Date: Sat, 23 May 1998 20:49:06 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: njs3@doc.ic.ac.uk (Niall Smart) Cc: hackers@FreeBSD.ORG Subject: Re: tcp states and sysctl's Message-ID: <199805232049.NAA12898@usr07.primenet.com> In-Reply-To: <E0ycyPn-0002lv-00@oak66.doc.ic.ac.uk> from "Niall Smart" at May 22, 98 09:27:42 pm
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> I don't think a shutdown(2) sysctl is necessary. > > a) the BSD stack is currently compliant in this regard, if > anything need's changing it's the client. > > b) no-one has produced any evidence to show that all > these sockets in TIME_WAIT_2 are actully having a > negative impact in performance on the system. Actually, > I would seriously hope not, because otherwise this > is a relatively easy DoS. (Though probably not as > effective as a SYN flood.) > > If you do decide to put in a sysctl bear in mind that rsh uses > shutdown(2) to close down one end of a socket so you don't want > the timeout to be too short. Actually, there is a bug in zero-window probing. This occurs when talking to an HP Laserwriter. Basically, the FreeBSD box closes the connection, and can't send a FIN because the printer announces a zero window. A mechanism for converting a shutdown 1 to a shutdown 2 would be useful here. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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