Wireshark-users: Re: [Wireshark-users] Capture Specific Ports
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From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Fri, 15 Jun 2007 09:16:08 -0700
Les Bowditch wrote:
Currently, the above syntax is capturing _/everything/_, not just the specified ports. Is the syntax incorrect, 

Yes.

From the man page:

  -d  <layer type>==<selector>,<decode-as protocol>
      Specify that if the layer type in question (for example, tcp.port
      or udp.port for a TCP or UDP port number) has the specified selec-
      tor value, packets should be dissected as the specified protocol.

      Example: -d tcp.port==8888,http will decode any traffic running
      over TCP port 8888 as HTTP.
The "-d" flag doesn't affect what gets captured; it affects how what gets captured is *interpreted*.
And if you're running with "-w" and without "-S", no dissection, and no interpretation, is done, so not only does "-d" not affect what gets captured, it doesn't affect *anything* in your example. 

What you want is
tshark -w /home/active_cap/ -b duration:900 -b filesize:50000 -i vr0 tcp port 5060 or tcp port 6800 or tcp port 6801 or tcp port 6802