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Blocking UDP 137

Posted on 2006-06-26
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Last Modified: 2010-03-19
Hello there!

I have a situation that is somewhat suspicious.  I notice in my router log requests to an outside IP address on UDP port 137 from an XP workstation on my LAN.  

The external IP is from a network that I used to log into via Cisco VPN client software (although the IP address of the PIX I used to log into is not the same as the address in my firewall).

I don't see any Cisco related processes running in task manager.  

I guess my question is two-fold:

1.  How can I track down the process that is generating these requests

2.  How can I use netsh to block the requests

Thanks in advance!
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Question by:ttist25
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naveedb earned 500 total points
ID: 16989424
To see which application is trying to connect, download the following software and run it on the workstation;

http://www.sysinternals.com/Utilities/TcpView.html

Most likely, the workstations is tryint to do NetBIOS name resolution. If you are using pure windows XP environment, you can disable Netbios resolution by going into Advanced TCP/IP properties under WINS.

The better method however would be to block it on the firewall.
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by:ttist25
ID: 17010767
Thanks naveedb.  That seems to have stopped the requests.  I can't figure out what process is causing it to call out though.  

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