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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.cs.su.oz.au!metro!metro!munnari.OZ.AU!spool.mu.edu!howland.erols.net!news.mathworks.com!enews.sgi.com!news.sgi.com!news1.best.com!nntp1.best.com!usenet From: dillon@flea.best.net (Matt Dillon) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Max TCP connections Date: 16 Dec 1996 19:15:56 GMT Organization: BEST Internet Communications, Inc. Lines: 35 Message-ID: <59475c$el0@nntp1.best.com> References: <593r4g$orq@Mercury.mcs.net> NNTP-Posting-Host: flea.best.net Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:32706 :In article <593r4g$orq@Mercury.mcs.net>, :Tim Daneliuk <tundra@tundraware.com> wrote: :>Is there a kernel or other configuration which determines the maximum :>number of TCP/IP connections allowed in a running FreeBSD image or is :>this dynamically allocated out of the memory pool? I am occasionally :>seeing a problem with remote sites unable to establish SMTP :>connections with my machine, even though it is up and running fine. I :>wonder if I am starved for TCP/IP connections. :>-- :>------------------------------------------------------------------------------ :>Tim Daneliuk / tundra@tundraware.com :>Voicemail/FAX 847.827.1706 There is an mbuf parameter for network clusters somewhere, but I doubt that is your problem. Try this when you are having problems: netstat -tn | fgrep SYN_R It could be that your sendmail is not setting the listen queue large enough. Nominally this is only 5 or 10, but in internet-connected sites remote machines often try to connect to you over broken networks which can fill up the listen queue with sockets in a SNY_RCVD state, causing other unrelated connection attempts to fail. If you are running a recent sendmail (8.7 or 8.8 I think), you can increase the liste queue size with the DaemonPortOptions option... DaemonPortOptions=Listen=255,Port=esmtp Your kernel must also be compiled with a large SOMAXCONN ... I'm not sure what the default is. -Matt