4.5 Handling the Potential Internet Agent Port Conflict

By default, Linux servers run the Postfix mail program. It typically uses an IP address of 127.0.0.1 and listens on port 25, which is the default for SMTP communication. By default, the GWIA binds to all IP addresses on the server and it also uses port 25. As a result, if Postfix is running on the Linux server, the GWIA cannot start because port 25 is already in use.

Occasionally, Postfix might be configured to listen on a different IP address. This would also cause a conflict if the GWIA is configured to use the same IP address. On the Linux server, use the following command to test for conflicts:

telnet IP_address 25

If you receive a response, then something is already listening on the specified IP address.

To resolve the conflict, you can bind the GWIA to a specific IP address that is not the address used by Postfix. As an alternative, you can disable Postfix. Disabling Postfix is not the preferred solution, because Postfix is responsible for sending system messages to the administrator.

GROUPWISE MIGRATION WORKSHEET

Under Item 10: Internet Agent Information, mark whether you want to bind the GWIA to a specific IP address and specify the IP address.

If you decide that you want to disable Postfix, rather than binding the GWIA to a specific IP address, you can do it now, during the planning phase, so that the Linux server is ready for the GWIA to run on it.

  1. In a terminal window at the Linux server, log in as root.

  2. Enter the following commands:

    /etc/init.d/postfix stop
    chkconfig postfix off
    
  3. To ensure that Postfix is not running, enter the following command:

    ps -eaf | grep postfix
    

    You should see no Postfix processes running. The server is now ready for the GWIA to run on it.