Date: Thu, 08 Nov 2007 12:26:18 +0000 From: Malcolm Clarke <malcolm.clarke@brunel.ac.uk> To: Bram <bram@diomedia.be> Cc: freebsd-questions@freebsd.org Subject: Re: TCP/IP questions Message-ID: <4733006A.5080804@brunel.ac.uk> In-Reply-To: <200711081408.22387.nvass@teledomenet.gr> References: <4731E1A4.6020809@diomedia.be> <200711081408.22387.nvass@teledomenet.gr>
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Dear Bram You may need to describe your intention more clearly. If you detach the network cable, the hardware will detect the disconnect and reset the hardware, which will provide an indicate to the higher layers to reset also. Reconnecting the cable will be seen as a new connection and it will perform initialisation (eg DHCP, etc). All TCP connections will be closed, etc. If it is the case that you are trying to test behaviour of an application to the effects of loss of packets then you will need a different approach. We use the IPFW firewall and set up pipes that can be configured to artificially lose packets, restrict BW or even close (hence my question to the group). Alternatively you must arrange to break the connection elsewhere, say on the otherside of a switch, taking care not to break the physical connetion to the far end to create a disconnect that does not reset the hardware.. Regards Malcolm Nikos Vassiliadis wrote: >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 > >_______________________________________________ >freebsd-questions@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-questions >To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" > > > -- --------------------------------------------------- Dr Malcolm Clarke Senior Lecturer in Data Communication Systems and Telemedicine Department of Information Systems and Computing Brunel University Uxbridge Middlesex UB8 3PH UK Tel: +44 1895 265053 Fax: +44 1895 251686 http://www.brunel.ac.uk/about/acad/siscm/research/themes/is/groups/bright/people ----------------------------------------------------
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