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List:       ipfilter
Subject:    Re: 3.4.10/gig ether/Solaris 7 retransmission problem
From:       Darren Reed <darrenr () reed ! wattle ! id ! au>
Date:       2000-09-24 21:08:03
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In some email I received from Chris Tilbury, sie wrote:
> 
> Darren:
[...]
> Tweaked this and it's done the trick. Thanks very much!
> 
> If it's not a daft question, what (apart from turn off the hardware-assist
> checksumming in the ge card) is this parameter doing that's relevant to
> ipfilter? I take it there is some kind of collision going on here between
> ipfilter and this feature?

What you weren't seeing was the retransmission of TCP packets due to received
packets with an incorrect checksum.

NAT fiddles with the TCP checksum and obviously isn't doing it in the right
way such that the ge card computes the right TCP checksum.  If you were able
to d/l the latest tcpdump from www.tcpdump.org, I'd be curious to know how
far out the checksum was (tcpdump -s 512 -v should do the trick).

Darren

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