A more robust filter that does not rely on fixed-length IP headers:
(dst 192.168.1.30) && (ip[9]==33) && (ip[((ip[0]&0x0f)<<2):2]==40001)
I did not test this exact filter but one very close to it for capturing
GRE packets where ip[9]==47 and a different 2-byte field match within
the GRE header.
- Chris
> -----Original Message-----
> From: wireshark-dev-bounces@xxxxxxxxxxxxx [mailto:wireshark-dev-
> bounces@xxxxxxxxxxxxx] On Behalf Of Guy Harris
> Sent: Thursday, September 10, 2009 2:32 PM
> To: Developer support list for Wireshark
> Subject: Re: [Wireshark-dev] libpcap support for capturing DCCP
packets
> withspecific port?
>
>
> On Sep 10, 2009, at 12:50 AM, Ktawut T.Pijarn wrote:
>
> > Dear all the experts on pcap/wireshark
>
> The official place to reach the experts on pcap is tcpdump-
> workers@xxxxxxxxxxx
> (tcpdump and libpcap both come from the same group).
>
> However, there are core libpcap developers who are also core Wireshark
> developers, so some of us will see them either way.
>
> > So, is there a special syntax for pcap to specify the DCCP port, if
> > that is
> > available at all?
>
> Unfortunately, there currently isn't any DCCP capture filter support
> in libpcap.
>
> I'll look at adding it at some point, but it probably won't be in any
> release soon. (Neither libpcap nor tcpdump nor Wireshark are my day
> job, and there's a bunch of other stuff going on as well.)
>
> Chris Maynard's workaround is worth trying.
>
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