Assuming it's DCCP/IPv4 with no IP options, then the following
(untested) capture filter might work for you:
(dst 192.168.1.30) && (ip[0]==0x45) && (ip[9]==33) && (ip[20:2]==40001)
If not, then you'll likely need to check the man page as Bill suggests.
- Chris
> -----Original Message-----
> From: wireshark-dev-bounces@xxxxxxxxxxxxx [mailto:wireshark-dev-
> bounces@xxxxxxxxxxxxx] On Behalf Of Bill Meier
> Sent: Thursday, September 10, 2009 9:26 AM
> To: Developer support list for Wireshark
> Subject: Re: [Wireshark-dev] libpcap support for capturing DCCP
packets
> with specific port?
>
> Ktawut T.Pijarn wrote:
>
> > However, I also need to differentiate different DCCP
> > connections using different DCCP ports too but libpcap doesn't
> capture
> > anything for me when I specify the desired port in addition to the
IP
> > address in the capture filter, e.g. "dst 192.168.1.30 and src port
> 40001".
> > It just does not capture anything for me.
> >
> > So, is there a special syntax for pcap to specify the DCCP port, if
> that is
> > available at all?
> >
>
> It appears that DCCP runs on top of IP and thus "DCCP port" is
> specified
> in the DCCP payload.
>
> I strongly doubt that DCCP is a protocol which can be specified in a
> libpcap Capture Filter (and thus can be decoded to determine the DCCP
> port).
>
> From the man tcpdump section about Capture filters:
>
> "dst port port
> True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and
has
> a
> destination port value of port. The port can be a number or a
> name
> "
>
>
> As the Wireshark man pages say:
>
> "Capture Filter Syntax
> See the manual page of pcap-filter(4) or, if that doesn't exist,
> tcpdump(8)."
>
> for all the gory details about using Capture filters. :)
>
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