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From: Norman Wilson <norman@oclsc.org>
To: tuhs@tuhs.org
Date: Fri, 13 Sep 2019 18:01:14 -0400
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Subject: Re: [TUHS] [SPAM] Re:  SCCS
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Peter Jeremy:

> NFS ran much faster when you turned off the UDP checksums as well.
> (Though there was still the Ethernet CRC32).

Dave Horsfall:

  Blerk...  That just tells you that the packet came across the wire more or
  less OK.

=====

UDP (and TCP) checksums are nearly useless against
the sort of corruption Larry described.  Since they
are a simple addition with carry wraparound, you
can insert or remove any number of word-aligned pairs
of zero octets without the checksum changing.

I discovered this the hard way, while tracking down
a kernel bug that caused exactly that sort of corruption.

Does IPv6 require a meaningful checksum, or just the
useless old ritual one?

Norman Wilson
Toronto ON