Wireshark mailing list archives
Re: specifying > 4 byte offsets / capture filters
From: Guy Harris <guy () alum mit edu>
Date: Mon, 8 Oct 2012 10:54:10 -0700
On Oct 8, 2012, at 10:33 AM, Stuart Kendrick <skendric () fhcrc org> wrote:
I want to capture ARP Requests/Responses around a particular MAC address (I'm looking for a rogue node intermittently impersonating this address). Thus, I want to filter on the ARP fields: Sender MAC Address and Target MAC Address
...
Trying a simpler capture filter: ether[22:6]==0x001e4f3d4204 also red OK, so reading the documentation ... http://www.wireshark.org/docs/man-pages/pcap-filter.html ... I see that pcap permits a length of either 1, 2, or 4 ... no sixes (6).
Correct. For filter tests, it currently only generates BPF code where the data can be tested with a single comparison instruction, which means no more than 4 bytes (the BPF pseudo-machine is a 32-bit machine).
Can anyone think of a creative way to do the same thing?
arp and ((ether[22:4]==0x001e4f3d and ether[26:2]==0x4204) or (ether[32:4]==0x001e4f3d) and ether[36:2]==0x4204)) ___________________________________________________________________________ Sent via: Wireshark-users mailing list <wireshark-users () wireshark org> Archives: http://www.wireshark.org/lists/wireshark-users Unsubscribe: https://wireshark.org/mailman/options/wireshark-users mailto:wireshark-users-request () wireshark org?subject=unsubscribe
Current thread:
- specifying > 4 byte offsets / capture filters Stuart Kendrick (Oct 08)
- Re: specifying > 4 byte offsets / capture filters Guy Harris (Oct 08)
- Re: specifying > 4 byte offsets / capture filters Stuart Kendrick (Oct 08)
- Re: specifying > 4 byte offsets / capture filters Guy Harris (Oct 08)