Published On: August 3ʳᵈ, 2020 08:22

Security Configuration Guide, Cisco IOS XE Amsterdam 17.3.x (Catalyst 9500 Switches)

Prerequisites for Configuring RADIUS

This section lists the prerequisites for controlling device access with RADIUS.

General:

  • RADIUS and Authentication, Authorization, and Accounting (AAA) must be enabled to use any of the configuration commands in this chapter.

  • RADIUS is facilitated through AAA and can be enabled only through AAA commands.

  • Use the aaa new-model global configuration command to enable AAA.

  • Use the aaa authentication global configuration command to define method lists for RADIUS authentication.

  • Use line and interface commands to enable the defined method lists to be used.

  • At a minimum, you must identify the host or hosts that run the RADIUS server software and define the method lists for RADIUS authentication. You can optionally define method lists for RADIUS authorization and accounting.

  • You should have access to and should configure a RADIUS server before configuring RADIUS features on your device.

  • The RADIUS host is normally a multiuser system running RADIUS server software from Cisco (Cisco Secure Access Control Server Version 3.0), Livingston, Merit, Microsoft, or another software provider. For more information, see the RADIUS server documentation.

  • To use the Change-of-Authorization (CoA) interface, a session must already exist on the switch. CoA can be used to identify a session and enforce a disconnect request. The update affects only the specified session.

For RADIUS operation:

  • Users must first successfully complete RADIUS authentication before proceeding to RADIUS authorization, if it is enabled.

Restrictions for Configuring RADIUS

This topic covers restrictions for controlling device access with RADIUS.

General:

  • To prevent a lapse in security, you cannot configure RADIUS through a network management application.

RADIUS is not suitable in the following network security situations:

  • Multiprotocol access environments. RADIUS does not support AppleTalk Remote Access (ARA), NetBIOS Frame Control Protocol (NBFCP), NetWare Asynchronous Services Interface (NASI), or X.25 PAD connections.

  • Switch-to-switch or router-to-router situations. RADIUS does not provide two-way authentication. RADIUS can be used to authenticate from one device to a non-Cisco device if the non-Cisco device requires authentication.

  • Networks using a variety of services. RADIUS generally binds a user to one service model.

Information about RADIUS

RADIUS and Switch Access

This section describes how to enable and configure RADIUS. RADIUS provides detailed accounting information and flexible administrative control over the authentication and authorization processes.

RADIUS Overview

RADIUS is a distributed client/server system that secures networks against unauthorized access. RADIUS clients run on supported Cisco devices. Clients send authentication requests to a central RADIUS server, which contains all user authentication and network service access information.

Use RADIUS in these network environments that require access security:

  • Networks with multiple-vendor access servers, each supporting RADIUS. For example, access servers from several vendors use a single RADIUS server-based security database. In an IP-based network with multiple vendors’ access servers, dial-in users are authenticated through a RADIUS server that has been customized to work with the Kerberos security system.

  • Turnkey network security environments in which applications support the RADIUS protocol, such as in an access environment that uses a smart card access control system.

  • Networks already using RADIUS. You can add a Cisco device containing a RADIUS client to the network. This might be the first step when you make a transition to a TACACS+ server. See the illustration: Transitioning from RADIUS to TACACS+ Services below.

    Figure 1. Transitioning from RADIUS to TACACS+ Services Transitioning from RADIUS to TACACS+ Services
  • Network in which the user must only access a single service. Using RADIUS, you can control user access to a single host, to a single utility such as Telnet, or to the network through a protocol such as IEEE 802.1x. For more information about this protocol, see the chapter Configuring IEEE 802.1x Port-Based Authentication.

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

RADIUS Operation

When a user attempts to log in and authenticate to a device that is access controlled by a RADIUS server, these events occur:

  1. The user is prompted to enter a username and password.

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

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

    • ACCEPT—The user is authenticated.

    • REJECT—The user is either not authenticated and is prompted to re-enter the username and password, or access is denied.

    • CHALLENGE—A challenge requires additional data from the user.

    • CHALLENGE PASSWORD—A response requests the user to select a new password.

    The ACCEPT or REJECT response is bundled with additional data that is used for privileged EXEC or network authorization. The additional data included with the ACCEPT or REJECT packets includes these items:

  • Telnet, SSH, rlogin, or privileged EXEC services

  • Connection parameters, including the host or client IP address, access list, and user timeouts

RADIUS Change of Authorization

The RADIUS Change of Authorization (CoA) provides a mechanism to change the attributes of an authentication, authorization, and accounting (AAA) session after it is authenticated. When a policy changes for a user or user group in AAA, administrators can send RADIUS CoA packets from the AAA server such as a Cisco Secure Access Control Server (ACS) to reinitialize authentication and apply the new policy. This section provides an overview of the RADIUS interface including available primitives and how they are used during a CoA.

  • Change-of-Authorization Requests

  • CoA Request Response Code

  • CoA Request Commands

  • Session Reauthentication

  • Stacking Guidelines for Session Termination

A standard RADIUS interface is typically used in a pulled model where the request originates from a network attached device and the response come from the queried servers. Cisco devices support the RADIUS CoA extensions defined in RFC 5176 that are typically used in a pushed model and allow for the dynamic reconfiguring of sessions from external AAA or policy servers.

Cisco devices supports these per-session CoA requests:

  • Session reauthentication

  • Session termination

  • Session termination with port shutdown

  • Session termination with port bounce

This feature is integrated with Cisco Secure Access Control Server (ACS) 5.1.

The RADIUS interface is enabled by default on Cisco devices. However, some basic configuration is required for the following attributes:

  • Security and Password—refer to the “Preventing Unauthorized Access to Your Switch” section in this guide.

  • Accounting—refer to the “Starting RADIUS Accounting” section in the Configuring Switch-Based Authentication chapter in this guide.

Cisco IOS XE software supports the RADIUS CoA extensions defined in RFC 5176 that are typically used in a push model to allow the dynamic reconfiguring of sessions from external AAA or policy servers. Per-session CoA requests are supported for session identification, session termination, host reauthentication, port shutdown, and port bounce. This model comprises one request (CoA-Request) and two possible response codes:

  • CoA acknowledgement (ACK) [CoA-ACK]

  • CoA nonacknowledgement (NAK) [CoA-NAK]

The request is initiated from a CoA client (typically a AAA or policy server) and directed to the device that acts as a listener.

The table below shows the RADIUS CoA commands and vendor-specific attributes (VSAs) supported by Identity-Based Networking Services. All CoA commands must include the session identifier between the device and the CoA client.

Table 1. RADIUS CoA Commands Supported by Identity-Based Networking Services

CoA Command

Cisco VSA

Activate service

Cisco:Avpair=“subscriber:command=activate-service”

Cisco:Avpair=“subscriber:service-name=<service-name>”

Cisco:Avpair=“subscriber:precedence=<precedence-number>”

Cisco:Avpair=“subscriber:activation-mode=replace-all”

Deactivate service

Cisco:Avpair=“subscriber:command=deactivate-service”

Cisco:Avpair=“subscriber:service-name=<service-name>”

Bounce host port

Cisco:Avpair=“subscriber:command=bounce-host-port”

Disable host port

Cisco:Avpair=“subscriber:command=disable-host-port”

Session query

Cisco:Avpair=“subscriber:command=session-query”

Session reauthenticate

Cisco:Avpair=“subscriber:command=reauthenticate”

Cisco:Avpair=“subscriber:reauthenticate-type=last” or

Cisco:Avpair=“subscriber:reauthenticate-type=rerun”

Session terminate

This is a standard disconnect request and does not require a VSA.

Interface template

Cisco:AVpair="interface-template-name=<interfacetemplate>"

Change-of-Authorization Requests

Change of Authorization (CoA) requests, as described in RFC 5176, are used in a push model to allow for session identification, host reauthentication, and session termination. The model is comprised of one request (CoA-Request) and two possible response codes:

  • CoA acknowledgment (ACK) [CoA-ACK]

  • CoA non-acknowledgment (NAK) [CoA-NAK]

The request is initiated from a CoA client (typically a RADIUS or policy server) and directed to the switch that acts as a listener.

RFC 5176 Compliance

The Disconnect Request message, which is also referred to as Packet of Disconnect (POD), is supported by the switch for session termination.

This table shows the IETF attributes are supported for this feature.

Table 2. Supported IETF Attributes

Attribute Number

Attribute Name

24

State

31

Calling-Station-ID

44

Acct-Session-ID

80

Message-Authenticator

101

Error-Cause

This table shows the possible values for the Error-Cause attribute.

Table 3. Error-Cause Values

Value

Explanation

201

Residual Session Context Removed

202

Invalid EAP Packet (Ignored)

401

Unsupported Attribute

402

Missing Attribute

403

NAS Identification Mismatch

404

Invalid Request

405

Unsupported Service

406

Unsupported Extension

407

Invalid Attribute Value

501

Administratively Prohibited

502

Request Not Routable (Proxy)

503

Session Context Not Found

504

Session Context Not Removable

505

Other Proxy Processing Error

506

Resources Unavailable

507

Request Initiated

508

Multiple Session Selection Unsupported

CoA Request Response Code

The CoA Request response code can be used to convey a command to the switch.

The packet format for a CoA Request Response code as defined in RFC 5176 consists of the following fields: Code, Identifier, Length, Authenticator, and Attributes in the Type:Length:Value (TLV) format. The Attributes field is used to carry Cisco vendor-specific attributes (VSAs).

Session Identification

For disconnect and CoA requests targeted at a particular session, the switch locates the session based on one or more of the following attributes:

  • Acct-Session-Id (IETF attribute #44)

  • Audit-Session-Id (Cisco VSA)

  • Calling-Station-Id (IETF attribute #31 which contains the host MAC address)

  • IPv6 Attributes, which can be one of the following:

    • Framed-IPv6-Prefix (IETF attribute #97) and Framed-Interface-Id (IETF attribute #96), which together create a full IPv6 address per RFC 3162

    • Framed-IPv6-Address

  • Plain IP Address (IETF attribute #8)

Unless all session identification attributes included in the CoA message match the session, the switch returns a Disconnect-NAK or CoA-NAK with the “Invalid Attribute Value” error-code attribute.

If more than one session identification attribute is included in the message, all the attributes must match the session or the switch returns a Disconnect- negative acknowledgment (NAK) or CoA-NAK with the error code “Invalid Attribute Value.”

The packet format for a CoA Request code as defined in RFC 5176 consists of the fields: Code, Identifier, Length, Authenticator, and Attributes in Type:Length:Value (TLV) format.



    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Code      |  Identifier   |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                         Authenticator                         |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Attributes ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-


The attributes field is used to carry Cisco vendor-specific attributes (VSAs).

For CoA requests targeted at a particular enforcement policy, the device returns a CoA-NAK with the error code “Invalid Attribute Value” if any of the above session identification attributes are included in the message.

CoA ACK Response Code

If the authorization state is changed successfully, a positive acknowledgment (ACK) is sent. The attributes returned within CoA ACK will vary based on the CoA Request and are discussed in individual CoA Commands.

CoA NAK Response Code

A negative acknowledgment (NAK) indicates a failure to change the authorization state and can include attributes that indicate the reason for the failure. Use show commands to verify a successful CoA.

CoA Request Commands

Table 4. Supported CoA Commands

Command

1

Cisco VSA

Reauthenticate host

Cisco:Avpair=“subscriber:command=reauthenticate”

Terminate session

This is a standard disconnect request that does not require a VSA.

Bounce host port

Cisco:Avpair=“subscriber:command=bounce-host-port”

Disable host port

Cisco:Avpair=“subscriber:command=disable-host-port”

1 All CoA commands must include the session identifier between the device and the CoA client.
Session Reauthentication

The AAA server typically generates a session reauthentication request when a host with an unknown identity or posture joins the network and is associated with a restricted access authorization profile (such as a guest VLAN). A reauthentication request allows the host to be placed in the appropriate authorization group when its credentials are known.

To initiate session authentication, the AAA server sends a standard CoA-Request message which contains a Cisco VSA in this form: Cisco:Avpair=“subscriber:command=reauthenticate” and one or more session identification attributes.

The current session state determines the switch response to the message. If the session is currently authenticated by IEEE 802.1x, the switch responds by sending an EAPoL (Extensible Authentication Protocol over Lan) -RequestId message to the server.

If the session is currently authenticated by MAC authentication bypass (MAB), the switch 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 switch receives the command, the switch terminates the process, and restarts the authentication sequence, starting with the method configured to be attempted first.

If the session is not yet authorized, or is authorized via guest VLAN, or critical VLAN, or similar policies, the reauthentication message restarts the access control methods, beginning with the method configured to be attempted first. The current authorization of the session is maintained until the reauthentication leads to a different authorization result.

Session Termination

There are three types of CoA requests that can trigger session termination. A CoA Disconnect-Request terminates the session, without disabling the host port. This command causes re-initialization of the authenticator state machine for the specified host, but does not restrict that host access to the network.

To restrict a host’s access to the network, use a CoA Request with the Cisco:Avpair="subscriber:command=disable-host-port" VSA. This command is useful when a host is known to be causing problems on the network, and you need to immediately block network access for the host. When you want to restore network access on the port, re-enable it using a non-RADIUS mechanism.

When a device with no supplicant, such as a printer, needs to acquire a new IP address (for example, after a VLAN change), terminate the session on the host port with port-bounce (temporarily disable and then re-enable the port).

CoA Disconnect-Request

This command is a standard Disconnect-Request. 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, the device terminates the session. After the session has been completely removed, the device returns a Disconnect-ACK.

If the device fails-over to a standby device before returning a Disconnect-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the session is not found following re-sending, a Disconnect-ACK is sent with the “Session Context Not Found” error-code attribute.

CoA Request: Disable Host Port

The RADIUS server CoA disable port command administratively shuts down the authentication port that is hosting a session, resulting in session termination. This command is useful when a host is known to cause problems on the network and network access needs to be immediately blocked for the host. To restore network access on the port, reenable it using a non-RADIUS mechanism. This command is carried in a standard CoA-Request message that has this new vendor-specific attribute (VSA):

Cisco:Avpair="subscriber:command=disable-host-port"

Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes described in the “Session Identification” section. If the session cannot be located, the device returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the device disables the hosting port and returns a CoA-ACK message.

If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation has completed, the operation is restarted on the new active device.


Note

A Disconnect-Request failure following command re-sending could be the result of either a successful session termination before change-over (if the Disconnect-ACK was not sent) or a session termination by other means (for example, a link failure) that occurred after the original command was issued and before the standby device became active.


CoA Request: Bounce-Port

A RADIUS server CoA bounce port sent from a RADIUS server can cause a link flap on an authentication port, which triggers DHCP renegotiation from one or more hosts connected to this port. This incident can occur when there is a VLAN change and the endpoint is a device (such as a printer) that does not have a mechanism to detect a change on this authentication port. The CoA bounce port is carried in a standard CoA-Request message that contains the following VSA:

Cisco:Avpair="subscriber:command=bounce-host-port"

Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes. If the session cannot be located, the device returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the device disables the hosting port for a period of 10 seconds, re-enables it (port-bounce), and returns a CoA-ACK.

If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation has completed, the operation is re-started on the new active device.

Default RADIUS Configuration

RADIUS and AAA are disabled by default.

To prevent a lapse in security, you cannot configure RADIUS through a network management application. When enabled, RADIUS can authenticate users accessing the device through the CLI.

RADIUS Server Host

Device-to-RADIUS-server communication involves several components:

  • Hostname or IP address

  • Authentication destination port

  • Accounting destination port

  • Key string

  • Timeout period

  • Retransmission value

You identify RADIUS security servers by their hostname or IP address, hostname and specific UDP port numbers, or their IP address and specific UDP port numbers. The combination of the IP address and the UDP port number creates a unique identifier, allowing different ports to be individually defined as RADIUS hosts providing a specific AAA service. This unique identifier enables RADIUS requests to be sent to multiple UDP ports on a server at the same IP address.

If two different host entries on the same RADIUS server are configured for the same service—for example, accounting—the second host entry configured acts as a fail-over backup to the first one. Using this example, if the first host entry fails to provide accounting services, the %RADIUS-4-RADIUS_DEAD message appears, and then the device tries the second host entry configured on the same device for accounting services. (The RADIUS host entries are tried in the order that they are configured.)

A RADIUS server and the device use a shared secret text string to encrypt passwords and exchange responses. To configure RADIUS to use the AAA security commands, you must specify the host running the RADIUS server daemon and a secret text (key) string that it shares with the device.

The timeout, retransmission, and encryption key values can be configured globally for all RADIUS servers, on a per-server basis, or in some combination of global and per-server settings.

RADIUS Login Authentication

To configure AAA authentication, you define a named list of authentication methods and then apply that list to various ports. The method list defines the types of authentication to be performed and the sequence in which they are performed; it must be applied to a specific port before any of the defined authentication methods are performed. The only exception is the default method list. The default method list is automatically applied to all ports except those that have a named method list explicitly defined.

A method list describes the sequence and authentication methods to be queried to authenticate a user. You can designate one or more security protocols to be used for authentication, thus ensuring a backup system for authentication in case the initial method fails. The software uses the first method listed to authenticate users; if that method fails to respond, the software selects the next authentication method in the method list. This process continues until there is successful communication with a listed authentication method or until all defined methods are exhausted. If authentication fails at any point in this cycle—meaning that the security server or local username database responds by denying the user access—the authentication process stops, and no other authentication methods are attempted.

AAA Server Groups

You can configure the device to use AAA server groups to group existing server hosts for authentication. You select a subset of the configured server hosts and use them for a particular service. The server group is used with a global server-host list, which lists the IP addresses of the selected server hosts.

Server groups also can include multiple host entries for the same server if each entry has a unique identifier (the combination of the IP address and UDP port number), allowing different ports to be individually defined as RADIUS hosts providing a specific AAA service. This unique identifier enables RADIUS requests to be sent to different UDP ports on a server at the same IP address. If you configure two different host entries on the same RADIUS server for the same service, (for example, accounting), the second configured host entry acts as a fail-over backup to the first one. If the first host entry fails to provide accounting services, the network access server tries the second host entry configured on the same device for accounting services. (The RADIUS host entries are tried in the order in which they are configured.)

AAA Authorization

AAA authorization limits the services available to a user. When AAA authorization is enabled, the device uses information retrieved from the user’s profile, which is in the local user database or on the security server, to configure the user’s session. The user is granted access to a requested service only if the information in the user profile allows it.

RADIUS Accounting

The AAA accounting feature tracks the services that users are using and the amount of network resources that they are consuming. When you enable AAA accounting, the device reports user activity to the RADIUS security server in the form of accounting records. Each accounting record contains accounting attribute-value (AV) pairs and is stored on the security server. You can then analyze the data for network management, client billing, or auditing.

Vendor-Specific RADIUS Attributes

The Internet Engineering Task Force (IETF) draft standard specifies a method for communicating vendor-specific information between the device and the RADIUS server by using the vendor-specific attribute (attribute 26). Vendor-specific attributes (VSAs) allow vendors to support their own extended attributes not suitable for general use. The Cisco RADIUS implementation supports one vendor-specific option by using the format recommended in the specification. Cisco’s vendor-ID is 9, and the supported option has vendor-type 1, which is named cisco-avpair. The value is a string with this format:


protocol : attribute sep value *


Protocol is a value of the Cisco protocol attribute for a particular type of authorization. Attribute and value are an appropriate attributevalue (AV) pair defined in the Cisco TACACS+ specification, and sep is = for mandatory attributes and is * for optional attributes. The full set of features available for TACACS+ authorization can then be used for RADIUS.

For example, the following AV pair causes Cisco’s “multiple named IP address pools” feature to be activated during IP authorization (during PPP’s Internet Protocol Control Protocol (IPCP) address assignment):
cisco-avpair= ”ip:addr-pool=first“


If you insert an “*”, the AV pair “ip:addr-pool=first” becomes optional. Note that any AV pair can be made optional:
cisco-avpair= ”ip:addr-pool*first“


The following example shows how to cause a user logging in from a network access server to have immediate access to EXEC commands:
cisco-avpair= ”shell:priv-lvl=15“ 


Other vendors have their own unique vendor-IDs, options, and associated VSAs. For more information about vendor-IDs and VSAs, see RFC 2138, “Remote Authentication Dial-In User Service (RADIUS).”

Attribute 26 contains the following three elements:

  • Type

  • Length

  • String (also known as data)

    • Vendor-ID

    • Vendor-Type

    • Vendor-Length

    • Vendor-Data

The figure below shows the packet format for a VSA encapsulated “behind” attribute 26.

Figure 2. VSA Encapsulated Behind Attribute 26

Note

It is up to the vendor to specify the format of their VSA. The Attribute-Specific field (also known as Vendor-Data) is dependent on the vendor's definition of that attribute.


The table below describes significant fields listed in the Vendor-Specific RADIUS IETF Attributes table (second table below), which lists supported vendor-specific RADIUS attributes (IETF attribute 26).

Table 5. Vendor-Specific Attributes Table Field Descriptions

Field

Description

Number

All attributes listed in the following table are extensions of IETF attribute 26.

Vendor-Specific Command Codes

A defined code used to identify a particular vendor. Code 9 defines Cisco VSAs, 311 defines Microsoft VSAs, and 529 defines Ascend VSAs.

Sub-Type Number

The attribute ID number. This number is much like the ID numbers of IETF attributes, except it is a “second layer” ID number encapsulated behind attribute 26.

Attribute

The ASCII string name of the attribute.

Description

Description of the attribute.

Table 6. Vendor-Specific RADIUS IETF Attributes

Number

Vendor-Specific Company Code

Sub-Type Number

Attribute

Description

MS-CHAP Attributes

26

311

1

MSCHAP-Response

Contains the response value provided by a PPP MS-CHAP user in response to the challenge. It is only used in Access-Request packets. This attribute is identical to the PPP CHAP Identifier. ( RFC 2548

26

311

11

MSCHAP-Challenge

Contains the challenge sent by a network access server to an MS-CHAP user. It can be used in both Access-Request and Access-Challenge packets. ( RFC 2548 )

VPDN Attributes

26

9

1

l2tp-cm-local-window-size

Specifies the maximum receive window size for L2TP control messages. This value is advertised to the peer during tunnel establishment.

26

9

1

l2tp-drop-out-of-order

Respects sequence numbers on data packets by dropping those that are received out of order. This does not ensure that sequence numbers will be sent on data packets, just how to handle them if they are received.

26

9

1

l2tp-hello-interval

Specifies the number of seconds for the hello keepalive interval. Hello packets are sent when no data has been sent on a tunnel for the number of seconds configured here.

26

9

1

l2tp-hidden-avp

When enabled, sensitive AVPs in L2TP control messages are scrambled or hidden.

26

9

1

l2tp-nosession-timeout

Specifies the number of seconds that a tunnel will stay active with no sessions before timing out and shutting down.

26

9

1

tunnel-tos-reflect

Copies the IP ToS field from the IP header of each payload packet to the IP header of the tunnel packet for packets entering the tunnel at the LNS.

26

9

1

l2tp-tunnel-authen

If this attribute is set, it performs L2TP tunnel authentication.

26

9

1

l2tp-tunnel-password

Shared secret used for L2TP tunnel authentication and AVP hiding.

26

9

1

l2tp-udp-checksum

This is an authorization attribute and defines whether L2TP should perform UDP checksums for data packets. Valid values are “yes” and “no.” The default is no.

Store and Forward Fax Attributes

26

9

3

Fax-Account-Id-Origin

Indicates the account ID origin as defined by system administrator for the mmoip aaa receive-id or the mmoip aaa send-id commands.

26

9

4

Fax-Msg-Id=

Indicates a unique fax message identification number assigned by Store and Forward Fax.

26

9

5

Fax-Pages

Indicates the number of pages transmitted or received during this fax session. This page count includes cover pages.

26

9

6

Fax-Coverpage-Flag

Indicates whether or not a cover page was generated by the off-ramp gateway for this fax session. True indicates that a cover page was generated; false means that a cover page was not generated.

26

9

7

Fax-Modem-Time

Indicates the amount of time in seconds the modem sent fax data (x) and the amount of time in seconds of the total fax session (y), which includes both fax-mail and PSTN time, in the form x/y. For example, 10/15 means that the transfer time took 10 seconds, and the total fax session took 15 seconds.

26

9

8

Fax-Connect-Speed

Indicates the modem speed at which this fax-mail was initially transmitted or received. Possible values are 1200, 4800, 9600, and 14400.

26

9

9

Fax-Recipient-Count

Indicates the number of recipients for this fax transmission. Until e-mail servers support Session mode, the number should be 1.

26

9

10

Fax-Process-Abort-Flag

Indicates that the fax session was aborted or successful. True means that the session was aborted; false means that the session was successful.

26

9

11

Fax-Dsn-Address

Indicates the address to which DSNs will be sent.

26

9

12

Fax-Dsn-Flag

Indicates whether or not DSN has been enabled. True indicates that DSN has been enabled; false means that DSN has not been enabled.

26

9

13

Fax-Mdn-Address

Indicates the address to which MDNs will be sent.

26

9

14

Fax-Mdn-Flag

Indicates whether or not message delivery notification (MDN) has been enabled. True indicates that MDN had been enabled; false means that MDN had not been enabled.

26

9

15

Fax-Auth-Status

Indicates whether or not authentication for this fax session was successful. Possible values for this field are success, failed, bypassed, or unknown.

26

9

16

Email-Server-Address

Indicates the IP address of the e-mail server handling the on-ramp fax-mail message.

26

9

17

Email-Server-Ack-Flag

Indicates that the on-ramp gateway has received a positive acknowledgment from the e-mail server accepting the fax-mail message.

26

9

18

Gateway-Id

Indicates the name of the gateway that processed the fax session. The name appears in the following format: hostname.domain-name.

26

9

19

Call-Type

Describes the type of fax activity: fax receive or fax send.

26

9

20

Port-Used

Indicates the slot/port number of the Cisco AS5300 used to either transmit or receive this fax-mail.

26

9

21

Abort-Cause

If the fax session aborts, indicates the system component that signaled the abort. Examples of system components that could trigger an abort are FAP (Fax Application Process), TIFF (the TIFF reader or the TIFF writer), fax-mail client, fax-mail server, ESMTP client, or ESMTP server.

H323 Attributes

26

9

23

Remote-Gateway-ID (h323-remote-address)

Indicates the IP address of the remote gateway.

26

9

24

Connection-ID

(h323-conf-id)

Identifies the conference ID.

26

9

25

Setup-Time

(h323-setup-time)

Indicates the setup time for this connection in Coordinated Universal Time (UTC) formerly known as Greenwich Mean Time (GMT) and Zulu time.

26

9

26

Call-Origin

(h323-call-origin)

Indicates the origin of the call relative to the gateway. Possible values are originating and terminating (answer).

26

9

27

Call-Type

(h323-call-type)

Indicates call leg type. Possible values are telephony and VoIP .

26

9

28

Connect-Time

(h323-connect-time)

Indicates the connection time for this call leg in UTC.

26

9

29

Disconnect-Time

(h323-disconnect-time)

Indicates the time this call leg was disconnected in UTC.

26

9

30

Disconnect-Cause

(h323-disconnect-cause)

Specifies the reason a connection was taken offline per Q.931 specification.

26

9

31

Voice-Quality

(h323-voice-quality)

Specifies the impairment factor (ICPIF) affecting voice quality for a call.

26

9

33

Gateway-ID

(h323-gw-id)

Indicates the name of the underlying gateway.

Large Scale Dialout Attributes

26

9

1

callback-dialstring

Defines a dialing string to be used for callback.

26

9

1

data-service

No description available.

26

9

1

dial-number

Defines the number to dial.

26

9

1

force-56

Determines whether the network access server uses only the 56 K portion of a channel, even when all 64 K appear to be available.

26

9

1

map-class

Allows the user profile to reference information configured in a map class of the same name on the network access server that dials out.

26

9

1

send-auth

Defines the protocol to use (PAP or CHAP) for username-password authentication following CLID authentication.

26

9

1

send-name

PPP name authentication. To apply for PAP, do not configure the ppp pap sent-name password command on the interface. For PAP, “preauth:send-name” and “preauth:send-secret” will be used as the PAP username and PAP password for outbound authentication. For CHAP, “preauth:send-name” will be used not only for outbound authentication, but also for inbound authentication. For a CHAP inbound case, the NAS will use the name defined in “preauth:send-name” in the challenge packet to the caller box.

Note 
The send-name attribute has changed over time: Initially, it performed the functions now provided by both the send-name and remote-name attributes. Because the remote-name attribute has been added, the send-name attribute is restricted to its current behavior.

26

9

1

send-secret

PPP password authentication. The vendor-specific attributes (VSAs) “preauth:send-name” and “preauth:send-secret” will be used as the PAP username and PAP password for outbound authentication. For a CHAP outbound case, both “preauth:send-name” and “preauth:send-secret” will be used in the response packet.

26

9

1

remote-name

Provides the name of the remote host for use in large-scale dial-out. Dialer checks that the large-scale dial-out remote name matches the authenticated name, to protect against accidental user RADIUS misconfiguration. (For example, dialing a valid phone number but connecting to the wrong device.)

Miscellaneous Attributes

26

9

2

Cisco-NAS-Port

Specifies additional vendor specific attribute (VSA) information for NAS-Port accounting. To specify additional NAS-Port information in the form an Attribute-Value Pair (AVPair) string, use the radius-server vsa send global configuration command.

Note 
This VSA is typically used in Accounting, but may also be used in Authentication (Access-Request) packets.

26

9

1

min-links

Sets the minimum number of links for MLP.

26

9

1

proxyacl#<n>

Allows users to configure the downloadable user profiles (dynamic ACLs) by using the authentication proxy feature so that users can have the configured authorization to permit traffic going through the configured interfaces.

26

9

1

spi

Carries the authentication information needed by the home agent to authenticate a mobile node during registration. The information is in the same syntax as the ip mobile secure host <addr> configuration command. Basically it contains the rest of the configuration command that follows that string, verbatim. It provides the Security Parameter Index (SPI), key, authentication algorithm, authentication mode, and replay protection timestamp range.

Vendor-Proprietary RADIUS Server Communication

Although an IETF draft standard for RADIUS specifies a method for communicating vendor-proprietary information between the device and the RADIUS server, some vendors have extended the RADIUS attribute set in a unique way. Cisco IOS XE software supports a subset of vendor-proprietary RADIUS attributes.

As mentioned earlier, to configure RADIUS (whether vendor-proprietary or IETF draft-compliant), you must specify the host running the RADIUS server daemon and the secret text string it shares with the device. You specify the RADIUS host and secret text string by using the radius server global configuration commands.

How to Configure RADIUS

Identifying the RADIUS Server Host

To apply these settings globally to all RADIUS servers communicating with the device, use the three unique global configuration commands: radius-server timeout , radius-server retransmit , and key string .

You can configure the device to use AAA server groups to group existing server hosts for authentication.

You also need to configure some settings on the RADIUS server. These settings include the IP address of the device and the key string to be shared by both the server and the device.

Follow these steps to configure per-server RADIUS server communication.

Before you begin

If you configure both global and per-server functions (timeout, retransmission, and key commands) on the device, the per-server timer, retransmission, and key value commands override global timer, retransmission, and key value commands.

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

radius server server name

Example:


Device(config)# radius server rsim


Specifies the name for the RADIUS server configuration for Protected Access Credential (PAC) provisioning, and enters RADIUS server configuration mode.

Step 4

address {ipv4 | ipv6}ip address{ auth-port port number | acct-port port number}

Example:


Device(config-radius-server)# address ipv4 124.2.2.12 auth-port 1612


(Optional) Specifies the RADIUS server parameters.

For auth-port port-number , specify the UDP destination port for authentication requests. The default is 1645. The range is 0 to 65536.

For acct-port port-number , specify the UDP destination port for authentication requests. The default is 1646.

Step 5

key string

Example:


Device(config-radius-server)#  key rad123


(Optional) For key string , specify the authentication and encryption key used between the device and the RADIUS daemon running on the RADIUS server.

Note 

The key is a text string that must match the encryption key used on the RADIUS server. Always configure the key as the last item in the radius server command. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

Step 6

retransmit value

Example:


Device(config-radius-server)# retransmit 10


(Optional) Specifies the number of times a RADIUS request is resent when the server is not responding or responding slowly. The range is 1 to 100. This setting overrides the radius-server retransmit global configuration command setting.

Step 7

timeout seconds

Example:


Device(config-radius-server)# timeout 60


(Optional) Specifies the time interval that the device waits for the RADIUS server to reply before sending a request again. The range is 1 to 1000. This setting overrides the radius-server timeout global configuration command setting.

Step 8

end

Example:


Device(config-radius-server)# end


Exits RADIUS server configuration mode and enters privileged EXEC mode.

Configuring RADIUS Login Authentication

Follow these steps to configure RADIUS login authentication:

Before you begin

To secure the device for HTTP access by using AAA methods, you must configur the ip http authentication aaa global configuration command. Configuring AAA authentication does not secure the device for HTTP access by using AAA methods.

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Device(config)# aaa new-model


Enables AAA.

Step 4

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

Example:


Device(config)# aaa authentication login default local


Creates a login authentication method list.

  • To create a default list that is used when a named list is not specified in the login authentication command, use the default keyword followed by the methods that are to be used in default situations. The default method list is automatically applied to all ports.

  • For list-name , specify a character string to name the list you are creating.

  • For method1... , specify the actual method the authentication algorithm tries. The additional methods of authentication are used only if the previous method returns an error, not if it fails.

    Select one of these methods:

    • enable —Use the enable password for authentication. Before you can use this authentication method, you must define an enable password by using the enable password global configuration command.

    • group radius —Use RADIUS authentication. Before you can use this authentication method, you must configure the RADIUS server.

    • line —Use the line password for authentication. Before you can use this authentication method, you must define a line password. Use the password password line configuration command.

    • local —Use the local username database for authentication. You must enter username information in the database. Use the username name password global configuration command.

    • local-case —Use a case-sensitive local username database for authentication. You must enter username information in the database by using the username password global configuration command.

    • none —Do not use any authentication for login.

Step 5

line [console | tty | vty] line-number [ending-line-number]

Example:


Device(config)# line 1 4


Enters line configuration mode, and configure the lines to which you want to apply the authentication list.

Step 6

login authentication {default | list-name}

Example:


Device(config-line)# login authentication default 

Applies the authentication list to a line or set of lines.

  • If you specify default , use the default list created with the aaa authentication login command.

  • For list-name , specify the list created with the aaa authentication login command.

Step 7

end

Example:

Device(config-line)# end

Exits line configuration mode and enters privileged EXEC mode.

Defining AAA Server Groups

You use the server group server configuration command to associate a particular server with a defined group server. You can either identify the server by its IP address or identify multiple host instances or entries by using the optional auth-port and acct-port keywords.

Follow these steps to define AAA server groups:

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

radius server name

Example:


Device(config)# radius server ISE


Specifies the name of the RADIUS server configuration for Protected Access Credential (PAC) provisioning and enters RADIUS server configuration mode.

The device also supports RADIUS for IPv6.

Step 4

address {ipv4 | ipv6} {ip-address | hostname} auth-port port-number acct-port port-number

Example:


Device(config-radius-server)# address ipv4 10.1.1.1 auth-port 1645 acct-port 1646


Configures the IPv4 address for the RADIUS server accounting and authentication parameters.

Step 5

key string

Example:


Device(config-radius-server)# key cisco123


Specifies the authentication and encryption key for all RADIUS communications between the device and the RADIUS server.

Step 6

end

Example:


Device(config-radius-server)# end


Exits RADIUS server configuration mode and returns to privileged EXEC mode.

Configuring RADIUS Authorization for User Privileged Access and Network Services


Note

Authorization is bypassed for authenticated users who log in through the CLI even if authorization has been configured.


Follow these steps to configure RADIUS authorization for user priviledged access and network services:

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

aaa authorization network authorization-list radius

Example:


Device(config)# aaa authorization network list1 radius


Configures the device for user RADIUS authorization for all network-related service requests.

Step 4

aaa authorization exec authorization-list radius

Example:


Device(config)# aaa authorization exec list1 radius


Configures the device for user RADIUS authorization if the user has privileged EXEC access.

The exec keyword might return user profile information (such as autocommand information).

Step 5

end

Example:

Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

What to do next

You can use the aaa authorization global configuration command with the radius keyword to set parameters that restrict a user’s network access to privileged EXEC mode.

The aaa authorization exec radius local command sets these authorization parameters:

  • Use RADIUS for privileged EXEC access authorization if authentication was performed by using RADIUS.

  • Use the local database if authentication was not performed by using RADIUS.

Starting RADIUS Accounting

Follow these steps to start RADIUS accounting:

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

aaa accounting network accounting-liststart-stop radius

Example:


Device(config)# aaa accounting network start-stop radius


Enables RADIUS accounting for all network-related service requests.

Step 4

aaa accounting exec accounting-liststart-stop radius

Example:

Device(config)# aaa accounting exec acc-list start-stop radius


Enables RADIUS accounting to send a start-record accounting notice at the beginning of a privileged EXEC process and a stop-record at the end.

Step 5

end

Example:

Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuring Settings for All RADIUS Servers

Beginning in privileged EXEC mode, follow these steps to configure settings for all RADIUS servers:

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

radius server server name

Example:


Device(config)# radius server rsim


Specifies the name for the RADIUS server configuration for Protected Access Credential (PAC) provisioning, and enters RADIUS server configuration mode.

Step 4

key string

Example:


Device(config-radius-server)# key your_server_key


Specifies the shared secret text string used between the switch and all RADIUS servers.

Note 

The key is a text string that must match the encryption key used on the RADIUS server. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

Step 5

retransmit retries

Example:

Device(config-radius-server)# retransmit 5


Specifies the number of times the switch sends each RADIUS request to the server before giving up. The default is 3; the range 1 to 1000.

Step 6

timeout seconds

Example:


Device(config-radius-server)# timeout 3


Specifies the number of seconds a switch waits for a reply to a RADIUS request before resending the request. The default is 5 seconds; the range is 1 to 1000.

Step 7

end

Example:


Device(config-radius-server)# end


Exits RADIUS server configuration mode and enters privileged EXEC mode.

Configuring the Device to Use Vendor-Specific RADIUS Attributes

Follow these steps to configure vendor-specific RADIUS attributes:

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

radius-server vsa send [accounting | authentication]

Example:


Device(config)# radius-server vsa send accounting


Enables the device to recognize and use VSAs as defined by RADIUS IETF attribute 26.

  • (Optional) Use the accounting keyword to limit the set of recognized vendor-specific attributes to only accounting attributes.

  • (Optional) Use the authentication keyword to limit the set of recognized vendor-specific attributes to only authentication attributes.

If you enter this command without keywords, both accounting and authentication vendor-specific attributes are used.

Step 4

end

Example:


Device(config)# end


Exits global configuration mode and enters privileged EXEC mode.

Configuring the Device for Vendor-Proprietary RADIUS Server Communication

Follow these steps to configure vendor-proprietary RADIUS server communication:

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

radius server server name

Example:


Device(config)# radius server rsim


Specifies the name for the RADIUS server configuration for Protected Access Credential (PAC) provisioning, and enters RADIUS server configuration mode.

Step 4

address { ipv4 | ipv6 } ip address

Example:


Device(config-radius-server)# address ipv4 172.24.25.10


(Optional) Specifies the IP address of the RADIUS server.

Step 5

non-standard

Example:


Device(config-radius-server)# non-standard


Identifies that the RADIUS server using a vendor-proprietary implementation of RADIUS.

Step 6

key string

Example:


Device(config-radius-server)# key rad123


Specifies the shared secret text string used between the device and the vendor-proprietary RADIUS server. The device and the RADIUS server use this text string to encrypt passwords and exchange responses.

Step 7

end

Example:


Device(config-radius-server)# end


Exits RADIUS server mode and enters privileged EXEC mode.

Configuring CoA on the Device

Follow these steps to configure CoA on a device. This procedure is required.

Procedure

  Command or Action Purpose
Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Device(config)# aaa new-model


Enables AAA.

Step 4

aaa server radius dynamic-author

Example:


Device(config)# aaa server radius dynamic-author


Configures the device as an authentication, authorization, and accounting (AAA) server to facilitate interaction with an external policy server, and enters dynamic authorization local server configuration mode.

Step 5

client {ip-address | name} [vrf vrfname] [server-key string]

Example:


Device(config-locsvr-da-radius)# client client1 vrf vrf1


Specifies a RADIUS client from which a device will accept CoA and disconnect requests.

Step 6

server-key [0 | 7] string

Example:


Device(config-locsvr-da-radius)# server-key your_server_key


Configures the RADIUS key to be shared between a device and RADIUS clients.

Step 7

port port-number

Example:


Device(config-locsvr-da-radius)# port 25


Specifies the port on which a device listens for RADIUS requests from configured RADIUS clients.

Step 8

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

Example:


Device(config-locsvr-da-radius)# auth-type any


Specifies the type of authorization the device uses for RADIUS clients.

The client must match all the configured attributes for authorization.

Step 9

ignore server-key

Example:


Device(config-locsvr-da-radius)# ignore server-key


(Optional) Configures the device to ignore the server-key.

Step 10

exit

Example:


Device(config-locsvr-da-radius)# exit


Exits dynamic authorization local server configuration mode and returns to global configuration mode.

Step 11

authentication command bounce-port ignore

Example:


Device(config)# authentication command bounce-port ignore


(Optional) Configures the device to ignore a CoA request to temporarily disable the port hosting a session. The purpose of temporarily disabling the port is to trigger a DHCP renegotiation from the host when a VLAN change occurs and there is no supplicant on the endpoint to detect the change.

Step 12

authentication command disable-port ignore

Example:


Device(config)# authentication command disable-port ignore


(Optional) Configures the device to ignore a nonstandard command requesting that the port hosting a session be administratively shut down. Shutting down the port results in termination of the session.

Use standard CLI or SNMP commands to re-enable the port.

Step 13

end

Example:


Device(config)# end


Exits global configuration mode an returns to privileged EXEC mode.

Monitoring CoA Functionality

Table 7. Privileged EXEC show Commands

Command

Purpose

show aaa attributes protocol radius

Displays AAA attributes of RADIUS commands.

Table 8. Global Troubleshooting Commands

Command

Purpose

debug radius

Displays information for troubleshooting RADIUS.

debug aaa coa

Displays information for troubleshooting CoA processing.

debug aaa pod

Displays information for troubleshooting POD packets.

debug aaa subsys

Displays information for troubleshooting POD packets.

debug cmdhd [detail | error | events]

Displays information for troubleshooting command headers.

Additional References for RADIUS

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

Technical Assistance

Description

Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport

Feature History for RADIUS

This table provides release and related information for features explained in this module.

These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.

Release

Feature

Feature Information

Cisco IOS XE Everest 16.5.1a

RADIUS

RADIUS is a distributed client/server system that secures networks against unauthorized access. RADIUS clients run on supported Cisco devices. Clients send authentication requests to a central RADIUS server, which contains all user authentication and network service access information.

Support for this feature was introduced on all the models of the Cisco Catalyst 9500 Series Switches.

Cisco IOS XE Fuji 16.8.1a

RADIUS

Support for this feature was introduced on the C9500-32C, C9500-32QC, C9500-48Y4C, and C9500-24Y4C models of the Cisco Catalyst 9500 Series Switches.

Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.