Internet Key Exchange for IPsec VPNs Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 1000)
Distinguished Name Based Crypto Maps
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Distinguished Name Based Crypto Maps

Distinguished Name Based Crypto Maps

Feature History

Release

Modification

12.2(4)T

This feature was introduced.


Note


Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.


This feature module describes the Distinguished Name Based Crypto Map feature in Cisco IOS Release 12.2(4)T. It includes the following sections:

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Feature Overview

The Distinguished Name Based Crypto Maps feature allows you to configure the router to restrict access to selected encrypted interfaces for those peers with specific certificates, especially certificates with particular Distinguished Names (DNs).

Previously, if the router accepted a certificate or a shared secret from the encrypting peer, Cisco IOS did not have a method of preventing the peer from communicating with any encrypted interface other than the restrictions on the IP address of the encrypting peer. This feature allows you to configure which crypto maps are usable to a peer based on the DN that a peer used to authenticate itself, thereby, enabling you to control which encrypted interfaces a peer with a specified DN can access.

Benefits

The Distinguished Name Based Crypto Maps feature allows you to set restrictions in the router configuration that prevent peers with specific certificates--especially certificates with particular DNs-- from having access to selected encrypted interfaces.

Restrictions

System Requirements

To configure this feature, your router must support IP Security.

Performance Impact

If you restrict access to a large number of DNs, it is recommended that you specify a few number of crypto maps referring to large identity sections instead of specifying a large number of crypto maps referring to small identity sections.

Related Documents

The following documents provide information related to the Distinguished Name Based Crypto Maps feature:

  • Cisco IOS Security Command Reference
  • Cisco IOS Security Configuration Guide: Secure Connectivity, Release 12.4T
  • Next Generation Encryption (NGE) white paper.

Supported Platforms

This feature is supported on the following platforms:

  • Cisco 1700 series
  • Cisco 2600 series
  • Cisco 3620
  • Cisco 3640
  • Cisco 3660
  • Cisco 7100 series
  • Cisco 7200 series
  • Cisco uBR905 Cable Access Router
  • Cisco uBR925 Cable Access Router

Determining Platform Support Through Feature Navigator

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Supported Standards MIBs and RFCs

Standards

None

MIBs

None

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http:/​/​www.cisco.com/​go/​mibs

RFCs

None

Prerequisites

Before configuring a DN based crypto map, you must perform the following tasks:

  • Create an Internet Key Exchange (IKE) policy at each peer.

For more information on creating IKE policies, refer to the “ Configuring Internet Key Exchange for IPsec VPNs ” chapter in the Cisco IOS Security Configuration Guide: Secure Connectivity ..

  • Create crypto map entries for IPSec.

For more information on creating crypto map entries, refer to the “ Configuring Security for VPNs with IPsec ” chapter in the Cisco IOS Security Configuration Guide: Secure Connectivity

Configuration Tasks

See the following sections for configuration tasks for the Distinguished Name Based Crypto Maps feature. Each task in the list is identified as either required or optional.

Configuring DN Based Crypto Maps (authenticated by DN)

To configure a DN based crypto map that can be used only by peers that have been authenticated by a DN, use the following commands beginning in global configuration mode:

SUMMARY STEPS

    1.    Router(config)# crypto identity name

    2.    Router(crypto-identity)# dn name=string [,name=string]


DETAILED STEPS
     Command or ActionPurpose
    Step 1 Router(config)# crypto identity name 

    Configures the identity of a router with the given list of DNs in the certificate of the router and enters crypto identity configuration mode.

     
    Step 2 Router(crypto-identity)# dn name=string [,name=string] 

    Associates the identity of the router with the DN in the certificate of the router.

    Note   

    The identity of the peer must match the identity in the exchanged certificate.

     

    Configuring DN Based Crypto Maps (authenticated by hostname)

    To configure a DN based crypto map that can be used only by peers that have been authenticated by a hostname, use the following commands beginning in global configuration mode:

    SUMMARY STEPS

      1.    Router(config)# crypto identity name

      2.    Router(crypto-identity)# fqdn name


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 Router(config)# crypto identity name 

      Configures the identity of a router with the given list of DNs in the certificate of the router and enters crypto identity configuration mode.

       
      Step 2 Router(crypto-identity)# fqdn name 

      Associates the identity of the router with the hostname that the peer used to authenticate itself.

      Note   

      The identity of the peer must match the identity in the exchanged certificate.

       

      Applying Identity to DN Based Crypto Maps

      To apply the identity (within the crypto map context), use the following commands beginning in global configuration mode:

      SUMMARY STEPS

        1.    Router(config)# crypto map map-name seq-num ipsec-isakmp

        2.    Router(config-crypto-map)# identity name


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 Router(config)# crypto map map-name seq-num ipsec-isakmp 

        Creates or modifies a crypto map entry and enters the crypto map configuration mode.

         
        Step 2 Router(config-crypto-map)# identity name 

        Applies the identity to the crypto map.

        When this command is applied, only the hosts that match a configuration listed within the identity name can use the specified crypto map.

        Note   

        If the identity command does not appear within the crypto map, the encrypted connection does not have any restrictions other than the IP address of the encrypting peer.

         

        Verifying DN Based Crypto Maps

        To verify that this functionality is properly configured, use the following command in EXEC mode:

        Command

        Purpose

        Router# show crypto identity

        Displays the configured identities.

        Troubleshooting Tips

        If an encrypting peer attempts to establish a connection that is blocked by the DN based crypto map configuration, the following error message will be logged:

        <time>: %CRYPTO-4-IKE_QUICKMODE_BAD_CERT: encrypted connection attempted with a peer without the configured certificate attributes.

        Configuration Examples

        DN Based Crypto Map Configuration Example

        The following example shows how to configure DN based crypto maps that have been authenticated by DN and hostname. Comments are included inline to explain various commands.

        ! DN based crypto maps require you to configure an IKE policy at each peer.
        crypto isakmp policy 15
         encryption aes
         hash sha
         authentication rsa-sig
         group 14
         lifetime 5000
        crypto isakmp policy 20
         encryption aes
         hash sha
         authentication pre-share
         group 14
         lifetime 10000
        crypto isakmp key 1234567890 address 171.69.224.33
        !
        ! The following is an IPSec crypto map (part of IPSec configuration). It can be used only 
        ! by peers that have been authenticated by DN and if the certificate belongs to BigBiz.
        crypto map map-to-bigbiz 10 ipsec-isakmp
         set peer 172.21.114.196
         set transform-set my-transformset 
         match address 124
         identity to-bigbiz
        !
        crypto identity to-bigbiz
         dn ou=BigBiz
        !
        !
        ! This crypto map can be used only by peers that have been authenticated by hostname
        ! and if the certificate belongs to little.com.
        crypto map map-to-little-com 10 ipsec-isakmp
         set peer 172.21.115.119
         set transform-set my-transformset 
         match address 125
         identity to-little-com
        !
        crypto identity to-little-com
         fqdn little.com
        !