RADIUS Attribute 8 Framed-IP-Address in Access Requests

The RADIUS Attribute 8 (Framed-IP-Address) in Access Requests feature makes it possible for a network access server (NAS) to provide the RADIUS server with a hint of the user IP address in advance of user authentication. An application can be run on the RADIUS server to use this hint and build a table (map) of user names and addresses. Using the mapping information, service applications can begin preparing user login information to have available upon successful user authentication.

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Prerequisites for RADIUS Attribute 8 Framed-IP-Address in Access Requests

Sending RADIUS attribute 8 in the RADIUS access requests assumes that the login host has been configured to request its IP address from the NAS server. It also assumes that the login host has been configured to accept an IP address from the NAS.

The NAS must be configured with a pool of network addresses on the interface supporting the login hosts.

Information About RADIUS Attribute 8 Framed-IP-Address in Access Requests

How This Feature Works

When a network device dials in to a NAS that is configured for RADIUS authentication, the NAS begins the process of contacting the RADIUS server in preparation for user authentication. Typically, the IP address of the dial-in host is not communicated to the RADIUS server until after successful user authentication. Communicating the device IP address to the server in the RADIUS access request allows other applications to begin to take advantage of that information.

As the NAS is setting up communication with the RADIUS server, the NAS assigns an IP address to the dial-in host from a pool of IP addresses configured at the specific interface. The NAS sends the IP address of the dial-in host to the RADIUS server as attribute 8. At that time, the NAS sends other user information, such as the user name, to the RADIUS server.

After the RADIUS server receives the user information from the NAS, it has two options:

  • If the user profile on the RADIUS server already includes attribute 8, the RADIUS server can override the IP address sent by the NAS with the IP address defined as attribute 8 in the user profile. The address defined in the user profile is returned to the NAS.

  • If the user profile does not include attribute 8, the RADIUS server can accept attribute 8 from the NAS, and the same address is returned to the NAS.

The address returned by the RADIUS server is saved in memory on the NAS for the life of the session. If the NAS is configured for RADIUS accounting, the accounting start packet sent to the RADIUS server includes the same IP address as in attribute 8. All subsequent accounting packets, updates (if configured), and stop packets will also include the same IP address provided in attribute 8.

However, the RADIUS attribute 8 (Framed-IP-Address) is not included in the accounting start packets in the following two conditions:

  • If the user is a dual-stack (IPv4 or IPv6) subscriber.

  • If the IP address is from a local pool and not from the RADIUS server.

In both these conditions, use the aaa accounting delay-start extended-time delay-value command to delay the Internet Protocol Control Protocol version 6 (IPCPv6) address negotiation using the configured delay value. During the delay, the IPCPv4 address is posted and the framed IPv4 address is added to the accounting start packet.

Benefits

The RADIUS Attribute 8 (Framed-IP-Address) in Access Requests feature makes it possible to run applications on the RADIUS server that builds mapping tables of users and IP addresses. The server can then use the mapping table information in other applications, such as preparing customized user login pages in advance of a successful user authentication with the RADIUS server.

How to Configure RADIUS Attribute 8 Framed-IP-Address in Access Requests

Configuring RADIUS Attribute 8 in Access Requests

To send RADIUS attribute 8 in the access request, perform the following steps:

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    radius-server attribute 8 include-in-access-req


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 radius-server attribute 8 include-in-access-req


    Example:
    Router(config)# radius-server attribute 8 include-in-access-req
     

    Sends RADIUS attribute 8 in access-request packets.

     

    Verifying RADIUS Attribute 8 in Access Requests

    To verify that RADIUS attribute 8 is being sent in access requests, perform the following steps. Attribute 8 should be present in all PPP access requests.

    SUMMARY STEPS

      1.    enable

      2.    more system:running-config

      3.    debug radius


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Router> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 more system:running-config


      Example:
      Router# more system:running-config
       

      Displays the contents of the current running configuration file. (Note that the more system:running-config command has replaced the show running-config command.)

       
      Step 3 debug radius


      Example:
      Router# debug radius
       

      Displays information associated with RADIUS. The output of this command shows whether attribute 8 is being sent in access requests.

       

      Configuration Examples for RADIUS Attribute 8 Framed-IP-Address in Access Requests

      NAS Configuration That Sends the IP Address of the Dial-in Host Example

      The following example shows a NAS configuration that sends the IP address of the dial-in host to the RADIUS server in the RADIUS access request. The NAS is configured for RADIUS authentication, authorization, and accounting (AAA). A pool of IP addresses (async1-pool) has been configured and applied at interface virtual-template1.

      aaa new-model
aaa authentication login default group radius
aaa authentication ppp default group radius
aaa authorization network default group radius 
aaa accounting network default start-stop group radius
!
ip address-pool local
!
interface virtual-template1
 peer default ip address pool async1-pool
!
ip local pool async1-pool 209.165.200.225 209.165.200.229
!
radius-server host 172.31.71.146 auth-port 1645 acct-port 1646
radius-server retransmit 3
radius-server attribute 8 include-in-access-req
radius-server key radhost<xxx>: Example

      Additional References

      The following sections provide references related to the RADIUS Attribute 8 (Framed-IP-Address) in Access Requests feature.

      Related Documents

      Related Topic

      Document Title

      Configuring authentication and c onfiguring RADIUS

      “Configuring Authentication” and “Configuring RADIUS” chapters in the Cisco IOS XE Security Configuration Guide: Configuring User Services , Release 2.

      Security commands

      Cisco IOS Security Command Reference

      Standards

      Standard

      Title

      No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

      --

      MIBs

      MIB

      MIBs Link

      No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

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

      http:/​/​www.cisco.com/​go/​mibs

      RFCs

      RFC

      Title

      RFC 2138

      Remote Authentication Dial In User Service (RADIUS)

      Technical Assistance

      Description

      Link

      The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

      To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

      Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

      http:/​/​www.cisco.com/​techsupport

      Feature Information for RADIUS Attribute 8 Framed-IP-Address in Access Requests

      The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

      Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.
      Table 1 Feature Information for RADIUS Attribute 8 (Framed-IP-Address) in Access Requests

      Feature Name

      Releases

      Feature Information

      RADIUS Attribute 8 (Framed-IP-Address) in Access Requests

      (Also called Sticky IP)

      Cisco IOS XE Release 2.1

      The RADIUS Attribute 8 (Framed-IP-Address) in Access Requests feature makes it possible for a network access server (NAS) to provide the RADIUS server with a hint of the user IP address in advance of user authentication.

      In Cisco IOS XE Release 2.1, this feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers.

      The following commands were introduced or modified: radius-server attribute 8 include-in-access-req.