From owner-freebsd-net@FreeBSD.ORG Mon Nov 10 00:03:19 2003 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8290E16A4CE for ; Mon, 10 Nov 2003 00:03:19 -0800 (PST) Received: from gw.catspoiler.org (217-ip-163.nccn.net [209.79.217.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 81FAA43FAF for ; Mon, 10 Nov 2003 00:03:18 -0800 (PST) (envelope-from truckman@FreeBSD.org) Received: from FreeBSD.org (mousie.catspoiler.org [192.168.101.2]) by gw.catspoiler.org (8.12.9p2/8.12.9) with ESMTP id hAA83AeF065509; Mon, 10 Nov 2003 00:03:14 -0800 (PST) (envelope-from truckman@FreeBSD.org) Message-Id: <200311100803.hAA83AeF065509@gw.catspoiler.org> Date: Mon, 10 Nov 2003 00:03:10 -0800 (PST) From: Don Lewis To: elessar@galgenberg.net In-Reply-To: <20031110072426.0607baf4.elessar@galgenberg.net> MIME-Version: 1.0 Content-Type: TEXT/plain; charset=us-ascii cc: freebsd-net@FreeBSD.org Subject: Re: problems caused by net.inet.tcp.blackhole=2 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Nov 2003 08:03:19 -0000 On 10 Nov, Joerg Pernfuss wrote: > On Sat, 8 Nov 2003 15:25:18 -0800 (PST) > Don Lewis wrote: > >> On 8 Nov, Michal wrote: >> > Hello, >> > maybe someone will be able to help me with the problem. Namely setting >> > net.inet.tcp.blackhole=2 make samba to start very slow (90sec). Also >> > smbclient is slow. After samba starts there is no delay to connect from >> > the another machine with persistant local problems (smbclient). >> > Additionally the sysctl setting has veird impact on mozilla: trying to >> > write to web forms causes freezing of mozilla. Now setting >> > net.inet.tcp.blackhole=0 reverts all the problemsr: samba starts fast >> > and no problems with writing to the web forms. >> > my system: >> > FreeBSD 5.1-CURRENT #0: Thu Oct 30 17:49:13 EST 2003 >> > ports updated 11-08-03 >> > >> > I appreciate any suggestions >> >> I looked at a similar problem that someone was having a while back. It >> appears that the problem is that this sysctl setting is suppressing the >> sending of TCP RST packets which are needed to tear down dead >> connections, and if one end of the connection thinks the connection is >> still established, it is not possible to create a new connection between >> the hosts that reuses the same addresses and ports as the old >> connection. >> >> Since the whole point of net.inet.tcp.blackhole=2 is to block the RST >> packets that could allow the host to be scanned, I suspect you are >> stuck. > > That's not a bug, that is the only feature :) > > First of all, check on which ports the connections that time out occur. > One possibility would be `tcpdump', the other is to set the sysctl > net.inet.tcp.log_in_vain to 1. Then start samba and look in the logs to > which closed ports connection attempts were made. > Maybe there is a decent solution to provide these packets the answer they > desire so hard. You'll probably need to crank net.inet.tcp.log_in_vain all the way up to 2. If you just set it to 1, it won't tell you about packets that don't have the SYN flag set.