October 23, 2020

Open UDP port 123 on Windows Firewall (Network Time Protocol)

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On my internet time post there seems to be a lot of questions based on the firewall questions. Unfortunately I cant help every single person with every single different type of firewall. I will go through how to enable the Windows Firewall with explicit rules for inbound and outbound traffic that might help with others.

There are many ways to get this into the rules but here is the one I find easiest.

  1. Go to the Start menu and type Security Center in the search box and start it up. Then in the left pane click Windows Firewall

  2. On the Windows Firewall window in the left pane click Allow a program through Windows Firewall

  3. You should now have the Windows Firewall Settings window up. Click on the Exceptions tab. At the bottom of that tab click the button Add port

  4. In the Add a Port window fill out the information requested in this case it will be Internet Time Server, 123, and choose UDP for the protocol. Click Ok

  5. That should be it! As you can see it will now be added to the list of exceptions, so we can click Ok

  6. Hopefully this will help those of you that have been having troubles with the Internet Time Server portion of Vista.

As a added bonus here is a mini instruction to open the port for Mcafee Security Center I found: (No screenshots because I don’t use this product)

Configure -> Internet & Firewall -> Firewall Protection -> Advanced -> System Services -> Network Time Protocol Port 123


  1. my defensewall firewall tells

    Attempt to set value Desktop within the key HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\
    Attempt to post message 412 into the window of the process D:\WINDOWS\explorer.exe.
    Attempt of connect to the UDP port 123
    Attempt to set value Common AppData within the key HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\
    what does it mean is it hacked

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