Bug in TCP/IP stack in 2.2.17? (fwd)

[Patrik Rak <patrik@xxxxxx>]

Hi!

Alan told me I should forward attached message to this list.

Please note that it was the Linux host initiating the SMTP connection that
corrupted the packet and the tcpdump was run directly on this sending
host. The original message is perhaps somewhat unclear about this.

I am really eager to hear your comments about all this.

Thanks.

Patrik

--- Begin Message ---

To:	alan.cox@xxxxxxxxx
Subject:	Bug in TCP/IP stack in 2.2.17?
From:	Patrik Rak <patrik@xxxxxxxxxxxxxxxx>
Date:	Thu, 2 Nov 2000 16:13:59 +0100 (CET)

Hi!

I have a suspicion that there is some bug in TCP/IP stack in 2.2.17
regarding TCP options.

I was tracking down a problem with mail delivery over SMTP. It turned out
that the smtp client attempts to send "EHLO bay.ein.cz<cr><lf>" but the
first 12 bytes of this came out as junk (as seen by tcpdump run on the
same host as the smtp client). Wietse Venema pointed out that it actually
looks like the TCP options stored in the data part of the packet.

I think that the stack might be confused by the fact that the SYN response
doesn't contain any options and they come later in the first ACK.

I include the tcpdump log of the sessions plus its textual version for
your convenience.

Please let me know what your opinion about this issue is.

Thanks.

Patrik Rak

tcpdump-log.tgz
Description: GNU Unix tar archive

--- End Message ---