From owner-freebsd-hackers  Wed Jan 24 15: 1:58 2001
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From: Luigi Rizzo <rizzo@aciri.org>
Message-Id: <200101242301.f0ON1cX21729@iguana.aciri.org>
Subject: Re: Divert Sockets & Fragmentation
In-Reply-To: <Pine.SOL.4.21.0101241755480.2862-100000@gradient.cis.upenn.edu> from Alwyn Goodloe at "Jan 24, 2001  6: 0:10 pm"
To: agoodloe@gradient.cis.upenn.edu (Alwyn Goodloe)
Date: Wed, 24 Jan 2001 15:01:38 -0800 (PST)
Cc: rizzo@aciri.org, hackers@FreeBSD.ORG
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> I was originally diverting udp packets heading to a particular port then
> I flushed the ipfw and tried:
> 
>  ipfw  add 60000 divert 4422 ip all from any to any in
> and still no packets are received by recvfrom(). Would the port numbers 
> matter for this case.

probably not but better check if you have any former rule which
matches fragments

	luigi
> Alwyn
> agoodloe@gradient.cis.upenn.edu
>  
> 
> 
> 
> 
> On Wed, 24 Jan 2001, Luigi Rizzo wrote:
> 
> > it depends on what template do you use for matching.
> > the firewall acts before reassembly, so for the fragments you will
> > not be able to see the port numbers.
> > 
> > 	cheers
> > 	luigi
> > 
> > > I have been using divert sockets for a while sending small (< MTU) UDP
> > > packets and everything worked fine. Now that the UDP packets are larger
> > > (>MTU = 1500) and hence fragmentation is taking place there seems to be a
> > > problem. tcpdump tells me that the fragmented packets arrive but it seems
> > > that they are never diverted. I say this because after they are received
> > > recvfrom () never gets the packet. I've done things like play with the
> > > nbytes field of the recvfrom() fn. without any success. Any
> > > suggestions, I'm sure its something stupid.
> > > 
> > > 
> > > Alwyn
> > > agoodloe@gradient.cis.upenn.edu
> > > 
> > > 
> > > 
> > > 
> > > 
> > > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > > with "unsubscribe freebsd-hackers" in the body of the message
> > > 
> > 
> > 
> 
> 



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