ADMIN_RESTRICTIONS_listener_name=on

Oracle Listener: ADMIN_RESTRICTIONS Parameter

The ADMIN_RESTRICTIONS_<listener_name> parameter in the listener.ora file is a security feature that controls the ability to modify listener parameters at runtime using the LSNRCTL SET command.

Purpose and Functionality

• Parameter Name: ADMIN_RESTRICTIONS_<listener_name>

• Location: listener.ora file (typically located in $ORACLE_HOME/network/admin/)

• Value: ON or OFF (default is OFF)

When ADMIN_RESTRICTIONS_<listener_name> is set to ON, it disables the runtime modification of parameters within the listener.ora file via the LSNRCTL utility. Specifically:

• The listener will refuse to accept SET commands that attempt to alter its parameters (e.g., LSNRCTL SET LOG_FILE listener.log).

• This includes attempts to change ADMIN_RESTRICTIONS_<listener_name> itself at runtime.

How to Change Parameters with ADMIN_RESTRICTIONS Set to ON

If ADMIN_RESTRICTIONS_<listener_name> is ON, and you need to modify any listener parameter:

1. Manually edit the listener.ora file: Open the listener.ora file with a text editor.

2. Make the desired changes: Modify the parameter values as required.

3. Reload listener parameters: Use the RELOAD command from LSNRCTL to apply the new changes without explicitly stopping and restarting the listener.

   lsnrctl reload <listener_name>
   
   

   (Replace <listener_name> with the actual name of your listener, e.g., LISTENER)

Security Benefit

This parameter is particularly useful as a security measure if the listener is not password-protected.

• Without ADMIN_RESTRICTIONS set to ON and without a password, anyone with access to the server could potentially use LSNRCTL SET commands to alter listener behavior, potentially compromising database security or availability.

• By setting ADMIN_RESTRICTIONS to ON, you add a layer of protection, preventing unauthorized runtime changes even if the listener is not password-secured. It forces all configuration changes to be made directly in the listener.ora file, which typically has more restricted file system permissions.

In summary, ADMIN_RESTRICTIONS_<listener_name>=ON enhances listener security by enforcing that all parameter modifications are done through direct file editing and a RELOAD command, rather than dynamic SET commands, especially when the listener is not password-protected.