Michael Horowitz
The firewall in my router blocks outbound traffic to port 137. And idea why Windows 10 tries to contact Windows Update servers on UDP port 137? First IP is sls.update.microsoft.com, second is *.delivery.mp.microsoft.com
Nov 16, 2023 at 9:47pmWeb
Show threadLucas B. Cohen 🍇Nov 21, 2023

@defensivecomputing Looks like a last-resort attempt at name resolution by gethostbyaddr(): https://community.fortinet.com/t5/Support-Forum/UDP-137-Traffic-to-Microsoft-during-Windows-Update/m-p/71041

This machine might be experiencing transient issues with talking to DNS servers.

UDP 137 Traffic to Microsoft during Windows Update

Was working on a Windows 7 Pro x64 laptop. Was having trouble using the Dell Client Update so I enabled a real-time traffic monitor in my FAZ. A little while later I was prompted to apply 13 Windows Updates, almost all related to .NET 4 Client. I started noticing UDP 137 calls to the following IPs: ...