Re: The TCP and UDP checksum algorithm may soon need updating

Nico Williams <nico@cryptonector.com> Thu, 04 June 2020 21:34 UTC

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Date: Thu, 4 Jun 2020 16:34:14 -0500
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From: Nico Williams <nico@cryptonector.com>
To: Craig Partridge <craig@tereschau.net>
Cc: Richard Barnes <rlb@ipv.sx>, IETF discussion list <ietf@ietf.org>
Subject: Re: The TCP and UDP checksum algorithm may soon need updating
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On Thu, Jun 04, 2020 at 03:26:17PM -0600, Craig Partridge wrote:
> The SSH spec says terminate on failure and that it requires a reliable
> underpinning.
> 
> Termination on error is no good.  One of the studies shows huge failure
> rates (over 50%) for large file transfers.  One guess is that's due to
> security protocols terminating when TCP hands up something with an error.

+1 (though, of course, one could have the protocol above TLS/SSH be
resumable in some cases).

Note too that recovery by retransmission requires more buffering unless
TLS/SSH and TCP could coordinate and share buffers.

My take is that better checksums are needed even for TLS/SSH, but 
not for TCP over IPsec, and maybe not for DTLS apps.

Nico
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