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
