Login Password Retry Lockout

The Login Password Retry Lockout feature allows system administrators to lock out a local authentication, authorization, and accounting (AAA) user account after a configured number of unsuccessful attempts by the user to log in.

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Prerequisites for Login Password Retry Lockout

  • You must be running a Cisco IOS image that contains the AAA component.

Restrictions for Login Password Retry Lockout

  • Authorized users can lock themselves out because there is no distinction between an attacker who is guessing passwords and an authorized user who is entering the password incorrectly multiple times.

  • A denial of service (DoS) attack is possible; that is, an authorized user could be locked out by an attacker if the username of the authorized user is known to the attacker.

Information About Login Password Retry Lockout

Lock Out of a Local AAA User Account

The Login Password Retry Lockout feature allows system administrators to lock out a local AAA user account after a configured number of unsuccessful attempts by the user to log in using the username that corresponds to the AAA user account. A locked-out user cannot successfully log in again until the user account is unlocked by the administrator.

A system message is generated when a user is either locked by the system or unlocked by the system administrator. The following is an example of such a system message:

%AAA-5-USER_LOCKED: User user1 locked out on authentication failure.

The system administrator cannot be locked out.


Note

The system administrator is a special user who has been configured using the maximum privilege level (root privilege--level 15). A user who has been configured using a lesser privilege level can change the privilege level using the enable command. A user that can change to the root privilege (level 15) is able to act as a system administrator.

This feature is applicable to any login authentication method, such as ASCII, Challenge Handshake Authentication Protocol (CHAP), and Password Authentication Protocol (PAP).


Note

No messages are displayed to users after authentication failures that are due to the locked status (that is, there is no distinction between a normal authentication failure and an authentication failure due to the locked status of the user).

How to Configure Login Password Retry Lockout

Configuring Login Password Retry Lockout

To configure the Login Password Retry Lockout feature, perform the following steps.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    username name [privilege level] password encryption-type password

    4.    aaa new-model

    5.    aaa local authentication attempts max-fail number-of-unsuccessful-attempts

    6.    aaa authentication login default method


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 username name [privilege level] password encryption-type password


    Example: 
    Device(config)# username user1 privilege 15 password 0 cisco
     

    Establishes a username-based authentication system.

     
    Step 4 aaa new-model


    Example: 
    Device(config)# aaa new-model
     

    Enables the AAA access control model.

     
    Step 5 aaa local authentication attempts max-fail number-of-unsuccessful-attempts


    Example: 
    Device(config)# aaa local authentication attempts max-fail 3
     

    Specifies the maximum number of unsuccessful attempts before a user is locked out.

     
    Step 6 aaa authentication login default method


    Example: 
    Device(config)# aaa authentication login default local
     

    Sets the authentication, authorization, and accounting (AAA) authentication method at login. For example, aaa authentication login default local specifies the local AAA user database.

     

    Unlocking a Login Locked-Out User

    To unlock a login locked-out user, perform the following steps.


    Note

    This task can be performed only by users having the root privilege (level 15).

    SUMMARY STEPS

      1.    enable

      2.    clear aaa local user lockout {username username | all}


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example: 
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 clear aaa local user lockout {username username | all}


      Example: 
      Device# clear aaa local user lockout username user1
       

      Unlocks a locked-out user.

       

      Clearing the Unsuccessful Login Attempts of a User

      This task is useful for cases in which the user configuration was changed and the unsuccessful login attempts of a user that are already logged must be cleared.

      To clear the unsuccessful login attempts of a user that have already been logged, perform the following steps.

      SUMMARY STEPS

        1.    enable

        2.    clear aaa local user fail-attempts {username username | all}


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example: 
        Device> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 clear aaa local user fail-attempts {username username | all}


        Example: 
        Device# clear aaa local user fail-attempts username user1
         

        Clears the unsuccessful attempts of the user.

        • This command is useful for cases in which the user configuration was changed and the unsuccessful attempts that are already logged must be cleared.

         

        Monitoring and Maintaining Login Password Retry Lockout Status

        To monitor and maintain the status of the Login Password Retry Lockout configuration, perform the following steps.

        SUMMARY STEPS

          1.    enable

          2.    show aaa local user lockout


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable


          Example: 
          Device> enable
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.

           
          Step 2 show aaa local user lockout


          Example: 
          Device# show aaa local user lockout
           

          Displays a list of the locked-out users for the current login password retry lockout configuration.

           

          Example

          The following output shows that user1 is locked out: 

          Device# show aaa local user lockout
           Local-user          Lock time
           user1               04:28:49 UTC Sat Jun 19 2004

          Configuration Examples for Login Password Retry Lockout

          Displaying the Login Password Retry Lockout Configuration Example

          The following show running-config command output illustrates that the maximum number of failed user attempts has been set for 2 as the login password retry lockout configuration: 

          Device # show running-config
Building configuration...
Current configuration : 1214 bytes
!
version 12.3
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname LAC-2
!
boot-start-marker
boot-end-marker
!
!
username sysadmin
username sysad privilege 15 password 0 cisco
username user1 password 0 cisco
aaa new-model
aaa local authentication attempts max-fail 2
!
!
aaa authentication login default local
aaa dnis map enable
aaa session-id common

          Additional References

          The following sections provide references related to Login Password Retry Lockout.

          Related Documents

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          Cisco IOS security commands

          Cisco IOS Security Command Reference

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          Feature Information for Login Password Retry Lockout

          The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

          Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.
          Table 1 Feature Information for Login Password Retry Lockout

          Feature Name

          Releases

          Feature Information

          Login Password Retry Lockout

          Cisco IOS XE Release 3.9S

          The Login Password Retry Lockout feature allows system administrators to lock out a local AAA user account after a configured number of unsuccessful attempts by the user to log in.

          The following commands were introduced or modified: aaa local authentication attempts max-fail, clear aaa local user fail-attempts, clear aaa local user lockout.

          Glossary

          • local AAA method --Method by which it is possible to configure a local user database on a router and to have AAA provision authentication or authorization of users from this database.

          • local AAA user --User who is authenticated using the local AAA method.