Enabling ISG to Interact with External Policy Servers

Intelligent Services Gateway (ISG) is a software feature set that provides a structured framework in which edge devices can deliver flexible and scalable services to subscribers. This document describes how to enable the ISG to retrieve session policies or accept dynamic updates to session policies from external policy servers.

Restrictions for ISG Interaction with External Policy Servers

The ISG and external policy servers should be available in the same virtual routing and forwarding (VRF) instance.

Information About ISG Interaction with External Policy Servers

Initial and Dynamic Authorization

ISG works with external devices, referred to as policy servers that store per-subscriber and per-service information. ISG supports two models of interaction between the ISG and external policy servers: initial authorization and dynamic authorization.

In the initial authorization model, ISG must retrieve policies from the external policy server at specific points in a session. In this model, the external policy server is typically an authentication, authorization, and accounting (AAA) server that uses RADIUS. ISG is the RADIUS client. Instead of a AAA server, some systems use a RADIUS proxy component that converts to other database protocols, such as Lightweight Directory Access Protocol (LDAP).

The dynamic authorization model allows the external policy server to dynamically send policies to ISG. These operations can be initiated in-band by subscribers (through service selection) or through the actions of an administrator, or applications can change policies on the basis of some algorithm (for example, change session quality of service (QoS) at a certain time of day). This model is facilitated by the Change of Authorization (CoA) RADIUS extension. CoA introduces peer-to-peer capability to RADIUS that enables ISG and the external policy server to act as the RADIUS client and server respectively.

Triple Key Authentication for ISG

Triple key authentication is a method of authenticating users based on their username, password, and location after ISG redirects them to the Cisco Service Management Engine (SME) portal. The SME server provides the location based on the source IP address of the subscriber being authenticated. Before the Triple Key Authentication Support feature was introduced, users were authenticated only on the basis of the username and password (two-key authentication). The Triple Key Authentication Support feature also eases migration from Service Selection Gateway (SSG) to an ISG platform because SSG uses triple key authentication.

For SSG, the Cisco Subscriber Edge Services Manager (SESM) server populates RADIUS attribute 31 (calling-station ID) in the user-login request that it sends to the SSG with a string containing the subscriber’s location. The SSG then includes this location string in the access-request message that it sends to the RADIUS server where the login is authenticated based on the username, password, and location string.

With ISG triple key authentication, the ISG sends the location string within a Cisco vendor-specific attribute (VSA) that is included in the access-request message to the RADIUS server.

The location information is received from SME as Cisco VSA 250. This location information is included in session authentication requests, session accounting requests from the ISG, and prepaid authorization requests.

The table below shows the Cisco vendor-specific non-AVPair attribute used for triple key authentication.

Table 1. Cisco Vendor-Specific Non-AVPair Attribute

Sub-AttrID

Attribute Type

Value

Function

Example

Used in

250

account-info

L<location- string>

Third key in triple key authentication

LWiFiHotSpot001

Acc-Req CoA Req Accounting

How to Enable ISG to Interact with External Policy Servers

Configuring ISG as a AAA Client

Perform this task to configure AAA method lists and enable ISG to retrieve policies from a AAA server. This task must be performed for both initial and dynamic authorization models.

Before you begin

The servers and server groups referenced by the AAA methods must be configured.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa authentication login {default | list-name } method1 [method2 ...]
  4. aaa authentication ppp {default | list-name } method1 [method2 ...]
  5. aaa authorization {network | exec | commands level | reverse-access | configuration } {default | list-name } [method1 [method2 ...]]
  6. aaa authorization subscriber-service {default | list-name } method1 [method2 ...]
  7. aaa accounting {auth-proxy | system | network | exec | connection | commands level } {default | list-name } [vrf vrf-name ] {start-stop | stop-only | none } [broadcast ] group group-name
  8. end

DETAILED STEPS

  Command or Action Purpose

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

aaa authentication login {default | list-name } method1 [method2 ...]

Example:


Router(config)# aaa authentication login PPP1 group radius

Specifies one or more AAA authentication methods to be used at login.

Step 4

aaa authentication ppp {default | list-name } method1 [method2 ...]

Example:


Router(config)# aaa authentication ppp default group radius

Specifies one or more AAA authentication methods for use on serial interfaces that are running PPP.

Step 5

aaa authorization {network | exec | commands level | reverse-access | configuration } {default | list-name } [method1 [method2 ...]]

Example:


Router(config)# aaa authorization network NET1 radius

Specifies one or more AAA authorization methods to be used for restricting subscriber access to a network.

Step 6

aaa authorization subscriber-service {default | list-name } method1 [method2 ...]

Example:


Router(config)# aaa authorization subscriber-service default radius

Specifies one or more AAA authorization methods for ISG to use in providing a service.

Step 7

aaa accounting {auth-proxy | system | network | exec | connection | commands level } {default | list-name } [vrf vrf-name ] {start-stop | stop-only | none } [broadcast ] group group-name

Example:


Router(config)# aaa accounting network default start-stop group radius

Enables AAA accounting of requested services for billing or security purposes.

Step 8

end

Example:


Router(config)# end

Exits global configuration mode.

Configuring ISG as a AAA Server

Dynamic authorization allows a policy server to dynamically send policies to ISG. Perform this task to configure ISG as a AAA server and enable dynamic authorization.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa server radius dynamic-author
  4. client {name | ip-address } [key [0 | 7 ] word ] [vrf vrf-id ]
  5. port port-number
  6. server-key [0 | 7 ] word
  7. auth-type {all | any | session-key }
  8. ignore {server-key | session-key }
  9. end

DETAILED STEPS

  Command or Action Purpose

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

aaa server radius dynamic-author

Example:


Router(config)# aaa server radius dynamic-author

Configures ISG as a AAA server and enters dynamic authorization local server configuration mode.

Step 4

client {name | ip-address } [key [0 | 7 ] word ] [vrf vrf-id ]

Example:


Router(config-locsvr-da-radius)# client 10.76.86.90 key cisco

Specifies a client with which ISG will be communicating.

Step 5

port port-number

Example:


Router(config-locsvr-da-radius)# port 1600

Specifies the RADIUS server port.

  • Default is 1700.

Step 6

server-key [0 | 7 ] word

Example:


Router(config-locsvr-da-radius)# server-key cisco

Specifies the encryption key shared with the RADIUS client.

Step 7

auth-type {all | any | session-key }

Example:


Router(config-locsvr-da-radius)# auth-type all

Specifies the attributes to be used for session authorization.

Step 8

ignore {server-key | session-key }

Example:


Router(config-locsvr-da-radius)# ignore session-key

Configures ISG to ignore the shared encryption key or attribute 151.

Step 9

end

Example:


Router(config-locsvr-da-radius)# end

Exits dynamic authorization local server configuration mode.

Enabling the Location VSA for Triple Key Authentication

Perform this task to enable ISG to include the location VSA in authentication and accounting requests.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. radius-server vsa send accounting
  5. radius-server vsa send authentication
  6. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enters privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Router(config)# aaa new-model

Enables AAA.

Step 4

radius-server vsa send accounting

Example:


Router(config)# radius-server vsa send accounting

Enables ISG to recognize and use accounting VSAs as defined by RADIUS attribute 26.

Step 5

radius-server vsa send authentication

Example:


Router(config)# radius-server vsa send authentication

Enables ISG to recognize and use authentication VSAs as defined by RADIUS attribute 26.

Step 6

end

Example:


Router(config)# end

Exits to privileged EXEC mode.

Configuration Examples for ISG Interaction with External Policy Servers

Example: Enabling ISG to Interact with External Policy Servers

The following example shows how to configure ISG as a AAA client. 



aaa group server radius CAR_SERVER
 server 10.100.2.36 auth-port 1812 acct-port 1813

aaa authentication login default none
aaa authentication login IP_AUTHEN_LIST group CAR_SERVER
aaa authentication ppp default group CAR_SERVER
aaa authorization network default group CAR_SERVER 
aaa authorization subscriber-service default local group radius 
aaa accounting network default start-stop group CAR_SERVER

The following example shows how to configure ISG as a AAA server. 


aaa server radius dynamic-author
  client 10.76.86.90 server-key cisco
  port 1600
  server-key cisco 
  auth-type all
  ignore session-key

Example: Enabling the Location VSA for Triple Key Authentication

The following example shows how to enable ISG to use VSAs for accounting and authentication. 


aaa new-model
radius-server vsa send accounting
radius-server vsa send authentication

The following example shows an authentication record with the session information, including the location attribute. You can display this output by using the debug radius accounting command or the gw-accounting syslog command. 


Device# debug radius accounting

*Feb  5 01:20:50.413: RADIUS/ENCODE: Best Local IP-Address 10.0.1.1 for Radius-Server 10.0.1.2
*Feb  5 01:20:50.425: RADIUS(0000000F): Send Access-Request to 10.0.1.2:1645 id 1645/5, len 107
*Feb  5 01:20:50.425: RADIUS:  authenticator 4D 86 12 BC BD E9 B4 9B - CB FC B8 7E 4C 8F B6 CA
*Feb  5 01:20:50.425: RADIUS:  Vendor, Cisco       [26]  19  
*Feb  5 01:20:50.425: RADIUS:   ssg-account-info   [250] 13  "LWiFiHotSpot001"   
*Feb  5 01:20:50.425: RADIUS:  Calling-Station-Id  [31]  16  "AAAA.BBBB.CCCC"
*Feb  5 01:20:50.425: RADIUS:  User-Name           [1]   7   "george"
*Feb  5 01:20:50.425: RADIUS:  User-Password       [2]   18  *
*Feb  5 01:20:50.425: RADIUS:  NAS-Port-Type       [61]  6   Virtual                   [5]
*Feb  5 01:20:50.425: RADIUS:  NAS-Port            [5]   6   0                         
*Feb  5 01:20:50.425: RADIUS:  NAS-Port-Id         [87]  9   "0/0/0/0"
*Feb  5 01:20:50.425: RADIUS:  NAS-IP-Address      [4]   6   10.0.1.1                  
*Feb  5 01:20:50.425: RADIUS(0000000F): Started 5 sec timeout
*Feb  5 01:20:50.425: RADIUS: Received from id 1645/5 10.0.1.2:1645, Access-Accept, len 68
*Feb  5 01:20:50.425: RADIUS:  authenticator 49 A1 2C 7F C5 E7 9D 1A - 97 B3 E3 72 F3 EA 56 56
*Feb  5 01:20:50.425: RADIUS:  Vendor, Cisco       [26]  17  
*Feb  5 01:20:50.425: RADIUS:   ssg-account-info   [250] 11  "S10.0.0.2"
*Feb  5 01:20:50.425: RADIUS:  Vendor, Cisco       [26]  31  
*Feb  5 01:20:50.425: RADIUS:   Cisco AVpair       [1]   25  "accounting-list=default"
*Feb  5 01:20:50.433: RADIUS(0000000F): Received from id 1645/5
*Feb  5 01:20:50.437: RADIUS/ENCODE(0000000F):Orig. component type = Iedge IP SIP
*Feb  5 01:20:50.437: RADIUS(0000000F): Config NAS IP: 0.0.0.0
*Feb  5 01:20:50.437: RADIUS(0000000F): sending

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

ISG commands

Cisco IOS Intelligent Services Gateway Command Reference

AAA configuration tasks

Part 1, “Authentication, Authorization, and Accounting (AAA),” Cisco IOS XE Security Configuration Guide

AAA commands

Cisco IOS Security Command Reference

MIBs

MIB

MIBs Link

No new or modified MIBs are supported.

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

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

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for ISG Interaction with External Policy Servers

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 www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 2. Feature Information for ISG Interaction with External Policy Servers

Feature Name

Releases

Feature Information

ISG—Policy Control Policy Server CoA

Cisco IOS XE Release 3.3SG

This feature provides ISG support for the RADIUS Change of Authorization (CoA) extension, which facilitates dynamic authorization.

This feature was integrated into Cisco IOS XE Release 3.3SG.

ISG—Session Lifecycle Packet of Disconnect (POD)

Cisco IOS XE Release 3.3SG

This feature enables an external policy server to terminate an ISG session when it receives a RADIUS Packet of Disconnect (POD).