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Table Of Contents
Configuring a VPN Using Easy VPN and an IPSec Tunnel
Configure Group Policy Information
Apply Mode Configuration to the Crypto Map
Configure IPSec Transforms and Protocols
Configure the IPSec Crypto Method and Parameters
Apply the Crypto Map to the Physical Interface
Create an Easy VPN Remote Configuration
Verifying Your Easy VPN Configuration
Configuring a VPN Using Easy VPN and an IPSec Tunnel
The Cisco 870 series routers support the creation of Virtual Private Networks (VPNs).
Cisco routers and other broadband devices provide high-performance connections to the Internet, but many applications also require the security of VPN connections which perform a high level of authentication and which encrypt the data between two particular endpoints.
Two types of VPNs are supported—site-to-site and remote access. Site-to-site VPNs are used to connect branch offices to corporate offices, for example. Remote access VPNs are used by remote clients to log in to a corporate network.
The example in this chapter illustrates the configuration of a remote access VPN that uses the Cisco Easy VPN and an IPSec tunnel to configure and secure the connection between the remote client and the corporate network. Figure 6-1 shows a typical deployment scenario.
Note
The material in this chapter does not apply to Cisco 850 series routers. Cisco 850 series routers do not support Cisco Easy VPN.
Figure 6-1 Remote Access VPN Using IPSec Tunnel
Cisco Easy VPN
The Cisco Easy VPN client feature eliminates much of the tedious configuration work by implementing the Cisco Unity Client protocol. This protocol allows most VPN parameters, such as internal IP addresses, internal subnet masks, DHCP server addresses, WINS server addresses, and split-tunneling flags, to be defined at a VPN server, such as a Cisco VPN 3000 series concentrator that is acting as an IPSec server.
An Easy VPN server-enabled device can terminate VPN tunnels initiated by mobile and remote workers who are running Cisco Easy VPN Remote software on PCs. Easy VPN server-enabled devices allow remote routers to act as Easy VPN Remote nodes.
The Cisco Easy VPN client feature can be configured in one of two modes—client mode or network extension mode. Client mode is the default configuration and allows only devices at the client site to access resources at the central site. Resources at the client site are unavailable to the central site. Network extension mode allows users at the central site (where the VPN 3000 series concentrator is located) to access network resources on the client site.
After the IPSec server has been configured, a VPN connection can be created with minimal configuration on an IPSec client, such as a supported Cisco 870 series access router. When the IPSec client initiates the VPN tunnel connection, the IPSec server pushes the IPSec policies to the IPSec client and creates the corresponding VPN tunnel connection.
Note
Configuration Tasks
Perform the following tasks to configure your router for this network scenario:
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An example showing the results of these configuration tasks is provided in the "Configuration Example" section.
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Configure the IKE Policy
Perform these steps to configure the Internet Key Exchange (IKE) policy, beginning in global configuration mode:
Configure Group Policy Information
Perform these steps to configure the group policy, beginning in global configuration mode:
Step 1
crypto isakmp client configuration group {group-name | default}
Example:
Router(config)# crypto isakmp client configuration group rtr-remoteRouter(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-passwordRouter(config-isakmp-group)#Specifies the IKE pre-shared key for the group policy.
Step 3
dns primary-server
Example:
Router(config-isakmp-group)# dns 10.50.10.1Router(config-isakmp-group)#Specifies the primary Domain Name System (DNS) server for the group.
Note
Step 4
domain name
Example:
Router(config-isakmp-group)# domain company.comRouter(config-isakmp-group)#Specifies group domain membership.
Step 5
exit
Example:
Router(config-isakmp-group)# exitRouter(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 30.30.30.30Router(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.
Apply Mode Configuration to the Crypto Map
Perform these steps to apply mode configuration to the crypto map, beginning in global configuration mode:
Enable Policy Lookup
Perform these steps to enable policy lookup through AAA, beginning in global configuration mode:
Step 1
aaa new-model
Example:
Router(config)# aaa new-modelRouter(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 localRouter(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.
Step 3
aaa authorization {network | exec | commands level | reverse-access | configuration} {default | list-name} [method1 [method2...]]
Example:
Router(config)# aaa authorization network rtr-remote localRouter(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 CiscoRouter(config)#Establishes a username-based authentication system.
This example implements a username of Cisco with an encrypted password of Cisco.
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.
Perform these steps to specify the IPSec transform set and protocols, beginning in global configuration mode:
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-hmacRouter(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 86400Router(config)#Specifies global lifetime values used when IPSec security associations are negotiated.
See the Cisco IOS Security Command Reference for details.
Note
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:
Step 1
crypto dynamic-map dynamic-map-name dynamic-seq-num
Example:
Router(config)# crypto dynamic-map dynmap 1Router(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 vpn1Router(config-crypto-map)#Specifies which transform sets can be used with the crypto map entry.
Step 3
reverse-route
Example:
Router(config-crypto-map)# reverse-routeRouter(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)# exitRouter(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 dynmapRouter(config)#Creates a crypto map profile.
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 1
interface type number
Example:
Router(config)# interface fastethernet 4Router(config-if)#Enters the interface configuration mode for the interface to which you want the crypto map applied.
Step 2
crypto map map-name
Example:
Router(config-if)# crypto map static-mapRouter(config-if)#Applies the crypto map to the interface.
See the Cisco IOS Security Command Reference for more detail about this command.
Step 3
exit
Example:
Router(config-crypto-map)# exitRouter(config)#Returns to global configuration mode.
Create an Easy VPN Remote Configuration
The router acting as the IPSec remote router must create an Easy VPN remote configuration and assign it to the outgoing interface.
Perform these steps to create the remote configuration, beginning in global configuration mode:
Verifying Your Easy VPN Configuration
Router# show crypto ipsec client ezvpnTunnel name :ezvpnclientInside interface list:vlan 1Outside interface:fastethernet 4Current State:IPSEC_ACTIVELast Event:SOCKET_UPAddress:8.0.0.5Mask:255.255.255.255Default Domain:cisco.comConfiguration Example
The following configuration example shows a portion of the configuration file for the VPN and IPSec tunnel described in this chapter.
!aaa new-model!aaa authentication login rtr-remote localaaa authorization network rtr-remote localaaa session-id common!username Cisco password 0 Cisco!crypto isakmp policy 1encryption 3desauthentication pre-sharegroup 2lifetime 480!crypto isakmp client configuration group rtr-remotekey secret-passworddns 10.50.10.1 10.60.10.1domain company.compool dynpool!crypto ipsec transform-set vpn1 esp-3des esp-sha-hmac!crypto ipsec security-association lifetime seconds 86400!crypto dynamic-map dynmap 1set transform-set vpn1reverse-route!crypto map static-map 1 ipsec-isakmp dynamic dynmapcrypto map dynmap isakmp authorization list rtr-remotecrypto map dynmap client configuration address respondcrypto ipsec client ezvpn ezvpnclientconnect autogroup 2 key secret-passwordmode clientpeer 192.168.100.1!interface fastethernet 4crypto ipsec client ezvpn ezvpnclient outsidecrypto map static-map!interface vlan 1crypto ipsec client ezvpn ezvpnclient inside!
