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Date: Wed, 15 Jan 1997 23:17:45 -0800
From: Julian Elischer <julian@whistle.com>
Organization: Whistle Communications
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To: Brian Somers <brian@awfulhak.demon.co.uk>
CC: "Daniel O'Callaghan" <danny@panda.hilink.com.au>,
        Archie Cobbs <archie@whistle.com>, freebsd-hackers@FreeBSD.ORG
Subject: Re: FreeBSD as an ISDN Router
References: <199701160031.AAA15181@awfulhak.demon.co.uk>
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Brian Somers wrote:
> 
> [.....]
> > And some might want to run alias stuff over ethernet or other, and not
> > want ppp at all.
> 
> I agree completely - but the last time this was discussed (AFAIK) people
> didn't really want to dirty the tcp stack.

that's why divert(4) sockets exist..
they pass things OUT of the kernel for processing..

> 
>
> 
> I think the best way to do this sort of thing would be to take advantage of
> something like a firewall'ing hook, and writing an alias lkm that massaged the
> packets at that level.  That way, unless you "modload lkm_alias.o" and then
> condition a few interfaces, the tcp stack will be pure.

look at divert sockets and the 'divert' keywork in ipfw..
that's EXACTLY how it works..