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Date:      Sun, 2 Nov 2003 14:11:02 +0100 (CET)
From:      Michal Mertl <mime@traveller.cz>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        current@freebsd.org
Subject:   Re: jumbograms (& em) & nfs a no go
Message-ID:  <20031102140720.Q33518@prg.traveller.cz>
In-Reply-To: <3FA41782.8FB1DFF8@mindspring.com>
References:  <20031029183808.M99053@prg.traveller.cz> <200310300804.58296.sam@errno.com> <20031031151312.Y55560@prg.traveller.cz> <3FA41782.8FB1DFF8@mindspring.com>

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On Sat, 1 Nov 2003, Terry Lambert wrote:
> I think at this point, you are going to have to look at the
> sources; IMO, it's a problem in some code that calls the
> ether_output() function directly with too large a packet, and
> since NFS doesn't manually implement TCP, that's not it.
>
> Hmmm.  Is this maybe UDP?  If so, the easiest fix is "don't
> use UDP"; FreeBSD's UDP fragment reassembly code sucks anyway,
> and gives an excellent means of implementing a DOS attack on
> the target system's available mbufs.
>
> If it's UDP, and you insist on it working, you might want to
> make sure that the packet goes through the UDP fragmentation
> and NFS rsize/wsize limitation code.
>

I noticed in src/sys/dev/em/README that there are problems with jumbograms
and UDP so I use TCP.


-- 
Michal Mertl



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