Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a strange issue while trying to capture RTP (UDP) traffic. I have a phone using IP and a Windows 2003 PC connected to the same switch (actually to the monitor port of the switch - that's how I'm able to sniff the traffic).

When I run:

windump -i <interface_name> -tnnq

I can see all the RTP traffic of an open VOIP connection, but when I run:

windump -i <interface_name> -tnnq host

.. or even ..

windump -i <interface_name> -tnnq udp

I cannot see RTP traffic at all.

I'm using RTP in the description because I think I saw 1 UDP packet - ARP somewhere during my tests, so maybe not all UTP is affected.

I tried to connect my laptop to the monitoring port (Win7) and on both scenarios it worked OK (I was able to see RTP traffic from the phone).

Any ideas what can I check to find out what's wrong in the config of my Windows 2003 machine?

share|improve this question

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.