Date: Fri, 01 Aug 2003 15:07:24 -0400 From: misha <misha@research.att.com> To: Bruce M Simpson <bms@spc.org>, Michael Sierchio <kudzu@tenebras.com> Cc: freebsd-net@freebsd.org Subject: Re: T/TCP useless on FreeBSD 4.7? Message-ID: <3F2ABA6C.3932CA5@research.att.com> References: <200308011514.LAA46005@chips.research.att.com> <20030801152408.GF27921@spc.org>
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Bruce, Michael: Thanks a lot for the sysctl values tips. While 4.7 release does not seem to have drop_synfin option, syncookies indeed used to be 1 (but now we changed it to 0) on both machines: > sysctl net.inet.tcp | grep -E 'rfc1644|drop_synfin|cook' net.inet.tcp.rfc1644: 1 net.inet.tcp.syncookies: 0 > Unfortunately, setting it to 0 did not help: the tcp dump looks exactly the same. In addition, I tried the following changes on the server (although it was clear this would not make any diff, but just to be diligent) (a) replace "send" call (as in T/TCP book) with "sendto" call according to the ttcp manpage: sendto(sock, buf, len, MSG_EOF, (struct sockaddr *)0, 0) (b) not send any reply at all, just read from the socket and close it. (c) set "TCP_NOPUSH" option on the server's socket before writing response to it (with sendto call above). In all cases, the tcp dump shows a timeout + retransmission by the client... Also, what do you think about that source ode snippet I included into my original mail? It would certainly explain the behavior, except it would also mean that T/TCP is no longer usable. Unless that piece of code is somehow bypassed with proper options... Thanks again, Michael Bruce M Simpson wrote: > On Fri, Aug 01, 2003 at 11:14:12AM -0400, michael rabinovich wrote: > > Does anyone know the status of T/TCP support on FreeBSD 4.7? > ... > > Am I missing something (after all, FreeBSD is supposed to be a ref > > implementation of T/TCP!) and if not is there is a simple way around > > this problem, short of going back to earlier FreeBSD releases? > > I don't use T/TCP on my production 4.8-RELEASE system, and the following > sysctl values look fairly default:- > > net.inet.tcp.rfc1644: 0 > net.inet.tcp.syncookies: 1 > net.inet.tcp.drop_synfin: 0 > > SYN cookies and T/TCP can't co-exist. Please do check the above sysctl > values; I know RFC 1644 has to be enabled, and syncookies have to be disabled, > as well as drop_synfin. > > HTH, > BMS > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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