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This chapter describes the commands used to configure both AAA and non-AAA authentication methods. Authentication identifies users before they are allowed access to the network and network services. Basically, the Cisco IOS software implementation of authentication is divided into two main categories:
Authentication, for the most part, is implemented through the AAA security services. We recommend that, whenever possible, AAA be used to implement authentication.
For information on how to configure authentication using either AAA or non-AAA methods, refer to the "Configuring Authentication" chapter in the Cisco IOS Security Configuration Guide. For configuration examples using the commands in this chapter, refer to the "Authentication Examples" section located at the end of the "Configuring Authentication" chapter in the Cisco IOS Security Configuration Guide.
Syntax Description
default Uses the listed methods that follow this argument as the default list of methods when a user logs in. list-name Character string used to name the following list of authentication methods tried when a user logs in. method1 [method2...] At least one of the keywords described in Table 3.
Defaults
If the default list is not set, only the local user database is checked. This has the same effect as the following command:
aaa authentication arap default local
Command Modes
Global configuration
Command History
10.3 This command was introduced. 12.0(5)T Group server and local-case support were added as method keywords for this command.
Release
Modification
Usage Guidelines
The list names and default that you set with the aaa authentication arap command are used with the arap authentication command. Note that ARAP guest logins are disabled by default when you enable AAA. To allow guest logins, you must use either the guest or auth-guest method listed in Table 3. You can only use one of these methods; they are mutually exclusive.
Create a list by entering the aaa authentication arap list-name method command, where list-name is any character string used to name this list (such as MIS-access). The method argument identifies the list of methods the authentication algorithm tries in the given sequence. See Table 3 for descriptions of method keywords.
To create a default list that is used if no list is specified in the arap authentication command, use the default keyword followed by the methods you want to be used in default situations.
The additional methods of authentication are used only if the previous method returns an error, not if it fails.
Use the more system:running-config command to view currently configured lists of authentication methods.
 |
Note In Table 3, the group radius, group tacacs+, and group group-name methods refer to a set of previously defined RADIUS or TACACS+ servers. Use the radius-server host and tacacs+-server host commands to configure the host servers. Use the aaa group server radius and aaa group server tacacs+ commands to create a named group of servers. |
| Keyword | Description |
|---|---|
guest | Allows guest logins. This method must be the first method listed, but it can be followed by other methods if it does not succeed. |
auth-guest | Allows guest logins only if the user has already logged in to EXEC. This method must be the first method listed, but can be followed by other methods if it does not succeed. |
line | Uses the line password for authentication. |
local | Uses the local username database for authentication. |
local-case | Uses case-sensitive local username authentication. |
group radius | Uses the list of all RADIUS servers for authentication. |
group tacacs+ | Uses the list of all TACACS+ servers for authentication. |
group group-name | Uses a subset of RADIUS or TACACS+ servers for authentication as defined by the aaa group server radius or aaa group server tacacs+ command. |
Examples
The following example creates a list called MIS-access, which first tries TACACS+ authentication and then none:
aaa authentication arap MIS-access group tacacs+ none
The following example creates the same list, but sets it as the default list that is used for all ARA protocol authentications if no other list is specified:
aaa authentication arap default group tacacs+ none
Related Commands
aaa new-model Enables the AAA access control model.
Command
Description
Syntax Description
d The delimiting character at the beginning and end of the string that notifies the system that the string is to be displayed as the banner. The delimiting character can be any character in the extended ASCII character set, but once defined as the delimiter, that character cannot be used in the text string making up the banner. string Any group of characters, excluding the one used as the delimiter. The maximum number of characters that you can display is 2996.
Defaults
Not enabled
Command Modes
Global configuration
Command History
11.3(4)T This command was introduced.
Release
Modification
Usage Guidelines
Use the aaa authentication banner command to create a personalized message that appears when a user logs in to the system. This message or banner will replace the default message for user login.
To create a login banner, you need to configure a delimiting character, which notifies the system that the following text string is to be displayed as the banner, and then the text string itself. The delimiting character is repeated at the end of the text string to signify the end of the banner. The delimiting character can be any character in the extended ASCII character set, but once defined as the delimiter, that character cannot be used in the text string making up the banner.
Examples
The following example shows the default login message if aaa authentication banner is not configured. (RADIUS is specified as the default login authentication method.)
aaa new-model aaa authentication login default group radius
This configuration produces the following standard output:
User Verification Access Username: Password:
The following example configures a login banner (in this case, the phrase "Unauthorized use is prohibited.") that will be displayed when a user logs in to the system. In this case, the asterisk (*) symbol is used as the delimiter. (RADIUS is specified as the default login authentication method.)
aaa new-model aaa authentication banner *Unauthorized use is prohibited.* aaa authentication login default group radius
This configuration produces the following login banner:
Unauthorized use is prohibited. Username:
Related Commands
Configures a personalized banner that will be displayed when a user fails login.
Command
Description
Syntax Description
method1 [method2...] At least one of the keywords described in Table 4.
Defaults
If the default list is not set, only the enable password is checked. This has the same effect as the following command:
aaa authentication enable default enable
On the console, the enable password is used if it exists. If no password is set, the process will succeed anyway.
Command Modes
Global configuration
Command History
10.3 This command was introduced. 12.0(5)T Group server support was added as various method keywords for this command.
Release
Modification
Usage Guidelines
Use the aaa authentication enable default command to create a series of authentication methods that are used to determine whether a user can access the privileged command level. Method keywords are described in Table 4. The additional methods of authentication are used only if the previous method returns an error, not if it fails. To specify that the authentication should succeed even if all methods return an error, specify none as the final method in the command line.
If a default authentication routine is not set for a function, the default is none and no authentication is performed. Use the more system:running-config command to view currently configured lists of authentication methods.
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Note In Table 4, the group radius, group tacacs+, and group group-name methods refer to a set of previously defined RADIUS or TACACS+ servers. Use the radius-server host and tacacs+-server host commands to configure the host servers. Use the aaa group server radius and aaa group server tacacs+ commands to create a named group of servers. |
| Keyword | Description |
|---|---|
enable | Uses the enable password for authentication. |
line | Uses the line password for authentication. |
none | Uses no authentication. |
group radius | Uses the list of all RADIUS servers for authentication. |
group tacacs+ | Uses the list of all TACACS+ servers for authentication. |
group group-name | Uses a subset of RADIUS or TACACS+ servers for authentication as defined by the aaa group server radius or aaa group server tacacs+ command. |
Examples
The following example creates an authentication list that first tries to contact a TACACS+ server. If no server can be found, AAA tries to use the enable password. If this attempt also returns an error (because no enable password is configured on the server), the user is allowed access with no authentication.
aaa authentication enable default group tacacs+ enable none
Related Commands
aaa authorization Sets parameters that restrict network access to a user. aaa new-model Enables the AAA access control model. enable password Sets a local password to control access to various privilege levels.
Command
Description
Syntax Description
d The delimiting character at the beginning and end of the string that notifies the system that the string is to be displayed as the banner. The delimiting character can be any character in the extended ASCII character set, but once defined as the delimiter, that character cannot be used in the text string making up the banner. string Any group of characters, excluding the one used as the delimiter. The maximum number of characters that you can display is 2996.
Defaults
Not enabled
Command Modes
Global configuration
Command History
11.3(4)T This command was introduced.
Release
Modification
Usage Guidelines
Use the aaa authentication fail-message command to create a personalized message that appears when a user fails login. This message will replace the default message for failed login.
To create a failed-login banner, you need to configure a delimiting character, which notifies the system that the following text string is to be displayed as the banner, and then the text string itself. The delimiting character is repeated at the end of the text string to signify the end of the banner. The delimiting character can be any character in the extended ASCII character set, but once defined as the delimiter, that character cannot be used in the text string making up the banner.
Examples
The following example shows the default login message and failed login message that is displayed if aaa authentication banner and aaa authentication fail-message are not configured. (RADIUS is specified as the default login authentication method.)
aaa new-model aaa authentication login default group radius
This configuration produces the following standard output:
User Verification Access Username: Password: % Authentication failed.
The following example configures both a login banner ("Unauthorized use is prohibited.") and a login-fail message ("Failed login. Try again."). The login message will be displayed when a user logs in to the system. The failed-login message will display when a user tries to log in to the system and fails. (RADIUS is specified as the default login authentication method.) In this example, the asterisk (*) is used as the delimiting character.
aaa new-model aaa authentication banner *Unauthorized use is prohibited.* aaa authentication fail-message *Failed login. Try again.* aaa authentication login default group radius
This configuration produces the following login and failed login banner:
Unauthorized use is prohibited. Username: Password: Failed login. Try again.
Related Commands
Configures a personalized banner that will be displayed at user login.
Command
Description
Syntax Description
default Uses the listed authentication methods that follow this argument as the default list of methods when a user list-name Character string used to name the list of authentication methods activated when a user logs in. method1 [method2...] At least one of the keywords described in Table 5.
logs in.
Defaults
If the default list is not set, only the local user database is checked. This has the same effect as the following command:
aaa authentication login default local
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Note On the console, login will succeed without any authentication checks if default is not set. |
Command Modes
Global configuration
Command History
10.3 This command was introduced. 12.0(5)T Group server and local-case support were added as method keywords for this command.
Release
Modification
Usage Guidelines
The default and optional list names that you create with the aaa authentication login command are used with the login authentication command.
Create a list by entering the aaa authentication login list-name method command for a particular protocol, where list-name is any character string used to name this list (such as MIS-access). The method argument identifies the list of methods that the authentication algorithm tries, in the given sequence. Method keywords are described in Table 5.
To create a default list that is used if no list is assigned to a line, use the login authentication command with the default argument followed by the methods you want to use in default situations.
The additional methods of authentication are used only if the previous method returns an error, not if it fails. To ensure that the authentication succeeds even if all methods return an error, specify none as the final method in the command line.
If authentication is not specifically set for a line, the default is to deny access and no authentication is performed. Use the more system:running-config command to display currently configured lists of authentication methods.
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Note In Table 5, the group radius, group tacacs+, and group group-name methods refer to a set of previously defined RADIUS or TACACS+ servers. Use the radius-server host and tacacs+-server host commands to configure the host servers. Use the aaa group server radius and aaa group server tacacs+ commands to create a named group of servers. |
| Keyword | Description |
|---|---|
enable | Uses the enable password for authentication. |
krb5 | Uses Kerberos 5 for authentication. |
krb5-telnet | Uses Kerberos 5 Telnet authentication protocol when using Telnet to connect to the router. |
line | Uses the line password for authentication. |
local | Uses the local username database for authentication. |
local-case | Uses case-sensitive local username authentication. |
none | Uses no authentication. |
group radius | Uses the list of all RADIUS servers for authentication. |
group tacacs+ | Uses the list of all TACACS+ servers for authentication. |
group group-name | Uses a subset of RADIUS or TACACS+ servers for authentication as defined by the aaa group server radius or aaa group server tacacs+ command. |
Examples
The following example creates an AAA authentication list called MIS-access. This authentication first tries to contact a TACACS+ server. If no server is found, TACACS+ returns an error and AAA tries to use the enable password. If this attempt also returns an error (because no enable password is configured on the server), the user is allowed access with no authentication.
aaa authentication login MIS-access group tacacs+ enable none
The following example creates the same list, but it sets it as the default list that is used for all login authentications if no other list is specified:
aaa authentication login default group tacacs+ enable none
The following example sets authentication at login to use the Kerberos 5 Telnet authentication protocol when using Telnet to connect to the router:
aaa authentication login default KRB5-TELNET krb5
Related Commands
aaa new-model Enables the AAA access control model. Enables AAA authentication for logins.
Command
Description
Syntax Description
default Makes the listed authentication methods that follow this argument the default list of methods used when a user logs in. list-name Character string used to name the list of authentication methods activated when a user logs in. method1 [method2...] At least one of the methods described in Table 6.
Defaults
If the default list is not set, only the local user database is selected. This has the same effect as the following command:
aaa authentication nasi default local
Command Modes
Global configuration
Command History
11.1 This command was introduced. 12.0(5)T Group server and local-case support were added as method keywords for this command.
Release
Modification
Usage Guidelines
The default and optional list names that you create with the aaa authentication nasi command are used with the nasi authentication command.
Create a list by entering the aaa authentication nasi command, where list-name is any character string that names the list (such as MIS-access). The method argument identifies the list of methods the authentication algorithm tries in the given sequence. Method keywords are described in Table 6.
To create a default list that is used if no list is assigned to a line with the nasi authentication command, use the default argument followed by the methods that you want to use in default situations.
The remaining methods of authentication are used only if the previous method returns an error, not if it fails. To ensure that the authentication succeeds even if all methods return an error, specify none as the final method in the command line.
If authentication is not specifically set for a line, the default is to deny access and no authentication is performed. Use the more system:running-config command to display currently configured lists of authentication methods.
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Note In Table 6, the group radius, group tacacs+, and group group-name methods refer to a set of previously defined RADIUS or TACACS+ servers. Use the radius-server host and tacacs+-server host commands to configure the host servers. Use the aaa group server radius and aaa group server tacacs+ commands to create a named group of servers. |
| Keyword | Description |
|---|---|
enable | Uses the enable password for authentication. |
line | Uses the line password for authentication. |
local | Uses the local username database for authentication. |
local-case | Uses case-sensitive local username authentication. |
none | Uses no authentication. |
group radius | Uses the list of all RADIUS servers for authentication. |
group tacacs+ | Uses the list of all TACACS+ servers for authentication. |
group group-name | Uses a subset of RADIUS or TACACS+ servers for authentication as defined by the aaa group server radius or aaa group server tacacs+ command. |
Examples
The following example creates an AAA authentication list called list1. This authentication first tries to contact a TACACS+ server. If no server is found, TACACS+ returns an error and AAA tries to use the enable password. If this attempt also returns an error (because no enable password is configured on the server), the user is allowed access with no authentication.
aaa authentication nasi list1 group tacacs+ enable none
The following example creates the same list, but sets it as the default list that is used for all login authentications if no other list is specified:
aaa authentication nasi default group tacacs+ enable none
Related Commands
ipx nasi-server enable Enables NASI clients to connect to asynchronous devices attached to a router. Enables the automated part of double authentication at a device. Enables AAA authentication for NASI clients connecting to a router. show ipx nasi connections Displays the status of NASI connections. show ipx spx-protocol Displays the status of the SPX protocol stack and related counters.
Command
Description
Syntax Description
text-string String of text that will be displayed when the user is prompted to enter a password. If this text-string contains spaces or unusual characters, it must be enclosed in double-quotes (for example, "Enter your password:").
Defaults
There is no user-defined text-string, and the password prompt appears as "Password."
Command Modes
Global configuration
Command History
11.0 This command was introduced.
Release
Modification
Usage Guidelines
Use the aaa authentication password-prompt command to change the default text that the Cisco IOS software displays when prompting a user to enter a password. This command changes the password prompt for the enable password as well as for login passwords that are not supplied by remote security servers. The no form of this command returns the password prompt to the default value:
Password:
The aaa authentication password-prompt command does not change any dialog that is supplied by a remote TACACS+ or RADIUS server.
Examples
The following example changes the text for the password prompt:
aaa authentication password-prompt "Enter your password now:"
Related Commands
Changes the text displayed when users are prompted to enter a username. aaa new-model Enables the AAA access control model. enable password Sets a local password to control access to various privilege levels.
Command
Description
Syntax Description
default Uses the listed authentication methods that follow this argument as the default list of methods when a user logs in. list-name Character string used to name the list of authentication methods tried when a user logs in. method1 [method2...] At least one of the keywords described in Table 7.
Defaults
If the default list is not set, only the local user database is checked. This has the same effect as the following command:
aaa authentication ppp default local
Command Modes
Global configuration
Command History
10.3 This command was introduced. 12.0(5)T Group server and local-case support were added as method keywords for this command.
Release
Modification
Usage Guidelines
The lists that you create with the aaa authentication ppp command are used with the ppp authentication command. These lists contain up to four authentication methods that are used when a user tries to log in to the serial interface.
Create a list by entering the aaa authentication ppp list-name method command, where list-name is any character string used to name this list (such as MIS-access). The method argument identifies the list of methods that the authentication algorithm tries in the given sequence. You can enter up to four methods. Method keywords are described in Table 7.
The additional methods of authentication are only used if the previous method returns an error, not if it fails. Specify none as the final method in the command line to have authentication succeed even if all methods return an error.
If authentication is not specifically set for a function, the default is none and no authentication is performed. Use the more system:running-config command to display currently configured lists of authentication methods.
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Note In Table 7, the group radius, group tacacs+, and group group-name methods refer to a set of previously defined RADIUS or TACACS+ servers. Use the radius-server host and tacacs+-server host commands to configure the host servers. Use the aaa group server radius and aaa group server tacacs+ commands to create a named group of servers. |
| Keyword | Description |
|---|---|
if-needed | Does not authenticate if user has already been authenticated on a TTY line. |
krb5 | Uses Kerberos 5 for authentication (can only be used for PAP authentication). |
local | Uses the local username database for authentication. |
local-case | Uses case-sensitive local username authentication. |
none | Uses no authentication. |
group radius | Uses the list of all RADIUS servers for authentication. |
group tacacs+ | Uses the list of all TACACS+ servers for authentication. |
group group-name | Uses a subset of RADIUS or TACACS+ servers for authentication as defined by the aaa group server radius or aaa group server tacacs+ command. |
Examples
The following example creates an AAA authentication list called MIS-access for serial lines that use PPP. This authentication first tries to contact a TACACS+ server. If this action returns an error, the user is allowed access with no authentication.
aaa authentication ppp MIS-access group tacacs+ none
Related Commands
aaa new-model Enables the AAA access control model. Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface.
Command
Description
Syntax Description
text-string String of text that will be displayed when the user is prompted to enter a username. If this text-string contains spaces or unusual characters, it must be enclosed in double-quotes (for example, "Enter your name:").
Defaults
There is no user-defined text-string, and the username prompt appears as "Username."
Command Modes
Global configuration
Command History
11.0 This command was introduced.
Release
Modification
Usage Guidelines
Use the aaa authentication username-prompt command to change the default text that the Cisco IOS software displays when prompting a user to enter a username. The no form of this command returns the username prompt to the default value:
Username:
Some protocols (for example, TACACS+) have the ability to override the use of local username prompt information. Using the aaa authentication username-prompt command will not change the username prompt text in these instances.
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Note The aaa authentication username-prompt command does not change any dialog that is supplied by a remote TACACS+ server. |
Examples
The following example changes the text for the username prompt:
aaa authentication username-prompt "Enter your name here:"
Related Commands
Changes the text displayed when users are prompted for a password. aaa new-model Enables the AAA access control model. enable password Sets a local password to control access to various privilege levels.
Command
Description
To map a Dialed Number Information Service (DNIS) number to a particular authentication server group (this server group will be used for AAA authentication), use the aaa dnis map authentication ppp group command in global configuration mode. To remove the DNIS number from the defined server group, use the no form of this command.
aaa dnis map dnis-number authentication ppp group server-group-name
Syntax Description
dnis-number Number of the DNIS. server-group-name Character string used to name a group of security servers associated in a server group.
Defaults
Disabled
Command Modes
Global configuration
Command History
12.0(7)T This command was introduced.
Release
Modification
Usage Guidelines
This command lets you assign a DNIS number to a particular AAA server group, so that the server group can process authentication requests for users dialing in to the network using that particular DNIS. To use this command, you must first enable AAA, define an AAA server group, and enable DNIS mapping.
Examples
The following example maps DNIS number 7777 to the RADIUS server group called group1. Server group group1 will use RADIUS server 172.30.0.0 for authentication requests for users dialing in with DNIS 7777.
aaa new-model radius-server host 172.30.0.0 auth-port 1645 key cisco1 aaa group server radius group1 server 172.30.0.0 aaa dnis map enable aaa dnis map 7777 authentication ppp group group1
Related Commands
aaa new-model Enables the AAA access control model. aaa dnis map accounting network group Maps a DNIS number to a particular accounting server group. aaa dnis map enable Enables AAA server selection based on DNIS. aaa group server Groups different server hosts into distinct lists and distinct methods. radius-server host Specifies a RADIUS server host.
Command
Description
Syntax Description
This command has no arguments or keywords.
Defaults
AAA is not enabled.
Command Modes
Global configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command enables the AAA access control system.
Examples
The following example initializes AAA:
aaa new-model
Related Commands
aaa accounting Enables AAA accounting of requested services for billing or security purposes. Enables an AAA authentication method for ARA using TACACS+. Enables AAA authentication to determine if a user can access the privileged command level. Sets AAA authentication at login. Specifies one or more AAA authentication method for use on serial interfaces running PPP. aaa authorization Sets parameters that restrict network access to a user.
Command
Description
Syntax Description
number Specifies the number of background processes allocated for AAA requests for PPP. Valid entries are 1 to 2147483647.
Defaults
The default for this command is one allocated background process.
Command Modes
Global configuration
Command History
11.3(2)AA This command was introduced.
Release
Modification
Usage Guidelines
Use the aaa processes command to allocate a specific number of background processes to simultaneously handle multiple AAA authentication and authorization requests for PPP. Previously, only one background process handled all AAA requests for PPP, so only one new user could be authenticated or authorized at a time. This command configures the number of processes used to handle AAA requests for PPP, increasing the number of users that can be simultaneously authenticated or authorized.
The argument number defines the number of background processes earmarked to process AAA authentication and authorization requests for PPP. This argument also defines the number of new users that can be simultaneously authenticated and can be increased or decreased at any time.
Examples
The following examples shows the aaa processes command within a standard AAA configuration. The authentication method list "dialins" specifies RADIUS as the method of authentication, then (if the RADIUS server does not respond) local authentication will be used on serial lines using PPP. Ten background processes have been allocated to handle AAA requests for PPP.
configure terminal aaa new-model aaa authentication ppp dialins group radius local aaa processes 10 interface 10 encap ppp ppp authentication pap dialins
Related Commands
Monitors the number of requests processed by each AAA background process.
Command
Description
Syntax Description
merge (Optional) Like the default form of the command, this option removes existing ACLs while retaining other existing authorization attributes for the interface. However, using this option also installs per-user authorization attributes in addition to the existing attributes. (The default form of the command installs only new ACLs.) The per-user authorization attributes come from all AV pairs defined in the AAA per-user configuration (the user's authorization profile). The interface's resulting authorization attributes are a combination of the previous and new configurations. replace (Optional) This option removes existing ACLs and all other existing authorization attributes for the interface. A complete new authorization configuration is then installed, using all AV pairs defined in the AAA per-user configuration. This option is not normally recommended because it initially deletes all existing configuration, including static routes. This could be detrimental if the new user profile does not reinstall appropriate static routes and other critical information. ignore-sanity-checks (Optional) Enables you to use any AV pairs, whether or not they are valid.
Command Modes
User EXEC
Command History
11.2 F This command was introduced.
Release
Modification
Usage Guidelines
Remote users can use this command to activate double authentication for a PPP session. Double authentication must be correctly configured for this command to have the desired effect.
You should use this command when remote users establish a PPP link to gain local network access.
After you have been authenticated with CHAP (or PAP), you will have limited authorization. To activate double authentication and gain your appropriate user network authorization, you must Telnet to the network access server and execute the access-profile command. (This command could also be set up as an autocommand, which would eliminate the need to manually enter the command.)
This command causes all subsequent network authorizations to be made in your username, instead of in the remote host's username.
Any changes to the interface caused by this command will stay in effect for as long as the interface stays up. These changes will be removed when the interface goes down. This command does not affect the normal operation of the router or the interface.
The default form of the command, access-profile, causes existing ACLs to be unconfigured (removed), and new ACLs to be installed. The new ACLs come from your per-user configuration on an AAA server (such as a TACACS+ server). The ACL replacement constitutes a reauthorization of your network privileges.
The default form of the command can fail if your per-user configuration contains statements other than ACL AV pairs. Any protocols with non-ACL statements will be deconfigured, and no traffic for that protocol can pass over the PPP link.
The access-profile merge form of the command causes existing ACLs to be unconfigured (removed) and new authorization information (including new ACLs) to be added to the interface. This new authorization information consists of your complete per-user configuration on an AAA server. If any of the new authorization statements conflict with existing statements, the new statements could "override" the old statements or be ignored, depending on the statement and applicable parser rules. The resulting interface configuration is a combination of the original configuration and the newly installed per-user configuration.
The access-profile replace form of the command causes the entire existing authorization configuration to be removed from the interface, and the complete per-user authorization configuration to be added. This per-user authorization consists of your complete per-user configuration on an AAA server.
Invalid AV pair types
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Note These AV pair types are only "invalid" when used with double authentication, in the user-specific authorization profile---they cause the access-profile command to fail. However, these AV pair types can be appropriate when used in other contexts. |
Examples
The following example activates double authentication for a remote user. This example assumes that the access-profile command was not configured as an autocommand.
The remote user connects to the corporate headquarters network per Figure 2.
The remote user runs a terminal emulation application to Telnet to the corporate network access server, an AS5200 local host named "hqnas." The remote user, named Bob, has the username "BobUser."
The following example replaces ACLs on the local host PPP interface. The ACLs previously applied to the interface during PPP authorization are replaced with ACLs defined in the per-user configuration AV pairs.
The remote user Telnets to the local host and logs in:
login: BobUser Password: <welcome> hqnas> access-profile
Bob is reauthenticated when he logs in to hqnas, because hqnas is configured for login AAA authentication using the corporate RADIUS server. When Bob enters the access-profile command, he is reauthorized with his per-user configuration privileges. This causes the access lists and filters in his per-user configuration to be applied to the network access server interface.
After the reauthorization is complete, Bob is automatically logged out of the AS5200 local host.
Related Commands
connect Logs in to a host that supports Telnet, rlogin, or LAT. telnet Logs in to a host that supports Telnet.
Command
Description
 |
Caution If you use a list-name value that was not configured with the aaa authentication arap command, ARA protocol will be disabled on this line. |
Syntax Description
default Default list created with the aaa authentication arap command. list-name Indicated list created with the aaa authentication arap command. one-time (Optional) Accepts the username and password in the username field.
Defaults
ARA protocol authentication uses the default set with aaa authentication arap command. If no default is set, the local user database is checked.
Command Modes
Line configuration
Command History
10.3 This command was introduced. 11.0 The one-time keyword was added.
Release
Modification
Usage Guidelines
This command is a per-line command that specifies the name of a list of AAA authentication methods to try at login. If no list is specified, the default list is used (whether or not it is specified in the command line). You create defaults and lists with the aaa authentication arap command. Entering the no version of arap authentication has the same effect as entering the command with the default keyword. Before issuing this command, create a list of authentication processes by using the aaa authentication arap global configuration command.
Examples
The following example specifies that the TACACS+ authentication list called MIS-access is used on ARA line 7:
line 7 arap authentication MIS-access
Related Commands
Enables an AAA authentication method for ARA using TACACS+.
Command
Description
To clear the list of remote hosts for which automated double authentication has been attempted, use the clear ip trigger-authentication command in privileged EXEC mode.
clear ip trigger-authenticationSyntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
11.3 T This command was introduced.
Release
Modification
Usage Guidelines
Use this command when troubleshooting automated double authentication. This command clears the entries in the list of remote hosts displayed by the show ip trigger-authentication command.
Examples
The following example clears the remote host table:
router# show ip trigger-authentication Trigger-authentication Host Table: Remote Host Time Stamp 172.21.127.114 2940514234 router# clear ip trigger-authentication router# show ip trigger-authentication router#
Related Commands
Displays the list of remote hosts for which automated double authentication has been attempted.
Command
Description
Syntax Description
timeout seconds (Optional) Specifies how frequently the local device sends a UDP packet to the remote host to request the user's username and password (or PIN). The default is 90 seconds. See "The Timeout Keyword" for details. port number (Optional) Specifies the UDP port to which the local router should send the UPD packet requesting the user's username and password (or PIN). The default is port 7500. See "The Port Keyword" for details.
Defaults
The default timeout is 90 seconds, and the default port number is 7500.
Command Modes
Global configuration
Command History
11.3 T This command was introduced.
Release
Modification
Usage Guidelines
Configure this command on the local device (router or network access server) that remote users dial in to. Use this command only if the local device has already been configured to provide double authentication; this command enables automation of the second authentication of double authentication.
The Timeout Keyword
During the second authentication stage of double authentication---when the remote user is authenticated---the remote user must send a username and password (or PIN) to the local device. With automated double authentication, the local device sends a UDP packet to the remote user's host during the second user-authentication stage. This UDP packet triggers the remote host to launch a dialog box requesting a username and password (or PIN).
If the local device does not receive a valid response to the UDP packet within a timeout period, the local device will send another UDP packet. The device will continue to send UDP packets at the timeout intervals until it receives a response and can authenticate the user.
By default, the UDP packet timeout interval is 90 seconds. Use the timeout keyword to specify a different interval.
(This timeout also applies to how long entries will remain in the remote host table; see the show ip trigger-authentication command for details.)
The Port Keyword
As described in the previous section, the local device sends a UDP packet to the remote user's host to request the user's username and password (or PIN). This UDP packet is sent to UDP port 7500 by default. (The remote host client software listens to UDP port 7500 by default.) If you need to change the port number because port 7500 is used by another application, you should change the port number using the port keyword. If you change the port number you need to change it in both places---both on the local device and in the remote host client software.
Examples
The following example globally enables automated double authentication and sets the timeout to 120 seconds:
ip trigger-authentication timeout 120
Related Commands
Specifies automated double authentication at an interface. Displays the list of remote hosts for which automated double authentication has been attempted.
Command
Description
Syntax Description
This command has no arguments or keywords.
Defaults
Automated double authentication is not enabled for specific interfaces.
Command Modes
Interface configuration
Command History
11.3 T This command was introduced.
Release
Modification
Usage Guidelines
Configure this command on the local router or network access server that remote users dial into. Use this command only if the local device has already been configured to provide double authentication and if automated double authentication has been enabled with the ip trigger-authentication (global) command.
This command causes double authentication to occur automatically when users dial into the interface.
Examples
The following example turns on automated double authentication at the ISDN BRI interface BRI0:
interface BRI0 ip trigger-authentication encapsulation ppp ppp authentication chap
Related Commands
Enables the automated part of double authentication at a device.
Command
Description
Syntax Description
default Uses the default list created with the aaa authentication login command. list-name Uses the indicated list created with the aaa authentication login command.
Defaults
Uses the default set with aaa authentication login.
Command Modes
Line configuration
Command History
10.3 This command was introduced.
Release
Modification
Usage Guidelines
This command is a per-line command used with AAA that specifies the name of a list of AAA authentication methods to try at login. If no list is specified, the default list is used (whether or not it is specified in the command line).
|
Caution If you use a list-name value that was not configured with the aaa authentication login command, you will disable login on this line. |
Entering the no version of login authentication has the same effect as entering the command with the default keyword.
Before issuing this command, create a list of authentication processes by using the global configuration aaa authentication login command.
Examples
The following example specifies that the default AAA authentication is to be used on line 4:
line 4 login authentication default
The following example specifies that the AAA authentication list called list1 is to be used on line 7:
line 7 login authentication list1
Related Commands
Sets AAA authentication at login.
Command
Description
Syntax Description
default Uses the default list created with the aaa authentication nasi command. list-name Uses the list created with the aaa authentication nasi command.
Defaults
Uses the default set with the aaa authentication nasi command.
Command Modes
Line configuration
Command History
11.1 This command was introduced.
Release
Modification
Usage Guidelines
This command is a per-line command used with AAA authentication that specifies the name of a list of authentication methods to try at login. If no list is specified, the default list is used, even if it is not specified in the command line. (You create defaults and lists with the aaa authentication nasi command.) Entering the no form of this command has the same effect as entering the command with the default argument.
|
Caution If you use a list-name value that was not configured with the aaa authentication nasi command, you will disable login on this line. |
Before issuing this command, create a list of authentication processes by using the aaa authentication nasi global configuration command.
Examples
The following example specifies that the default AAA authentication be used on line 4:
line 4 nasi authentication default
The following example specifies that the AAA authentication list called list1 be used on line 7:
line 7 nasi authentication list1
Related Commands
Specifies AAA authentication for NASI clients connecting through the access server. ipx nasi-server enable Enables NASI clients to connect to asynchronous devices attached to a router. show ipx nasi connections Displays the status of NASI connections. show ipx spx-protocol Displays the status of the SPX protocol stack and related counters.
Command
Description
Syntax Description
protocol1 [protocol2...] Specify at least one of the keywords described in Table 8. if-needed (Optional) Used with TACACS and extended TACACS. Does not perform CHAP or PAP authentication if the user has already provided authentication. This option is available only on asynchronous interfaces. list-name (Optional) Used with AAA. Specifies the name of a list of methods of authentication to use. If no list name is specified, the system uses the default. The list is created with the aaa authentication ppp command. default (Optional) The name of the method list is created with the aaa authentication ppp command. callin (Optional) Specifies authentication on incoming (received) calls only. one-time (Optional) Accepts the username and password in the username field.
Defaults
PPP authentication is not enabled.
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
When you enable CHAP, MS-CHAP or PAP authentication (or both), the local router requires the remote device to prove its identity before allowing data traffic to flow. PAP authentication requires the remote device to send a name and a password, which is checked against a matching entry in the local username database or in the remote security server database. CHAP authentication sends a Challenge to the remote device. The remote device encrypts the challenge value with a shared secret and returns the encrypted value and its name to the local router in a Response message. The local router attempts to match the remote device's name with an associated secret stored in the local username or remote security server database; it uses the stored secret to encrypt the original challenge and verify that the encrypted values match.
You can enable CHAP, MS-CHAP, or PAP in any order. If you enable all three methods, the first method specified is requested during link negotiation. If the peer suggests using the second method, or refuses the first method, the second method is tried. Some remote devices support only one method. Base the order in which you specify methods on the remote device's ability to correctly negotiate the appropriate method, and on the level of data line security you require. PAP usernames and passwords are sent as clear text strings, which can be intercepted and reused.
|
Caution If you use a list-name value that was not configured with the aaa authentication ppp command, you will disable PPP on this interface. |
Table 8 lists the protocols used to negotiate PPP authentication.
chap | Enables CHAP on a serial interface. |
|---|---|
ms-chap | Enables Microsoft's version of CHAP (MS-CHAP) on a serial interface. |
pap | Enables PAP on a serial interface. |
Enabling or disabling PPP authentication does not affect the local router's ability to authenticate itself to the remote device.
If you are using autoselect on a TTY line, you can use the ppp authentication command to turn on PPP authentication for the corresponding interface.
MS-CHAP is the Microsoft version of CHAP. Like the standard version of CHAP, MS-CHAP is used for PPP authentication; in this case, authentication occurs between a PC using Microsoft Windows NT or Microsoft Windows 95 and a Cisco router or access server acting as a network access server.
Enabling or disabling PPP authentication does not affect the local router's willingness to authenticate itself to the remote device.
If you are using autoselect on a TTY line, you probably want to use the ppp authentication command to turn on PPP authentication for the corresponding interface.
Examples
The following example enables CHAP on asynchronous interface 4 and uses the authentication list MIS-access:
interface async 4 encapsulation ppp ppp authentication chap MIS-access
Related Commands
Specifies one or more AAA authentication method for use on serial interfaces running PPP. aaa new-model Enables the AAA access control model. autoselect Configures a line to start an ARA, PPP, or SLIP session. encapsulation Sets the encapsulation method used by the interface. username Establishes a username-based authentication system, such as PPP CHAP and PAP.
Command
Description
Syntax Description
hostname The name sent in the CHAP challenge.
Defaults
Disabled. The router name is sent in any CHAP challenges.
Command Modes
Interface configuration
Command History
11.2 This command was introduced.
Release
Modification
Usage Guidelines
Currently, a router dialing a pool of access routers requires a username entry for each possible router in the pool because each router challenges with its hostname. If a router is added to the dialup rotary pool, all connecting routers must be updated. The ppp chap hostname command allows you to specify a common alias for all routers in a rotary group to use so that only one username must be configured on the dialing routers.
This command is normally used with local CHAP authentication (when the router authenticates to the peer), but it can also be used for remote CHAP authentication.
Examples
The following example identifies dialer interface 0 as the dialer rotary group leader and specifies ppp as the encapsulation method used by all member interfaces. This example shows that CHAP authentication is used on received calls only and the username ISPCorp will be sent in all CHAP challenges and responses.
interface dialer 0 encapsulation ppp ppp authentication chap callin ppp chap hostname ISPCorp
Related Commands
Specifies one or more AAA authentication methods for use on serial interfaces running PPP. Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface. Enables a router calling a collection of routers that do not support this command (such as routers running older Cisco IOS software images) to configure a common CHAP secret password to use in response to challenges from an unknown peer. Refuses CHAP authentication from peers requesting it. Specifies that the router will not authenticate to a peer requesting CHAP authentication until after the peer has authenticated itself to the router.
Command
Description
Syntax Description
secret The secret used to compute the response value for any CHAP challenge from an unknown peer.
Defaults
Disabled
Command Modes
Interface configuration
Command History
11.2 This command was introduced.
Release
Modification
Usage Guidelines
This command allows you to replace several username and password configuration commands with a single copy of this command on any dialer interface or asynchronous group interface.
This command is used for remote CHAP authentication only (when routers authenticate to the peer) and does not affect local CHAP authentication.
Examples
The commands in the following example specify ISDN Basic Rate Interface (BRI) number 0. The method of encapsulation on the interface is PPP. If a CHAP challenge is received from a peer whose name is not found in the global list of usernames, the encrypted secret 7 1267234591 is decrypted and used to create a CHAP response value.
interface bri 0 encapsulation ppp ppp chap password 7 1234567891
Related Commands
Specifies one or more AAA authentication methods for use on serial interfaces running PPP. Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface. Creates a pool of dialup routers that all appear to be the same host when authenticating with CHAP. Refuses CHAP authentication from peers requesting it. Specifies that the router will not authenticate to a peer requesting CHAP authentication until after the peer has authenticated itself to the router.
Command
Description
Syntax Description
callin (Optional) This keyword specifies that the router will refuse to answer CHAP authentication challenges received from the peer, but will still require the peer to answer any CHAP challenges the router sends.
Defaults
Disabled
Command Modes
Interface configuration
Command History
10.3 This command was introduced.
Release
Modification
Usage Guidelines
This command specifies that CHAP authentication is disabled for all calls, meaning that all attempts by the peer to force the user to authenticate using CHAP will be refused. If the callin keyword is used, CHAP authentication is disabled for incoming calls from the peer, but will still be performed on outgoing calls to the peer.
If outbound PAP has been enabled (using the ppp pap sent-username command), PAP will be suggested as the authentication method in the refusal packet.
Examples
The following example specifies ISDN Basic Rate Interface (BRI) number 0. The method of encapsulation on the interface is PPP. This example disables CHAP authentication from occurring if a peer calls in requesting CHAP authentication.
interface bri 0 encapsulation ppp ppp chap refuse
Related Commands
Specifies one or more AAA authentication methods for use on serial interfaces running PPP. Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface. Creates a pool of dialup routers that all appear to be the same host when authenticating with CHAP. Enables a router calling a collection of routers that do not support this command (such as routers running older Cisco IOS software images) to configure a common CHAP secret password to use in response to challenges from an unknown peer. Specifies that the router will not authenticate to a peer requesting CHAP authentication until after the peer has authenticated itself to the router.
Command
Description
Syntax Description
secret The secret used to compute the response value for any CHAP challenge from an unknown peer.
Defaults
Enabled
Command Modes
Interface configuration
Command History
10.3 This command was introduced.
Release
Modification
Usage Guidelines
This command (which is the default) specifies that the router will not authenticate to a peer requesting CHAP authentication until the peer has authenticated itself to the router. The no form of this command specifies that the router will respond immediately to an authentication challenge.
Examples
The following example specifies ISDN Basic Rate Interface (BRI) number 0. The method of encapsulation on the interface is PPP. This example disables the default, meaning that users do not have to wait for peers to complete CHAP authentication before authenticating themselves.
interface bri 0 encapsulation ppp no ppp chap wait
Related Commands
Specifies one or more AAA authentication methods for use on serial interfaces running PPP. Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface. Creates a pool of dialup routers that all appear to be the same host when authenticating with CHAP. Enables a router calling a collection of routers that do not support this command (such as routers running older Cisco IOS software images) to configure a common CHAP secret password to use in response to challenges from an unknown peer. Refuses CHAP authentication from peers requesting it.
Command
Description
ppp pap sent-username username password password
no ppp pap sent-username
Syntax Description
username Username sent in the PAP authentication request. password Password sent in the PAP authentication request. password Must contain from 1 to 25 uppercase and lowercase alphanumeric characters.
Defaults
Remote PAP support disabled.
Command Modes
Interface configuration
Command History
11.2 This command was introduced.
Release
Modification
Usage Guidelines
Use this command to reenable remote PAP support (for example to respond to the peer's request to authenticate with PAP) and to specify the parameters to be used when sending the PAP authentication request.
This is a per-interface command. You must configure this command for each interface.
Examples
The following example identifies dialer interface 0 as the dialer rotary group leader and specify PPP as the method of encapsulation used by the interface. Authentication is by CHAP or PAP on received calls only. ISPCorp is the username sent to the peer if the peer requires the router to authenticate with PAP.
interface dialer0 encapsulation ppp ppp authentication chap pap callin ppp chap hostname ISPCorp ppp pap sent username ISPCorp password 7 fjhfeu ppp pap sent-username ISPCorp password 7 1123659238
Related Commands
Specifies one or more AAA authentication methods for use on serial interfaces running PPP. Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface. Creates a pool of dialup routers that all appear to be the same host when authenticating with CHAP. Enables a router calling a collection of routers that do not support this command (such as routers running older Cisco IOS software images) to configure a common CHAP secret password to use in response to challenges from an unknown peer.
Command
Description
To view the list of remote hosts for which automated double authentication has been attempted, use the show ip trigger-authentication command in privileged EXEC mode.
show ip trigger-authenticationSyntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
11.3 T This command was introduced.
Release
Modification
Usage Guidelines
Whenever a remote user needs to be user-authenticated in the second stage of automated double authentication, the local device sends a UDP packet to the remote user's host. When the UDP packet is sent, the user's host IP address is added to a table. If additional UDP packets are sent to the same remote host, a new table entry is not created; instead, the existing entry is updated with a new time stamp. This remote host table contains a cumulative list of host entries; entries are deleted after a timeout period or after you manually clear the table using the clear ip trigger-authentication command. You can change the timeout period with the ip trigger-authentication (global) command.
Use this command to view the list of remote hosts for which automated double authentication has been attempted.
Examples
The following example shows output from the show ip trigger-authentication command:
myfirewall# show ip trigger-authentication Trigger-authentication Host Table: Remote Host Time Stamp 172.21.127.114 2940514234
This output shows that automated double authentication was attempted for a remote user; the remote user's host has the IP address 172.21.127.114. The attempt to automatically double authenticate occurred when the local host (myfirewall) sent the remote host (172.21.127.114) a packet to UDP port 7500. (The default port was not changed in this example.)
Related Commands
Clears the list of remote hosts for which automated double authentication has been attempted.
Command
Description
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
11.3(2)AA This command was introduced.
Release
Modification
Usage Guidelines
Use the show ppp queues command to display the number of requests handled by each AAA background process, the average amount of time it takes to complete each request, and the requests still pending in the work queue. This information can help you balance the data load between the network access server and the AAA server.
This command displays information about the background processes configured by the aaa processes global configuration command. Each line in the display contains information about one of the background processes. If there are AAA requests in the queue when you enter this command, the requests will be printed as well as the background process data.
Examples
The following example shows output from the show ppp queues command:
router# show ppp queues Proc #0 pid=73 authens=59 avg. rtt=118s. authors=160 avg. rtt=94s. Proc #1 pid=74 authens=52 avg. rtt=119s. authors=127 avg. rtt=115s. Proc #2 pid=75 authens=69 avg. rtt=130s. authors=80 avg. rtt=122s. Proc #3 pid=76 authens=44 avg. rtt=114s. authors=55 avg. rtt=106s. Proc #4 pid=77 authens=70 avg. rtt=141s. authors=76 avg. rtt=118s. Proc #5 pid=78 authens=64 avg. rtt=131s. authors=97 avg. rtt=113s. Proc #6 pid=79 authens=56 avg. rtt=121s. authors=57 avg. rtt=117s. Proc #7 pid=80 authens=43 avg. rtt=126s. authors=54 avg. rtt=105s. Proc #8 pid=81 authens=139 avg. rtt=141s. authors=120 avg. rtt=122s. Proc #9 pid=82 authens=63 avg. rtt=128s. authors=199 avg. rtt=80s. queue len=0 max len=499
Table 9 describes the fields shown in the example.
| Field | Description |
|---|---|
Proc # | Identifies the background process allocated by the aaa processes command to handle AAA requests for PPP. All of the data in this row relates to this process. |
pid= | Identification number of the background process. |
authens= | Number of authentication requests the process has performed. |
avg. rtt= | Average delay (in seconds) until the authentication request was completed. |
authors= | Number of authorization requests the process has performed. |
avg. rtt= | Average delay (in seconds) until the authorization request was completed. |
queue len= | Current queue length. |
max len= | Maximum length the queue ever reached. |
Related Commands
Allocates a specific number of background processes to be used to process AAA authentication and authorization requests for PPP.
Command
Description
Syntax Description
seconds Integer that determines the number of seconds the system will wait for login input before timing out. Available settings are from 1 to 300 seconds.
Defaults
The default login timeout value is 30 seconds.
Command Modes
Line configuration
Command History
11.3 This command was introduced.
Release
Modification
Examples
The following example changes the login timeout value to 60 seconds:
line 10 timeout login response 60
Posted: Tue Apr 4 17:28:13 PDT 2000
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