What port is used to authenticate to a server?

Posted on 2011-10-26
Last Modified: 2012-05-12
I have a site that has no DC but authenticates to a server across a VPN. I am thinking that one of the ports is being blocked by a piece of hardware. What port is used to authenticate a user to the domain? I have a packet capture at the server end to be able to monitor if it is coming in or not.
Question by:pamplinit
    LVL 39

    Accepted Solution

    Hi, plese check these ports if they are allowed on firewall

    TCP/UDP 135
    TCP/UDP 137
    TCP/UDP 53
    TCP/UDP 88
    TCP 3268
    TCP 389
    TC/UDP 445

    for reference, please check this Microsoft document at


    Author Closing Comment

    Solution was good - put me in the right direction; had to figure out some additional things along the way, but that's typical. Thanks.

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