Subject: Re: ipf "dup-to" altering packet IDs
To: Michael Graff <email@example.com>
From: Darren Reed <firstname.lastname@example.org>
Date: 06/26/2002 14:04:14
In some email I received from Michael Graff, sie wrote:
> I have a need to do routing based on source address (not the normal
> destination address) and so am using IPF rules to do this disgusting
> What I'm doing is:
> pass in on fxp1 dup-to tun0 from 126.96.36.199/27 to any
> block out quick on fxp0 from 188.8.131.52/27 to any
> This causes the packets to be duplicated to tun0 and dropped on the
> outgoing interface, so the only copy of the packet will go over the
> tun0 device.
> I have a user-level tunnel taking the packets from tun0 and
> encapsulating them in UDP and sending them on their way.
> However, the packet as seen on fxp1 and tun0 have differences. The
> duplicated packet has its ip id field byte-swapped.
Is the checksum correct in the packet coming out tun0 ?