existing physical interface is used
to attach virtual machines to, with host-only networking a new “loopback” interface
is created on the host. And whereas with internal networking, the traffic between the
virtual machines cannot be seen, the traffic on the “loopback” interface on the host
can be intercepted.
Host-only networking is particularly useful for preconfigured virtual appliances,
where multiple virtual machines are shipped together and designed to cooperate. For
example, one virtual machine may contain a web server and a second one a database,
and since they are intended to talk to each other, the appliance can instruct VirtualBox
to set up a host-only network for the two. A second (bridged) network would then
connect the web server to the outside world to serve data to, but the outside world
cannot connect to the database.
To change a virtual machine’s virtual network interface to “host only” mode:
• either go to the “Network” page in the virtual machine’s settings notebook in the
graphical user interface and select “Host-only networking”, or
• on the command line, type VBoxManage modifyvm <VM name> --nic<x>
hostonly; see chapter 8.5, VBoxManage modifyvm, page 114 for details.
For host-only networking, like with internal networking, you may find the DHCP
server useful that is built into VirtualBox. This can be enabled to then manage the IP
addresses in the host-only network since otherwise you would need to configure all IP
addresses statically.
• In the VirtualBox graphical user interface, you can configure all these items in
the global settings via “File” -> “Settings” -> “Network”, which lists all host-only
networks which are presently in use. Click on the network name and then on the
“Edit” button to the right, and you can modify the adapter and DHCP settings.
• Alternatively, you can use VBoxManage dhcpserver on the command line;
please see chapter 8.26, VBoxManage dhcpserver, page 133 for details.
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virtual machines
7.1 Introduction
As briefly mentioned in chapter 1.3, Features overview, page 12, VirtualBox has a very
flexible internal design that allows you to use different front-ends to control the same
virtual machines. To illustrate, you can, for example, start a virtual machine with
VirtualBox’s easy-to-use graphical user interface and then stop it from the command
line. With VirtualBox’s support for the Remote Desktop Protocol (VRDP), you can even
run virtual machines remotely on a headless server and have all the graphical output
redirected over the network.
In detail, the following front-ends are shipped in the standard VirtualBox package:
1. VirtualBox is our graphical user interface (GUI), which most of this User
Manual is dedicated to describing, especially in chapter 3, Configuring virtual
machines, page 44. While this is the easiest-to-use of our interfaces, it does not
(yet) cover all the features that VirtualBox provides. Still, this is the best way to
get to know VirtualBox initially.
2. VBoxManage is our command-line interface and is described in the next section.
3. VBoxSDL is an alternative, simple graphical front-end with an intentionally limited feature set, designed to only display virtual machines that are controlled in
detail with VBoxManage. This is interesting for business environments where
displaying all the bells and whistles of the full GUI is not feasible. VBoxSDL is
described in chapter 7.3, VBoxSDL, the simplified VM displayer, page 98.
4. Finally, VBoxHeadless is yet another front-end that produces no visible output
on the host at all, but merely acts as a VRDP server. Now, even though the other
graphical front-ends (VirtualBox and VBoxSDL) also have VRDP support builtin and can act as a VRDP server, this particular front-end requires no graphics
support. This is useful, for example, if you want to host your virtual machines
on a headless Linux server that has no X Window system installed. For details,
see chapter 7.4.2, VBoxHeadless, the VRDP-only server, page 101.
If the above front-ends still do not satisfy your particular needs, it is relatively painless
to create yet another front-end to the complex virtualization engine that is the core
of VirtualBox, as the VirtualBox core neatly exposes all of its features in a clean API;
please refer to chapter 10, VirtualBox programming interfaces, page 154.
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7.2 Using VBoxManage to control virtual machines
This section will give you a brief introduction to VBoxManage and how you can use it
to create and operate virtual machines.
In essence, VBoxManage supports everything that our graphical user interface allows you to do with the click of a button. VBoxManage supports a lot more than that,
however. It exposes really all the features of the virtualization engine, even those that
cannot (yet) be accessed from the GUI.
You will need to use the command line if you want to
• use a different user interface than the main GUI (for example, VBoxSDL or the
VBoxHeadless server);
• control some of the more advanced and experimental configuration settings for
a VM.
There are two main things to keep in mind when using VBoxManage: First,
VBoxManage must always be used with a specific “subcommand”, such as “list” or
“createvm” or “startvm”. All the subcommands that VBoxManage supports are described in detail in chapter 8, VBoxManage reference, page 106.
Second, most of these subcommands require that you specify a particular virtual
machine after the subcommand. There are two ways you can do this:
• You can specify the VM name, as it is shown in the VirtualBox GUI. Note that
if that name contains spaces, then you must enclose the entire name in double quotes (as it is always required with command line arguments that contain
spaces).
For example:
VBoxManage startvm "Windows XP"
• You can specify the UUID, which is the internal unique identifier that VirtualBox
uses to refer to the virtual machine. Assuming that the aforementioned VM
called “Windows XP” has the UUID shown below, the following command has
the same effect as the previous:
VBoxManage startvm 670e746d-abea-4ba6-ad02-2a3b043810a5
You can type VBoxManage list vms to have all currently registered VMs listed
with all their settings, including their respective names and UUIDs.
Some typical examples of how to control VirtualBox from the command line are
listed below:
• To create a new virtual machine from the command line and immediately register it with VirtualBox, use VBoxManage createvm with the --register
option,1like this:
1
For details, see chapter 8.4, VBoxManage createvm, page 113.
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$ VBoxManage createvm --name "SUSE 10.2" --register
VirtualBox Command Line Management Interface Version 3.1.0
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.
Virtual machine ’SUSE 10.2’ is created.
UUID: c89fc351-8ec6-4f02-a048-57f4d25288e5
Settings file: ’/home/username/.VirtualBox/Machines/SUSE 10.2/SUSE 10.2.xml’
As can be seen from the above output, a new virtual machine has been created
with a new UUID and a new XML settings file.
• To show the configuration of a particular VM, use VBoxManage showvminfo;
see chapter 8.2, VBoxManage showvminfo, page 112 for details and an example.
• To change VM settings, use VBoxManage modifyvm, e.g. as follows:
VBoxManage modifyvm "Windows XP" --memory "512MB"
For details, see chapter 8.5, VBoxManage modifyvm, page 114.
• To control VM operation, use one of the following:
– To start a VM that is currently powered off, use VBoxManage startvm;
see chapter 8.8, VBoxManage startvm, page 120 for details.
– To pause or save a VM that is currently running, use VBoxManage
controlvm; see chapter 8.9, VBoxManage controlvm, page 121 for details.
7.3 VBoxSDL, the simplified VM displayer
VBoxSDL is a simple graphical user interface (GUI) that lacks the nice point-and-click
support which VirtualBox, our main GUI, provides. VBoxSDL is currently primarily
used internally for debugging VirtualBox and therefore not officially supported. Still,
you may find it useful for environments where the virtual machines are not necessarily
controlled by the same person that uses the virtual machine.
As you can see in the following screenshot, VBoxSDL does indeed only provide a
simple window that contains only the “pure” virtual machine, without menus or other
controls to click upon and no additional indicators of virtual machine activity:
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To start a virtual machine with VBoxSDL instead of the VirtualBox GUI, enter the
following on a command line:
VBoxSDL --startvm <vm>
where <vm> is, as usual with VirtualBox command line parameters, the name or
UUID of an existing virtual machine.
7.4 Remote virtual machines (VRDP support)
VirtualBox, the graphical user interface, has a built-in server for the VirtualBox Remote
Desktop Protocol (VRDP). This allows you to see the output of a virtual machine’s
window remotely on any other computer and control the virtual machine from there,
as if the virtual machine was running locally.
VRDP is a backwards-compatible extension to Microsoft’s Remote Desktop Protocol
(RDP). Typically graphics updates and audio are sent from the remote machine to the
client, while keyboard and mouse events are sent back. As a result, you can use any
standard RDP client to control the remote VM.
With VirtualBox, the graphical user interface, the VRDP server is disabled by
default, but can easily be enabled on a per-VM basis either in the “Display” settings
(see chapter 3.5, Display settings, page 51) or with VBoxManage:
VBoxManage modifyvm <vmname> --vrdp on
If you use VBoxHeadless (described further below), VRDP support will be automatically enabled since VBoxHeadless has no other means of output.
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7.4.1 Common third-party RDP viewers
You can use any standard RDP viewer to connect to such a remote virtual machine
(examples follow below). For this to work, you must specify the IP address of your
host system (not of the virtual machine!) as the server address to connect to, as well
as the port number that the RDP server is using.
By default, the VRDP server uses the standard RDP TCP port 3389. You will need
to change the default port if you run more than one VRDP server, since the port can
only be used by one server at a time; you might also need to change it on Windows
hosts since the default port might already be used by the RDP server that is built into
Windows itself. Ports 5000 through 5050 are typically not used and might be a good
choice.
The port can be changed either in the “Display” settings of the graphical user interface or with --vrdpport option of the VBoxManage modifyvm command. You can
specify a comma-separated list of ports or ranges of ports. Use a dash between two
port numbers to specify a range. The VRDP server will bind to one of available ports
from the specified list. For example, VBoxManage modifyvm <vm> --vrdpport
5000,5010-5012 will configure the server to bind to one of the ports 5000, 5010,
5011 or 5012. See chapter 8.5, VBoxManage modifyvm, page 114 for details.
The actual port used by a running VM can be either queried with VBoxManage
showvminfo command or seen in the GUI on the Runtime tab of the Session
Information Dialog, which is accessible via the Machine menu of the VM win-
dow.
Here follow examples for the most common RDP viewers:
• On Windows, you can use the Microsoft Terminal Services Connector
(mstsc.exe) that ships with Windows. You can start it by bringing up the
“Run” dialog (press the Windows key and “R”) and typing “mstsc”. You can also
find it under “Start” -> “All Programs” -> “Accessories” -> “Remote Desktop
Connection”. If you use the “Run” dialog, you can type in options directly:
mstsc 1.2.3.4[:3389]
Replace “1.2.3.4” with the host IP adress, and 3389 with a different port if necessary.
• On other systems, you can use the standard open-source rdesktop program.
This ships with most Linux distributions, but VirtualBox also comes with a modified variant of rdesktop for remote USB support (see chapter 7.4.4, Remote USB,
page 103 below).
With rdesktop, use a command line such as the following:
rdesktop -a 16 -N 1.2.3.4:3389
As said for the Microsoft viewer above, replace “1.2.3.4” with the host IP address,
and 3389 with a different port if necessary. The -a 16 option requests a color
depth of 16 bits per pixel, which we recommend. (For best performance, after
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