tcpdump mailing list archives
Re: vlan tagged packets and libpcap breakage
From: Guy Harris <guy () alum mit edu>
Date: Wed, 31 Oct 2012 17:50:45 -0700
On Oct 31, 2012, at 3:35 PM, Ani Sinha <ani () aristanetworks com> wrote:
yes but if the packet is passed to the filter within libpcap (when we are not using the kernel filter) before the reinsertion,
...that would be a bug. Currently, that bug doesn't exist in the recvfrom() code path, but *does* appear to exist in the tpacket code path - and that code path also runs the filter before the SLL header is constructed. That should be fixed. Yes, it means constructing the SLL header and inserting the tags blah blah blah on packets that might not pass the filter, but in most cases the filtering should be done in the kernel, not userland, when doing a live capture, and in those cases where the filtering can't done in the kernel, you're already somewhat hosed by the fact that the packets are being copied to the buffer and wakeups are being delivered before the packets are being filtered. _______________________________________________ tcpdump-workers mailing list tcpdump-workers () lists tcpdump org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
Current thread:
- vlan tagged packets and libpcap breakage Ani Sinha (Oct 31)
- Message not available
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Oct 31)
- Re: vlan tagged packets and libpcap breakage Guy Harris (Nov 01)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Oct 31)
- Re: vlan tagged packets and libpcap breakage Guy Harris (Nov 01)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Oct 31)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Oct 31)
- Re: vlan tagged packets and libpcap breakage Bill Fenner (Nov 11)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Nov 13)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Nov 13)
- Re: vlan tagged packets and libpcap breakage Michael Richardson (Nov 14)
- Message not available
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Nov 18)
- Message not available
- Re: vlan tagged packets and libpcap breakage Daniel Borkmann (Nov 18)
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Nov 18)
- Message not available
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Nov 18)