From owner-freebsd-hackers@FreeBSD.ORG Wed Sep 17 17:49:34 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0F5B316A4B3 for ; Wed, 17 Sep 2003 17:49:33 -0700 (PDT) Received: from pd5mo3so.prod.shaw.ca (shawidc-mo1.cg.shawcable.net [24.71.223.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id C62DA43F3F for ; Wed, 17 Sep 2003 17:49:32 -0700 (PDT) (envelope-from colin.percival@wadham.ox.ac.uk) Received: from pd4mr2so.prod.shaw.ca (pd4mr2so-qfe3.prod.shaw.ca [10.0.141.213]) by l-daemon (iPlanet Messaging Server 5.2 HotFix 1.16 (built May 14 2003)) with ESMTP id <0HLD001QIWYKK8@l-daemon> for freebsd-hackers@freebsd.org; Wed, 17 Sep 2003 18:49:32 -0600 (MDT) Received: from pn2ml5so.prod.shaw.ca (pn2ml5so-qfe0.prod.shaw.ca [10.0.121.149]) by l-daemon (iPlanet Messaging Server 5.2 HotFix 1.16 (built May 14 2003)) with ESMTP id <0HLD00M13WYKPQ@l-daemon> for freebsd-hackers@freebsd.org; Wed, 17 Sep 2003 18:49:32 -0600 (MDT) Received: from piii600.wadham.ox.ac.uk (h24-87-233-42.vc.shawcable.net [24.87.233.42]) by l-daemon (iPlanet Messaging Server 5.2 HotFix 1.16 (built May 14 2003)) with ESMTP id <0HLD00F3BWYJ8H@l-daemon> for freebsd-hackers@freebsd.org; Wed, 17 Sep 2003 18:49:32 -0600 (MDT) Date: Wed, 17 Sep 2003 17:49:18 -0700 From: Colin Percival In-reply-to: X-Sender: cperciva@popserver.sfu.ca To: deepak@ai.net, freebsd-hackers@freebsd.org Message-id: <5.0.2.1.1.20030917173951.02df29e8@popserver.sfu.ca> MIME-version: 1.0 X-Mailer: QUALCOMM Windows Eudora Version 5.0.2 Content-type: text/plain; charset=us-ascii; format=flowed Content-transfer-encoding: 7BIT Subject: Re: TCP information X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Sep 2003 00:49:34 -0000 At 20:34 17/09/2003 -0400, Deepak Jain wrote: >Is there a utility/hack/patch that would allow a diligent sysadmin to obtain >which specific TCP connections are generating retransmits and receiving >packet drops? netstat will show me drops on an interface, but not on a >specific source/dest pair? If you've got a small enough amount of traffic, you could use tcpdump to snarf the headers and then use your favourite scripting languge to look for repeated sequence numbers (retransmits) and repeated acks (lost packets); but I suspect this would be too slow for most purposes. Colin Percival