Exclusive Configuration Change Access and Access Session Locking

Exclusive Configuration Change Access (also called the “Configuration Lock” feature) allows you to have exclusive change access to the Cisco IOS XE running configuration, preventing multiple users from making concurrent configuration changes.

The Access Session Locking addition to this feature extends the Exclusive Configuration Change Access feature such that show and debug commands entered by the user holding the configuration lock always have execution priority; show and debug commands entered by other users are only allowed to run after the processes initiated by the configuration lock owner have finished.

The Exclusive Configuration Change Access feature (“exposed lock”) is complementary with the locking mechanism in the Configuration Replace and Configuration Rollback feature (“rollback lock”).

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Information About Locking the Configuration

Exclusive Configuration Change Access and Access Session Locking

Devices running Cisco IOS software maintain a running configuration that determines the configuration state of the device. Changes to the running configuration alter the behavior of the device. Because Cisco IOS software allows multiple users to change the running configuration via the device CLI (including the device console and telnet Secure Shell (SSH)), in some operating environments it would be beneficial to prevent multiple users from making concurrent changes to the Cisco IOS running configuration. Temporarily limiting access to the Cisco IOS running configuration prevents inadvertent conflicts or cases where two users attempt to configure the same portion of the running configuration.

The Exclusive Configuration Change Access feature (also called the “Configuration Lock” feature) allows you to have exclusive change access to the Cisco IOS running configuration, preventing multiple users from making concurrent configuration changes.

This feature provides exclusive change access to the Cisco IOS running configuration from the time you enter global configuration mode by using the configure terminal command. This gives the effect of a “configuration lock,” preventing other users from changing the Cisco IOS running configuration. The configuration lock is automatically released when the user exits Cisco IOS configuration mode.

The Exclusive Configuration Change Access feature is enabled using the configuration mode exclusive command in global configuration mode. Exclusive configuration change access can be set to auto , so that the Cisco IOS configuration mode is locked whenever anyone uses the configure terminal command, or it can be set to manual , so that the Cisco IOS configuration mode is locked only when the configure terminal lock command is issued.

The Exclusive Configuration Change Access feature is complementary with the locking mechanism for the Configuration Replace and Configuration Rollback feature introduced in Cisco IOS Release 12.2(25)S and 12.3(7)T.

Access Session Locking

The Access Session Locking feature extends the Exclusive Configuration Change Access feature such that show and debug commands entered by the user holding the configuration lock always have execution priority. This feature prevents concurrent configuration access and also provides an option to prevent simultaneous processes, such as a show command entered by another user, from executing while other configuration commands are being executed. When this feature is enabled, the commands entered by the user with the configuration lock (such as configuration commands) always have priority over commands entered by other users.

How to Configure Configuration Exclusive Confguration Change-Access and Access Session Locking

Enabling Exclusive Configuration Change Access and Access Session Locking


Note

Effective with Cisco IOS Release 12.2(33)SRE, the Exclusive Configuration Change Access and Access Session Locking feature is not available in Cisco IOS software. Use the Parser Concurrency and Locking Improvements feature instead of this feature. See the “Enabling Parser Concurrency and Locking Improvements” section for more information.

Perform this task to enable the Exclusive Configuration Change Access and Access Session Locking feature.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. configuration mode exclusive
  4. end

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

configuration mode exclusive

Example:


Router(config)# configuration mode exclusive

Enables exclusive configuration change access (configuration lock feature).

  • When the command is enabled, configuration sessions are performed in single-user (exclusive) mode.

  • Execution of this command locks the configuration sessions automatically.

Step 4

end

Example:


Router(config)# end

Ends your configuration session and returns the CLI to privileged EXEC mode.

Obtaining Exclusive Configuration Change Access

Perform this task to obtain exclusive configuration change access manually for the duration of your configuration session. Use the lock keyword with the configure terminal command.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. configure terminal lock
  4. Configure the system by entering your changes to the running configuration.
  5. Do one of the following:
    • end
    • or
    • exit

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

configure terminal lock

Example:


Router(config)# configure terminal lock

(Optional) Locks the Cisco IOS software in exclusive (single-user) mode.

  • This command can be used only if you have previously enabled configuration locking by using the configuration mode exclusive command.

    Note 

    This command is not required for performing a manual lock.

  • This command is available in Cisco IOS Release 12.3(14)T or later releases.

Step 4

Configure the system by entering your changes to the running configuration.

--

Step 5

Do one of the following:

  • end
  • or
  • exit

Example:


Router(config)# end

Example:

Example:


Router(config)# exit

Ends your configuration session, automatically releases the session lock obtained in Step 1, and exits to privileged EXEC mode.

Note 

Either the end command, the exit command, or the Ctrl-Z key combination releases the configuration lock. Use of the end command is recommended.

Monitoring and Troubleshooting Configuration Locking

Perform either or both steps in this task to monitor or troubleshoot the Exclusive Configuration Change Access and Access Session Locking feature.

SUMMARY STEPS

  1. show configuration lock
  2. debug configuration lock

DETAILED STEPS

Step 1

show configuration lock

Use this command to display the status and details of any current configuration locks, including the owner, user, terminal, lock state, and lock class.

If you cannot enter global configuration mode, you can use this command to determine if the configuration session is locked by another user, and who that user is.

Example:


Router# show configuration lock
Config Session Lock
------------------------------------------------------
Owner PID : 543
TTY number : 2
TTY username : unknown
User debug info : CLI Session Lock
Lock Active time (in Sec) : 63
Router(config)#

Step 2

debug configuration lock

Use this command to enable debugging of Cisco IOS configuration locks (exposed class locks or rollback class locks):

Example:


Router# debug configuration lock
 
Session1 from console
==========================
Router# configure terminal lock 
Configuration mode locked exclusively. The lock will be cleared once you exit out of configuration mode using end/exit
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#
Parser : LOCK REQUEST in EXCLUSIVE mode
Parser: <configure terminal lock> - Config. Lock requested by process <3> client <PARSER Client>
Parser: <configure terminal lock> - Config. Lock acquired successfully !
Router(config)#

Configuration Examples for Locking the Configuration

Configuring an Exclusive Lock in Auto Mode Example

The following example shows how to enable the exclusive lock in auto mode for single-user auto configuration mode using the configurationmodeexclusive command. Once the Cisco IOS configuration file is locked exclusively, you can verify this configuration by using the showconfigurationlock command. 


Router# configure terminal 
Router(config)# configuration mode exclusive
Router(config)# exit 
Router# configure terminal 
! Locks configuration mode exclusively.
Router# show configuration lock
Parser Configure Lock
Owner PID        :  10
User             :  User1
TTY              :  3
Type             :  EXCLUSIVE
State            :  LOCKED
Class            :  Exposed 
Count            :  0 
Pending Requests :  0 
User debug info  :  0

Configuring an Exclusive Lock in Manual Mode Example

The following example shows how to enable the exclusive locking feature in manual mode by using the configure terminal lock command. Use the configure terminal lock command to lock manually. In this mode, the configure terminal command will not automatically lock the parser configuration mode. 


Router# configure terminal
Router# configure terminal lock
Enter configuration commands, one per line.  End with CNTL/Z.
*Mar 25 17:02:45.928:  Configuration mode locked exclusively. The lock will be cleared once you exit out of configuration mode using end/exit

Additional References

The following sections provide references related to locking the configuration.

Related Documents

Related Topic

Document Title

Commands for managing configuration files

Cisco IOS Configuration Management Command Reference

Information about managing configuration files

Managing Configuration Files

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

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MIBs

MIB

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

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

RFC

Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

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Description

Link

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