Date: Mon, 05 Oct 2009 10:24:33 +0200 From: Andre Oppermann <andre@freebsd.org> To: Kevin Oberman <oberman@es.net> Cc: net@freebsd.org Subject: Re: Unusual TCP options can cause FreeBSD to issue a reset Message-ID: <4AC9AD41.2070200@freebsd.org> In-Reply-To: <20091002231826.066291CC0E@ptavv.es.net> References: <20091002231826.066291CC0E@ptavv.es.net>
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Kevin Oberman wrote: > I have a system that is unable to connect to a FreeBSD system due to > the odd formatting of the TCP options. The options contains only the > timestamp which, if recommendations in RFC1323 are followed, are > preceded by two NOP bytes to put the timestamp values on 4 byte > boundaries. > > This system sends the 12 byte timestamp option alone, followed by two > zero bytes to pad it. This meets the requirements of RFC793 and 1323 is > explicit that stacks must accept this, even though it results in > sub-optimal performance and does not meet the recommendations in 1323 > appendix A. Just this alone should not cause a reset from FreeBSD. > Any idea if this is hard to fix? I see in on both 7.2 and 8.0. Can you post a detailed tcpdump of a failing connect? And please enable net.inet.tcp.log_debug which should give a better explanation on why FreeBSD thinks the connection is bad. -- Andre
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