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From: devik <devik@cdi.cz>
To: lartc@vger.kernel.org
Subject: [LARTC] checksum update in TCP
Date: Mon, 20 Jan 2003 09:23:16 +0000	[thread overview]
Message-ID: <marc-lartc-104305763511093@msgid-missing> (raw)

Hi,

anyone knows when TCP checksum is updated ? I have problem
with FTP transfers. I tested with two linux servers both
as ftp client or server. In all cases large (cca 50MB) file
transfers are corrupted inside.
I want to spot the problem, so that my question is:
if packet goes thru 2.4.18 router, does the router TCP
checksum recomputation ? Router has NAT enabled but not for
packets I'm interested in.
If yes then if router itself corrupts packet's data the case
will not be caught because it simply computes valid checksum
of corrupted data.
On other side if it simply passes packet thru (because nothing
except TTL is changed and TTL is not part of TCP checksum) then
the checksum should really ensure that nothing is changed
between sender and reciever and if data are invalid then error
would be on sender's or reciever's side.

thanks,
-------------------------------
    Martin Devera aka devik
Linux kernel QoS/HTB maintainer
  http://luxik.cdi.cz/~devik/

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             reply	other threads:[~2003-01-20  9:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-01-20  9:23 devik [this message]
2003-01-20 10:35 ` [LARTC] checksum update in TCP Pavel Mores
2003-01-20 11:09 ` Patrick McHardy
2003-01-20 11:19 ` Patrick McHardy
2003-01-20 14:09 ` devik
2003-01-21 11:58 ` Pavel Mores
2003-01-21 13:59 ` devik
2003-01-22 23:24 ` Pavel Mores
2003-01-23  7:31 ` devik

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