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Date:      Wed, 7 May 1997 09:13:29 +1000 (EST)
From:      "Daniel O'Callaghan" <danny@panda.hilink.com.au>
To:        Archie Cobbs <archie@whistle.com>
Cc:        Darren Reed <avalon@coombs.anu.edu.au>, zbs@softec.sk, freebsd-hackers@FreeBSD.ORG
Subject:   Re: divert still broken?
Message-ID:  <Pine.BSF.3.91.970507091049.4479u-100000@panda.hilink.com.au>
In-Reply-To: <199705062214.PAA20349@bubba.whistle.com>

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On Tue, 6 May 1997, Archie Cobbs wrote:

> 
> > So long as the packet is a fragment, is at offset 0, then for UDP, it is
> > either not going to have any header data (ip_len == ip_hl << 2) or it
> > will have at least both ports (first 4 bytes of the header) - well it
> > should as fragmenting of data is done on 8 byte boundaries.
> 
> Should the firewall then always & automatically reject any packet
> that doesn't have length a multiple of eight?

Not applicable, see below.

> Is fragmentation *required* to be on multiples of eight?

Yes.  Because the fragment offset is store in the packet as bytes/8.
In other words, FO=1 means 'starting at byte 8'.  Reject all packets with 
FO=1.

Danny



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