We have a Windows 2003 R2 server. And are trying to connect to it via LDAP, there so far are no firewalls, or other blocking systems in place, However it seems we cannot connect to it via LDAP over port 389.

Is there something i have to set to enable it? IF it is disabled how can i renable it?

Anyone know what i can do to verify everything?

The computer is a PDC.


  • Have you confirmed DNS is functional? – Campo Mar 29 '11 at 16:43
  • Locally, yes... remotely no... we use this box for testing, and we access it via IP. – grmartin Mar 29 '11 at 17:04

You can verify if the server is listening for requests by running the netstat command like this:

netstat -ano

In the output, look for entries like this:


UDP <serverIP>:389 *:* 123

The number in the last column is the process ID of whatever is listening on the ports. Run the tasklist command to validate that the Local Security Authority (this is the Net Logon service) is the one listening:

tasklist /FI "PID eq 123"

You should see output like this (image name should be lsass.exe):

lsass.exe 488 Console 0 32,292 K

Generally, if you do not see this service running (and the server listening on port 389) it means that probably DNS is not configured correctly, but it could be other problems. If Net Logon won't start, look in the event log to see why. The first place to go with any errors is http://www.eventid.net/

If it is started then it's very likely there is some kind of firewall software (or network hardware based firewall) that is blocking the port. It is easy to overlook software based firewalls or discover that someone else has added an incorrect acl to a network switch or router.

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  • Following the line of thought here... i put an LDAP browser on the server itself... Everything worked... Turned out the engineer who started the box, neglected to turn off Windows Firewall. As such, and since i wouldnt have figured it out without the first command... i am giving the correct answer to the above. Thank you. – grmartin Mar 31 '11 at 11:50

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