Avaya IP Security User Manual
Configuring IPsec Services
BayRS Version 13.20
Site Manager Software Version 7.20
Part No. 304111-B Rev 00
April 1999
Bay Networ ks, Inc.
4401 Great America Parkway
Santa Clara, CA 95054
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304111-B Rev 00 iii
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Contents
Preface
Before You Begin .............................................................................................................xiii
Text Conventions .............................................................................................................xiv
Acronyms ........................... .......................... .......................... ......................... ................. xv
Bay Networks Technical Publications .............................................................................xvii
How to Get Help .............................................................................................................xvii
Chapter 1
Overview of IPsec
About IPsec .... ...... ...... ....... ...... ....................................... ....... ...... ...... ....... ...... ....... ...... ...1-2
IPsec Services ................................................................................................................1-2
Confidentiality ....... ....... ...... ....... ...... ....... ...... ....... ...... ....... ...... ...... ....... ...... ....... ...... ...1-2
Integrity ....................................................................................................................1-3
Authentication ..........................................................................................................1-3
Additional IPsec Services ........................................................................................1-3
How IPsec Works ...........................................................................................................1-3
IPsec Protection .......................................................................................................1-4
IPsec Tunnel Mode ...................................................................................................1-5
Elements of IPsec ...........................................................................................................1-5
Security Gateways ..........................................................................................................1-7
Security Policies .............................................................................................................1-8
Policy Templates ......................................................................................................1-8
Inbound Policies .......................................................................................................1-9
Outbound Policies ....................................................................................................1-9
Policy Criteria Specification ....................................................................................1-10
Security Associations ...................................................................................................1-11
Automated Security Associations Using Internet Key Exchange (IKE) ..................1-11
Manual Security Associations ................................................................................1-12
Security Associations for Bidirectional Traffic .........................................................1-12
304111-B Rev 00 v
How IKE Negotiates Security Associations ............................................................1-13
Security Parameter Index (SPI) ..............................................................................1-13
Summarizing Security Policies and SAs .......................................................................1-14
Security Protocols .........................................................................................................1-15
Encapsulating Security Payload .............................................................................1-15
Authentication Header ............................................................................................1-16
Internet Key Exchange (IKE) Protocol ..........................................................................1-17
Perfect Forward Secrecy ........................................................................................1-17
Network Requirements for Bay Networks Routers .......................................................1-18
Supported Routers .................................................................................................1-18
Supported WAN Protocols .....................................................................................1-18
Chapter 2
Getting Started With IPsec
Upgrading Router Software ............................................................................................2-2
Installing the IPsec Software ................................................. ...... ...... ....... ...... ....... ...... ...2-2
Completing the Installation Process ..................................................................2-3
Installing Triple DES Encryption ...............................................................................2-3
Securing Your Site ..........................................................................................................2-4
Securing Your Configuration ...........................................................................................2-4
Encryption Keys .......................................................................................................2-4
Random Number Generator (RNG) .........................................................................2-5
Creating a Node Protection Key (NPK) ..........................................................................2-5
Generating NPKs .....................................................................................................2-5
Entering an Initial NPK and a Seed for Encryption .........................................................2-6
Changing an NPK ....................................................................................................2-8
Monitoring NPKs ......................................................................................................2-8
Chapter 3
Configuring IPsec
Enabling IPsec and IKE ........... ....... ...... ....... ...... ....... ...... ....... ...... ...... ....... ......................3-1
Creating Policies .............................................................................................................3-2
Specifying Criteria ....................................................................................................3-2
Specifying an Action .................................................................................................3-3
Policy Considerations ...............................................................................................3-3
Creating an Outbound Policy ...................................................................................3-4
vi 304111-B Rev 00
Creating an Inbound Policy ......................................................................................3-6
Creating Security Associations .......................................................................................3-8
About Automated SA Creation ........................... ...... ....... ...................................... ...3-8
About Manual SA Creation .......................................................................................3-8
Creating a Protect SA Automatically Using IKE .......................................................3-9
Creating an Unprotect SA Automatically Using IKE ...............................................3-10
Creating a Protect SA Manually .............................................................................3-11
Creating an Unprotect SA Manually .......................................................................3-12
Disabling IPsec .................. ...... ....... ...... ....... ...... ....................................... ...... ....... ...... .3-13
Appendix A
Site Manager Parameters
Node Protection Key Para meter .................................................................................... A-1
Enabling IPsec Parameters ........................................................................................... A-2
IPsec Policy Parameters ................................................................................................ A-3
Manual Security Association Parameters ...................................................................... A-4
Automated Security Association (IKE) Parameters ....................................................... A-9
Appendix B
Definitions of k Commands
Appendix C
Configuration Examples
Inbound and Outbound Policies .....................................................................................C-1
Automated SA (IKE) Policy Examples ..................................................................... C-2
Manual SA Policy Examples ...................................................................................C-5
Manual Protect and Unprotect SA Configuration ........................................................... C-9
Appendix D
Protocol Numbers
Assigned Internet Proto co l Number by Name ....................................................... ...... .. D-2
Assigned Internet Protocol Numbers by Number .......................................................... D-6
Index
304111-B Rev 00 vii
Figures
Figure 1-1. IPsec Environment: Unique Security Associations (SAs)
Between Routers .....................................................................................1-4
Figure 1-2. IPsec Concepts: Security Gateways, Security Policies, and SAs ............1-6
Figure 1-3. IPsec Security Gateways and Security Policies .......................................1-7
Figure 1-4. Security Associations for Bidirectional Traffic .........................................1-12
Figure C-1. IPsec Automated Outbound Policies for RTR1, RTR2, and RTR3 ..........C-2
Figure C-2. IPsec Manual Outbound Policies for RTR1, RTR2, and RTR3 ...............C-5
Figure C-3. Single Protect/Unprotect SA Pair ............................................................ C-9
Figure C-4. Multiple Protect/Unprotect SA Pairs ...................................................... C-12
304111-B Rev 00 ix
Tables
Table 1-1. Security Policy Specifications ................................................................1-14
Table 1-2. Manual Security Association (SA) Configurations .................................1-15
Table D-1. Internet Protocol Numbers, Sorted by Acronym .................................... D-2
Table D-2. Internet Protocol Numbers, Sorted by Number ......................................D-6
304111-B Rev 00 xi
This guide describes the Bay Networks® implementation of IP Security and how
to configure it on a Bay Networks router.
Before You Begin
Before using this guide, you must complete the following procedures. For a new
router:
• Install the router (see the installation guide that came w ith your router).
• Connect the router to the network and create a pilot configuration file (see
Quick-Starting Routers or Configuring BayStack Remote Access).
Preface
Make sure that you are running the latest version of Bay Networks BayRS
Site Manager software. For information about upgrading BayRS and Site
Manager, see the upgrading guide for your version of BayRS.
304111-B Rev 00 xiii
™
and
Configuring IPsec Services
Text Conventions
This guide uses the following text conventions:
angle brackets (< >) Indicate that you choose the text to enter based on the
description inside the brackets. Do not type the
brackets when entering the command.
Example: If the command syntax is:
ping
<
ip_address
ping 192.32.10.12
>, you enter:
bold text
Indicates command names and options and text that
you need to enter.
Example: Enter
show ip {alerts | routes
Example: Use the
dinfo
command.
}.
braces ({}) Indicate required elements in syntax descriptions
where there is more than one option. You must choose
only one of the options. D o not type the braces when
entering the command.
Example: If the command syntax is:
show ip {alerts | routes
show ip alerts or show ip routes
}
, you must enter either:
, but not both.
brackets ([ ]) Indicate optional elements in syntax descriptions. Do
not type the brackets when entering the command.
Example: If the command syntax is:
show ip interfaces [-alerts
show ip interfaces
or
]
, you can enter either:
show ip interfaces -alerts
.
italic text Indicates file and directory names, new terms, book
titles, and variables in command syntax descriptions.
Where a variable is two or more words, the words are
connected by an underscore.
Example: If the command syntax is:
show at
valid_route
<
valid_route
>
is one variable and you substitute one value
for it.
xiv 304111-B Rev 00
Preface
screen text Indicates system output, for example, prompts and
system messages.
Acronyms
Example:
Set Bay Networks Trap Monitor Filters
separator ( > ) Shows menu paths.
Example: Protocols > I P ide nti fies the IP option on the
Protocols menu.
vertical line (
) Separates choices for command keywords and
|
arguments. Enter only one of the choices. Do not type
the vertical line when entering the command.
Example: If the command syntax is:
show ip {alerts | routes
show ip alerts
or
This guide uses the following acronyms:
3DES Triple DES
AH authentication header
CBC cipher block chaining
}
, you enter either:
show ip routes
, but not both.
DES Data Encryption Standard
ESP Encapsulating Security Payload
HMAC Hashing Message Authentication Code
IANA Internet Assigned Numbers Authority
ICMP Internet Control Me ssage Protocol
ICV integri ty check value
IETF Internet Engineering Task Force
IKE Internet Key Exchange protocol
IP Internet P rotocol
IPsec Internet Protocol Security
304111-B Rev 00 xv
Configuring IPsec Services
ISAKMP/Oakley Internet Security Association and Key Management
IV initialization vector
MD5 Message Digest 5
MIB management information base
NPK node protection key
NVRAM nonvolatile random access memory
PPP Point-to-Point Protocol
RNG random number generator
RSA RSA Data Security, Inc.’s public-key encryption
SA security association
SAD security associations database
SHA Secure Hash Algorithm
SPD security policy database
Protocol (also known as IKE)
algorithm
SPI security parameter index
VPN virtual private network
WAN wide area network
xvi 304111-B Rev 00
Bay Networks Technical Publications
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Preface
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304111-B Rev 00 xvii
Chapter 1
Overview of IPsec
This chapter descr ibes the emer ging Inte rnet Engineer ing Task Force st andards fo r
security services over public networks, commonly referred to a s IP Security or
IPsec. The chapter also includes information specific to the Bay Networks
implementation of IPsec and requirements for that implementation.
This chapter includes the following information:
Topic Page
304111-B Rev 00
About IPsec 1-2
IPsec Services 1-2
How IPsec Works 1-3
Elements of IPsec 1-5
Security Gateways 1-7
Security Policies 1-8
Security Associations 1-11
Summarizi ng Security Policies and SAs 1-14
Security Protocols 1-15
Internet Key Exchan ge (IKE) Protocol 1-17
Network Requirements for Bay Networks Routers 1-18
1-1
Configuring IPsec Services
About IPsec
IP Security (I Psec) is the Internet Engineering Task Force (IETF) set of emerging
standards for security services for communications over public networks. The
standards are documented in the IETF Requests for Comments (RFCs) 2401
through 2412. Additional RFCs may be relevant as well.
These standards were developed to ensure secure, private communications for the
remote access, extranet, and intranet virtual pr ivate networks (VPNs) used in
enterprise communications. They are the security architecture for the next
generation of IP, called IP v6, but are available for the current IPv4 Internet as
well.
The Bay Networks implementation of the IETF standards provides network
(layer 3) security services for wide area network (WAN) communications on Bay
Networks routers.
IPsec Ser vices
IPsec serv ices consist of confidentiality, integrity, and authentication services for
data packets traveling between security gate ways.
• Confidentiality ensures the privacy of communications.
• The integrity service detects modification of data packets.
• Authentication ser vices verify the origin of every data packet.
Confidentiality
Confidentiality is accomplished by encrypting and decrypting data packets. The
Encapsulating Security Payload (ESP) protocol uses the Data Encryption
Standard (DES) algorithm in cipher block chaining (CBC) mode to encrypt and
decrypt data packets.
You set confidentiality with the cipher algorithm and cipher key parameters. The
cipher algorithm and cipher key are specified in security associat ions (SAs). A
security association is a relationship in which two peers share the necessary
information to secur ely prote ct and unpr otect data. Th e algori thm and ke y must b e
identical on both ends of an IPsec SA.
1-2
304111-B Rev 00
Integrity
Integrity determines whether the data has been altered during trans it. The ESP
protocol ensures that data has not been modified as it passes between the security
gateways . The ESP protoco l uses the HMAC MD5 (RFC 2403) or HMAC SHA-1
(RFC 2404) transform.
You set integrit y with the integrity algorithm a nd integrity key parameters. The
integrity algorithm and integrity key must be identical on both e nds of an IPsec
SA.
Authentication
Authentication ensures that data has been transmitted by the identified source.
Additional IPsec Services
Within the IPsec framework, additional security services are provided. An access
control service ensures authorized use of the network, and an auditing service
tracks all actions and events.
Overview of IPsec
IPsec services can be configured on an interface-by-interface basis. Up to 127
inbound and 127 outbound security policies (customized) are supported on each
IPsec interface.
How IPsec Works
IPsec services are bundled as an Internet Protocol (IP) encryption packet. The
packets resemble ordinary IP packets to Internet rout ing nodes; only the sending
and receiving devices are involved in the encryption. IPsec packets are delivered
over the Internet like ordinary IP packets to branch offices, corporate partners, or
other remote organizations in a secure, encrypted, and private manner.
Sever al well-est ablished tech nologies pro vide enc ryption and aut henticatio n at the
application laye r. IPsec adds security at the underlying network layer, providing a
higher degree of secur ity fo r all a ppl icati ons, inc luding those wit hou t an y secur ity
features of their own.
304111-B Rev 00
1-3
Configuring IPsec Services
IPsec Protection
To configure a router with IPsec, you first configure the router interface as an
IP interface. Then you add the IPsec software to the IP interface, creating a
security gateway. A security gateway is a router between a trusted network (for
example, the enterprise intranet) and an untrusted network (the Internet) that
provides a security service such as IPsec.
The router interface is secured with inbound and outbound security policies that
filter traffic to and from the router module. The data packets themselves are
protected by IPsec protocol processing specified by security associations (SAs).
Figure 1-1 sho ws ho w IPsec can prote ct data c ommunication s within a n enterpr ise
and from external hosts.
Corporate
headquarters
Server
Router A
IP security
gateway
Security
associations
(SAs A,B)
Partner
Router B Router C
Host Host
IP security
gateway
IPsec
services
Public
network
Security associations
(SAs B,C)
IPsec
services
Security
associations
(SAs C,A)
Branch office
IP security
gateway
IPsec
services
IP0088A
Figure 1-1. IPsec Environment: Unique Security Associations (SAs)
Between Routers
1-4
304111-B Rev 00
IPsec Tunnel Mode
When there is a security gateway at each end of a communication, the security
associations between the gateways are said to be in tunnel mode. The tunnel
metaphor refers to data being visible only at the beginning and end points of the
communication. The IP packets protected by IPsec have regular, “visible” IP
headers, but the packet contents are encrypted, and thus hidden. All BayRS IPsec
communications occur in tunnel mode. Tunnel mode is especially effective for
isolating and prot ecting enterp rise traf f ic tra veli ng across a publ ic data net work, as
shown in Figure 1-1.
Elements of IPsec
IPsec has three important constructs:
• Security gateways
• Security policies
• Security associatio ns (SAs)
Overview of IPsec
304111-B Rev 00
In the IPsec context, hosts communicate across an untrusted network through
security gateways (routers configured for IPsec interfaces). Security policies
determine ho w the IPsec interfaces handle data packets for the hosts on both ends
of a connection. Security associations apply IPsec services to data packets
traveling between the security gateways.
Figure 1-2
associations.
shows the logical relationship between security policies and security
1-5
Configuring IPsec Services
Security associations
IPsec gateway WAN interface
Inbound process
Unprotect SAs
Source/Dest Addr, SPI
Cipher Algo/Key,
Integrity Algo/Key
Protect SAs
Source/Dest Addr, SPI
Cipher Algo/Key,
Integrity Algo/Key
Inbound policies
criteria & action
(bypass, drop, log)
Outbound policies
criteria & action
(bypass, drop, log,
protect)
Outbound process
Security
policy
database
Figure 1-2. IPsec Concepts: Security Gateways, Security Policies, and SAs
Untrusted
network
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Security Gateways
A security gateway establishes SAs between router interfaces configured with
IPsec software. A Bay Networks router becomes a security gateway when you
enable IPsec on a WAN interface. In this way, a Bay Networks router operati ng as
a security gateway provides IPsec services to its internal hosts and subnetworks.
Hosts or networks on th e e xte rnal si de of a sec urit y ga te w ay (typic ally, the overall
Internet) are considered “untrusted.” Hosts or subnetworks on the internal side of
a security gat e w ay (nodes on your l ocal i ntra net) are consi dered “trus te d” beca use
they are controlled and securely managed by the same network administration
(Figure 1-3
).
Overview of IPsec
Trusted
network
Local
host
Outbound policy
Security
gateway
Inbound policy (clear text only)
IPsec interface
Untrusted
network
IPsec interface
Outbound policy
Security
gateway
Inbound policy (clear text only)
Figure 1-3. IPsec Security Gateways and Security Policies
When you add IPsec services to a router to create a security gateway, its internal
hosts and subnetworks can communicate with external hosts that directly operate
IPsec services, or with a remote security gateway that provides IPsec services for
its set of hosts and subnetworks.
Trusted
network
Remote
host
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Configuring IPsec Services
Security Policies
When you create an IPsec policy, you control which packets a security gateway
protects, how it handles packets to or from particular addresses or in a particular
protocol, and whether it logs information about these actions.
There are two types of IPsec policies: inbound and outbound. An inbound policy
is used for data packets arriving at a security gateway, and an outbound policy is
used for data pa ck ets leaving a security gateway. Each IPsec interface can support
up to 127 inbound and 127 outbound security policies (refer to Figure 1-3
page 1-7
The criteria (“selectors”) and action specifications used in your inbound and
outbound policies are stored in the security policy database (SPD).
IPsec defaults i n fa v or of more securit y rather th an less. I f an outbou nd or inbou nd
packet does not match the criteria of any configured outbound or inbound policy
in the SPD, the packet is dropped.
IPsec discards an y out bound clear-text data packet unle ss you explicitly configure
a policy to bypass or protect it.
).
on
Policy Templates
Every IPsec polic y is ba sed on a policy template. A policy template is a pr edef ined
policy definition that you can use on any IP interface. The template specifies one
or more criteria and an action to apply to incoming or outgoing data packets.
A policy template and every policy based on it must includ e at least one criterion,
for example, an IP source address, and one action. For example, an outbound
policy might specify a pr otect ac tion. A poli cy t emplate or po lic y may inc lude tw o
actions if one of the actions is logging. The criterion specification determines
whether a data pack et matches a pa rticula r securit y polic y, and the action speci fi es
how the policy is applied to the packet.
The action specifications that you can include in inbound and outbound policies
are listed in the two sections that follow.
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Inbound Policies
An inbound policy determines how a security gateway processes data packets
receiv ed from a n u ntrus ted ne tw ork. Ev ery pack e t ar ri v ing at a secu rity g ateway is
compared with the criteria to determine whether it matches an IPsec policy for
that router. If the incoming packet matches a bypass policy, the router accepts the
packet and, if the policy is so configured, logs it.
If the packet d oes n ot mat ch an y poli cy o r matches a drop poli c y, the router rejects
the packet. When a packet does not match any policy, IPsec’s default action is to
drop it.
For an inbound security policy, the action may be:
•Drop
• Bypass
•Log
Drop and bypass are mutua lly e xc lusive. The log action may be a dded t o eit her, or
used alone.
Overview of IPsec
Outbound Policies
An outbound policy determines ho w a se curity gat e way proces ses data pac kets f or
transmission across an untrust ed netwo rk. You must assign an outbound poli cy fo r
all unicast traffic leaving an IPsec interface.
For an outbound policy, the action specification may be:
• Protect
•Drop
• Bypass
•Log
Any outbound policy with a protect action specification is mapped to a Protect
SA. See “
information about Protect and Unprotect SAs.
Drop, protect, and bypass are mutually exclusive. The log action may be added to
any of the three, or used alone.
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Summarizing Security Policies and SAs” on page 1-14 for detailed
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Configuring IPsec Services
Policy Criteria Specification
IPsec software inspects IP packet headers based on the specified criteria to
determine whether a policy applies to a data packet.
You must include at least one of the following crit eria, and you may specify all
three criteria in an IPsec policy:
• IP source address
• IP destination address
• Protocol
To specify the protocol criterion, you must provide the numeric value assigned to
the protocol for use o v er the I ntern et. You can specify only a sin gle pr otocol value
for each policy. The protocol number is represented in the 1-byte protocol field in
an IP packet header.
Refer to Appendix D
for a list of protocol numbers. To obtain the most recent list
of the numeric values assigned to various protocols, see the Internet Assigned
Numbers Authority (IANA) Web site at:
http://www.iana.org
The direct path to the list of legal values tha t you can specify for an IP sec policy
protocol criterion as of this printing is:
http://www.isi.edu/in-notes/iana/assignments/protocol -numbers
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Overview of IPsec
Security Associations
A security association (SA) is a relationship in which two peers share the
necessary information to securely protect and unprotect data. An IPsec SA is
uniquely identified by an IP destination addr ess, securit y parameter index (S PI),
and security protocol identifier (for example, ESP in tunnel mode).
An IPsec policy deter mine s which pack et s will be hand le d. An IPsec SA spe cif i es
which IPsec security service (for example, confidentiality) IPsec will apply to the
packets. You can apply one or more IPsec security services.
SAs themselves must be created and shared in a secure manner. There are two
ways of achieving this: by using the automated security negotiation process
provided by the Internet Key Exchange (IKE) protocol; or by manually
configuring the sending and receiving devices with a shared secret. A shared
secret is a unique security identifier.
Automated Security Associations Using Internet Key Exchange (IKE)
Internet Key Exchange (IKE) is an automated protocol to establish security
associations over the Internet. (IKE is also referred to as the Internet Security
Association Key Management Protocol with Oakley Key Determination, or
ISAKMP/Oakley.) IKE handles negot iating, esta blishing, modifying, and deleting
security associations.
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To set up these security associations, IKE itself must create a confidential, secure
connection between the sender and receiver. Authentication is accomplished with
one or more of the following:
• Pre-shared keys: These are set up ahead of time at eac h node in a tr ansact ion.
• Public key cryptography: Using the RSA public key algorithm, each
member of a transaction authenticates itself to the other using the other
member’s public key to encrypt an authentication value.
• Digital signature: Each member of a transaction sends a digital signature to
the other. The signatures are authenticated using the member’s public key,
obtained via an X.509 digital certificate.
The BayRS implementation of IKE uses pre-shared keys only.
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Configuring IPsec Services
Manual Security Associations
Manually configuring security associations is a more cumbersome and
labor-intensive process than using IKE. If possible, IKE should be used to make
large-scale secure communications practical.
Manually configured SAs often rely on static, symmetric keys on communicating
hosts or security gate w ays. As such, you must coordina te wit hin your or ganizat ion
and with outside parties to configure keys that will protect your information.
Security Associations for Bidirectional Traffic
An SA specifies the security services that are applied to data packets traveling in
one direction between security gateways. To secure the traffic in both directions,
the security gateway must have a Protect SA for data transmitted from the local
IPsec interface and an Unprotect SA for data received by the local IPsec interface
(Figure 1-4)
.
Protect SA
Source: 132.245.145.195
Security gateway Security gateway
132.245.145.195
Destination: 132.245.145.205
Unprotect SA
Source: 132.245.145.205
Destination: 132.245.145.195
Unprotect SA
Source: 132.245.145.195
Destination: 132.245.145.205
Network
Protect SA
Source: 132.245.145.205
Destination: 132.245.145.195
Figure 1-4. Security Associations for Bidirectional Traffic
Under most circumstances, you will configure the Internet Key Exchange (IKE)
protocol to negotiate SAs between security gateways automatically. You can also
manually config ure SAs.
132.245.145.205
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