Table Of Contents

Switch Access: Using Authentication, Authorization, and Accounting

Understanding How Authentication Works

Authentication Overview

Understanding How Local Authentication Works

Understanding How TACACS+ Authentication Works

Understanding How RADIUS Authentication Works

Understanding How Kerberos Authentication Works

Using Kerberized Login Procedure

Using a Non-Kerberized Login Procedure

Configuring Authentication

Authentication Default Configuration

Authentication Configuration Guidelines

Configuring Local Authentication

Enabling Local Authentication

Setting the Login Password

Setting the Enable Password

Disabling Local Authentication

Recovering a Lost Password

Configuring TACACS+ Authentication

Specifying TACACS+ Servers

Enabling TACACS+ Authentication

Specifying the TACACS+ Key

Setting the TACACS+ Timeout Interval

Setting the TACACS+ Login Attempts

Enabling TACACS+ Directed Request

Disabling TACACS+ Directed Request

Clearing TACACS+ Servers

Clearing the TACACS+ Key

Disabling TACACS+ Authentication

Configuring RADIUS Authentication

Specifying RADIUS Servers

Enabling RADIUS Authentication

Specifying the RADIUS Key

Setting the RADIUS Timeout Interval

Setting the RADIUS Retransmit Count

Setting the RADIUS Deadtime

Clearing RADIUS Servers

Clearing the RADIUS Key

Disabling RADIUS Authentication

Configuring Kerberos Authentication

Enabling Kerberos

Defining the Kerberos Local-Realm

Specifying a Kerberos Server

Mapping a Kerberos Realm to a Host Name or DNS Domain

Copying SRVTAB Files

Enabling Credentials Forwarding

Defining a Private DES Key

Encrypting a Telnet Session

Monitoring and Maintaining Kerberos

Authentication Example

Understanding How Authorization Works

Authorization Overview

Authorization Events

TACACS+ Primary Options and Fallback Options

TACACS+ Command Authorization

RADIUS Authorization

Configuring Authorization

Authorization Default Configuration

TACACS+ Authorization Configuration Guidelines

Configuring TACACS+ Authorization

Enabling TACACS+ Authorization

Disabling TACACS+ Authorization

Authorization Example

Understanding How Accounting Works

Accounting Overview

Accounting Events

Specifying When to Create Accounting Records

Specifying RADIUS Servers

Updating the Server

Suppressing Accounting

Configuring Accounting

Accounting Default Configuration

Accounting Configuration Guidelines

Configuring Accounting

Enabling Accounting

Disabling Accounting

Accounting Example

Switch Access: Using Authentication, Authorization, and Accounting

---

This chapter describes how to configure authentication, authorization, and accounting (AAA) to monitor and control access to the command-line interface (CLI) on the Catalyst enterprise LAN switches.

---

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command Reference publication for your switch.

---

This chapter consists of these sections:

•Understanding How Authentication Works

•Configuring Authentication

•Authentication Example

•Understanding How Authorization Works

•Configuring Authorization

•Authorization Example

•Understanding How Accounting Works

•Configuring Accounting

•Accounting Example

Understanding How Authentication Works

These sections describe how the different authentication methods work:

•Authentication Overview

•Understanding How Local Authentication Works

•Understanding How TACACS+ Authentication Works

•Understanding How RADIUS Authentication Works

•Understanding How Kerberos Authentication Works

Authentication Overview

You can configure any combination of these authentication methods to control access to the switch:

•Local authentication

•TACACS+ authentication

•RADIUS authentication

•Kerberos authentication

---

Note Kerberos authentication does not work if TACACS+ is used as the authentication method.

---

When multiple authentication methods are enabled, if local authentication is enabled, it is always attempted last. In supervisor engine software release 4.4 and later, you can specify the authentication method to use for console and Telnet connections independently. For example, you might use local authentication for console connections and RADIUS authentication for Telnet connections.

Understanding How Local Authentication Works

Local authentication uses locally configured login and enable passwords to authenticate login attempts. The login and enable passwords are local to each switch and are not mapped to individual user names.

Local authentication is enabled by default, but can be disabled if one of the other authentication methods is enabled. If local authentication is disabled and you then disable all other authentication methods, local authentication is reenabled automatically.

You can enable local authentication and one or more of the other authentication methods at the same time. Local authentication is only attempted if the other authentication methods fail.

Understanding How TACACS+ Authentication Works

TACACS+ controls access to network devices by exchanging Network Access Server (NAS) information between a network device and a centralized database to determine the identity of a user or device. TACACS+ is an enhanced version of TACACS, a User Datagram Protocol (UDP)-based access-control protocol specified by RFC 1492. TACACS+ uses TCP to ensure reliable delivery and encrypt all traffic between the TACACS+ server and the TACACS+ daemon on a network device.

TACACS+ works with many authentication types, including fixed password, one-time password, and challenge-response authentication. TACACS+ authentication usually occurs in these instances:

•When you first log onto a machine

•When you send a service request that requires privileged access

When you request privileged or restricted services, TACACS+ encrypts your user password information using the MD5 encryption algorithm and adds a TACACS+ packet header. This header information identifies the packet type being sent (for example, an authentication packet), the packet sequence number, the encryption type used, and the total packet length. The TACACS+ protocol then forwards the packet to the TACACS+ server.

A TACACS+ server can provide authentication, authorization, and accounting functions. These services, while all part of TACACS+, are independent of one another, so that a given TACACS+ configuration can use any or all of the three services.

When the TACACS+ server receives the packet, it does the following:

•Authenticates the user information and notifies the client that authentication has either passed or failed.

•Notifies the client that authentication will continue and that the client must provide additional information. This challenge-response process can continue through multiple iterations until authentication either passes or fails.

You can configure a TACACS+ key on the client and server. If you configure a key on the switch, it must be the same as the one configured on the TACACS+ servers. The TACACS+ clients and servers use the key to encrypt all TACACS+ packets transmitted. If you do not configure a TACACS+ key, packets are not encrypted.

You can configure the following TACACS+ parameters on the switch:

•Enable or disable TACACS+ authentication to determine if a user has permission to access the switch

•Enable or disable TACACS+ authentication to determine if a user has permission to enter privileged mode

•Specify a key used to encrypt the protocol packets

•Specify the server on which the TACACS+ server daemon resides

•Set the number of login attempts allowed

•Set the timeout interval for server daemon response

•Enable or disable the directed-request option

TACACS+ authentication is disabled by default. You can enable TACACS+ authentication and local authentication at the same time.

If local authentication is disabled and you then disable all other authentication methods, local authentication is reenabled automatically.

Understanding How RADIUS Authentication Works

RADIUS is a client-server authentication and authorization access protocol used by the NAS to authenticate users attempting to connect to a network device. The NAS functions as a client, passing user information to one or more RADIUS servers. The NAS permits or denies network access to a user based on the response it receives from one or more RADIUS servers. RADIUS uses UDP for transport between the RADIUS client and server.

You can configure a RADIUS key on the client and server. If you configure a key on the client, it must be the same as the one configured on the RADIUS servers. The RADIUS clients and servers use the key to encrypt all RADIUS packets transmitted. If you do not configure a RADIUS key, packets are not encrypted. The key itself is never transmitted over the network.

---

Note For more information about how the RADIUS protocol operates, see RFC 2138, "Remote Authentication Dial In User Service (RADIUS)."

---

You can configure the following RADIUS parameters on the switch:

•Enable or disable RADIUS authentication to control login access

•Enable or disable RADIUS authentication to control enable access

•Specify the IP addresses and UDP ports of the RADIUS servers

•Specify the RADIUS key used to encrypt RADIUS packets

•Specify the RADIUS server timeout interval

•Specify the RADIUS retransmit count

•Specify the RADIUS server deadtime interval

RADIUS authentication is disabled by default. You can enable RADIUS authentication and other authentication methods at the same time. You can specify which method to use first using the primary keyword.

If local authentication is disabled and you then disable all other authentication methods, local authentication is reenabled automatically.

Understanding How Kerberos Authentication Works

Kerberos is a client-server based secret-key network authentication method that uses a trusted Kerberos server to verify secure access to both services and users. In Kerberos, this trusted server is called the key distribution center (KDC). The KDC issues tickets to validate users and services. A ticket is a temporary set of electronic credentials that verify the identity of a client for a particular service.

These tickets have a limited life span and can be used in place of the standard user password authentication mechanism if a service trusts the Kerberos server from which the ticket was issued. If the standard user password method is used, Kerberos encrypts user passwords into the tickets, ensuring that passwords are not sent on the network in clear text. When you use Kerberos, passwords are not stored on any machine, except for the Kerberos server, for more than a few seconds. Kerberos also guards against intruders who might pick up the encrypted tickets from the network.

Table 30-1 defines the terms used in Kerberos.

Table 30-1 Kerberos Terminology 

Term	Definition
Kerberos Credential	General term referring to authentication tickets, such as ticket granting tickets (TGTs) and service credentials. Kerberos credentials verify the ticket of a user or service. If a network service decides to trust the Kerberos server that issued the ticket, it can be used in place of retyping in a username and password. Credentials have a default life span of eight hours.
Kerberos Principal	Also known as a Kerberos identity. The Kerberos principal is who you are or what a service is according to the Kerberos server.
Kerberos Realm	A domain consisting of users, hosts, and network services that are registered to a Kerberos server. The Kerberos server is trusted to verify the identity of a user or network service to another user or network service. Kerberos realms must always be in uppercase characters.
Kerberos Server	A daemon running on a network host. Users and network services register their identity with the Kerberos server. Network services query the Kerberos server to authenticate to other network services.
Key Distribution Center (KDC)	A Kerberos server and database program running on a network host that allocates the Kerberos Credentials to different users or network services.
Ticket Granting Ticket (TGT)	A credential that the KDC issues to authenticated users. When users receive a TGT, they can authenticate to network services within the Kerberos realm represented by the KDC.
Service Credential	A credential for a network service. When issued from the KDC, this credential is encrypted with the password shared by the network service and the KDC and with the user's TGT.
SRVTAB	A password that a network service shares with the KDC. The network service authenticates an encrypted service credential by using the SRVTAB (also known as a KEYTAB) to decrypt it.
Kerberized	Applications and services that have been modified to support the Kerberos credential infrastructure.

In the Catalyst 5000 family switches, Telnet clients and servers through both the console and in-band management port can be Kerberized.

---

Note Kerberos authentication does not work if TACACS+ is used as the authentication mechanism.

---

---

Note If you are logged in to the console through a modem or a terminal server, a Kerberized login procedure cannot be used.

---

Using Kerberized Login Procedure

You can use a Kerberized Telnet session if you are logging in through the in-band management port. After the Telnet client and services have been Kerberized, the following process takes place when a user attempts to Telnet to the switch:

1. The Telnet client asks the user for the username and issues a request for a TGT to the KDC on the Kerberos server.

2. The KDC creates the TGT, which contains the user's identity, the KDC's identity, and the TGT's expiration time. The KDC then encrypts the TGT with the user's password and sends the TGT to the client.

3. When the Telnet client receives the encrypted TGT, it prompts the user for the password. If the Telnet client can decrypt the TGT with the entered password, the user is successfully authenticated to the KDC. The client then builds a service credential request and sends this to the KDC. This request contains the user's identity and a message saying that it wants to Telnet to the switch. This request is encrypted using the TGT.

4. When the KDC successfully decrypts the service credential request with the TGT that it issued to the client, it builds a service to the switch. The service credential has the client's identity and the identity of the desired Telnet server. The KDC then encrypts the credential with the password that it shares with the switch's Telnet server and encrypts the resulting packet with the Telnet client's TGT and sends this packet to the client.

5. The Telnet client decrypts the packet first with its TGT. If encryption is successful, the client then sends the resulting packet to the switch's Telnet server. At this point, the packet is still encrypted with the password that the switch's Telnet server and the KDC share.

6. If the Telnet client has been instructed to do so, it forwards the TGT to the switch. This ensures that the user does not need to get another TGT in order to use another network service from the switch.

Figure 30-1 illustrates the Kerberos Telnet connection process.

Figure 30-1 Kerberized Telnet Connection

Using a Non-Kerberized Login Procedure

If a non-Kerberized login procedure is used to log in to the switch, the switch takes care of authentication to the KDC on behalf of the login client. However, the user password is now transferred in clear text from the login client to the switch.

---

Note A non-Kerberized login can be performed through a modem or terminal server through the in-band management port. Telnet does not support non-Kerberized login.

---

If a non-Kerberized login is launched, the following process takes place:

1. The switch prompts you for a username and password.

2. The switch requests a TGT from the KDC so that you can be authenticated to the switch.

3. The KDC sends an encrypted TGT to the switch, which contains your identity, KDC's identity, and TGT's expiration time.

4. The switch tries to decrypt the TGT with the password that you entered. If the decryption is successful, you are authenticated to the switch.

5. If you want to access other network services, the KDC must be contacted directly for authentication. To obtain the TGT, you can run the program "kinit," the client software provided with the Kerberos package.

Figure 30-2 illustrates the non-Kerberized login process.

Figure 30-2 Non-Kerberized Telnet Connection

Configuring Authentication

These sections describe how to configure the different authentication methods:

•Authentication Default Configuration

•Authentication Configuration Guidelines

•Configuring Local Authentication

•Configuring TACACS+ Authentication

•Configuring RADIUS Authentication

•Configuring Kerberos Authentication

Authentication Default Configuration

Table 30-2 shows the default authentication configuration.

Table 30-2 Authentication Default Configuration 

Feature	Default Value
Local login authentication (console and Telnet)	Enabled
Local enable authentication (console and Telnet)	Enabled
Kerberos login authentication (console and Telnet)	Disabled
Kerberos enable authentication (console and Telnet)	Disabled
Kerberos server IP address	None specified
Kerberos DES key	None specified
Kerberos server auth-port	Port 750
Kerberos local-realm name	NULL string
Kerberos credentials forwarding	Disabled
Kerberos clients mandatory	Not mandatory
Kerberos preauthentication	Disabled
RADIUS login authentication (console and Telnet)	Disabled
RADIUS enable authentication (console and Telnet)	Disabled
RADIUS server IP address	None specified
RADIUS server UDP auth-port	Port 1812
RADIUS key	None specified
RADIUS server timeout	5 seconds
RADIUS server deadtime	0 (servers not marked dead)
RADIUS retransmit attempts	2 times
TACACS+ login authentication (console and Telnet)	Disabled
TACACS+ enable authentication (console and Telnet)	Disabled
TACACS+ key	None specified
TACACS+ login attempts	3
TACACS+ server timeout	5 seconds
TACACS+ directed request	Disabled

Authentication Configuration Guidelines

These guidelines apply when configuring authentication on the switch:

•Authentication configuration applies both to console and Telnet connection attempts unless you use the console and telnet keywords to specify the authentication methods to use for each connection type individually.

•If you configure a RADIUS or TACACS+ key on the switch, make sure you configure an identical key on the RADIUS or TACACS+ server.

•You must specify a RADIUS or TACACS+ server before enabling RADIUS or TACACS+ on the switch.

•If you configure multiple RADIUS or TACACS+ servers, the first server configured is the primary and authentication requests are sent to this server first. You can specify a particular server as primary by using the primary keyword.

•RADIUS and TACACS+ supports one privileged mode only (level 1).

•Kerberos authentication does not work if TACACS+ is also used as an authentication mechanism.

Configuring Local Authentication

These sections describe how to configure local authentication on the switch:

•Enabling Local Authentication

•Setting the Login Password

•Setting the Enable Password

•Disabling Local Authentication

•Recovering a Lost Password

Enabling Local Authentication

---

Note Local login and enable authentication are enabled for both console and Telnet connections by default. You do not need to perform this task unless you want to modify the default configuration or you have disabled local authentication.

---

To enable local authentication on the switch, perform this task in privileged mode:

	Task	Command
Step 1	Enable local login authentication. Use the console or telnet keywords to enable local authentication only for console or Telnet connection attempts.	set authentication login local enable [all | console | http | telnet]
Step 2	Enable local enable authentication. Use the console or telnet keywords to enable local authentication only for console or Telnet connection attempts.	set authentication enable local enable [all | console | http | telnet]
Step 3	Verify the local authentication configuration.	show authentication

This example shows how to enable local login and enable authentication for both console and Telnet connections and how to verify the configuration:

Console> (enable) set authentication login local enable

local login authentication set to enable for console and telnet session.

Console> (enable) set authentication enable local enable

local enable authentication set to enable for console and telnet session.

Console> (enable) show authentication

Login Authentication:  Console Session   Telnet Session

---------------------  ----------------  ----------------

tacacs                 disabled          disabled

radius                 disabled          disabled

kerberos                 disabled          disabled

local                  enabled(primary)  enabled(primary)

Enable Authentication: Console Session   Telnet Session

---------------------- ----------------- ----------------

tacacs                 disabled          disabled

radius                 disabled          disabled

kerberos                 disabled          disabled

local                  enabled(primary)  enabled(primary)

Console> (enable)

Setting the Login Password

The login password controls access to the user mode CLI. Passwords are case sensitive, can contain up to 30 characters, and use any printable character, including a space.

---

Note Passwords set in releases prior to software release 5.4 remain non-case sensitive. You must reset the password after installing release 5.4 to activate case sensitivity.

---

To set the login password for local authentication, perform this task in privileged mode:

Task	Command
Set the login password for access. Enter your old password (press Return on a switch with no password configured), enter your new password, and reenter your new password.	set password

This example shows how to set the login password on the switch:

Console> (enable) set password

Enter old password:old_password

Enter new password:new_password

Retype new password:new_password

Password changed.

Console> (enable)

Setting the Enable Password

The enable password controls access to the privileged mode CLI. Passwords are case sensitive, can contain up to 30 characters, and can use any printable character, including a space.

---

Note Passwords set in releases prior to software release 5.4 remain non-case sensitive. You must reset the password after installing Version 5.4 to activate case sensitivity.

---

To set the enable password for local authentication, perform this task in privileged mode:

Task	Command
Set the password for privileged mode. Enter your old password (press Return on a switch with no password configured), enter your new password, and reenter your new password.	set enablepass

This example shows how to set the enable password on the switch:

Console> (enable) set enablepass

Enter old password:<old_password>

Enter new password:<new_password>

Retype new password:<new_password>

Password changed.

Console> (enable)

Disabling Local Authentication

---

Caution Make sure that RADIUS or TACACS+ authentication is configured and operating correctly before disabling local login or enable authentication. If you disable local authentication and RADIUS or TACACS+ is not configured correctly, or if the RADIUS or TACACS+ server is not online, you may be unable to log in to the switch.

---

To disable local authentication on the switch, perform this task in privileged mode:

	Task	Command
Step 1	Disable local login authentication. Use the console or telnet keywords to disable local authentication only for console or Telnet connection attempts.	set authentication login local disable [all | console | http | telnet]
Step 2	Disable local enable authentication. Use the console or telnet keywords to disable local authentication only for console or Telnet connection attempts.	set authentication enable local disable [all | console | http | telnet]
Step 3	Verify the local authentication configuration.	show authentication

This example shows how to disable local login and enable authentication for both console and Telnet connections, and how to verify the configuration (you must have RADIUS or TACACS+ authentication enabled before you disable local authentication):

Console> (enable) set authentication login local disable

local login authentication set to disable for console and telnet session.

Console> (enable) set authentication enable local disable

local enable authentication set to disable for console and telnet session.

Console> (enable) show authentication

Login Authentication:  Console Session   Telnet Session

---------------------  ----------------  ----------------

tacacs                 disabled          disabled        

radius                 enabled(primary)  enabled(primary)

kerberos                 disabled          disabled

local                  disabled          disabled        

Enable Authentication: Console Session   Telnet Session

---------------------- ----------------- ----------------

tacacs                 disabled          disabled        

radius                 enabled(primary)  enabled(primary)

kerberos                 disabled          disabled

local                  disabled          disabled        

Console> (enable) 

Recovering a Lost Password

To recover a lost local authentication password, perform this procedure. You must complete Steps
3 through 7 within 30 seconds of a power cycle or the recovery will fail. If you lost both the login and enable passwords, repeat the process for each password.

---

Step 1 Connect to the switch through the supervisor engine console port (you cannot recover the password if you are connected through a Telnet connection).

Step 2 Enter the reset system command to reboot the switch.

Step 3 At the "Enter Password" prompt, press Return (the login password is null for 30 seconds when you are connected to the console port).

Step 4 Enter privileged mode using the enable command.

Step 5 At the "Enter Password" prompt, press Return (the enable password is null for 30 seconds when you are connected to the console port).

Step 6 Enter the set password or set enablepass command, as appropriate.

Step 7 When prompted for your old password, press Return.

Step 8 Enter and confirm your new password.

---

Configuring TACACS+ Authentication

These sections describe how to configure TACACS+ authentication on the switch.

•Specifying TACACS+ Servers

•Enabling TACACS+ Authentication

•Specifying the TACACS+ Key

•Setting the TACACS+ Timeout Interval

•Setting the TACACS+ Login Attempts

•Enabling TACACS+ Directed Request

•Disabling TACACS+ Directed Request

•Clearing TACACS+ Servers

•Clearing the TACACS+ Key

•Disabling TACACS+ Authentication

Specifying TACACS+ Servers

Specify one or more TACACS+ servers before you enable TACACS+ authentication on the switch. The first server you specify is the primary server, unless you explicitly make one server the primary server by using the primary keyword.

To specify one or more TACACS+ servers, perform this task in privileged mode:

	Task	Command
Step 1	Specify the IP address of one or more TACACS+ servers.	set tacacs server ip_addr [primary]
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to specify TACACS+ servers and verify the configuration:

Console> (enable) set tacacs server 172.20.52.3

172.20.52.3 added to TACACS server table as primary server.

Console> (enable) set tacacs server 172.20.52.2 primary

172.20.52.2 added to TACACS server table as primary server.

Console> (enable) set tacacs server 172.20.52.10

172.20.52.10 added to TACACS server table as backup server.

Console> (enable) show tacacs

Login Authentication:  Console Session   Telnet Session

---------------------  ----------------  ----------------

tacacs                 disabled          disabled        

radius                 disabled          disabled        

local                  enabled(primary)  enabled(primary)

Enable Authentication: Console Session   Telnet Session

---------------------- ----------------- ----------------

tacacs                 disabled          disabled        

radius                 disabled          disabled        

local                  enabled(primary)  enabled(primary)

Tacacs key: 

Tacacs login attempts: 3

Tacacs timeout: 5 seconds

Tacacs direct request: disabled

Tacacs-Server                              Status

----------------------------------------   -------

172.20.52.3                                

172.20.52.2                                primary

172.20.52.10                               

Console> (enable)

Enabling TACACS+ Authentication

---

Note Specify at least one TACACS+ server before enabling TACACS+ authentication on the switch. For information on specifying a TACACS+ server, see the "Specifying TACACS+ Servers" section.

---

You can enable TACACS+ authentication for login and enable access to the switch. If desired, you can use the console and telnet keywords to specify that TACACS+ authentication be used only on console or Telnet connections. If you are using both RADIUS and TACACS+, you can use the primary keyword to force the switch to try TACACS+ authentication first.

To enable TACACS+ authentication, perform this task in privileged mode:

	Task	Command
Step 1	Enable TACACS+ authentication for normal login mode. Use the console or telnet keywords if you want to enable TACACS+ only for console port or Telnet connection attempts.	set authentication login tacacs enable [all | console | http | telnet] [primary]
Step 2	Enable TACACS+ authentication for enable mode. Use the console or telnet keywords if you want to enable TACACS+ only for console port or Telnet connection attempts.	set authentication enable tacacs enable [all | console | http | telnet] [primary]
Step 3	Verify the TACACS+ configuration.	show authentication

This example shows how to enable TACACS+ authentication for console and Telnet connections and how to verify the configuration:

Console> (enable) set authentication login tacacs enable

tacacs login authentication set to enable for console and telnet session.

Console> (enable) set authentication enable tacacs enable

tacacs enable authentication set to enable for console and telnet session.

Console> (enable) show authentication

Login Authentication:  Console Session   Telnet Session

---------------------  ----------------  ----------------

tacacs                 enabled(primary)  enabled(primary)

radius                 disabled          disabled        

local                  enabled           enabled 

Enable Authentication: Console Session   Telnet Session

---------------------- ----------------- ----------------

tacacs                 enabled(primary)  enabled(primary)

radius                 disabled          disabled        

local                  enabled           enabled         

Console> (enable)

Specifying the TACACS+ Key

---

Note If you configure a TACACS+ key on the client, make sure you configure an identical key on the TACACS+ server.

---

To specify the TACACS+ key, perform this task in privileged mode:

	Task	Command
Step 1	Configure the key used to encrypt packets.	set tacacs key key
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to specify the TACACS+ key and verify the configuration:

Console> (enable) set tacacs key Secret_TACACS_key

The tacacs key has been set to Secret_TACACS_key.

Console> (enable) show tacacs

Tacacs key: Secret_TACACS_key

Tacacs login attempts: 3

Tacacs timeout: 5 seconds

Tacacs direct request: disabled

Tacacs-Server                              Status

----------------------------------------   -------

172.20.52.3                                

172.20.52.2                                primary

172.20.52.10                               

Console> (enable)

Setting the TACACS+ Timeout Interval

You can specify the timeout interval between retransmissions to the TACACS+ server. The default timeout is 5 seconds.

To specify the TACACS+ timeout interval, perform this task in privileged mode:

	Task	Command
Step 1	Configure the TACACS+ timeout interval.	set tacacs timeout seconds
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to set the server timeout interval and verify the configuration:

Console> (enable) set tacacs timeout 30 

Tacacs timeout set to 30 seconds.

Console> (enable) show tacacs

Tacacs key: Secret_TACACS_key

Tacacs login attempts: 3

Tacacs timeout: 30 seconds

Tacacs direct request: disabled

Tacacs-Server                              Status

----------------------------------------   -------

172.20.52.3                                

172.20.52.2                                primary

172.20.52.10                               

Console> (enable) 

Setting the TACACS+ Login Attempts

You can specify the number of failed login attempts allowed.

To specify the number of login attempts allowed, perform this task in privileged mode:

	Task	Command
Step 1	Configure the number of allowed login attempts.	set tacacs attempts number
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to set the number of login attempts and verify the configuration:

Console> (enable) set tacacs attempts 5

Tacacs number of attempts set to 5.

Console> (enable) show tacacs

Tacacs key: Secret_TACACS_key

Tacacs login attempts: 5

Tacacs timeout: 30 seconds

Tacacs direct request: disabled

Tacacs-Server                              Status

----------------------------------------   -------

172.20.52.3                                

172.20.52.2                                primary

172.20.52.10                               

Console> (enable) 

Enabling TACACS+ Directed Request

When TACACS+ directed request is enabled, users must specify the host name of a configured TACACS+ server (in the form username@server_hostname) or the authentication request will fail.

To enable TACACS+ directed request, perform this task in privileged mode:

	Task	Command
Step 1	Enable TACACS+ directed request on the switch.	set tacacs directedrequest enable
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to enable TACACS+ directed request and verify the configuration:

Console> (enable) set tacacs directedrequest enable

Tacacs direct request has been enabled.

Console> (enable) show tacacs

Tacacs key: Secret_TACACS_key

Tacacs login attempts: 5

Tacacs timeout: 30 seconds

Tacacs direct request: enabled

Tacacs-Server                              Status

----------------------------------------   -------

172.20.52.3                                

172.20.52.2                                primary

172.20.52.10                               

Console> (enable) 

Disabling TACACS+ Directed Request

To disable TACACS+ directed request, perform this task in privileged mode:

	Task	Command
Step 1	Disable TACACS+ directed request on the switch.	set tacacs directedrequest disable
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to disable TACACS+ directed request:

Console> (enable) set tacacs directedrequest disable 

Tacacs direct request has been disabled.

Console> (enable) 

Clearing TACACS+ Servers

To clear one or more TACACS+ servers, perform this task in privileged mode:

	Task	Command
Step 1	Specify the IP address of the TACACS+ server to clear from the configuration. Use the all keyword to clear all of the servers from the configuration.	clear tacacs server [ip_addr | all]
Step 2	Verify the TACACS+ server configuration.	show tacacs

This example shows how to clear a specific TACACS+ server from the configuration:

Console> (enable) clear tacacs server 172.20.52.3

172.20.52.3 cleared from TACACS table

Console> (enable)

This example shows how to clear all TACACS+ servers from the configuration:

Console> (enable) clear tacacs server all

All TACACS servers cleared

Console> (enable)

Clearing the TACACS+ Key

To clear the TACACS+ key, perform this task in privileged mode:

	Task	Command
Step 1	Clear the TACACS+ key.	clear tacacs key
Step 2	Verify the TACACS+ configuration.	show tacacs

This example shows how to clear the TACACS+ key:

Console> (enable) clear tacacs key

TACACS server key cleared.

Console> (enable) 

Disabling TACACS+ Authentication

If you disable TACACS+ authentication with both RADIUS and local authentication disabled, local authentication is reenabled automatically.

To disable TACACS+ authentication, perform this task in privileged mode:

	Task	Command
Step 1	Disable TACACS+ authentication for normal login mode. Use the console or telnet keywords if you want to disable TACACS+ only for console port or Telnet connection attempts.	set authentication login tacacs disable [all | console | http | telnet]
Step 2	Disable TACACS+ authentication for enable mode. Use the console or telnet keywords if you want to disable TACACS+ only for console port or Telnet connection attempts.	set authentication enable tacacs disable [all | console | http | telnet]
Step 3	Verify the TACACS+ configuration.	show authentication

This example shows how to disable TACACS+ authentication for console and Telnet connections and how to verify the configuration:

Console> (enable) set authentication login tacacs disable

tacacs login authentication set to disable for console and telnet session.

Console> (enable) set authentication enable tacacs disable

tacacs enable authentication set to disable for console and telnet session.

Console> (enable) show authentication

Login Authentication:  Console Session   Telnet Session

---------------------  ----------------  ----------------

tacacs                 disabled          disabled        

radius                 disabled          disabled        

local                  enabled(primary)  enabled(primary)

Enable Authentication: Console Session   Telnet Session

---------------------- ----------------- ----------------

tacacs                 disabled          disabled        

radius                 disabled          disabled        

local                  enabled(primary)  enabled(primary)

Console> (enable) 

Configuring RADIUS Authentication

These sections describe how to configure RADIUS authentication on the switch.

•Specifying RADIUS Servers

•Enabling RADIUS Authentication

•Specifying the RADIUS Key

•Setting the RADIUS Timeout Interval

•Setting the RADIUS Retransmit Count

•Setting the RADIUS Deadtime

•Clearing RADIUS Servers

•Clearing the RADIUS Key

•Disabling RADIUS Authentication

Specifying RADIUS Servers

To specify one or more RADIUS servers, perform this task in privileged mode:

	Task	Command
Step 1	Specify the IP address of up to three RADIUS servers. Specify the primary server using the primary keyword. Optionally, specify the destination UDP port to use on the server.	set radius server ip_addr [auth-port port_number] [primary]
Step 2	Verify the RADIUS server configuration.	show radius

This example shows how to specify a RADIUS server and verify the configuration:

Console> (enable) set radius server 172.20.52.3

172.20.52.3 with auth-port 1812 added to radius server table as primary server.

Console> (enable) show radius

Login Authentication:  Console Session   Telnet Session

---------------------  ----------------  ----------------