From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Mores Date: Mon, 20 Jan 2003 10:35:55 +0000 Subject: Re: [LARTC] checksum update in TCP Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org On Mon, Jan 20, 2003 at 10:23:16AM +0100, devik wrote: > Hi, > > anyone knows when TCP checksum is updated ? Normally, TCP checksum is not supposed to be changed (or even read) at all during transfer (see rfc793 or TCP/IP Illustrated Vol.1). If NAT is in use then it needs to be accounted for, of course, because TCP chksum involves a pseudoheader which contains both source and destination addresses - but this is not the case, as you say. > 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. Or imho even more probably, the problem could be the line. I've had a couple of these during last 3 years. Namely, is there a serial line (possibly wireless) involved? pvl _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/