Configuring RADIUS

This chapter describes how to configure the Remote Access Dial-In User Service (RADIUS) protocol on Cisco NX-OS devices.

This chapter includes the following sections:

About RADIUS

The RADIUS distributed client/server system allows you to secure networks against unauthorized access. In the Cisco implementation, RADIUS clients run on Cisco NX-OS devices and send authentication and accounting requests to a central RADIUS server that contains all user authentication and network service access information.

RADIUS Network Environments

RADIUS can be implemented in a variety of network environments that require high levels of security while maintaining network access for remote users.

You can use RADIUS in the following network environments that require access security:

  • Networks with multiple-vendor network devices, each supporting RADIUS. For example, network devices from several vendors can use a single RADIUS server-based security database.

  • Networks already using RADIUS. You can add a Cisco NX-OS device with RADIUS to the network. This action might be the first step when you make a transition to a AAA server.

  • Networks that require resource accounting. You can use RADIUS accounting independent of RADIUS authentication or authorization. The RADIUS accounting functions allow data to be sent at the start and end of services, indicating the amount of resources (such as time, packets, bytes, and so on) used during the session. An Internet service provider (ISP) might use a freeware-based version of the RADIUS access control and accounting software to meet special security and billing needs.

  • Networks that support authentication profiles. Using the RADIUS server in your network, you can configure AAA authentication and set up per-user profiles. Per-user profiles enable the Cisco NX-OS device to better manage ports using their existing RADIUS solutions and to efficiently manage shared resources to offer different service-level agreements.

RADIUS Operation

When a user attempts to log in and authenticate to a Cisco NX-OS device using RADIUS, the following process occurs:

  • The user is prompted for and enters a username and password.

  • The username and encrypted password are sent over the network to the RADIUS server.

  • The user receives one of the following responses from the RADIUS server:

    ACCEPT
    The user is authenticated.
    REJECT
    The user is not authenticated and is prompted to reenter the username and password, or access is denied.
    CHALLENGE
    A challenge is issued by the RADIUS server. The challenge collects additional data from the user.
    CHANGE PASSWORD
    A request is issued by the RADIUS server, asking the user to select a new password.

The ACCEPT or REJECT response is bundled with additional data that is used for EXEC or network authorization. You must first complete RADIUS authentication before using RADIUS authorization. The additional data included with the ACCEPT or REJECT packets consists of the following:

  • Services that the user can access, including Telnet, rlogin, or local-area transport (LAT) connections, and Point-to-Point Protocol (PPP), Serial Line Internet Protocol (SLIP), or EXEC services.

  • Connection parameters, including the host or client IPv4 or IPv6 address, access list, and user timeouts.

RADIUS Server Monitoring

An unresponsive RADIUS server can cause a delay in processing AAA requests. You can configure the Cisco NX-OS device to periodically monitor a RADIUS server to check whether it is responding (or alive) to save time in processing AAA requests. The Cisco NX-OS device marks unresponsive RADIUS servers as dead and does not send AAA requests to any dead RADIUS servers. The Cisco NX-OS device periodically monitors the dead RADIUS servers and brings them to the alive state once they respond. This monitoring process verifies that a RADIUS server is in a working state before real AAA requests are sent its way. Whenever a RADIUS server changes to the dead or alive state, a Simple Network Management Protocol (SNMP) trap is generated and the Cisco NX-OS device displays an error message that a failure is taking place.

Figure 1. RADIUS Server States. This figure shows the states for RADIUS server monitoring.

Note

The monitoring interval for alive servers and dead servers are different and can be configured by the user. The RADIUS server monitoring is performed by sending a test authentication request to the RADIUS server.

Vendor-Specific Attributes

The Internet Engineering Task Force (IETF) draft standard specifies a method for communicating VSAs between the network access server and the RADIUS server. The IETF uses attribute 26. VSAs allow vendors to support their own extended attributes that are not suitable for general use. The Cisco RADIUS implementation supports one vendor-specific option using the format recommended in the specification. The Cisco vendor ID is 9, and the supported option is vendor type 1, which is named cisco-av-pair. The value is a string with the following format: 

protocol : attribute separator value *

The protocol is a Cisco attribute for a particular type of authorization, the separator is = (equal sign) for mandatory attributes, and * (asterisk) indicates optional attributes.

When you use RADIUS servers for authentication on a Cisco NX-OS device, the RADIUS protocol directs the RADIUS server to return user attributes, such as authorization information, with authentication results. This authorization information is specified through VSAs.

The following VSA protocol options are supported by the Cisco NX-OS software:

Shell
Protocol used in access-accept packets to provide user profile information.
Accounting
Protocol used in accounting-request packets. If a value contains any white spaces, you should enclose the value within double quotation marks.

The Cisco NX-OS software supports the following attributes:

roles
Lists all the roles to which the user belongs. The value field is a string that lists the role names delimited by white space. For example, if the user belongs to roles network-operator and network-admin, the value field would be network-operator network-admin. This subattribute, which the RADIUS server sends in the VSA portion of the Access-Accept frames, can only be used with the shell protocol value. The following examples show the roles attribute that is supported by the Cisco Access Control Server (ACS): 

								shell:roles=network-operator network-admin 
								shell:roles*“network-operator network-admin

The following examples show the roles attribute that is supported by FreeRADIUS:


								Cisco-AVPair = shell:roles=\network-operator network-admin\
								Cisco-AVPair = shell:roles*\network-operator network-admin\

Note

When you specify a VSA as shell:roles*"network-operator network-admin" or "shell:roles*\"network-operator network-admin\"", this VSA is flagged as an optional attribute and other Cisco devices ignore this attribute.

accountinginfo
Stores accounting information in addition to the attributes covered by a standard RADIUS accounting protocol. This attribute is sent only in the VSA portion of the Account-Request frames from the RADIUS client on the switch. It can be used only with the accounting protocol data units (PDUs).

About RADIUS Change of Authorization

A standard RADIUS interface is typically used in a pulled model, in which the request originates from a device attached to a network and the response is sent from the queried servers. Cisco NX-OS sofware supports the RADIUS Change of Authorization (CoA) request defined in RFC 5176 that is used in a pushed model, in which the request originates from the external server to the device attached to the network, and enables the dynamic reconfiguring of sessions from external authentication, authorization, and accounting (AAA) or policy servers.

When Dot1x is enabled, the network device acts as the authenticator and is responsible for processing dynamic COA per session.

The following requests are supported:

  • Session reauthentication

  • Session termination

Session Reauthentication

To initiate session reauthentication, the authentication, authorization, and accounting (AAA) server sends a standard CoA-Request message that contains a Cisco VSA and one or more session identification attributes. The Cisco VSA is in the form of Cisco:Avpair=“subscriber:command=reauthenticate”.

The current session state determines the response of the device to the message in the following scenarios:

  • If the session is currently authenticated by IEEE 802.1x, the device responds by sending an Extensible Authentication Protocol over LAN (EAPOL)-RequestId message to the server.

  • If the session is currently authenticated by MAC authentication bypass (MAB), the device sends an access request to the server, passing the same identity attributes used for the initial successful authentication.

  • If session authentication is in progress when the device receives the command, the device terminates the process and restarts the authentication sequence, starting with the method configured to be attempted first.

Session Termination

A CoA Disconnect-Request terminates the session without disabling the host port. CoA Disconnect-Request termination causes reinitialization of the authenticator state machine for the specified host, but does not restrict the host’s access to the network.

If the session cannot be located, the device returns a Disconnect-NAK message with the “Session Context Not Found” error-code attribute.

If the session is located, but the NAS was unable to remove the session due to some internal error, the device returns a Disconnect-NAK message with the Session Context Not Removable error-code attribute.

If the session is located, the device terminates the session. After the session has been completely removed, the device returns a Disconnect-ACK message.

Prerequisites for RADIUS

RADIUS has the following prerequisites:

  • Obtain IPv4 or IPv6 addresses or hostnames for the RADIUS servers.

  • Obtain keys from the RADIUS servers.

  • Ensure that the Cisco NX-OS device is configured as a RADIUS client of the AAA servers.

Guidelines and Limitations for RADIUS

Guidelines and limitations for RADIUS on Cisco N9300 Smart switches

RADIUS has the following guidelines and limitations:

  • You can configure a maximum of 64 RADIUS servers on the Cisco NX-OS device.

  • If you have a user account configured on the local Cisco NX-OS device that has the same name as a remote user account on an AAA server, the Cisco NX-OS software applies the user roles for the local user account to the remote user, not the user roles configured on the AAA server.

  • Only the RADIUS protocol supports one-time passwords.

  • For N9K-X9636C-R and N9K-X9636Q-R line cards and the N9K-C9508-FM-R fabric module, RADIUS authentication fails for usernames with special characters.

  • Cisco Nexus 9K Series switches support the CLI command, aaa authentication login ascii-authentication, only for TACAAS+, but not for RADIUS. Ensure that you have disabled aaa authentication login ascii-authentication switch so that the default authentication, PAP, is enabled. Otherwise, you will see syslog errors.

  • Beginning with Cisco NX-OS Release 10.3(1)F , RADIUS is supported on the Cisco Nexus 9808 platform switches.

    • Beginning with Cisco NX-OS Release 10.4(1)F, RADIUS is supported on Cisco Nexus X98900CD-A and X9836DM-A line cards with 9808 switches.

  • Beginning with Cisco NX-OS Release 10.4(1)F, RADIUS is supported on the Cisco Nexus 9804 switches, X98900CD-A, and X9836DM-A line cards.

  • The value of the key in the radius-server key and radius-server host hostname key commands must be specified either unquoted (example: secret) or properly quoted (example: "secret"). However, the following are not allowed:

    • Unmatched Quotes: Leading or trailing unmatched quotes (example: a", "abc).

    • Embedded Quotes: Double quotes embedded within the input, whether unquoted (example: ab"cd) or within a quoted string (example: "ab"cd")."

  • Beginning with Cisco NX-OS Release 10.4(4), the radius-server CLI allows a value of 0 for the timeout and retransmit parameters.

    Starting with Cisco NX-OS Release 10.4(4), a value of 0 for timeout and retransmit is also shown in the show running-config output.

    During a downgrade between releases 10.4(4) and 9.3(11) or later, without these fixes, any RADIUS server configuration that uses a timeout value of 0 or a retransmit value of 0 could be lost or may not work. To ensure configuration consistency, avoid using 0 as a value for these parameters when migrating between affected releases, or verify support for these values in both the source and target releases.

Beginning with Cisco Nexus Release 10.6(2)F, RADIUS is supported on the Cisco N9324C-SE1U and Cisco N9348Y2C6D-SE1U Smart switches.

Guidelines and Limitations for RadSec

RadSec has the following guidelines and limitations:

  • Beginning with Cisco NX-OS Release 10.3(1)F, the RADIUS Secure (RadSec) support is provided on Cisco Nexus switches to secure the communication between RADIUS/TCP peers at the transport layer.

  • RadSec must be enabled/disabled at the switch level, as the combination of servers having different transport protocols (i.e. UDP and TCP-with-TLS) is not possible.

  • radius-server directed-request command is not supported along with the RadSec feature.

  • test aaa server radius command is not supported for the RadSec servers, only test aaa group command is supported with the RadSec.

  • Dot1x is not officially supported with RadSec.

  • RADIUS server monitoring is not supported along with the RadSec servers.

  • RADIUS server re-transmit and timeout are applicable to UDP based RADIUS mode and not supported for RadSec servers.

  • Beginning with Cisco NX-OS Release 10.4(3)F, TLS version 1.3 and 1.2 is supported on Cisco Nexus switches. TLS v1.1 is deprecated.

Guidelines and Limitations for RADIUS Change of Authorization

RADIUS Change of Authorization has the following guidelines and limitations:

  • RADIUS Change of Authorization is supported on FEX.

  • RADIUS change of Authorization is supported for VXLAN EVPN.

Default Settings for RADIUS

The following table lists the default settings for RADIUS parameters, including server roles, timers, ports, and monitoring credentials that are applied unless explicitly modified by the user.

This table lists the default settings for RADIUS parameters.

Table 1. Default RADIUS Parameter Settings

Parameters

Default

Server roles

Authentication and accounting

Dead timer interval

0 minutes

Retransmission count

1

Retransmission timer interval

5 seconds

Authentication port

1812

Accounting port

1813

Idle timer interval

0 minutes

Periodic server monitoring username

test

Periodic server monitoring password

test

Configuring RADIUS Servers

This section describes how to configure RADIUS servers on a Cisco NX-OS device.

Note
If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature might differ from the Cisco IOS commands that you would use.

Note
Cisco Nexus 9K Series switches support the CLI command, aaa authentication login ascii-authentication, only for TACAAS+, but not for RADIUS. Ensure that you have disabled aaa authentication login ascii-authentication switch so that the default authentication, PAP, is enabled. Otherwise, you will see syslog errors.

RADIUS Server Configuration Process

  1. Establish the RADIUS server connections to the Cisco NX-OS device.

  2. Configure the RADIUS secret keys for the RADIUS servers.

  3. If needed, configure RADIUS server groups with subsets of the RADIUS servers for AAA authentication methods.

  4. If needed, configure any of the following optional parameters:

    • Dead-time interval

    • RADIUS server specification allowed at user login

    • Timeout interval

    • TCP port

  5. (Optional) If RADIUS distribution is enabled, commit the RADIUS configuration to the fabric.

Configuring RADIUS Server Hosts

To access a remote RADIUS server, you must configure the IP address or hostname of a RADIUS server. You can configure up to 64 RADIUS servers.


Note

By default, when you configure a RADIUS server IP address or hostname of the Cisco NX-OS device, the RADIUS server is added to the default RADIUS server group. You can also add the RADIUS server to another RADIUS server group.

Before you begin

Ensure that the server is already configured as a member of the server group.

Ensure that the server is configured to authenticate RADIUS traffic.

Ensure that the Cisco NX-OS device is configured as a RADIUS client of the AAA servers.

Procedure

Step 1

Use the radius-server host { ipv4-address | ipv6-address | hostname } command to specify the IPv4 or IPv6 address or hostname for a RADIUS server to use for authentication.

Example:

switch# configure terminal
switch(config)# radius-server host 10.10.1.1

Step 2

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:

switch# show radius-server

Step 3

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure Global RADIUS Keys

Configure global RADIUS keys to establish a shared secret between your device and remote RADIUS servers for secure authentication.

You can configure RADIUS keys for all servers used by the Cisco NX-OS device. A RADIUS key is a shared secret text string between the Cisco NX-OS device and the RADIUS server hosts.

Before you begin

Obtain the RADIUS key values for the remote RADIUS servers.

Configure the RADIUS key on the remote RADIUS servers.

Procedure

Step 1

Use the radius-server key [ 0 | 6 | 7 ] key-value command to specify a RADIUS key for all RADIUS servers.

Example:

switch# configure terminal
switch(config)# radius-server key 0 QsEfThUkO

switch(config)# exit

Example:

switch(config)# radius-server key 7 "fewhg”

You can specify that the key-value is in clear text format ( 0 ), is type-6 encrypted ( 6 ), or is type-7 encrypted ( 7 ). The Cisco NX-OS software encrypts a clear text key before saving it to the running configuration. The default format is clear text. The maximum length is 63 characters.

By default, no RADIUS key is configured.

Note

 

If you already configured a shared secret using the generate type7_encrypted_secret command, enter it in quotation marks, as shown in the second example. For more information, see Configuring the Shared Secret for RADIUS or TACACS+ .

Step 2

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:

switch# show radius-server

Note

 

The RADIUS keys are saved in encrypted form in the running configuration. Use the show running-config command to display the encrypted RADIUS keys.

Step 3

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:


switch# copy running-config startup-config

Configure a Key for a Specific RADIUS Server

Configure a key for a specific RADIUS server to ensure secure communication between your device and the RADIUS server.

You can configure a key on the Cisco NX-OS device for a specific RADIUS server. A RADIUS key is a secret text string shared between the Cisco NX-OS device and a specific RADIUS server.

Before you begin

Configure one or more RADIUS server hosts.

Obtain the key value for the remote RADIUS server.

Configure the key on the RADIUS server.

Procedure

Step 1

Use the radius-server host { ipv4-address | ipv6-address | hostname } key [ 0 | 6 | 7 ] key-value command to specify a RADIUS key for a specific RADIUS server.

Example:

switch# configure terminal
switch(config)# radius-server host 10.10.1.1 key 0 PlIjUhYg
switch(config)# exit

Example:


switch(config)# radius-server host 10.10.1.1 key 7 "fewhg”

You can specify that the key-value is in clear text format ( 0 ), is type-6 encrypted ( 6 ), or is type-7 encrypted ( 7 ). The Cisco NX-OS software encrypts a clear text key before saving it to the running configuration. The default format is clear text. The maximum length is 63 characters.

This RADIUS key is used instead of the global RADIUS key.

Note

 

If you already configured a shared secret using the generate type7_encrypted_secret command, enter it in quotation marks, as shown in the second example. For more information, see Configuring the Shared Secret for RADIUS or TACACS+ .

Step 2

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:

switch# show radius-server

Note

 

The RADIUS keys are saved in encrypted form in the running configuration. Use the show running-config command to display the encrypted RADIUS keys.

Step 3

(Optional) Use the copy running-config startup-config copy the running configuration to the startup configuration.

Example:


switch# copy running-config startup-config

Configure the RADIUS Attribute Message Authenticator

You can configure a RADIUS attribute message authenticator for all servers that use Cisco NX-OS switches. The RADIUS attribute encapsulates Extended Access Protocol (EAP) packets to allow the switch to authenticate dial-in users through EAP using HMAC-MD5.


Note

Cisco Fabric Services (CFS) does not distribute RADIUS attribute message authenticators.

Beginning with Cisco NX-OS Release 10.2(9)M , the radius-server attribute message-authenticator command is introduced on the Cisco Nexus 9000 switches.

Procedure

Step 1

Use the radius-server attribute message-authenticator specify a RADIUS attribute message-authenticaton for all RADIUS servers.

Example:

switch# configure terminal
switch(config)# radius-server attribute message-authenticator
switch(config)# exit

By default, the RADIUS attribute message-authenticator is disabled.

Step 2

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:


                        switch# 
                        show radius-server
                        etransmission count:1
                        timeout value:5
                        deadtime value:0
                        
                            message-authenticator attribute:enabled
                         
                        source interface:any available
                        total number of servers:4
                        following RADIUS servers are configured:
                        10.10.1.1:
                        available for authentication on port:1812
                        available for accounting on port:1813
                        RADIUS shared secret:********
                        timeout:60

Step 3

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure RadSec

RadSec is a protocol for transporting RADIUS datagrams over TLS.

This procedure describes how to enable or disable RadSec on a switch.

Before you begin

  • Ensure that the client identity certificate and CA certificate of the server are installed on the switch.

  • Ensure that the subject name in the server certificate is matching with the server host name/IP address that is configured on the switch.

  • Before configuring AAA authentication and accounting to use RadSec servers, use test aaa group command and ensure RadSec authentication is success.

  • Configure TLS idle-timeout to maximum value on RadSec server to avoid frequent TLS sessions retries from switch.

Procedure

Step 1

Use the radius-server secure tls command to enable the RadSec at global level.

Example:

switch# configure terminal
switch# radius-server secure tls

Note

 

This CLI will not change or affect the port numbers that is used for RadSec.

Step 2

Use the radius-server host t { ipv4-address | ipv6-address | hostname } key { key } auth-port 2083 acct-port 2083 authentication accounting command to configure the RadSec server with shared secret key along with the authentication and accounting ports.

Example:

switch# radius-server host 10.105.222.161 key radsec auth-port 2083 acct-port 2083 authentication accounting

Note

 

For server, the default RadSec port for authentication and accounting is "2083" and the key is “radsec”. For switch, there is no default configuration for RadSec port and key, please add this configuration explicitly as defined on server.

Step 3

Use the radius-server host { ipv4-address | ipv6-address | hostname } tls client-trustpoint trustpoint command to configures the TLS client trustpoint where the client identity certificate is installed.

Example:

switch# radius-server host 10.105.222.161 tls client-trustpoint rad1

Step 4

Use the radius-server host { ipv4-address | ipv6-address | hostname } tls idle-timeout value command to configure the TLS idle-timeout.

Example:

switch# radius-server host 10.105.222.161 tls idle-timeout 80

The default value is 600 seconds.

Note

 

If there are no transactions from the RadSec client, server can close the connection based on its timeout value. The TLS idle-timeout on the client is not supported in this release. Client does not close connections on its own.


Note

When remote user logs-in, you can notice delay in login for approximately 20 seconds i.e when TLS session establishment is happening for the first time between switch and RadSec server, Once TLS sessions are up no delay will be seen for consecutive remote log-ins.


Note

When a RadSec client is facing certificate related issues such as no certificate or invalid certificates are being exchanged with the server, you may experience delay in show run commands.

About RADIUS with DTLS

RADIUS with DTLS is a protocol introduced in Cisco NX-OS Release 10.4(1)F for transporting RADIUS datagrams over a secure channel using UDP.

  • Provides secure communication between RADIUS peers at the transport layer.

  • Helps secure RADIUS packet transfer through different administrative domains.

  • Protects RADIUS traffic over suspicious and unsafe networks.

Configure RADIUS with DTLS

Before you begin

  • Ensure that you create client identity certificate with subject and alternative name same as the IP address/DNS hostname of the switch. Install the client identity certificate on the switch using a trustpoint.

  • Ensure that the server certificate of ISE server used for DTLS/RADIUS is installed on the switch.

  • Make sure that the CA certificate used to sign client identity certificate is installed in trusted certificate store of ISE server.

  • Ensure that the subject name in the server certificate is same as the server hostname/IP address that is configured on the switch.

  • Before configuring AAA authentication and accounting groups to use RADIUS servers, check with test aaa group command and ensure that the RADIUS authentication is successful.

  • You must enable RADIUS with DTLS protocol at the switch level.

  • Configuring combination of RADIUS servers to use different transports protocols such as DTLS and TLS is not supported. You can configure one protocol at an instant.

Procedure

Step 1

Use the radius-server secure dtls command to enable the RADIUS with DTLS protocol on the switch.

Example:
switch# configure terminal
 switch(config)# radius-server secure dtls

Step 2

Use the radius-server host { ipv4-address | ipv6-address | hostname } key { radius/dtls } auth-port 2083 acct-port 2083 authentication accounting command to configures the RADIUS server with shared secret key along with the authentication and accounting ports.

Example:
switch(config)#radius-server host 10.105.222.161 key radius/dtls auth-port 2083 acct-port 2083 authentication accounting

Note

 

The default destination DTLS port for authentication and accounting is UDP/2083 . There is no default server key for DTLS as per RFC. Ensure that you add this configuration explicitly as defined on server. The ISE server must be pre-set with the "radius/dtls" key at that instant. Check and add the key on the Nexus switch while configuring DTLS with an ISE server.

Step 3

Use the radius-server host { ipv4-address | ipv6-address | hostname } dtls client-trustpoint trustpoint command to configures the DTLS client-trustpoint parameter with a trustpoint where the switch identity certificate is installed.

Example:
switch(config)#radius-server host 10.105.222.161 dtls client-trustpoint rad1

The rad1 is a trustpoint on the switch which must have the client identity certificate.

Step 4

Use the radius-server host { ipv4-address | ipv6-address | hostname } dtls idle-timeout value command to onfigures the DTLS idle-timeout.

Example:
switch# radius-server host 10.105.222.161 dtls idle-timeout 80

The default value is 600 seconds.

Note

 

If there are no transactions from the RADIUS client, server can close the connection as per defined timeout value. The DTLS idle-timeout on the client is not supported in this release. Client does not close connections on its own.


Note

  • When a remote user logs in, you may notice a delay of approximately 20 seconds, which occurs when the TLS session is being established for the first time between the switch and the RADIUS server. Once the TLS sessions are up, no delay will be seen for consecutive remote logins.

  • When a RADIUS client is facing certificate related issues such as no certificate or invalid certificates are being exchanged with the server, you may experience delay in the show run commands.

Configure a RADIUS Server Group

Configure RADIUS server groups to specify one or more remote AAA servers for authentication. All servers in the group must be RADIUS servers.

You can specify one or more remote AAA servers for authentication using server groups. All members of a group must belong to the RADIUS protocol. The servers are tried in the same order in which you configure them.

You can configure these server groups at any time but they only take effect when you apply them to an AAA service.

Before you begin

Ensure that all servers in the group are RADIUS servers.

Procedure

Step 1

Use the aaa group server radius group-name command to create a RADIUS server group and enters the RADIUS server group configuration submode for that group.

Example:

switch# configure terminal
switch(config)# aaa group server radius RadServer
switch(config-radius)#

The group-name argument is a case-sensitive alphanumeric string with a maximum length of 127 characters.

To delete a RADIUS server group, use the no form of this command.

Note

 
You are not allowed to delete the default system generated default group (RADIUS).

Step 2

Use the server { ipv4-address | ipv6-address | hostname } command to configure the RADIUS server as a member of the RADIUS server group.

Example:

switch(config-radius)# server 10.10.1.1

If the specified RADIUS server is not found, configure it using the radius-server host command and retry this command.

Step 3

(Optional) Use the deadtime minutes command to configure the monitoring dead time.

Example:


						switch(config-radius)# 
						deadtime 30

The default is 0 minutes. The range is from 1 through 1440.

Note

 

If the dead-time interval for a RADIUS server group is greater than zero (0), that value takes precedence over the global dead-time value.

Step 4

(Optional) Use the server { ipv4-address | ipv6-address | hostname } command to configure the RADIUS server as a member of the RADIUS server group.

Example:


						switch(config-radius)# 
						server 10.10.1.1

Tip

 

If the specified RADIUS server is not found, configure it using the radius-server host command and retry this command.

Step 5

(Optional) Use the use-vrf vrf-name command to specifies the VRF to use to contact the servers in the server group.

Example:


switch(config-radius)# use-vrf vrf1
switch(config-radius)# exit

Step 6

(Optional) Use the show radius-server groups [ group-name ] command to display the RADIUS server group configuration.

Example:


						switch(config)# 
						show radius-server groups

Step 7

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:


switch(config)# copy running-config startup-config

Configure the Global Source Interface for a RADIUS Server Group

You can configure a global source interface for RADIUS server groups to use when accessing RADIUS servers. You can also configure a different source interface for a specific RADIUS server group. By default, the Cisco NX-OS software uses any available interface.

Procedure

Step 1

Use the ip radius source-interface interface command to configure the global source interface for all RADIUS server groups configured on the device.

Example:

switch#configure terminal
switch(config)# ip radius source-interface mgmt 0
switch(config)# exit

Step 2

(Optional) Use the show radius-server command to display the RADIUS server configuration information.

Example:


switch# show radius-server

Step 3

(Optional) Use the copy running-config startup config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Allow a User to Specify a RADIUS Server at Login

By default, the Cisco NX-OS device forwards an authentication request based on the default AAA authentication method. You can configure the Cisco NX-OS device to allow the user to specify a VRF and RADIUS server to send the authentication request by enabling the directed-request option. If you enable this option, the user can log in as username @ vrfname : hostname , where vrfname is the VRF to use and hostname is the name of a configured RADIUS server.


Note

If you enable the directed-request option, the Cisco NX-OS device uses only the RADIUS method for authentication and not the default local method.


Note

User-specified logins are supported only for Telnet sessions.

Procedure

Step 1

Use the radius-server directed-request command to allow users to specify a RADIUS server to send the authentication request when logging in. The default is disabled.

Example:

switch# configure terminal
switch(config)# radius-server directed-request

Step 2

(Optional) Use the show radius-server directed-request command to display the directed request configuration.

Example:


switch# show radius-server directed-request

Step 3

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure the Global RADIUS Transmission Retry Count and Timeout Interval

You can configure a global retransmission retry count and timeout interval for all RADIUS servers. By default, a Cisco NX-OS device retries transmission to a RADIUS server only once before reverting to local authentication. You can increase this number up to a maximum of five retries per server. The timeout interval determines how long the Cisco NX-OS device waits for responses from RADIUS servers before declaring a timeout failure.

Procedure

Step 1

Use the radius-server retransmit count command to specify the retransmission count for all RADIUS servers.

Example:

switch# configure terminal
switch(config)# radius-server retransmit 3

The default retransmission count is 1 and the range is from 0 to 5.

Step 2

Use the radius-server timeout seconds command to specify the transmission timeout interval for RADIUS servers.

Example:

switch(config)# radius-server timeout 10

The default timeout interval is 5 seconds and the range is from 1 to 60 seconds.

Step 3

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:


switch# show radius-server

Step 4

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure the RADIUS Transmission Retry Count and Timeout Interval for a Server

By default, a Cisco NX-OS device retries a transmission to a RADIUS server only once before reverting to local authentication. You can increase this number up to a maximum of five retries per server. You can also set a timeout interval that the Cisco NX-OS device waits for responses from RADIUS servers before declaring a timeout failure.

Before you begin

Configure one or more RADIUS server hosts.

Procedure

Step 1

Use the radius-server host { ipv4-address | ipv6-address | hostname } retransmit count command to specify the retransmission count for a specific server. The default is the global value.

Example:

switch# configure terminal
switch(config)# radius-server host server1 retransmit 3

Note

 

The retransmission count value specified for a RADIUS server overrides the count specified for all RADIUS servers.

Step 2

Use the radius-server host { ipv4-address | ipv6-address | hostname } timeout seconds command to specify the transmission timeout interval for a specific server. The default is the global value.

Example:

switch(config)# radius-server host server1 timeout 10

Note

 

The timeout interval value specified for a RADIUS server overrides the interval value specified for all RADIUS servers.

Step 3

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:


switch# show radius-server

Step 4

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure Accounting and Authentication Attributes for a RADIUS Server

You can specify that a RADIUS server is to be used only for accounting purposes or only for authentication purposes. By default, RADIUS servers are used for both accounting and authentication. You can also specify the destination UDP port numbers where RADIUS accounting and authentication messages should be sent if there is a conflict with the default port.

Before you begin

Configure one or more RADIUS server hosts.

Procedure

Step 1

(Optional) Use the radius-server host { ipv4-address | ipv6-address | hostname } acct-port udp-port command to specify a UDP port to use for RADIUS accounting messages.

Example:

switch# configure terminal
switch(config)# radius-server host 10.10.1.1 acct-port 2004

The range is from 0 to 65535.

Step 2

(Optional) Use the radius-server host { ipv4-address | ipv6-address | hostname } accounting command to specify to use the RADIUS server only for accounting purposes. The default is both accounting and authentication

Example:

switch(config)# radius-server host 10.10.1.1 accounting

Step 3

(Optional) Use the radius-server host { ipv4-address | ipv6-address | hostname } auth-port udp-port command to specify a UDP port to use for RADIUS authentication messages.

Example:

switch(config)# radius-server host 10.10.2.2 auth-port 2005

The default UDP port is 1812. The range is from 0 to 65535.

Step 4

(Optional) Use the radius-server host { ipv4-address | ipv6-address | hostname } authentication command to specify to use the RADIUS server only for authentication purposes.

Example:

switch(config)# radius-server host 10.10.2.2 authentication
switch(config)# exit

The default is both accounting and authentication.

Step 5

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:


switch# show radius-server

Step 6

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure Global Periodic RADIUS Server Monitoring

You can monitor the availability of all RADIUS servers without having to configure the test parameters for each server individually. Any servers for which test parameters are not configured are monitored using the global level parameters.


Note

Test parameters that are configured for individual servers take precedence over global test parameters.

The global configuration parameters include the username and password to use for the servers and an idle timer. The idle timer specifies the interval in which a RADIUS server receives no requests before the Cisco NX-OS device sends out a test packet. You can configure this option to test servers periodically, or you can run a one-time only test.


Note

To protect network security, we recommend that you use a username that is not the same as an existing username in the RADIUS database.


Note

The default idle timer value is 0 minutes. When the idle time interval is 0 minutes, periodic RADIUS server monitoring is not performed.

Before you begin

Enable RADIUS.

Procedure

Step 1

Use the radius-server test { idle-time minutes | password password [ idle-time minutes ] | username name [ password password [ idle-time minutes ]]} command to specify parameters for global server monitoring.

Example:

switch# configure terminal
switch(config)# radius-server test username user1 password Ur2Gd2BH idle-time 3

The default username is test, and the default password is test. The default value for the idle timer is 0 minutes, and the valid range is from 0 to 1440 minutes.

Note

 

For periodic RADIUS server monitoring, the idle timer value must be greater than 0.

Step 2

Use the radius-server deadtime minutes command to specify the number of minutes before the Cisco NX-OS device checks a RADIUS server that was previously unresponsive.

Example:

switch(config)#radius-server deadtime 5
switch(config)#exit

The default value is 0 minutes, and the valid range is from 0 to 1440 minutes.

Step 3

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:

switch# show radius-server

Step 4

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configure Periodic RADIUS Server Monitoring on Individual Servers

Configure periodic monitoring of individual RADIUS servers to proactively check server availability and performance in NX-OS environments.

You can monitor the availability of individual RADIUS servers. The configuration parameters include the username and password to use for the server and an idle timer. The idle timer specifies the interval during which a RADIUS server receives no requests before the Cisco NX-OS device sends out a test packet. You can configure this option to test servers periodically, or you can run a one-time only test.


Note

Test parameters that are configured for individual servers take precedence over global test parameters.

Note

For security reasons, we recommend that you do not configure a test username that is the same as an existing user in the RADIUS database.


Note

The default idle timer value is 0 minutes. When the idle time interval is 0 minutes, the Cisco NX-OS device does not perform periodic RADIUS server monitoring.

Before you begin

Enable RADIUS.

Add one or more RADIUS server hosts.

Procedure

Step 1

Use the radius-server host { ipv4-address | ipv6-address | hostname } test { idle-time minutes | password password [ idle-time minutes ] | username name [ password password [ idle-time minutes ]]} command to specify parameters for individual server monitoring.

Example:

switch# configure terminal
switch(config)# radius-server host 10.10.1.1 test username user1 password Ur2Gd2BH idle-time 3

The default username is test, and the default password is test. The default value for the idle timer is 0 minutes, and the valid range is from 0 to 1440 minutes.

Note

 

For periodic RADIUS server monitoring, you must set the idle timer to a value greater than 0.

Step 2

Use the radius-server deadtime minutes command to specify the number of minutes before the Cisco NX-OS device checks a RADIUS server that was previously unresponsive.

Example:

switch(config)# radius-server deadtime 5
switch(config)# exit

The default value is 0 minutes, and the valid range is from 1 to 1440 minutes.

Step 3

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:


switch# show radius-server

Step 4

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:


						switch# 
						copy running-config startup-config

Configure the RADIUS Dead-Time Interval

You can configure the dead-time interval for all RADIUS servers. The dead-time interval specifies the time that the Cisco NX-OS device waits after declaring a RADIUS server is dead, before sending out a test packet to determine if the server is now alive. The default value is 0 minutes.


Note

When the dead-time interval is 0 minutes, RADIUS servers are not marked as dead even if they are not responding. You can configure the dead-time interval for a RADIUS server group.

Procedure

Step 1

Use the radius-server deadtime minutes command to configure the dead-time interval.

Example:

switch# configure terminal
switch(config)# radius-server deadtime 5

The default value is 0 minutes. The range is from 1 to 1440 minutes.

Step 2

(Optional) Use the show radius-server command to display the RADIUS server configuration.

Example:


switch# show radius-server

Step 3

(Optional) Use the copy running-config startup-config command to copy the running configuration to the startup configuration.

Example:

switch# copy running-config startup-config

Configuring One-Time Passwords

  • One-time password (OTP) support is available for Cisco devices through the use of RSA SecurID token servers.

  • Users authenticate by entering a personal identification number or one-time password and the token code displayed on their RSA SecurID token.

  • The token code changes every 60 seconds to enhance security.

Prerequisites and Configuration Steps for One-Time Passwords

Before configuring one-time passwords, ensure the following prerequisites are met and follow the configuration steps.

  • Configure a RADIUS server host and remote default login authentication on the device.

  • Install Cisco Secure Access Control Server (ACS) version 4.2.

  • Install RSA Authentication Manager version 7.1 (the RSA SecurID token server).

  • Install RSA ACE Agent/Client.

  1. Enable RSA SecurID token server authentication on Cisco Secure ACS.

  2. Add the RSA SecurID token server to the Unknown User Policy database.


Note

The token code used for logging into the Cisco device changes every 60 seconds. To prevent problems with device discovery, it is recommended to use different usernames that are present on the Cisco Secure ACS internal database.

Example: Configuring One-Time Passwords

For example, after installing the required software and configuring the RADIUS server, enable RSA SecurID authentication and add the token server to the Unknown User Policy database in Cisco Secure ACS to support OTP logins.

Manually Monitor a RADIUS Server or Group

You can manually issue a test message to a RADIUS server or to a server group.

Procedure

Step 1

Use the test aaa server radius { ipv4-address | ipv6-address | hostname } [ vrf vrf-name ] username password command to send a test message to a RADIUS server to confirm availability.

Example:

switch# test aaa server radius 10.10.1.1 user1 Ur2Gd2BH

Step 2

Use the test aaa group group-name username password command to send a test message to a RADIUS server group to confirm availability.

Example:


switch# test aaa group RadGroup user2 As3He3CI

Enable or Disable the Dynamic Author Server

Procedure

Use the aaa server radius dynamic-author command to enable the RADIUS dynamic author server.

Example:

switch# configure terminal
switch(config)# aaa server radius dynamic-author

You can disable the RADIUS dynamic author server using the no form of this command.

Configure RADIUS Change of Authorization

Procedure

Step 1

Use the [ no ] aaa server radius dynamic-author command to configure the switch as an AAA server to facilitate interaction with an external policy server.

Example:

switch# configure terminal
switch(config)# aaa server radius dynamic-author

You can disable the RADIUS dynamic author and the associated clients using the no form of this command.

Step 2

Use the [ no ] client { ip-address | hostname } [ server-key [ 0 | 7 ] string ] command to configure the IP address or the hostname of the AAA server client.

Example:

switch(config-locsvr-da-radius)# client 192.168.0.5 server-key cisco1

Use the optional server-key keyword and string argument to configure the server key at the client level. You can remove the client server using the no form of this command.

Note

 
Configuring the server key at the client level overrides the server key that is configured at the global level.

Step 3

Use the [ no ] port port-number command to specify the port on which a device listens to the RADIUS requests from the configured RADIUS clients.

Example:

switch(config-locsvr-da-radius)# port 3799

The port range is 1 - 65535. You can revert to the default port using the no form of this command.

Note

 
The default port for a packet of disconnect is 1700.

Step 4

Use the [ no ] server-key [ 0 | 7 ] string command to configure the global RADIUS key to be shared between a device and the RADIUS clients.

You can remove the server-key using the no form of this command.

Verifying the RADIUS Configuration

  • RADIUS configuration verification involves using show commands to display current settings and server parameters.

  • Key commands include show radius , show running-config radius , show startup-config radius , and show radius-server .

  • These commands help administrators confirm the status and details of RADIUS services and servers.

RADIUS Configuration Verification Reference

To display RADIUS configuration information, perform one of the following tasks:

Table 2. RADIUS Verification Commands

Command

Purpose

show radius { status | pending | pending-diff }

Displays the RADIUS Cisco Fabric Services distribution status and other details.

show running-config radius [ all ]

Displays the RADIUS configuration in the running configuration.

show startup-config radius

Displays the RADIUS configuration in the startup configuration.

show radius-server [ hostname | ipv4-address | ipv6-address ] [ directed-request | groups | sorted | statistics ]

Displays all configured RADIUS server parameters.

Verifying RADIUS Change of Authorization Configuration

  • Verification of RADIUS Change of Authorization configuration involves using specific show and clear commands.

  • These commands display or clear configuration and statistics for dot1x, AAA, and RADIUS components.

  • Commands can be used to monitor both server and client RADIUS statistics.

RADIUS Change of Authorization Verification Commands

To display RADIUS Change of Authorization configuration information, perform one of the following tasks:

Command

Purpose

show running-config dot1x

Displays the dot1x configuration in the running configuration.

show running-config aaa

Displays the AAA configuration in the running configuration.

show running-config radius

Displays the RADIUS configuration in the running configuration.

show aaa server radius statistics

Displays the local RADIUS server statistics.

show aaa client radius statistics { ip address | hostname }

Displays the local RADIUS client statistics.

clear aaa server radius statistics

Clears the local RADIUS server statistics.

clear aaa client radius statistics { ip address | hostname }

Clears the local RADIUS client statistics.

Monitoring RADIUS Servers

You can monitor the statistics that the Cisco NX-OS device maintains for RADIUS server activity.

Before you begin

Configure one or more RADIUS server hosts.

Procedure

Command or Action Purpose

show radius-server statistics {hostname | ipv4-address | ipv6-address}

Example:

switch# show radius-server statistics 10.10.1.1

Displays the RADIUS statistics.

Clear the RADIUS Server Statistics

You can display the statistics that the Cisco NX-OS device maintains for RADIUS server activity.

Before you begin

Configure RADIUS servers on the Cisco NX-OS device.

Procedure

Step 1

(Optional) Use the show radius-server statistics { hostname | ipv4-address | ipv6-address } command to displays the RADIUS server statistics on the Cisco NX-OS device.

Example:

switch# show radius-server statistics 10.10.1.1

Step 2

Use the clear radius-server statistics { hostname | ipv4-address | ipv6-address } command to clears the RADIUS server statistics.

Example:


switch# clear radius-server statistics 10.10.1.1

Configuration Example for RADIUS

The configuration example demonstrates how to set up RADIUS authentication and accounting on NX-OS devices.

  • Specifies the RADIUS server key and host information.

  • Defines a RADIUS server group for authentication and accounting.

  • Associates the server with the RADIUS group.

Reference Information for RADIUS Configuration Example

The following example shows how to configure RADIUS:

  • Use the radius-server commands to specify server keys and hosts.

  • Configure the aaa group server radius to define server groups.

The following configuration sets up a RADIUS server and associates it with a server group for authentication and accounting:

radius-server key 7 "ToIkLhPpG"
radius-server host 10.10.1.1 key 7 "ShMoMhTl" authentication accounting
aaa group server radius RadServer
server 10.10.1.1

Configuration Examples of RADIUS Change of Authorization

RADIUS Change of Authorization (CoA) configuration involves setting up a RADIUS server and enabling dynamic authorization for clients.

  • Defines the RADIUS server host and authentication key.

  • Enables dynamic authorization for the RADIUS server.

  • Specifies the client IP, VRF, and server key for dynamic authorization.

Configuration Reference for RADIUS Change of Authorization

The following example shows how to configure RADIUS Change of Authorization:

  • Configure the RADIUS server host and key.

  • Enable dynamic authorization for the RADIUS server.

  • Specify the client IP, VRF, and server key for dynamic authorization.

Example: RADIUS Change of Authorization Configuration

radius-server host 10.77.143.170 key 7 "fewhg123" authentication accounting
                    aaa server radius dynamic-author
                    client 10.77.143.170 vrf management server-key 7 "fewhg123"

Where to Go Next

You can now configure AAA authentication methods to include the server groups.

Additional References for RADIUS

This section describes additional information related to implementing RADIUS.

Related Documents

Related Topic

Document Title

Cisco NX-OS Licensing

Cisco NX-OS Licensing Guide

VRF configuration

Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide

Standards

Standards

Title

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

—

MIBs

MIBs

MIBs Link

MIBs related to RADIUS

To locate and download supported MIBs, go to the following URL:

https://cisco.github.io/cisco-mibs/supportlists/nexus9000/Nexus9000MIBSupportList.html