Configuring Switch-Based Authentication

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Preventing Unauthorized Access

You can prevent unauthorized users from reconfiguring your switch and viewing configuration information. Typically, you want network administrators to have access to your switch while you restrict access to users who dial from outside the network through an asynchronous port, connect from outside the network through a serial port, or connect through a terminal or workstation from within the local network.

To prevent unauthorized access into your switch, you should configure one or more of these security features:

  • At a minimum, you should configure passwords and privileges at each switch port. These passwords are locally stored on the switch. When users attempt to access the switch through a port or line, they must enter the password specified for the port or line before they can access the switch.

  • For an additional layer of security, you can also configure username and password pairs, which are locally stored on the switch. These pairs are assigned to lines or ports and authenticate each user before that user can access the switch. If you have defined privilege levels, you can also assign a specific privilege level (with associated rights and privileges) to each username and password pair.

  • If you want to use username and password pairs, but you want to store them centrally on a server instead of locally, you can store them in a database on a security server. Multiple networking devices can then use the same database to obtain user authentication (and, if necessary, authorization) information.

  • You can also enable the login enhancements feature, which logs both failed and unsuccessful login attempts. Login enhancements can also be configured to block future login attempts after a set number of unsuccessful attempts are made. For more information, see the Cisco IOS Login Enhancements documentation.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Restrictions for Controlling Switch Access with Passwords and Privileges

The following are the restrictions for controlling switch access with passwords and privileges:

  • Disabling password recovery will not work if you have set the switch to boot up manually by using the boot manual global configuration command. This command produces the boot loader prompt (switch:) after the switch is power cycled.

Information About Passwords and Privilege Levels

Default Password and Privilege Level Configuration

A simple way of providing terminal access control in your network is to use passwords and assign privilege levels. Password protection restricts access to a network or network device. Privilege levels define what commands users can enter after they have logged into a network device.

This table shows the default password and privilege level configuration.

Table 1. Default Password and Privilege Levels

Feature

Default Setting

Enable password and privilege level

No password is defined. The default is level 15 (privileged EXEC level). The password is not encrypted in the configuration file.

Enable secret password and privilege level

No password is defined. The default is level 15 (privileged EXEC level). The password is encrypted before it is written to the configuration file.

Line password

No password is defined.

Additional Password Security

To provide an additional layer of security, particularly for passwords that cross the network or that are stored on a Trivial File Transfer Protocol (TFTP) server, you can use either the enable password or enable secret global configuration commands. Both commands accomplish the same thing; that is, you can establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify.

We recommend that you use the enable secret command because it uses an improved encryption algorithm.

If you configure the enable secret command, it takes precedence over the enable password command; the two commands cannot be in effect simultaneously.

If you enable password encryption, it applies to all passwords including username passwords, authentication key passwords, the privileged command password, and console and virtual terminal line passwords.

Password Recovery

By default, any end user with physical access to the switch can recover from a lost password by interrupting the boot process while the switch is powering on and then by entering a new password.

The password-recovery disable feature protects access to the switch password by disabling part of this functionality. When this feature is enabled, the end user can interrupt the boot process only by agreeing to set the system back to the default configuration. With password recovery disabled, you can still interrupt the boot process and change the password, but the configuration file (config.text) and the VLAN database file (vlan.dat) are deleted.

If you disable password recovery, we recommend that you keep a backup copy of the configuration file on a secure server in case the end user interrupts the boot process and sets the system back to default values. Do not keep a backup copy of the configuration file on the switch. If the switch is operating in VTP transparent mode, we recommend that you also keep a backup copy of the VLAN database file on a secure server. When the switch is returned to the default system configuration, you can download the saved files to the switch by using the Xmodem protocol.

To re-enable password recovery, use the service password-recovery global configuration command.

Terminal Line Telnet Configuration

When you power-up your switch for the first time, an automatic setup program runs to assign IP information and to create a default configuration for continued use. The setup program also prompts you to configure your switch for Telnet access through a password. If you did not configure this password during the setup program, you can configure it when you set a Telnet password for a terminal line.

Username and Password Pairs

You can configure username and password pairs, which are locally stored on the switch. These pairs are assigned to lines or ports and authenticate each user before that user can access the switch. If you have defined privilege levels, you can also assign a specific privilege level (with associated rights and privileges) to each username and password pair.

Privilege Levels

Cisco switches (and other devices) use privilege levels to provide password security for different levels of switch operation. By default, the Cisco IOS software operates in two modes (privilege levels) of password security: user EXEC (Level 1) and privileged EXEC (Level 15). You can configure up to 16 hierarchical levels of commands for each mode. By configuring multiple passwords, you can allow different sets of users to have access to specified commands.

Privilege Levels on Lines

Users can override the privilege level you set using the privilege level line configuration command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level. You might specify a high level or privilege level for your console line to restrict line usage.

For example, if you want many users to have access to the clear line command, you can assign it level 2 security and distribute the level 2 password fairly widely. But if you want more restricted access to the configure command, you can assign it level 3 security and distribute that password to a more restricted group of users.

Command Privilege Levels

When you set a command to a privilege level, all commands whose syntax is a subset of that command are also set to that level. For example, if you set the show ip traffic command to level 15, the show commands and show ip commands are automatically set to privilege level 15 unless you set them individually to different levels.

How to Control Switch Access with Passwords and Privilege Levels

Setting or Changing a Static Enable Password

The enable password controls access to the privileged EXEC mode. Follow these steps to set or change a static enable password:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. enable password password
  4. end
  5. show running-config
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

enable password password

Example:


Switch(config)# enable password secret321

Defines a new password or changes an existing password for access to privileged EXEC mode.

By default, no password is defined.

For password , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. It can contain the question mark (?) character if you precede the question mark with the key combination Crtl-v when you create the password; for example, to create the password abc?123, do this:

  1. Enter abc.

  2. Enter Crtl-v.

  3. Enter ?123.

When the system prompts you to enter the enable password, you need not precede the question mark with the Ctrl-v; you can simply enter abc?123 at the password prompt.

Step 4

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 5

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Protecting Enable and Enable Secret Passwords with Encryption

Follow these steps to establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. Use one of the following:
    • enable password [level level] {password | encryption-type encrypted-password}
    • enable secret [level level] {password | encryption-type encrypted-password}
  4. service password-encryption
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

Use one of the following:

  • enable password [level level] {password | encryption-type encrypted-password}
  • enable secret [level level] {password | encryption-type encrypted-password}

Example:

Switch(config)# enable password example102

or 

Switch(config)# enable secret level 1 password secret123sample

  • Defines a new password or changes an existing password for access to privileged EXEC mode.

  • Defines a secret password, which is saved using a nonreversible encryption method.

    • (Optional) For level , the range is from 0 to 15. Level 1 is normal user EXEC mode privileges. The default level is 15 (privileged EXEC mode privileges).

    • For password , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

    • (Optional) For encryption-type , only type 5, a Cisco proprietary encryption algorithm, is available. If you specify an encryption type, you must provide an encrypted password—an encrypted password that you copy from another switch configuration.

    Note 

    If you specify an encryption type and then enter a clear text password, you can not re-enter privileged EXEC mode. You cannot recover a lost encrypted password by any method.

Step 4

service password-encryption

Example:


Switch(config)# service password-encryption

(Optional) Encrypts the password when the password is defined or when the configuration is written.

Encryption prevents the password from being readable in the configuration file.

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Disabling Password Recovery

Follow these steps to disable password recovery to protect the security of your switch:

Before you begin

If you disable password recovery, we recommend that you keep a backup copy of the configuration file on a secure server in case the end user interrupts the boot process and sets the system back to default values. Do not keep a backup copy of the configuration file on the switch. If the switch is operating in VTP transparent mode, we recommend that you also keep a backup copy of the VLAN database file on a secure server. When the switch is returned to the default system configuration, you can download the saved files to the switch by using the Xmodem protocol.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. system disable password recovery switch {all | <1-9> }
  4. end

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

system disable password recovery switch {all | <1-9> }

Example:


Switch(config)# system disable password recovery switch all

Disables password recovery.

  • all - Sets the configuration on switches in stack.
  • <1-9> - Sets the configuration on the Switch Number selected.

This setting is saved in an area of the flash memory that is accessible by the boot loader and the Cisco IOS image, but it is not part of the file system and is not accessible by any user.

Step 4

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

What to do next

To remove disable password recovery , use the no system disable password recovery switch all global configuration command.

Setting a Telnet Password for a Terminal Line

Beginning in user EXEC mode, follow these steps to set a Telnet password for the connected terminal line:

Before you begin

  • Attach a PC or workstation with emulation software to the switch console port, or attach a PC to the Ethernet management port.

  • The default data characteristics of the console port are 9600, 8, 1, no parity. You might need to press the Return key several times to see the command-line prompt.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. line vty 0 15
  4. password password
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable
Note 

If a password is required for access to privileged EXEC mode, you will be prompted for it.

Enters privileged EXEC mode.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

line vty 0 15

Example:


Switch(config)# line vty 0 15

Configures the number of Telnet sessions (lines), and enters line configuration mode.

There are 16 possible sessions on a command-capable Switch. The 0 and 15 mean that you are configuring all 16 possible Telnet sessions.

Step 4

password password

Example:


Switch(config-line)# password abcxyz543

Sets a Telnet password for the line or lines.

For password , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

Step 5

end

Example:


Switch(config-line)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring Username and Password Pairs

Follow these steps to configure username and password pairs:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. username name [privilege level] {password encryption-type password}
  4. Use one of the following:
    • line console 0
    • line vty 0 15
  5. login local
  6. end
  7. show running-config
  8. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

username name [privilege level] {password encryption-type password}

Example:


Switch(config)# username adamsample privilege 1 password secret456


Switch(config)# username 111111111111 mac attribute

Sets the username, privilege level, and password for each user.

  • For name , specify the user ID as one word or the MAC address. Spaces and quotation marks are not allowed.

  • You can configure a maximum of 12000 clients each, for both username and MAC filter.

  • (Optional) For level , specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 1 gives user EXEC mode access.

  • For encryption-type , enter 0 to specify that an unencrypted password will follow. Enter 7 to specify that a hidden password will follow.

  • For password , specify the password the user must enter to gain access to the Switch. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.

Step 4

Use one of the following:

  • line console 0
  • line vty 0 15

Example:

Switch(config)# line console 0

or 

Switch(config)# line vty 15

Enters line configuration mode, and configures the console port (line 0) or the VTY lines (line 0 to 15).

Step 5

login local

Example:


Switch(config-line)# login local

Enables local password checking at login time. Authentication is based on the username specified in Step 3.

Step 6

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 7

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 8

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Setting the Privilege Level for a Command

Follow these steps to set the privilege level for a command:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. privilege mode level level command
  4. enable password level level password
  5. end
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

privilege mode level level command

Example:


Switch(config)# privilege exec level 14 configure

Sets the privilege level for a command.

  • For mode , enter configure for global configuration mode, exec for EXEC mode, interface for interface configuration mode, or line for line configuration mode.

  • For level , the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password.

  • For command , specify the command to which you want to restrict access.

Step 4

enable password level level password

Example:


Switch(config)# enable password level 14 SecretPswd14

Specifies the password to enable the privilege level.

  • For level , the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges.

  • For password , specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Changing the Default Privilege Level for Lines

Follow these steps to change the default privilege level for the specified line:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. line vty line
  4. privilege level level
  5. end
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

line vty line

Example:


Switch(config)# line vty 10

Selects the virtual terminal line on which to restrict access.

Step 4

privilege level level

Example:


Switch(config)# privilege level 15

Changes the default privilege level for the line.

For level , the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password.

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

What to do next

Users can override the privilege level you set using the privilege level line configuration command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level. You might specify a high level or privilege level for your console line to restrict line usage.

Logging into and Exiting a Privilege Level

Beginning in user EXEC mode, follow these steps to log into a specified privilege level and exit a specified privilege level.

SUMMARY STEPS

  1. enable level
  2. disable level

DETAILED STEPS

  Command or Action Purpose
Step 1

enable level

Example:


Switch> enable 15

Logs in to a specified privilege level.

Following the example, Level 15 is privileged EXEC mode.

For level , the range is 0 to 15.

Step 2

disable level

Example:


Switch# disable 1

Exits to a specified privilege level.

Following the example, Level 1 is user EXEC mode.

For level , the range is 0 to 15.

Monitoring Switch Access

Table 2. Commands for Displaying DHCP Information

show privilege

Displays the privilege level configuration.

Configuration Examples for Setting Passwords and Privilege Levels

Example: Setting or Changing a Static Enable Password

This example shows how to change the enable password to l1u2c3k4y5. The password is not encrypted and provides access to level 15 (traditional privileged EXEC mode access): 


Switch(config)# enable password l1u2c3k4y5

Example: Setting the Privilege Level for a Command

This example shows how to set the configure command to privilege level 14 and define SecretPswd14 as the password users must enter to use level 14 commands: 


Switch(config)# privilege exec level 14 configure
Switch(config)# enable password level 14 SecretPswd14

Additional References

Error Message Decoder

Description Link

To help you research and resolve system error messages in this release, use the Error Message Decoder tool.

https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

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/support

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Controlling Switch Access with Terminal Access Controller Access Control System Plus (TACACS+)

The following are the prerequisites for set up and configuration of switch access with Terminal Access Controller Access Control System Plus (TACACS+) (must be performed in the order presented):

  1. Configure the switches with the TACACS+ server addresses.

  2. Set an authentication key.

  3. Configure the key from Step 2 on the TACACS+ servers.

  4. Enable AAA.

  5. Create a login authentication method list.

  6. Apply the list to the terminal lines.

  7. Create an authorization and accounting method list.

The following are the prerequisites for controlling switch access with TACACS+:

  • You must have access to a configured TACACS+ server to configure TACACS+ features on your switch. Also, you must have access to TACACS+ services maintained in a database on a TACACS+ daemon typically running on a LINUX or Windows workstation.

  • You need a system running the TACACS+ daemon software to use TACACS+ on your switch.

  • To use TACACS+, it must be enabled.

  • Authorization must be enabled on the switch to be used.

  • Users must first successfully complete TACACS+ authentication before proceeding to TACACS+ authorization.

  • To use any of the AAA commands listed in this section or elsewhere, you must first enable AAA with the aaa new-model command.

  • At a minimum, you must identify the host or hosts maintaining the TACACS+ daemon and define the method lists for TACACS+ authentication. You can optionally define method lists for TACACS+ authorization and accounting.

  • 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 (which, by coincidence, is named default ). The default method list is automatically applied to all ports except those that have a named method list explicitly defined. A defined method list overrides the default method list.

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

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

Information About TACACS+

TACACS+ and Switch Access

This section describes TACACS+. TACACS+ provides detailed accounting information and flexible administrative control over the authentication and authorization processes. It is facilitated through authentication, authorization, accounting (AAA) and can be enabled only through AAA commands.

TACACS+ Overview

TACACS+ is a security application that provides centralized validation of users attempting to gain access to your switch.

TACACS+ services are maintained in a database on a TACACS+ daemon typically running on a LINUX or Windows workstation. You should have access to and should configure a TACACS+ server before you configure TACACS+ features on your switch.

TACACS+ provides for separate and modular authentication, authorization, and accounting facilities. TACACS+ allows for a single access control server (the TACACS+ daemon) to provide each service—authentication, authorization, and accounting—independently. Each service can be tied into its own database to take advantage of other services available on that server or on the network, depending on the capabilities of the daemon.

The goal of TACACS+ is to provide a method for managing multiple network access points from a single management service. Your switch can be a network access server along with other Cisco routers and access servers.

Figure 1. Typical TACACS+ Network Configuration
Typical TACACS+ Network Configuration

TACACS+, administered through the AAA security services, can provide these services:

  • Authentication—Provides complete control of authentication through login and password dialog, challenge and response, and messaging support.

    The authentication facility can conduct a dialog with the user (for example, after a username and password are provided, to challenge a user with several questions, such as home address, mother’s maiden name, service type, and social security number). The TACACS+ authentication service can also send messages to user screens. For example, a message could notify users that their passwords must be changed because of the company’s password aging policy.

  • Authorization—Provides fine-grained control over user capabilities for the duration of the user’s session, including but not limited to setting autocommands, access control, session duration, or protocol support. You can also enforce restrictions on what commands a user can execute with the TACACS+ authorization feature.

  • Accounting—Collects and sends information used for billing, auditing, and reporting to the TACACS+ daemon. Network managers can use the accounting facility to track user activity for a security audit or to provide information for user billing. Accounting records include user identities, start and stop times, executed commands (such as PPP), number of packets, and number of bytes.

The TACACS+ protocol provides authentication between the switch and the TACACS+ daemon, and it ensures confidentiality because all protocol exchanges between the switch and the TACACS+ daemon are encrypted.

TACACS+ Operation

When a user attempts a simple ASCII login by authenticating to a switch using TACACS+, this process occurs:

  1. When the connection is established, the switch contacts the TACACS+ daemon to obtain a username prompt to show to the user. The user enters a username, and the switch then contacts the TACACS+ daemon to obtain a password prompt. The switch displays the password prompt to the user, the user enters a password, and the password is then sent to the TACACS+ daemon.

    TACACS+ allows a dialog between the daemon and the user until the daemon receives enough information to authenticate the user. The daemon prompts for a username and password combination, but can include other items, such as the user’s mother’s maiden name.

  2. The switch eventually receives one of these responses from the TACACS+ daemon:

    • ACCEPT—The user is authenticated and service can begin. If the switch is configured to require authorization, authorization begins at this time.

    • REJECT—The user is not authenticated. The user can be denied access or is prompted to retry the login sequence, depending on the TACACS+ daemon.

    • ERROR—An error occurred at some time during authentication with the daemon or in the network connection between the daemon and the switch. If an ERROR response is received, the switch typically tries to use an alternative method for authenticating the user.

    • CONTINUE—The user is prompted for additional authentication information.

    After authentication, the user undergoes an additional authorization phase if authorization has been enabled on the switch. Users must first successfully complete TACACS+ authentication before proceeding to TACACS+ authorization.

  3. If TACACS+ authorization is required, the TACACS+ daemon is again contacted, and it returns an ACCEPT or REJECT authorization response. If an ACCEPT response is returned, the response contains data in the form of attributes that direct the EXEC or NETWORK session for that user and the services that the user can access:

    • Telnet, Secure Shell (SSH), rlogin, or privileged EXEC services

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

TACACS+ Configuration Options

You can configure the switch to use a single server or AAA server groups to group existing server hosts for authentication. You can group servers to 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 and contains the list of IP addresses of the selected server hosts.

TACACS+ Login Authentication

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.

TACACS+ Authorization for Privileged EXEC Access and Network Services

AAA authorization limits the services available to a user. When AAA authorization is enabled, the switch uses information retrieved from the user’s profile, which is located either 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.

TACACS+ Accounting

The AAA accounting feature tracks the services that users are accessing and the amount of network resources that they are consuming. When AAA accounting is enabled, the switch reports user activity to the TACACS+ security server in the form of accounting records. Each accounting record contains accounting attribute-value (AV) pairs and is stored on the security server. This data can then be analyzed for network management, client billing, or auditing.

Default TACACS+ Configuration

TACACS+ and AAA are disabled by default.

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


Note

Although TACACS+ configuration is performed through the CLI, the TACACS+ server authenticates HTTP connections that have been configured with a privilege level of 15.

How to Configure TACACS+

Identifying the TACACS+ Server Host and Setting the Authentication Key

Follow these steps to identify the TACACS+ server host and set the authentication key:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. aaa group server tacacs+ group-name
  5. server ip-address
  6. end
  7. show running-config
  8. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 4

aaa group server tacacs+ group-name

Example:


Switch(config)# aaa group server tacacs+ your_server_group

(Optional) Defines the AAA server-group with a group name.

This command puts the Switch in a server group subconfiguration mode.

Step 5

server ip-address

Example:


Switch(config)# server 10.1.2.3

(Optional) Associates a particular TACACS+ server with the defined server group. Repeat this step for each TACACS+ server in the AAA server group.

Each server in the group must be previously defined in Step 3.

Step 6

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 7

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 8

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring TACACS+ Login Authentication

Follow these steps to configure TACACS+ login authentication:

Before you begin

To configure AAA authentication, you define a named list of authentication methods and then apply that list to various ports.


Note

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

For more information about the ip http authentication command, see the Cisco IOS Security Command Reference, Release 12.4.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. aaa authentication login {default | list-name} method1 [method2...]
  5. line [console | tty | vty] line-number [ending-line-number]
  6. login authentication {default | list-name}
  7. end
  8. show running-config
  9. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 4

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

Example:


Switch(config)# aaa authentication login default tacacs+ 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 tacacs+ —Uses TACACS+ authentication. Before you can use this authentication method, you must configure the TACACS+ 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 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 name password global configuration command.

  • none —Do not use any authentication for login.

Step 5

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

Example:


Switch(config)# line 2 4

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

Step 6

login authentication {default | list-name}

Example:


Switch(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:


Switch(config-line)# end

Returns to privileged EXEC mode.

Step 8

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 9

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services

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


Note

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

Follow these steps to specify TACACS+ authorization for privileged EXEC access and network services:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa authorization network tacacs+
  4. aaa authorization exec tacacs+
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa authorization network tacacs+

Example:


Switch(config)# aaa authorization network tacacs+

Configures the switch for user TACACS+ authorization for all network-related service requests.

Step 4

aaa authorization exec tacacs+

Example:


Switch(config)# aaa authorization exec tacacs+

Configures the switch for user TACACS+ authorization if the user has privileged EXEC access.

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

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Starting TACACS+ Accounting

Follow these steps to start TACACS+ Accounting:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa accounting network start-stop tacacs+
  4. aaa accounting exec start-stop tacacs+
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa accounting network start-stop tacacs+

Example:


Switch(config)# aaa accounting network start-stop tacacs+

Enables TACACS+ accounting for all network-related service requests.

Step 4

aaa accounting exec start-stop tacacs+

Example:


Switch(config)# aaa accounting exec start-stop tacacs+

Enables TACACS+ 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:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

What to do next

To establish a session with a router if the AAA server is unreachable, use the aaa accounting system guarantee-first command. It guarantees system accounting as the first record, which is the default condition. In some situations, users might be prevented from starting a session on the console or terminal connection until after the system reloads, which can take more than 3 minutes.

To establish a console or Telnet session with the router if the AAA server is unreachable when the router reloads, use the no aaa accounting system guarantee-first command.

Establishing a Session with a Router if the AAA Server is Unreachable

To establishing a session with a router if the AAA server is unreachable, use the aaa accounting system guarantee-first command. It guarantees system accounting as the first record, which is the default condition. In some situations, users might be prevented from starting a session on the console or terminal connection until after the system reloads, which can take more than 3 minutes.

To establish a console or Telnet session with the router if the AAA server is unreachable when the router reloads, use the no aaa accounting system guarantee-first command.

Monitoring TACACS+

Table 3. Commands for Displaying TACACS+ Information
Command Purpose

show tacacs

Displays TACACS+ server statistics.

Additional References for TACACS+

Related Documents

Related Topic

Document Title

Cisco security commands

IPv6 commands

Cisco IOS IPv6 Command Reference

MIBs

MIB MIBs Link

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

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/support

Feature Information for TACACS+

Release Feature Information
Cisco IOS 12.2(58)SE

TACACS+ support for IPv6.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Controlling Switch Access with RADIUS

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

General:

  • RADIUS and 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.

  • 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 Switch.

  • 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 Controlling Switch Access with RADIUS

This topic covers restrictions for controlling Switch 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 Overview

RADIUS is a distributed client/server system that secures networks against unauthorized access. RADIUS clients run on supported Cisco routers and switches. 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. In one case, RADIUS has been used with Enigma’s security cards to validates users and to grant access to network resources.

  • Networks already using RADIUS. You can add a Cisco Switch containing a RADIUS client to the network. This might be the first step when you make a transition to a TACACS+ server. See Figure 2: Transitioning from RADIUS to TACACS+ Services below.

  • 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 Chapter 11, “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.

Figure 2. Transitioning from RADIUS to TACACS+ Services
Transitioning from RADIUS to TACACS+ Services

RADIUS Operation

When a user attempts to log in and authenticate to a Switch 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

This section provides an overview of the RADIUS interface including available primitives and how they are used during a Change of Authorization (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. Catalyst switches support the RADIUS Change of Authorization (CoA) extensions defined in RFC 5176 that are typically used in a pushed model and allow for the dynamic reconfiguring of sessions from external authentication, authorization, and accounting (AAA) or policy servers.

The switch 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 Identity Services Engine, and Cisco Secure Access Control Server (ACS) 5.1.

The RADIUS interface is enabled by default on Catalyst switches. 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.

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 4. 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 5. 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.

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:

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

  • Audit-Session-Id (Cisco VSA)

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

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).

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 6. CoA Commands Supported on the switch

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 switch 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’s 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 switch returns a Disconnect-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the switch terminates the session. After the session has been completely removed, the switch returns a Disconnect-ACK.

If the switch fails-over to a standby switch before returning a Disconnect-ACK to the client, the process is repeated on the new active switch 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

This command is carried in a standard CoA-Request message that has this new VSA:

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

If the session cannot be located, the switch returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the switch disables the hosting port and returns a CoA-ACK message.

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


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 switch became active.

CoA Request: Bounce-Port

This command 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 switch returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the switch disables the hosting port for a period of 10 seconds, re-enables it (port-bounce), and returns a CoA-ACK.

If the switch fails before returning a CoA-ACK to the client, the process is repeated on the new active switch when the request is re-sent from the client. If the switch 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 switch.

RADIUS Server Host

Switch-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 switch 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 switch 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 switch.

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 switch 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. 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.

AAA Authorization

AAA authorization limits the services available to a user. When AAA authorization is enabled, the switch 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 switch 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 switch 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 3. 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 7. 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 8. 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 cancelled or successful. True means that the session was cancelled; 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 cancels, indicates the system component that signaled the cancel operation. Examples of system components that could trigger a cancel operation 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 switch and the RADIUS server, some vendors have extended the RADIUS attribute set in a unique way. Cisco  IOS 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 switch. You specify the RADIUS host and secret text string by using the radius-server global configuration commands.

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 switch through the CLI.

How to Configure RADIUS

Identifying the RADIUS Server Host

To apply these settings globally to all RADIUS servers communicating with the Switch, use the three unique global configuration commands: radius-server timeout , radius-server retransmit , and radius-server key . To apply these values on a specific RADIUS server, use the radius-server host global configuration command.

You can configure the Switch to use AAA server groups to group existing server hosts for authentication. For more information, see Related Topics below.

You also need to configure some settings on the RADIUS server. These settings include the IP address of the Switch and the key string to be shared by both the server and the Switch. For more information, see the RADIUS server documentation.

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 switch, the per-server timer, retransmission, and key value commands override global timer, retransmission, and key value commands. For information on configuring these settings on all RADIUS servers, see Related Topics below.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]
  4. end
  5. show running-config
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]

Example:


Switch(config)# radius-server host 172.29.36.49 auth-port 1612 key rad1

Specifies the IP address or hostname of the remote RADIUS server host.

  • (Optional) For auth-port port-number , specify the UDP destination port for authentication requests.

  • (Optional) For acct-port port-number , specify the UDP destination port for accounting requests.

  • (Optional) For timeout seconds , specify the time interval that the Switch waits for the RADIUS server to reply before resending. The range is 1 to 1000. This setting overrides the radius-server timeout global configuration command setting. If no timeout is set with the radius-server host command, the setting of the radius-server timeout command is used.

  • (Optional) For retransmit retries , specify the number of times a RADIUS request is resent to a server if that server is not responding or responding slowly. The range is 1 to 1000. If no retransmit value is set with the radius-server host command, the setting of the radius-server retransmit global configuration command is used.

  • (Optional) For key string , specify the authentication and encryption key used between the Switch 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 host 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.

To configure the Switch to recognize more than one host entry associated with a single IP address, enter this command as many times as necessary, making sure that each UDP port number is different. The Switch software searches for hosts in the order in which you specify them. Set the timeout, retransmit, and encryption key values to use with the specific RADIUS host.

Step 4

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 5

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring RADIUS Login Authentication

Follow these steps to configure RADIUS login authentication:

Before you begin

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

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. aaa authentication login {default | list-name} method1 [method2...]
  5. line [console | tty | vty] line-number [ending-line-number]
  6. login authentication {default | list-name}
  7. end
  8. show running-config
  9. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 4

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

Example:


Switch(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:


Switch(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:


Switch(config)# 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:


Switch(config)# end

Returns to privileged EXEC mode.

Step 8

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 9

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

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:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]
  4. aaa new-model
  5. aaa group server radius group-name
  6. server ip-address
  7. end
  8. show running-config
  9. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]

Example:


Switch(config)# radius-server host 172.29.36.49 auth-port 1612 key rad1

Specifies the IP address or hostname of the remote RADIUS server host.

  • (Optional) For auth-port port-number , specify the UDP destination port for authentication requests.

  • (Optional) For acct-port port-number , specify the UDP destination port for accounting requests.

  • (Optional) For timeout seconds , specify the time interval that the switch waits for the RADIUS server to reply before resending. The range is 1 to 1000. This setting overrides the radius-server timeout global configuration command setting. If no timeout is set with the radius-server host command, the setting of the radius-server timeout command is used.

  • (Optional) For retransmit retries , specify the number of times a RADIUS request is resent to a server if that server is not responding or responding slowly. The range is 1 to 1000. If no retransmit value is set with the radius-server host command, the setting of the radius-server retransmit global configuration command is used.

  • (Optional) For key string , specify the authentication and encryption key used between the switch 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 host 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.

To configure the switch to recognize more than one host entry associated with a single IP address, enter this command as many times as necessary, making sure that each UDP port number is different. The switch software searches for hosts in the order in which you specify them. Set the timeout, retransmit, and encryption key values to use with the specific RADIUS host.

Step 4

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 5

aaa group server radius group-name

Example:


Switch(config)# aaa group server radius group1

Defines the AAA server-group with a group name.

This command puts the switch in a server group configuration mode.

Step 6

server ip-address

Example:


Switch(config-sg-radius)# server 172.20.0.1 auth-port 1000 acct-port 1001

Associates a particular RADIUS server with the defined server group. Repeat this step for each RADIUS server in the AAA server group.

Each server in the group must be previously defined in Step 2.

Step 7

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 8

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 9

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

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:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa authorization network radius
  4. aaa authorization exec radius
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa authorization network radius

Example:


Switch(config)# aaa authorization network radius

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

Step 4

aaa authorization exec radius

Example:


Switch(config)# aaa authorization exec radius

Configures the switch 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:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

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:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa accounting network start-stop radius
  4. aaa accounting exec start-stop radius
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa accounting network start-stop radius

Example:


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

Enables RADIUS accounting for all network-related service requests.

Step 4

aaa accounting exec start-stop radius

Example:

Switch(config)# aaa accounting exec 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:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

What to do next

To establishing a session with a router if the AAA server is unreachable, use the aaa accounting system guarantee-first command. This command guarantees system accounting as the first record, which is the default condition. In some situations, users might be prevented from starting a session on the console or terminal connection until after the system reloads, which can take more than 3 minutes.

To establish a console or Telnet session with the router if the AAA server is unreachable when the router reloads, use the no aaa accounting system guarantee-first command.

Configuring Settings for All RADIUS Servers

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

SUMMARY STEPS

  1. configure terminal
  2. radius-server key string
  3. radius-server retransmit retries
  4. radius-server timeout seconds
  5. radius-server deadtime minutes
  6. end
  7. show running-config
  8. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 2

radius-server key string

Example:


Switch(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 3

radius-server retransmit retries

Example:


Switch(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 4

radius-server timeout seconds

Example:


Switch(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 5

radius-server deadtime minutes

Example:


Switch(config)# radius-server deadtime 0

When a RADIUS server is not responding to authentication requests, this command specifies a time to stop the request on that server. This avoids the wait for the request to timeout before trying the next configured server. The default is 0; the range is 1 to 1440 minutes.

Step 6

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 7

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 8

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring the Switch to Use Vendor-Specific RADIUS Attributes

Follow these steps to configure the switch to use vendor-specific RADIUS attributes:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. radius-server vsa send [accounting | authentication]
  4. end
  5. show running-config
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

radius-server vsa send [accounting | authentication]

Example:


Switch(config)# radius-server vsa send

Enables the switch 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:


Switch(config)# end

Returns to privileged EXEC mode.

Step 5

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring the Switch for Vendor-Proprietary RADIUS Server Communication

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

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. radius-server host {hostname | ip-address} non-standard
  4. radius-server key string
  5. end
  6. show running-config
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

radius-server host {hostname | ip-address} non-standard

Example:


Switch(config)# radius-server host 172.20.30.15 nonstandard

Specifies the IP address or hostname of the remote RADIUS server host and identifies that it is using a vendor-proprietary implementation of RADIUS.

Step 4

radius-server key string

Example:


Switch(config)# radius-server key rad124

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

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

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

What to do next

This feature allows access and authentication requests to be evenly across all RADIUS servers in a server group. For more information, see the “RADIUS Server Load Balancing” chapter of the Cisco IOS Security Configuration Guide, Release 12.4.

Configuring CoA on the Switch

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

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. aaa server radius dynamic-author
  5. client {ip-address | name} [vrf vrfname] [server-key string]
  6. server-key [0 | 7] string
  7. port port-number
  8. auth-type {any | all | session-key}
  9. ignore session-key
  10. ignore server-key
  11. authentication command bounce-port ignore
  12. authentication command disable-port ignore
  13. end
  14. show running-config
  15. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 4

aaa server radius dynamic-author

Example:


Switch(config)# aaa server radius dynamic-author

Configures the switch as an authentication, authorization, and accounting (AAA) server to facilitate interaction with an external policy server.

Step 5

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

Enters dynamic authorization local server configuration mode and specifies a RADIUS client from which a device will accept CoA and disconnect requests.

Step 6

server-key [0 | 7] string

Example:


Switch(config-sg-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:


Switch(config-sg-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:


Switch(config-sg-radius)# auth-type any

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

The client must match all the configured attributes for authorization.

Step 9

ignore session-key

(Optional) Configures the switch to ignore the session-key.

For more information about the ignore command, see the Cisco IOS Intelligent Services Gateway Command Reference on Cisco.com.

Step 10

ignore server-key

Example:


Switch(config-sg-radius)# ignore server-key

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

For more information about the ignore command, see the Cisco IOS Intelligent Services Gateway Command Reference on Cisco.com.

Step 11

authentication command bounce-port ignore

Example:


Switch(config-sg-radius)# authentication command bounce-port ignore

(Optional) Configures the switch 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:


Switch(config-sg-radius)# authentication command disable-port ignore

(Optional) Configures the switch 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:


Switch(config-sg-radius)# end

Returns to privileged EXEC mode.

Step 14

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 15

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Monitoring CoA Functionality

Table 9. Privileged EXEC show Commands

Command

Purpose

show aaa attributes protocol radius

Displays AAA attributes of RADIUS commands.
Table 10. 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.

For detailed information about the fields in these displays, see the command reference for this release.

Configuration Examples for Controlling Switch Access with RADIUS

Examples: Identifying the RADIUS Server Host

This example shows how to configure one RADIUS server to be used for authentication and another to be used for accounting:


Switch(config)# radius-server host 172.29.36.49 auth-port 1612 key rad1
Switch(config)# radius-server host 172.20.36.50 acct-port 1618 key rad2

This example shows how to configure host1 as the RADIUS server and to use the default ports for both authentication and accounting: 


Switch(config)# radius-server host host1

Example: Using Two Different RADIUS Group Servers

In this example, the switch is configured to recognize two different RADIUS group servers (group1 and group2). Group1 has two different host entries on the same RADIUS server configured for the same services. The second host entry acts as a fail-over backup to the first entry. 


Switch(config)# radius-server host 172.20.0.1 auth-port 1000 acct-port 1001
Switch(config)# radius-server host 172.10.0.1 auth-port 1645 acct-port 1646
Switch(config)# aaa new-model
Switch(config)# aaa group server radius group1
Switch(config-sg-radius)# server 172.20.0.1 auth-port 1000 acct-port 1001
Switch(config-sg-radius)# exit
Switch(config)# aaa group server radius group2
Switch(config-sg-radius)# server 172.20.0.1 auth-port 2000 acct-port 2001
Switch(config-sg-radius)# exit

Examples: Configuring the Switch to Use Vendor-Specific RADIUS Attributes

For example, this AV pair activates Cisco’s multiple named ip address pools feature during IP authorization (during PPP IPCP address assignment): 


cisco-avpair= ”ip:addr-pool=first“

This example shows how to provide a user logging in from a switch with immediate access to privileged EXEC commands:


cisco-avpair= ”shell:priv-lvl=15“

This example shows how to specify an authorized VLAN in the RADIUS server database:


cisco-avpair= ”tunnel-type(#64)=VLAN(13)”
cisco-avpair= ”tunnel-medium-type(#65)=802 media(6)”
cisco-avpair= ”tunnel-private-group-id(#81)=vlanid”

This example shows how to apply an input ACL in ASCII format to an interface for the duration of this connection:


cisco-avpair= “ip:inacl#1=deny ip 10.10.10.10 0.0.255.255 20.20.20.20 255.255.0.0”
cisco-avpair= “ip:inacl#2=deny ip 10.10.10.10 0.0.255.255 any”
cisco-avpair= “mac:inacl#3=deny any any decnet-iv”

This example shows how to apply an output ACL in ASCII format to an interface for the duration of this connection:


cisco-avpair= “ip:outacl#2=deny ip 10.10.10.10 0.0.255.255 any”

Example: Configuring the Switch for Vendor-Proprietary RADIUS Server Communication

This example shows how to specify a vendor-proprietary RADIUS host and to use a secret key of rad124 between the switch and the server: 


Switch(config)# radius-server host 172.20.30.15 nonstandard
Switch(config)# radius-server key rad124

Additional References for RADIUS

Related Documents

Related Topic

Document Title

Cisco security commands

IPv6 commands

Cisco IOS IPv6 Command Reference

Standards and RFCs

Standard/RFC Title

RFC 5176

RADIUS Change of Authorization (CoA) extensions

Error Message Decoder

Description Link

To help you research and resolve system error messages in this release, use the Error Message Decoder tool.

https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

MIBs

MIB MIBs Link

All the supported MIBs for this release.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

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/support

Feature Information for RADIUS

Release Feature Information
This feature was introduced.

Cisco IOS 12.2(52)SE

Introduced support for per-session CoA requests.

Cisco IOS 12.2(52)SE

Introduced support for the following CoA Request commands:

  • Reauthenticate host

  • Terminate session

  • Bounce host port

  • Disable host port

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

How to Configure Local Authentication and Authorization

Configuring the Switch for Local Authentication and Authorization

You can configure AAA to operate without a server by setting the switch to implement AAA in local mode. The switch then handles authentication and authorization. No accounting is available in this configuration.


Note

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

Follow these steps to configure AAA to operate without a server by setting the switch to implement AAA in local mode:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. aaa new-model
  4. aaa authentication login default local
  5. aaa authorization exec local
  6. aaa authorization network local
  7. username name [privilege level] {password encryption-type password}
  8. end
  9. show running-config
  10. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

aaa new-model

Example:


Switch(config)# aaa new-model

Enables AAA.

Step 4

aaa authentication login default local

Example:


Switch(config)# aaa authentication login default local

Sets the login authentication to use the local username database. The default keyword applies the local user database authentication to all ports.

Step 5

aaa authorization exec local

Example:


Switch(config)# aaa authorization exec local

Configures user AAA authorization, check the local database, and allow the user to run an EXEC shell.

Step 6

aaa authorization network local

Example:


Switch(config)# aaa authorization network local

Configures user AAA authorization for all network-related service requests.

Step 7

username name [privilege level] {password encryption-type password}

Example:


Switch(config)# username your_user_name privilege 1 password 7 secret567

Enters the local database, and establishes a username-based authentication system.

Repeat this command for each user.

  • For name , specify the user ID as one word. Spaces and quotation marks are not allowed.

  • (Optional) For level , specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 0 gives user EXEC mode access.

  • For encryption-type , enter 0 to specify that an unencrypted password follows. Enter 7 to specify that a hidden password follows.

  • For password , specify the password the user must enter to gain access to the switch. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.

Step 8

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 9

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 10

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Monitoring Local Authentication and Authorization

To display Local Authentication and Authorization configuration, use the show running-config privileged EXEC command.

Additional References

Error Message Decoder

Description Link

To help you research and resolve system error messages in this release, use the Error Message Decoder tool.

https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi

MIBs

MIB MIBs Link

All the supported MIBs for this release.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

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/support

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Configuring the Switch for Secure Shell (SSH) and Secure Copy Protocol (SCP)

The following are the prerequisites for configuring the switch for secure shell (SSH):

  • To use SSH, you must install the cryptographic (encrypted) software image on your switch.

  • For SSH to work, the switch needs an RSA public/private key pair. This is the same with Secure Copy Protocol (SCP), which relies on SSH for its secure transport.

  • Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.

  • Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.

  • SCP relies on SSH for security.

  • SCP requires that authentication, authorization, and accounting (AAA) authorization be configured so the router can determine whether the user has the correct privilege level.

  • A user must have appropriate authorization to use SCP.

  • A user who has appropriate authorization can use SCP to copy any file in the Cisco IOS File System (IFS) to and from a switch by using the copy command. An authorized administrator can also do this from a workstation.

Restrictions for Configuring the Switch for SSH

The following are restrictions for configuring the Switch for secure shell.

  • The switch supports Rivest, Shamir, and Adelman (RSA) authentication.

  • SSH supports only the execution-shell application.

  • The SSH server and the SSH client are supported only on DES (56-bit) and 3DES (168-bit) data encryption software.

  • The Switch supports the Advanced Encryption Standard (AES) encryption algorithm with a 128-bit key, 192-bit key, or 256-bit key. However, symmetric cipher AES to encrypt the keys is not supported.

  • This software release does not support IP Security (IPSec).

  • When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted.

Information About SSH

SSH and Switch Access

Secure Shell (SSH) is a protocol that provides a secure, remote connection to a device. SSH provides more security for remote connections than Telnet does by providing strong encryption when a device is authenticated. This software release supports SSH Version 1 (SSHv1) and SSH Version 2 (SSHv2).

SSH functions the same in IPv6 as in IPv4. For IPv6, SSH supports IPv6 addresses and enables secure, encrypted connections with remote IPv6 nodes over an IPv6 transport.

SSH Servers, Integrated Clients, and Supported Versions

The SSH feature has an SSH server and an SSH integrated client, which are applications that run on the switch. You can use an SSH client to connect to a switch running the SSH server. The SSH server works with the SSH client supported in this release and with non-Cisco SSH clients. The SSH client also works with the SSH server supported in this release and with non-Cisco SSH servers.

The switch supports an SSHv1 or an SSHv2 server.

The switch supports an SSHv1 client.

SSH supports the Data Encryption Standard (DES) encryption algorithm, the Triple DES (3DES) encryption algorithm, and password-based user authentication.

SSH also supports these user authentication methods:

  • TACACS+

  • RADIUS

  • Local authentication and authorization

SSH Configuration Guidelines

Follow these guidelines when configuring the switch as an SSH server or SSH client:

  • An RSA key pair generated by a SSHv1 server can be used by an SSHv2 server, and the reverse.

  • If the SSH server is running on an active switch and the active switch fails, the new active switch uses the RSA key pair generated by the previous active switch.

  • If you get CLI error messages after entering the crypto key generate rsa global configuration command, an RSA key pair has not been generated. Reconfigure the hostname and domain, and then enter the crypto key generate rsa command.

  • When generating the RSA key pair, the message No host name specified might appear. If it does, you must configure a hostname by using the hostname global configuration command.

  • When generating the RSA key pair, the message No domain specified might appear. If it does, you must configure an IP domain name by using the ip domain-name global configuration command.

  • When configuring the local authentication and authorization authentication method, make sure that AAA is disabled on the console.

Secure Copy Protocol Overview

The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. SCP relies on Secure Shell (SSH), an application and a protocol that provides a secure replacement for the Berkeley r-tools.

For SSH to work, the switch needs an RSA public/private key pair. This is the same with SCP, which relies on SSH for its secure transport.

Because SSH also relies on AAA authentication, and SCP relies further on AAA authorization, correct configuration is necessary.

  • Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.

  • Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.


Note

When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted.

Secure Copy Protocol

The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. The behavior of SCP is similar to that of remote copy (rcp), which comes from the Berkeley r-tools suite, except that SCP relies on SSH for security. SCP also requires that authentication, authorization, and accounting (AAA) authorization be configured so the switch can determine whether the user has the correct privilege level. To configure the Secure Copy feature, you should understand the SCP concepts.

Information about SSH

Secure Shell (SSH) is a protocol that provides a secure, remote connection to a device. SSH provides more security for remote connections than Telnet does by providing strong encryption when a device is authenticated. This software release supports SSH Version 1 (SSHv1) and SSH Version 2 (SSHv2).

How to Configure SSH

Setting Up the Switch to Run SSH

Follow these steps to set up your Switch to run SSH:

Before you begin

Configure user authentication for local or remote access. This step is required. For more information, see Related Topics below.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. hostname hostname
  4. ip domain-name domain_name
  5. crypto key generate rsa
  6. end
  7. show running-config
  8. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

hostname hostname

Example:


Switch(config)# hostname your_hostname

Configures a hostname and IP domain name for your Switch.

Note 

Follow this procedure only if you are configuring the Switch as an SSH server.

Step 4

ip domain-name domain_name

Example:


Switch(config)# ip domain-name your_domain

Configures a host domain for your Switch.

Step 5

crypto key generate rsa

Example:


Switch(config)# crypto key generate rsa

Enables the SSH server for local and remote authentication on the Switch and generates an RSA key pair. Generating an RSA key pair for the Switch automatically enables SSH.

We recommend that a minimum modulus size of 1024 bits.

When you generate RSA keys, you are prompted to enter a modulus length. A longer modulus length might be more secure, but it takes longer to generate and to use.

Note 

Follow this procedure only if you are configuring the Switch as an SSH server.

Step 6

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 7

show running-config

Example:


Switch# show running-config

Verifies your entries.

Step 8

copy running-config startup-config

Example:


Switch# copy running-config startup-config