Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4

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Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4

Chapter Title

Login Password Retry Lockout

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Updated:
March 26, 2008

Chapter: Login Password Retry Lockout


Login Password Retry Lockout

First Published: March 24, 2005
Last Updated: November 20, 2009

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.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 for Login Password Retry Lockout" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.

Contents

•Prerequisites for Login Password Retry Lockout

•Restrictions for Login Password Retry Lockout

•Information About Login Password Retry Lockout

•How to Configure Login Password Retry Lockout

•Configuration Examples for Login Password Retry Lockout

•Additional References

•Feature Information for Login Password Retry Lockout

•Glossary

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

To configure the Login Password Retry Lockout feature, you should understand the following concept:

•Lock Out of a Local AAA User Account

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

This section contains the following procedures:

•Configuring Login Password Retry Lockout (optional)

•Unlocking a Login Locked-Out User (optional)

•Clearing the Unsuccessful Login Attempts of a User (optional)

•Monitoring and Maintaining Login Password Retry Lockout Status (optional)

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 Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3  

username name [privilege level] password 
encryption-type password
Example: 
Router(config)# username user1 privilege 15 
password 0 cisco

Establishes a username-based authentication system.

Step 4 

aaa new-model

Example:

Router(config)# aaa new-model

Enables the AAA access control model.

Step 5 

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

Example:

Router(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:

Router(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 Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

clear aaa local user lockout {username username | all}

Example:

Router# 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 Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

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

Example:

Router# 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 Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

show aaa local user lockout

Example:

Router# show aaa local user lockout

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

Examples

The following output shows that user1 is locked out: 

Router# 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

This section provides the following configuration examples:

•Displaying the Login Password Retry Lockout Configuration: Example

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: 

Router # 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

Related Topic
Document Title

Cisco IOS security commands

Cisco IOS Security Command Reference


Standards

Standards
Title

None

—


MIBs

MIBs
MIBs Link

None

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


RFCs

RFCs
Title

None

—


Technical Assistance

Description
Link

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

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

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

http://www.cisco.com/techsupport


Feature Information for Login Password Retry Lockout

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.

Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.

Table 1 Feature Information for Login Password Retry Lockout 

Feature Name
Releases
Feature Information

Login Password Retry Lockout

12.3(14)T 12.2(33)SRE

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.

This feature was introduced in Cisco IOS Release 12.3(14)T.

This feature was integrated into Cisco IOS Release 12.2(33)SRE.

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.

Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2005-2009 Cisco Systems, Inc. All rights reserved.

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