XADM: How to Change LDAP Port Assignments in Exchange Server

When you attempt to start the LDAP Server Service for ports 389 and 636, after you install Exchange Server on a computer running Windows 2000, you may find the following Event IDs in the Application Event Log.

Windows 2000 uses its own LDAP Server service which initializes prior to Exchange Server's LDAP Server service. This service uses Ports 389 and 636. When Exchange Server starts, the Exchange Directory attempts to initialize the same ports (for Secure Sockets Layer connectivity). The above stop errors are generated for this initialization failure.

Within the Exchange Administrator program, you have the ability to change the LDAP well-known port of 389 to another port that is currently not in use.

NOTE: Use caution when you select a new port number. For additional information, click the article number below to view the article in the Microsoft Knowledge Base: This article lists many of the port numbers that Microsoft services use. For example, if you change the port number from 389 to 3389 and then install Microsoft Terminal Services, a Terminal Services client will be unable to connect to the computer that is running Termianl Services because Terminal Services listens on port 3389 by default.

To change the port assignment for the Exchange Server LDAP service:

1. Start the Exchange Server Administrator program.
2. To change LDAP port assignments for all servers within the Site, make the following changes:
   1. Expand on Site Name\Configuration\Protocols\LDAP (Directory) Site Defaults object.
   2. Change the port assignment from 389 to a port which is currently not in use. This can be done by going to a command prompt, and typing the following command:
      netstat -an
      This command will display all active ports that are listening on all interfaces. Choose a port number that does not conflict with any of those ports that are in use.
   3. Click OK, stop, and restart the Exchange Directory service.
   Now all servers within the site will listen for LDAP requests on the newly assigned port. This requires Use site defaults for all properties to be selected for the LDAP protocol on each of the servers within the site.
   
   
3. To change LDAP port assignments for individual servers within the Site, make the following changes:
   1. Expand on Site Name\Configuration\Servers\Protocols\LDAP (Directory) Settings object.
   2. Change the port assignment from 389 to a port which is currently not in use. This can be done by going to a command prompt, and typing the following command:
      netstat -an
      This command will display all active ports that are listening on all interfaces. Choose a port number that does not conflict with any of these ports.
   3. Click to clear the Use site defaults for all properties option, which will direct the server to read the newly assigned LDAP port instead of using the port assignment from the Site Configuration.
   4. Click OK, stop, and restart the Exchange Directory service.

Now these specifically-configured servers within the site will listen for LDAP requests on the newly assigned port.

To change the SSL port assignment for LDAP within Exchange Server, please refer to the following Knowledge Base article: