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Chapter 6

Configuring a VPN Using Easy VPN and an IPSec Tunnel

Configure Group Policy Information

Configure Group Policy Information

Perform these steps to configure the group policy, beginning in global configuration mode:

Command or Action

Purpose

Step 1

crypto isakmp client configuration group

{

group-name

|

default

}

Example:

Router(config)#

crypto isakmp client

configuration group rtr-remote

Router(config-isakmp-group)#

Creates an IKE policy group containing attributes

to be downloaded to the remote client.

Also enters the Internet Security Association Key

and Management Protocol (ISAKMP) group

policy configuration mode.

Step 2

key

name

Example:

Router(config-isakmp-group)#

key

secret-password

Router(config-isakmp-group)#

Specifies the IKE pre-shared key for the group

policy.

Step 3

dns

primary-server

Example:

Router(config-isakmp-group)#

dns 10.50.10.1

Router(config-isakmp-group)#

Specifies the primary Domain Name System

(DNS) server for the group.

Note

You may also want to specify Windows

Internet Naming Service (WINS) servers

for the group by using the

wins

command.

Step 4

domain

name

Example:

Router(config-isakmp-group)#

domain

company.com

Router(config-isakmp-group)#

Specifies group domain membership.

Step 5

exit

Example:

Router(config-isakmp-group)#

exit

Router(config)#

Exits IKE group policy configuration mode, and

enters global configuration mode.

Step 6

ip local pool

{

default

|

poolname

}

[

low-ip-address

[

high-ip-address

]]

Example:

Router(config)#

ip local pool dynpool

30.30.30.20 30.30.30.30

Router(config)#

Specifies a local address pool for the group.

For details about this command and additional

parameters that can be set, see the

Cisco IOS Dial

Technologies Command Reference

.

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Chapter 6

Configuring a VPN Using Easy VPN and an IPSec Tunnel

Apply Mode Configuration to the Crypto Map

Apply Mode Configuration to the Crypto Map

Perform these steps to apply mode configuration to the crypto map, beginning in global configuration

mode:

Command or Action

Purpose

Step 1

crypto map

map-name

isakmp authorization list

list-name

Example:

Router(config)#

crypto map dynmap isakmp

authorization list rtr-remote

Router(config)#

Applies mode configuration to the crypto map and

enables key lookup (IKE queries) for the group

policy from an authentication, authorization, and

accounting (AAA) server.

Step 2

crypto map

tag

client configuration address

[

initiate

|

respond

]

Example:

Router(config)#

crypto map dynmap client

configuration address respond

Router(config)#

Configures the router to reply to mode

configuration requests from remote clients.

Enable Policy Lookup

Perform these steps to enable policy lookup through AAA, beginning in global configuration mode:

Command or Action

Purpose

Step 1

aaa new-model

Example:

Router(config)#

aaa new-model

Router(config)#

Enables the AAA access control model.

Step 2

aaa authentication login

{

default

|

list-name

}

method1

[

method2...

]

Example:

Router(config)#

aaa authentication login

rtr-remote local

Router(config)#

Specifies AAA authentication of selected users at

login, and specifies the method used.

This example uses a local authentication database.

You could also use a RADIUS server for this. For

details, see the

Cisco IOS Security Configuration

Guide

and

Cisco IOS Security Command

Reference

.

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Chapter 6

Configuring a VPN Using Easy VPN and an IPSec Tunnel

Configure IPSec Transforms and Protocols

Configure IPSec Transforms and Protocols

A transform set represents a certain combination of security protocols and algorithms. During IKE

negotiation, the peers agree to use a particular transform set for protecting data flow.

During IKE negotiations, the peers search in multiple transform sets for a transform that is the same at

both peers. When such a transform set is found, it is selected and applied to the protected traffic as a part

of both peers’ configurations.

Step 3

aaa authorization

{

network

|

exec

|

commands

level

|

reverse-access

|

configuration

} {

default

|

list-name

} [

method1

[

method2...

]]

Example:

Router(config)#

aaa authorization network

rtr-remote local

Router(config)#

Specifies AAA authorization of all

network-related service requests, including PPP,

and specifies the method of authorization.

This example uses a local authorization database.

You could also use a RADIUS server for this. For

details, see the

Cisco IOS Security Configuration

Guide

and

Cisco IOS Security Command

Reference

.

Step 4

username

name

{

nopassword

|

password

password

|

password

encryption-type

encrypted-password

}

Example:

Router(config)#

username Cisco password 0

Cisco

Router(config)#

Establishes a username-based authentication

system.

This example implements a username of

Cisco

with an encrypted password of

Cisco

.

Command or Action

Purpose

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Chapter 6

Configuring a VPN Using Easy VPN and an IPSec Tunnel

Configure the IPSec Crypto Method and Parameters

Perform these steps to specify the IPSec transform set and protocols, beginning in global configuration

mode:

Command or Action

Purpose

Step 1

crypto ipsec transform-set

transform-set-name

transform1

[

transform2

] [

transform3

]

[

transform4

]

Example:

Router(config)#

crypto ipsec transform-set

vpn1 esp-3des esp-sha-hmac

Router(config)#

Defines a transform set—an acceptable

combination of IPSec security protocols and

algorithms.

See the

Cisco IOS Security Command Reference

for detail about the valid transforms and

combinations.

Step 2

crypto ipsec security-association lifetime

{

seconds

seconds

|

kilobytes

kilobytes

}

Example:

Router(config)#

crypto ipsec

security-association lifetime seconds 86400

Router(config)#

Specifies global lifetime values used when IPSec

security associations are negotiated.

See the

Cisco IOS Security Command Reference

for details.

Note

With manually established security associations, there is no negotiation with the peer, and both sides

must specify the same transform set.

Configure the IPSec Crypto Method and Parameters

A dynamic crypto map policy processes negotiation requests for new security associations from remote

IPSec peers, even if the router does not know all the crypto map parameters (for example, IP address).

Perform these steps to configure the IPSec crypto method, beginning in global configuration mode:

Command or Action

Purpose

Step 1

crypto dynamic-map

dynamic-map-name

dynamic-seq-num

Example:

Router(config)#

crypto dynamic-map dynmap 1

Router(config-crypto-map)#

Creates a dynamic crypto map entry and enters

crypto map configuration mode.

See the

Cisco IOS Security Command Reference

for more detail about this command.

Step 2

set transform-set

transform-set-name

[

transform-set-name2...transform-set-name6

]

Example:

Router(config-crypto-map)#

set

transform-set vpn1

Router(config-crypto-map)#

Specifies which transform sets can be used with

the crypto map entry.

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Chapter 6

Configuring a VPN Using Easy VPN and an IPSec Tunnel

Apply the Crypto Map to the Physical Interface

Apply the Crypto Map to the Physical Interface

The crypto maps must be applied to each interface through which IP Security (IPSec) traffic flows.

Applying the crypto map to the physical interface instructs the router to evaluate all the traffic against

the security associations database. With the default configurations, the router provides secure

connectivity by encrypting the traffic sent between remote sites. However, the public interface still

allows the rest of the traffic to pass and provides connectivity to the Internet.

Perform these steps to apply a crypto map to an interface, beginning in global configuration mode:

Step 3

reverse-route

Example:

Router(config-crypto-map)#

reverse-route

Router(config-crypto-map)#

Creates source proxy information for the crypto

map entry.

See the

Cisco IOS Security Command Reference

for details.

Step 4

exit

Example:

Router(config-crypto-map)#

exit

Router(config)#

Returns to global configuration mode.

Step 5

crypto map

map-name seq-num

[

ipsec-isakmp

]

[

dynamic

dynamic-map-name

] [

discover

]

[

profile

profile-name

]

Example:

Router(config)#

crypto map static-map 1

ipsec-isakmp dynamic dynmap

Router(config)#

Creates a crypto map profile.

Command or Action

Purpose

Command or Action

Purpose

Step 1

interface

type number

Example:

Router(config)#

interface fastethernet 4

Router(config-if)#

Enters the interface configuration mode for the

interface to which you want the crypto map

applied.