Manual Chapter : RADIUS Accounting

Applies To:

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BIG-IP APM

  • 15.0.1, 15.0.0
Manual Chapter

RADIUS Accounting

About RADIUS accounting

You can report user session information to an external RADIUS accounting server. If you select this mode only, the system assumes that you have set up another type of authentication method to authenticate and authorize your users to access their resources.
How does RADIUS accounting work?
  1. After RADIUS accounting runs successfully in an access policy, Access Policy Manager sends an accounting start request message to the external RADIUS server. The
    start
    message typically contains the user's ID, networks address, point of attachment, and a unique session identifier.
  2. When the session is destroyed, Access Policy Manager issues an accounting
    stop
    message to the external RADIUS server, providing information on the final usage in terms of time, packets transferred, data transferred, and reason for disconnect, as well as other information related to the user's access.
This accounting data is used primarily for billing, statistical, and general network monitoring purposes.
You can perform both RADIUS authentication and accounting actions. Keep in mind that if you select this mode, the RADIUS server and the RADIUS accounting server must run on different service ports.

About how APM handles binary values in RADIUS attributes

For RADIUS authentication, Access Policy Manager (APM) converts an attribute value to hex if it contains unprintable characters, or if it is the
class
attribute. APM converts the class attribute to hex even if it contains only printable values (by attribute type). No other attributes are encoded to hex if they do not contain unprintable characters.
An attribute with a single unprintable value
1bf80e04.session.radius.last.attr.class 62 / 0x54230616000001370001ac1d423301caa87483dadf740000000000000007
Attribute with multiple values, both printable and unprintable (binary)
243be90d.session.radius.last.attr.class 119 0x6162636465666768696 / a6b6c6d6e6f707172737475767778797a | 0x54220615000001370001ac1d423301caa87483 / dadf740000000000000006
An attribute type that does not require hex encoding with both printable and unprintable values
3888eb70.session.radius.last.attr.login-lat-group 37 / 0x6d7920bda12067726f757032 | mygroup1
In this case, only values that are unprintable are encoded to hex.

Configuring a RADIUS Accounting server in APM

  1. On the Main tab, click
    Access
    Authentication
    RADIUS
    .
    The RADIUS servers screen opens.
  2. Click
    Create
    .
    The New Server properties screen opens.
  3. In the
    Name
    field, type a unique name for the authentication server.
  4. From the
    Mode
    list, select
    Accounting
    .
  5. For the
    Server Connection
    setting, select one of these options:
    • Select
      Use Pool
      to set up high availability for the AAA server.
    • Select
      Direct
      to set up the AAA server for standalone functionality.
  6. If you selected
    Use Pool
    , type a name in the
    Server Pool Name
    field.
    You create a pool of servers on this screen.
  7. Provide the addresses required for your server connection:
    • If you selected
      Direct
      , type an IP address in the
      Server Address
      field.
    • If you selected
      Use Pool
      , for each pool member you want to add, type an IP address in the
      Server Addresses
      field and click
      Add
      .
      When you configure a pool, you have the option to type the server address in route domain format:
      IPAddress
      %
      RouteDomain
      .
  8. If you selected
    Use Pool
    , you have the option to select a
    Server Pool Monitor
    to track the health of the server pool.
  9. In the
    Accounting Service Port
    field, type the service port for your accounting server if the default value is not appropriate.
    The default is
    1813
    .
  10. In the
    Secret
    field, type the shared secret password of the server.
  11. In the
    Confirm Secret
    field, re-type the shared secret password of the server.
  12. In the
    Timeout
    field, type a timeout interval (in seconds) for the AAA server.
    This setting is optional.
    If you use the
    Timeout
    setting, you can also use the
    Retries
    setting. If these settings are enabled, the Access Policy Manager attempts to reach the AAA server within the specified time frame, in seconds. If the server does not respond, the Access Policy Manager retries the authentication attempt, depending on how many retries you specify.
  13. In the
    Retries
    field, type the number of times the BIG-IP system should try to make a connection to the server after the first attempt fails.
    This setting is optional.
  14. Click
    Finished
    .
    The new server displays on the list.

Adding RADIUS accounting to an access policy

Before you set up an access policy to use RADIUS accounting, you must have at least one RADIUS AAA server configured. You should also have an access profile that is configured with actions that authenticate the user.
You add a RADIUS accounting action to an access policy to send RADIUS start and stop messages to a RADIUS server. RADIUS accounting does not authenticate a user.
  1. On the Main tab, click
    Access
    Profiles / Policies
    .
    The Access Profiles (Per-Session Policies) screen opens.
  2. In the Per-Session Policy column, click the
    Edit
    link for the access profile you want to configure.
    The visual policy editor opens the access policy in a separate screen.
  3. Click the
    (+)
    icon anywhere in the access policy to add a new item.
    Only an applicable subset of access policy items is available for selection in the visual policy editor for any access profile type.
    A popup screen opens, listing predefined actions on tabs such as General Purpose, Authentication, and so on.
  4. From the Authentication tab, select
    RADIUS Acct
    and click
    Add Item
    .
    The popup screen closes. A properties popup screen opens.
  5. From the
    AAA Server
    list, select a RADIUS accounting server and click
    Save
    .
    The properties popup screen closes and the visual policy editor displays.
  6. Click
    Apply Access Policy
    to save your configuration.
This adds the RADIUS accounting action to the access policy.
To apply this access policy to network traffic, add the access profile to a virtual server.
To ensure that logging is configured to meet your requirements, verify the log settings for the access profile.

RADIUS authentication and accounting troubleshooting tips

You might run into problems with RADIUS authentication and accounting in some instances. Follow these tips to try to resolve any issues you might encounter.

RADIUS authentication and accounting access policy action troubleshooting

Possible error messages
Possible explanations and actions
Authentication failed due to timeout
  • Verify that Access Policy Manager is configured as a client on the RADIUS server.
  • You might have encountered a general network connection problem.
Authentication failed due to RADIUS access reject
  • Verify that the shared secret on the RADIUS server is valid.
  • Verify that user credentials are entered correctly.

Additional troubleshooting tips for RADIUS authentication and accounting

Action
Steps
Check to see if your access policy is attempting to perform authentication
  • Add message boxes to your access policy to display information about what the access policy is attempting to do.
  • Refer to
    /var/log/apm
    to view authentication and accounting attempts by the access policy.
Make sure that your log level is set to the appropriate level. The default log level is
notice
.
Check the RADIUS Server configuration
  • Confirm that the Access Policy Manager is registered as a RADIUS client. Since the Access Policy Manager makes requests from the self IP address to the RADIUS server for authentication requests, the address of the self-IP address should be registered as a RADIUS client.
  • Check the RADIUS logs and check for any errors.
Confirm network connectivity
  • Access the BIG-IP system through the command line interface and check your connectivity by pinging the RADIUS server using the host entry in the AAA Server box.
  • Confirm that the RADIUS port 1812 is not blocked between the Access Policy Manager and the RADIUS server.
Capture a TCP dump
  • Take a TCP dump from the Access Policy Manager when authentication attempts are made. For example, %TCP dump-i 1.1 -s /tmp/dump. You must first determine what interface the self IP address is on. These TCP dumps indicate activities between the Access Policy Manager and the authentication server.
  • Run the authentication test. After authentication fails, stop the TCP dump, download the TCP dump records to a client system, and use an analyzer to troubleshoot.
If you decide to escalate the issue to customer support, you must provide a capture of the TCP dump when you encounter authentication issues that you cannot otherwise resolve on your own.