Manual Chapter : RADIUS Authentication

Applies To:

Show Versions

BIG-IP APM

14.1.5, 14.1.4

RADIUS Authentication

About RADIUS authentication

Access Policy Manager supports authenticating and authorizing the client against external RADIUS servers. When a client connects with the user name and password, Access Policy Manager authenticates against the external server on behalf of the client, and authorizes the client to access resources if the credentials are valid.

The client requests access to network resources through Access Policy Manager.

Access Policy Manager then issues a

RADIUS Access Request

message to the RADIUS server, requesting authorization to grant access.

The RADIUS server then processes the request, and issues one of three responses to Access Policy Manager:

Access Accept

Access Challenge

, or

Access Reject

About AAA high availability

Using AAA high availability with Access Policy Manager (APM), you can configure multiple authentication servers to process requests, so that if one authentication server goes down or loses connectivity, the others can resume authentication requests, and new sessions can be established, as usual.

Although new authentications fail if the BIG-IP® system loses connectivity to the server, existing sessions are unaffected provided that they do not attempt to re-authenticate.

APM supports the following AAA servers for high availability: RADIUS, Active Directory, LDAP, CRLDP, and TACACS+. APM supports high availability by providing the option to create a pool of server connections when you configure the supported type of AAA server.

If you use AAA with pools, such as RADIUS pools or Active Directory pools, APM assigns each pool member with a different number for the pool member's priority group value. APM must define each pool member with a different priority group because AAA load balancing is not used. The priority group number increases automatically with each created pool member. Alternative AAA pool configurations can be defined manually using the full flexibility of Local Traffic Manager (LTM) if high availability is desired.

Guidelines for setting up RADIUS authentication for AAA high availability

When you use RADIUS as the authentication method for AAA high availability, there are general guidelines that you must follow when you set up your server connections.

In a non-high availability environment, both the

Direct

and

Use Pool

options use the self IP address as a source IP address of the packet reaching the RADIUS server. For this scenario, you just need to add one IP address to the RADIUS allowed IP list to achieve this.

In a high availability environment where the

Use Pool

option is used, the floating self IP address is used as a source IP of the RADIUS packet reaching the back-end. For this scenario, you need to add one self IP address (which is floating self IP address) to the RADIUS allowed IP list because the IP address is used even after a failover occurs.

In a high availability environment where the

Direct

option is used, the static self IP address is used as a source IP address of the RADIUS packet reaching the back-end. In this scenario, you need to add the self IP address from both active and standby devices to the RADIUS allowed IP list so that when failover occurs, the self IP address from the second device is accepted by the RADIUS server.

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 RADIUS authentication

If you add RADIUS authentication to an existing access policy, you already have an access profile configured and the access policy might already include a logon access policy item.

Configuring a RADIUS AAA server in APM

The Access Policy Manager (APM) is a network access server (NAS) that operates as a client of the server configured here.

On the Main tab, click

Access

Authentication

RADIUS

The RADIUS servers screen opens.

Click

Create

The New Server properties screen opens.

In the

Name

field, type a unique name for the authentication server.

For the

Mode

setting, select

Authentication

For the

Server Connection

setting, select one of these options:

When configuring a RADIUS AAA server that is located in a nondefault route domain, you must select

Use Pool

and specify the pool containing the RADIUS server.

Select

Use Pool

to set up high availability for the AAA server.

Select

Direct

to set up the AAA server for standalone functionality.

If you selected

Use Pool

, type a name in the

Server Pool Name

field.

You create a pool of servers on this screen.

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

In the

Authentication Service Port

field, type the authentication port number of your server. The default is

1812

In the

Secret

field, type the shared secret password of the server.

In the

Confirm Secret

field, re-type the shared secret password of the server.

Click

Finished

The new server displays on the list.

The new AAA server displays on the RADIUS Servers list.

Creating an access profile

You create an access profile to provide the access policy configuration for a virtual server that establishes a secured session.

On the Main tab, click

Access

Profiles / Policies

The Access Profiles (Per-Session Policies) screen opens.

Click

Create

The New Profile screen opens.

In the

Name

field, type a name for the access profile.

A access profile name must be unique among all access profile and any per-request policy names.

From the

Profile Type

list, select one these options:

LTM-APM

: Select for a web access management configuration.

SSL-VPN

: Select to configure network access, portal access, or application access. (Most access policy items are available for this type.)

ALL

: Select to support LTM-APM and SSL-VPN access types.

SSO

: Select to configure matching virtual servers for Single Sign-On (SSO).

No access policy is associated with this type of access profile

RDG-RAP

: Select to validate connections to hosts behind APM when APM acts as a gateway for RDP clients.

SWG - Explicit

: Select to configure access using Secure Web Gateway explicit forward proxy.

SWG - Transparent

: Select to configure access using Secure Web Gateway transparent forward proxy.

System Authentication

: Select to configure administrator access to the BIG-IP system (when using APM as a pluggable authentication module).

Identity Service

: Used internally to provide identity service for a supported integration. Only APM creates this type of profile.

You can edit Identity Service profile properties.

Depending on licensing, you might not see all of these profile types.

Additional settings display.

In the Language Settings area, add and remove accepted languages, and set the default language.

A browser uses the highest priority accepted language. If no browser language matches the accepted languages list, the browser uses the default language.

Click

Finished

The access profile displays in the Access Profiles List. Default-log-setting is assigned to the access profile.

Verifying log settings for the access profile

Confirm that the correct log settings are selected for the access profile to ensure that events are logged as you intend.

Log settings are configured in the

Access

Overview

Event Log

Settings

area of the product. They enable and disable logging for access system and URL request filtering events. Log settings also specify log publishers that send log messages to specified destinations.

On the Main tab, click

Access

Profiles / Policies

The Access Profiles (Per-Session Policies) screen opens.

Click the name of the access profile that you want to edit.

The properties screen opens.

On the menu bar, click

Logs

The access profile log settings display.

Move log settings between the

Available

and

Selected

lists.

You can assign up to three log settings that enable access system logging to an access profile. You can assign additional log settings to an access profile provided that they enable logging for URl request logging only.

Logging is disabled when the

Selected

list is empty.

Click

Update

An access profile is in effect when it is assigned to a virtual server.

Using RADIUS authentication in an access policy

You configure an access policy with a RADIUS Auth action to provide RADIUS authentication as one of authentication options for users trying to gain accesss.

You can use RADIUS authentication in addition to other authentication types. You can require that users pass at least one type of authentication or that they pass multiple types of authentication.

On the Main tab, click

Access

Profiles / Policies

The Access Profiles (Per-Session Policies) screen opens.

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.

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.

On the Logon tab, select

Logon Page

and click the

Add Item

button.

The Logon Page Agent properties screen opens.

Make any changes that you require to the logon page properties and click

Save

The properties screen closes and the policy displays.

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.

From the Authentication tab, select

RADIUS Auth

and click

Add Item

The popup screen closes. A Properties popup screen opens.

On the Properties popup screen from the

AAA Server

list, select the AAA RADIUS server you configured previously and click

Save

The popup screen closes and the visual policy editor displays.

Complete the policy:

Add any additional policy items you require.

Change the ending from

Deny

Allow

on any access policy branch on which you want to grant access.

Click

Apply Access Policy

to save your configuration.

This creates an access policy that collects user credentials and uses them to authenticate with a RADIUS server.

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.

Creating a virtual server for an access policy

When creating a virtual server for an access policy, specify an IP address for a single host as the destination address.

On the Main tab, click

Local Traffic

Virtual Servers

The Virtual Server List screen opens.

Click

Create

The New Virtual Server screen opens.

In the

Name

field, type a unique name for the virtual server.

In the

Destination Address

field, type the IP address for a host virtual server.

This field accepts an address in CIDR format (IP address/prefix). However, when you type the complete IP address for a host, you do not need to type a prefix after the address.

In the

Service Port

field:

If you want to specify a single service port or all ports, confirm that the

Port

button is selected, and type or select a service port.

If you want to specify multiple ports other than all ports, select the

Port List

button, and confirm that the port list that you previously created appears in the box.

From the

HTTP Profile (Client)

list, select a previously-created HTTP/2 profile for client-side traffic.

If you use server SSL for this connection, from the

SSL Profile (Server)

list, select a server SSL profile.

If you use client SSL for this profile, from the

SSL Profile (Client)

list, select a client SSL profile.

In the Access Policy area, from the

Access Profile

list, select the access profile that you configured earlier.

From the

Connectivity Profile

list, select a connectivity profile.

You can select the default connectivity profile,

connectivity

if you have not defined a specific profile for the traffic that is directed to this virtual server.

Click

Finished

You have configured a host virtual server and associated an access profile with it.

Testing AAA high availability for supported authentication servers

To effectively test that high availability works for your authentication servers, you should have two servers that are accessible, where you can remove one of them from the network.

High availability is supported for these authentication server types only: RADIUS, Active Directory, LDAP, CRLDP, and TACACS+.

If you configured a supported authentication server type to use a pool of connection servers, you can test the configuration using these steps.

Begin a

tcpdump

on the Access Policy Manager, using a protocol analyzer, and scanning for packets destined for the specific port for your authentication server.

Using the

tcpdump

records, verify that the requests are being sent to the higher priority server.

Log out of the virtual server.

Disable the higher-priority server.

Verify that the request is being sent to the other server.

Log out again, re-enabling the server, and try one more time to verify that the new requests are being sent to the high priority server.

RADIUS attributes

The following table lists the specific RADIUS attributes that Access Policy Manager sends with RADIUS requests.

Attribute	Purpose
User-Name	Indicates the name of the authenticated user.
User-Password	Indicates the password of the authenticated user.
NAS-IP-Address	Indicates the identifying IP Address of the NAS.
NAS-IPv6-Address	Indicates the identifying IPv6 Address of the NAS.
NAS-Identifier	Indicates the identifying name of the NAS .
Service-Type	Indicates the type of service the user has requested.
NAS-Port	Indicates the physical port number of the NAS that is authenticating the user.

RADIUS session variables for access policy rules

When the RADIUS Auth access policy item runs, it populates session variables which are then available for use in access policy rules. The tables list the session variables for the RADIUS authentication access policy item and for a logon access policy item.

Session variables for RADIUS

Session Variable	Description
session.RADIUS.last.result	Provides the result of the RADIUS authentication. The available values are: 0: Failed 1: Passed
session.RADIUS.last.attr.$attr_name	`$attr_name` is a value that represents the user’s attributes received during RADIUS authentication. Each attribute is converted to separate session variables.
session.RADIUS.last.errmsg	Displays the error message for the last login. If session.RADIUS.last.result is set to 0, then session.RADIUS.last.errmsg might be useful for troubleshooting purposes. Example: c76a50c0.session.RADIUS.last.errmsg 13 Access-Reject

Common session variables

Session Variable	Description
session.logon.last.username	Provides user credentials. The username string is stored after encrypting, using the system's client key.
session.logon.last.password	Provides user credentials. The password string is stored after encrypting, using the system's client key.