[Ethereal-users] Re: Dissector based on UDP Src or Dst port to find the direction of packets

["ronnie sahlberg" <ronniesahlberg@xxxxxxxxx>]

you can check pinfo->srcport/pinfo->dstport at runtime


On 7/11/06, Vasanthi Ramasamy <Vasanthi.Ramasamy@xxxxxxxxxxxxxx> wrote:
> Hi,
>
>
>
> I'm new to Ethereal dissectors. I'm trying to write a dissector for a
> VOIP proprietary protocol. It is based on UDP. Phone uses a specific
> port number say X to communicate with the PBX. And the PBX uses port Y
> to communicate with the phone. X and Y are fixed. My problem is, I need
> to find the direction of the packet like who is talking to whom (Phone
> to PBX Or PBX to Phone?). That can be done only by analyzing the UDP
> Source or Destination port numbers. I tried using the following function
> call ->
>
>
>
> dissector_add("udp.srcport", PORT_NO, my_handle);
>
>
>
> but that gave me a runtime fatal error. It's my understanding that I
> can't use "udp.srcport"  for dissector_add(). If I use "udp.port",
> things work fine.  But with "udp.port" I can't find the direction of the
> packet.
>
>
>
> Is there any other solution for this problem ?  All I need is to find
> the direction of the packets.
>
>
>
> Thanks in advance,
>
> Vasanthi