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Configuring RADIUS Authentication and Accounting Servers

The number of RADIUS servers you can configure depends on available memory.

The order in which you configure servers determines the order in which the router contacts those servers on behalf of clients.

Initially, a RADIUS client sends a request to a RADIUS authentication or accounting server. The RADIUS server uses the configured IP address, the UDP port number, and the secret key to make the connection. The RADIUS client waits for a response for a configurable timeout period and then retransmits the request. The RADIUS client retransmits the request for a user-configurable retry limit.

For example, suppose that you have configured the following authentication servers: Auth1, Auth2, Auth3, Auth4, and Auth5. Your router attempts to send an authentication request to Auth1. If Auth1 is unavailable, the router submits the request to Auth2, then Auth3, and so on until an available server is found. If Auth5, the last configured authentication server, is not available, the router attempts the next method in the methods list. If the only method configured is RADIUS, then the router notifies the client that the request has been denied.

Server Access

The router offers two options by which servers are accessed:

Use the radius algorithm command to specify the server access method.

When you configure the first RADIUS accounting server, a RADIUS Acct-On message is sent. When you delete the last accounting server, a RADIUS Acct-Off message is sent.

Server Request Processing Limit

Authentication servers and accounting servers use different UDP ports on the router. This enables the same IP address to be used for both an authentication server and an accounting server. Note however, that the same IP address cannot be used for multiple authentication servers or for multiple accounting servers.

Each authentication and accounting server supports up to 4,000 concurrent RADIUS requests. For example, an authentication server at address 10.10.0.1, using UDP port 1812, supports a maximum of 4,000 authentication requests. The accounting server at 10.10.0.1, using UDP port 1813, supports a maximum of 4,000 accounting requests.

The E-series router listens to UDP source (or local) port 50000 for RADIUS authentication responses and to UDP source port 50016 for RADIUS accounting responses. Each UDP source port supports a maximum of 255 RADIUS requests. When the 255 limit is reached, the router opens the next source port. When the 4,000 requests-per-server limit is reached, the router submits the request to the next configured server.

Authentication and Accounting Methods

When you configure AAA authentication and accounting services for your B-RAS environment, one important task is to specify the authentication and accounting method used. The JUNOSe software gives you the flexibility to configure authentication or accounting methods based on the type of subscriber. This feature allows you to enable RADIUS authentication for some subscribers, while disabling authentication completely for other subscribers. Similarly, you can enable RADIUS accounting for some subscribers, but no accounting for others. For example, you might use RADIUS authentication for ATM 1483 subscribers, while granting IP subscriber management interfaces access without authentication (using the none keyword).

You can specify the authentication or accounting method you want to use, or you can specify multiple methods in the order in which you want them used. For example, if you specify the radius keyword followed by the none keyword when configuring authentication, AAA initially attempts to use RADIUS authentication. If no RADIUS servers are available, AAA uses no authentication. The JUNOSe software currently supports radius and none as accounting methods and radius, none, and local as authentication methods. See Configuring Local Authentication Servers on page 34 for information about local authentication.

You can configure authentication and accounting methods based on the following types of subscribers:

Immediate Accounting Updates

You can use the aaa accounting immediate-update command to configure immediate accounting updates on a per-VR basis. If you enable this feature, the E-series router sends an Acct-Update message to the accounting server immediately on receipt of a response (ACK or timeout) to the Acct-Start message.

This feature is disabled by default. Use the enable keyword to enable immediate updates and the disable keyword to halt them.

The accounting update contains 0 (zero) values for the input/output octets/packets and 0 (zero) for uptime. If you have enabled duplicate or broadcast accounting, the accounting update goes to both the primary virtual router context and the duplicate or broadcast virtual router context.

Duplicate and Broadcast Accounting

Normally, the JUNOSe software sends subscriber-related AAA accounting information to the virtual router that authenticates the subscriber. If an operational virtual router is configured that is different from the authentication router, it also receives the accounting information. You can optionally configure duplicate or broadcast AAA accounting, which sends the accounting information to additional virtual routers simultaneously. The accounting information continues to be sent to the authenticating virtual router, but not to the operational virtual router.

Both the duplicate and broadcast accounting features are supported on a per-virtual router context, and enable you to specify particular accounting servers that you want to receive the accounting information. For example, you might use broadcast accounting to send accounting information to a group of your private accounting servers. Or you might use duplicate accounting to send the accounting information to a customer's accounting server.

Configuring AAA Duplicate Accounting

To configure and enable duplicate accounting on a virtual router, you use the aaa accounting duplication command with the name of the accounting server that will receive the information. For example, to enable duplicate accounting for the default virtual router:

host1(config)#aaa accounting duplication xyzCompanyServer 

Configuring AAA Broadcast Accounting

To configure and enable broadcast accounting on a virtual router:

  1. Create the virtual router group and enter VR Group Configuration mode:
  2. host1(config)#aaa accounting vr-group groupXyzCompany
    
    host1(vr-group-config)#
    
    
    
  3. Add up to four virtual routers to the group. The accounting information will be sent to all virtual routers in the group.
  4. host1(vr-group-config)#aaa virtual-router 1 vrXyz1
    
    host1(vr-group-config)#aaa virtual-router 2 vrXyz2
    
    host1(vr-group-config)#aaa virtual-router 3 vrXyz3
    
    host1(vr-group-config)#exit
    
    host1(config)#
    
    
    
  5. Enable broadcast accounting. Enter the correct virtual router context, and specify the virtual router group whose virtual routers will receive the accounting information.
  6. host1(config)#virtual-router opVr100
    
    host1:opVr100(config)#aaa accounting broadcast groupXyzCompany 
    

Overriding AAA Accounting NAS Information

AAA accounting packets normally include two RADIUS attributes—NAS-IP-Address [4] and NAS-Identifier [32]—of the virtual router that generates the accounting information. You can override the default configuration and specify that accounting packets from particular broadcast virtual routers instead include the NAS-IP-Address and NAS-Identifier attributes of the authenticating virtual router.

To override the normal AAA accounting NAS information, access the correct virtual router context, and use the radius override nas-info command. For example:

host1(config)#virtual-router vrXyz1
host1:vrXyz1(config)#radius override nas-info 
host1:vrXyz1(config)#virtual-router vrXyz2
host1:vrXyz2(config)#radius override nas-info 
host1:vrXyz3(config)#exit 
host1(config)#

UDP Checksums

Each virtual router on which you configure B-RAS is enabled to perform UDP checksums by default. You can disable and reenable UDP checksums.

Configuring RADIUS AA Servers

The number of RADIUS servers you can configure depends on available memory. The router has an embedded RADIUS client for authentication and accounting.

NOTE: You can configure B-RAS with RADIUS accounting, but without RADIUS authentication. In this configuration, the username and password on the remote end are not authenticated and can be set to any value.


You must assign an IP address to a RADIUS authentication or accounting server to configure it.

If you do not configure a primary authentication or accounting server, all authentication and accounting requests will fail. You can configure other servers as backup in the event that the primary server cannot be reached. Configure each server individually.

To configure an authentication or accounting RADIUS server:

  1. Specify the authentication or accounting server address.
  2. host1(config)#radius authentication server 10.10.10.1
    
    host1(config-radius)#
    
    or
    
    host1(config)#radius accounting server 10.10.10.6
    
    host1(config-radius)#
    
    
    
  3. (Optional) Specify a UDP port for RADIUS authentication or accounting server requests.
  4. host1(config-radius)#udp-port 1645
    
    
    
  5. Specify an authentication or accounting server secret.
  6. host1(config-radius)#key gismo
    
    
    
  7. (Optional) Specify the number of retries the router makes to an authentication or accounting server before it attempts to contact another server.
  8. host1(config-radius)#retransmit 2
    
    
    
  9. (Optional) Specify the number of seconds between retries.
  10. host1(config-radius)#timeout 5
    
    
    
  11. (Optional) Specify the maximum number of outstanding requests.
  12. host1(config-radius)#max-sessions 100
    
    
    
  13. (Optional) Specify the amount of time to remove a server from the available list when a timeout occurs.
  14. host1(config-radius)#deadtime 10
    
    
    
  15. (Optional) In Global Configuration mode, specify whether the E-series router should move on to the next RADIUS server when the router receives an Access-Reject message for the user it is authenticating.
  16. host1(config)#radius rollover-on-reject enable
    
    
    
  17. (Optional) Enable duplicate address checking.
  18. host1(config)aaa duplicate-address-check enable
    
    
    
  19. (Optional) Specify that duplicate accounting records be sent to the accounting server for a virtual router.
  20. host1(config)#aaa accounting duplication routerBoston
    
    
    
  21. (Optional) Enter the correct virtual router context, and specify the virtual router group to which broadcast accounting records are sent.
  22. host1(config)#virtual-router vrSouth25
    
    host1:vrSouth25(config)#aaa accounting broadcast westVrGroup38
    
    host1:vrSouth25(config)#exit
    
    
    
  23. (Optional) Specify that immediate accounting updates be sent to the accounting server when a response is received to an Acct-Start message.
  24. host1(config)#aaa accounting immediate-update
    
    
    
  25. (Optional) Specify that tunnel accounting be enabled or disabled.
  26. host1(config)#radius tunnel-accounting enable
    
    
    
  27. (Optional) Specify the default authentication and accounting methods for the subscribers.
  28. host1(config)#aaa authentication ppp default radius none
    
    
    
  29. (Optional) Disable UDP checksums on virtual routers you configure for B-RAS.
  30. host1:(config)#virtual router boston
    
    host1:boston(config)#radius udp-checksum disable
    

aaa accounting broadcast

aaa accounting default

aaa accounting duplication

aaa accounting immediate-update

aaa accounting interval

aaa accounting vr-group

aaa authentication default

aaa duplicate-address-check

aaa virtual-router

deadtime

key

logout subscribers

max-sessions

no radius client

radius algorithm

radius override nas-info

radius rollover-on-reject

radius server

radius tunnel-accounting

radius udp-checksum

radius update-source-addr

retransmit

test aaa

timeout

udp-port

SNMP Traps and System Log Messages

The router can send Simple Network Management Protocol (SNMP) traps to alert network managers when:

Returning to active service means that the E-series RADIUS client receives a valid response to an outstanding RADIUS request after the server is marked unavailable.

The router also generates system log messages when RADIUS servers fail to respond or when they return to active service; no configuration is required for system log messages.

SNMP Traps

The router generates SNMP traps and system log messages as follows:

If the E-series RADIUS client receives a RADIUS response from a "dead" RADIUS server during the deadtime period, the RADIUS server is restored to active status.

If the router receives a valid RADIUS response to an outstanding RADIUS request, the E-series client issues a system log message and, if configured, an SNMP trap indicating that the RADIUS server is now available.

System Log Messages

You do not need to configure system log messages. The router automatically sends them when individual servers do not respond to RADIUS requests and when all servers on a VR fail to respond to requests. The following are the formats of the warning level system log messages:

RADIUS [ authentication | accounting ] server serverAddress unavailable in VR 
virtualRouterName [; trying nextServerAddress]

RADIUS no [ authentication | accounting ] servers responding in VR 
virtualRouterName

RADIUS [ authentication | accounting ] server serverAddress available in VR 
virtualRouterName

Configuring SNMP Traps

This section describes how to configure the router to send traps to SNMP when RADIUS servers fail to respond to messages, and how to configure SNMP to receive the traps.

To set up the router to send traps:

  1. (Optional) Enable SNMP traps when a particular RADIUS authentication server fails to respond to Access-Request messages.
  2. host1(config)#radius trap auth-server-not-responding enable 
    
    
    
  3. (Optional) Enable SNMP traps when all of the configured RADIUS authentication servers on a VR fail to respond to Access-Request messages.
  4. host1(config)#radius trap no-auth-server-responding enable
    
    
    
  5. (Optional) Enable SNMP traps when a RADIUS authentication server returns to active service.
  6. host1(config)#radius trap auth-server-responding enable
    
    
    
  7. (Optional) Enable SNMP traps when a RADIUS accounting server fails to respond to a RADIUS accounting request.
  8. host1(config)#radius trap acct-server-not-responding enable
    
    
    
  9. (Optional) Enable SNMP traps when all of the RADIUS accounting servers on a VR fail to respond to a RADIUS accounting request.
  10. host1(config)#radius trap no-acct-server-responding enable
    
    
    
  11. (Optional) Enable SNMP traps when a RADIUS accounting server returns to active service.
  12. host1(config)#radius trap acct-server-responding enable
    
    
    

To set up SNMP to receive RADIUS traps:

  1. Set up the appropriate SNMP community strings.
  2. host1(config)#snmp-server community admin view everything rw
    
    host1(config)#snmp-server community private view user rw 
    
    host1(config)#snmp-server community public view everything ro 
    
    
    
  3. Specify the interface whose IP address is the source address for SNMP traps.
  4. host1(config)#snmp-server trap-source fastEthernet 0/0
    
    
    
  5. Configure the host that should receive the SNMP traps.
  6. host1(config)#snmp-server host 10.10.132.93 version 2c 3 udp-port 162 radius 
    
    
    
  7. Enable the SNMP router agent to receive and forward RADIUS traps.
  8. host1(config)#snmp-server enable traps radius 
    
    
    
  9. Enable the SNMP on the router.
  10. host1(config)#snmp-server
    
    
    

    NOTE: For more information about these SNMP commands, see Configuring Traps in JUNOSe System Basics Configuration Guide, Chapter 3, Configuring SNMP.

radius trap acct-server-not-responding

radius trap acct-server-responding

radius trap auth-server-not-responding

radius trap auth-server-responding

radius trap no-acct-server-responding

radius trap no-auth-server-responding


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