Date: Tue, 16 Sep 1997 18:15:10 +0200 From: j@ida.interface-business.de (J Wunsch) To: fenner@parc.xerox.com (Bill Fenner) Cc: freebsd-hackers@freebsd.org (FreeBSD hackers) Subject: Re: Any TCP expert around? Message-ID: <19970916181510.OK51303@ida.interface-business.de> References: <19970916163525.KH02502@ida.interface-business.de> <97Sep16.090625pdt.177486@crevenia.parc.xerox.com>
next in thread | previous in thread | raw e-mail | index | archive | help
As Bill Fenner wrote: > Your server sends two different SYN/ACK replies back, both with > different initial sequence numbers, and then starts sending data with a > third different sequence number. FreeBSD ignores the second SYN/ACK > because it's outside of the window, and it ignores all of the data > packets because they're outside of the window. Well, no. This is merely misreading since tcpdump adjusts its idea of the base sequence number for the connection after seeing the second SYN. As i wrote you in the private mail, a tcpdump with absolute sequence numbers shows that the server is actually later using the sequence number space it suggested in its first SYN. So i think the BSD implementation is in error, since it never re-synchronizes after getting the bogus SYN packet. > >What makes me a little nervous is the couple of packets sent by the > >FreeBSD side at 15:39.54.132386 and 15:39:54.133176. Why are there > >two packets? > I'm confused - the two packets that you referenced were from different > machines. Well, i was confused, and didn't look close enough at first. I later realized that the actual problem is starting with the bogus SYN received from the server. -- J"org Wunsch Unix support engineer joerg_wunsch@interface-business.de http://www.interface-business.de/~j
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19970916181510.OK51303>