I find the "hack" more than just strange. Because of other OSes bugs FreeBSD breaks it's own stack. Don't want to know how many connections suffered from this.
(Sorry for top-posting) -- Christian On 14.10.2012, at 00:19, Jason Wolfe <nitrobo...@gmail.com> wrote: > On Fri, Oct 12, 2012 at 9:13 AM, John Baldwin <j...@freebsd.org> wrote: >> Back in 2001 FreeBSD added a hack to strip TCP options from retransmitted >> SYNs >> starting with the 3rd SYN in this block in tcp_timer.c: >> >> /* >> * Disable rfc1323 if we haven't got any response to >> * our third SYN to work-around some broken terminal servers >> * (most of which have hopefully been retired) that have bad VJ >> * header compression code which trashes TCP segments containing >> * unknown-to-them TCP options. >> */ >> if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3)) >> tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP); >> >> There is even a PR for the original bug report: kern/1689 >> >> [..snip..] >> >> The original motivation of this change is to work around broken terminal >> servers that were old when this change was added in 2001. Over 10 years >> later >> I think we should at least have an option to turn this work-around off, and >> possibly disable it by default. >> >> Thoughts? >> >> -- >> John Baldwin > > Not that it alone merits keeping the code in, but there are some cases > where this comes in handy. I ran into an issue with heavily > trafficked Linux <-> FBSD boxes here - > http://lists.freebsd.org/pipermail/freebsd-net/2012-March/031881.html. > > Linux would deny the connection because in FBSD ithe n and outbound > timestamp randomization isn't sync'd to the same base, so when FBSD > would hit a 2MSL connection Linux would simply ignore the SYN. After > the 3rd SYN FBSD would drop support, and Linux would finally honor the > request. I doubt this is too widespread, but it would probably break > things for a few folks. > > Jason > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
