From owner-freebsd-questions@FreeBSD.ORG Fri Nov 9 09:16:19 2007 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1D12D16A417 for ; Fri, 9 Nov 2007 09:16:19 +0000 (UTC) (envelope-from nvass@teledomenet.gr) Received: from smtp.teledomenet.gr (smtp.teledomenet.gr [213.142.128.2]) by mx1.freebsd.org (Postfix) with ESMTP id BC0F613C4BA for ; Fri, 9 Nov 2007 09:16:18 +0000 (UTC) (envelope-from nvass@teledomenet.gr) Received: by smtp.teledomenet.gr (Postfix, from userid 58) id DAAF8142163; Fri, 9 Nov 2007 11:16:09 +0200 (EET) X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on smtp.teledomenet.gr X-Spam-Level: X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00 autolearn=ham version=3.2.3 Received: from iris (unknown [192.168.1.71]) by smtp.teledomenet.gr (Postfix) with ESMTP id 4FEE3142170; Fri, 9 Nov 2007 11:16:07 +0200 (EET) From: Nikos Vassiliadis To: freebsd-questions@freebsd.org Date: Fri, 9 Nov 2007 11:18:31 +0200 User-Agent: KMail/1.9.7 References: <4731E1A4.6020809@diomedia.be> <200711081408.22387.nvass@teledomenet.gr> <47333C1A.7070709@diomedia.be> In-Reply-To: <47333C1A.7070709@diomedia.be> X-NCC-RegID: gr.telehouse MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200711091118.31621.nvass@teledomenet.gr> Cc: Bram Subject: Re: TCP/IP questions X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Nov 2007 09:16:19 -0000 On Thursday 08 November 2007 18:40:58 Bram wrote: > Nikos Vassiliadis schreef: > > On Wednesday 07 November 2007 18:02:44 Bram wrote: > >> Hi all, > >> > >> Can you change the timeout for a tcp connection ? > >> I need to do the following: start a tcp connection , unplug the > >> network cable (it's actually wifi but the effect is the same),send > >> some data over the connection,wait 20 seconds , reinsert the network > >> cable and just keep working. > >> When you normally do this the connection will be dead. > >> Is there a way in freebsd to change this ? are there parameters wich > >> you can set so that the above would work (20 seconds without network > >> can happen) ? > > > > TCP using the default FreeBSD settings, can survive > > 20 secs of inactivity. It can be an application forced > > timeout. What application/protocol are talking about? > > > > Nikos > > This is the more full explanation: > > I have setup a mobile pc to roam across our building. > By reducing the dwell time and changing the channel list to only the > channels I use roaming now works within ten seconds en sometimes within > one or two seconds. > The previous configuration was with fedora and there I was unable to get > roaming time under 25 seconds. > > I do have one very annoying problem however and I have no idea how to > solve it. > The software uses psycopg (a python postgresql module) wich uses the > standard system parameters for connections (At least that is what I > think). -On fedora if the connection gets lost and it takes 30 seconds > to remake a new connection operation is not interupted, after the 30 > seconds you get the data you've been waiting for. > -On freebsd however we get it a lot that the connection is "lost", you > can easily start a new connection wich works fine, but the old > connection you wore using stops working and the app. hangs (If I had to > guess I would say that roaming works about 95% of the time and the > connection is lost about 5% of the time). > > I also get a lot of IFDOWN IFUP messages but this seems normal to me. > > I am now going to program something in twisted using udp to see if this > works better. If your app is using SO_KEEPALIVE, you can increase sysctl net.inet.tcp.keepintvl. You could also trace the application to see what's going on. Something like: ktrace -i $application Nikos