From owner-freebsd-net@FreeBSD.ORG Thu Jul 31 00:53:22 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 3153C37B401; Thu, 31 Jul 2003 00:53:22 -0700 (PDT) Received: from apollo.laserfence.net (apollo.laserfence.net [196.44.69.138]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0143D43FAF; Thu, 31 Jul 2003 00:53:18 -0700 (PDT) (envelope-from will@unfoldings.net) Received: from localhost ([127.0.0.1]) by apollo.laserfence.net with esmtp (Exim 4.10) id 19i8FN-000Png-00; Thu, 31 Jul 2003 09:53:13 +0200 Received: from prometheus-p0.datel.laserfence.net ([192.168.255.1] helo=prometheus.home.laserfence.net) by apollo.laserfence.net with esmtp (Exim 4.10) id 19i8F5-000PnQ-00; Thu, 31 Jul 2003 09:52:57 +0200 Received: from phoenix.home.laserfence.net ([192.168.0.2]) by prometheus.home.laserfence.net with esmtp (Exim 4.10) id 19i8F1-0005M6-00; Thu, 31 Jul 2003 09:52:51 +0200 Received: from will by phoenix.home.laserfence.net with local (Exim 4.10) id 19i8F0-0001Zp-00; Thu, 31 Jul 2003 09:52:50 +0200 From: Willie Viljoen To: freebsd-questions@freebsd.org Date: Thu, 31 Jul 2003 09:52:49 +0200 User-Agent: KMail/1.5.1 MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200307310952.49995.will@unfoldings.net> Sender: Willie Viljoen X-Spam-Score: (/) X-Scanner: exiscan for exim4 (http://duncanthrax.net/exiscan/) *19i8F5-000PnQ-00*Yf2/Eo7Y3Sc* X-Virus-Scanned: by AMaViS snapshot-20020422 cc: freebsd-net@freebsd.org Subject: (Solved) Strange dial-up related DNS problems 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: Thu, 31 Jul 2003 07:53:22 -0000 I got it fixed (or atleast, as good as it can be fixed) For future reference, here's what went wrong. During the weekend, SAIX upgraded and repaired all Cisco equipment on their network. During this repair, they somehow managed to break something major. The /etc/ppp/options file on the offending BSD box contained the asyncmap 0 option. This tells pppd not to escape characters leaving as part of packets that could be misunderstood as being controle characters by the other side. This has been woking fine for a long time. however, during SAIX's tinkering, they managed to get their PPP gateways to not ignore controle characters coming in as part of IP packets, as they should be doing. What was going wrong was that some part of the DNS query must have been seen as some arb. controle character. The machine then handled the packet incorrectly, and it never reached the NS it was meant for. To fix this, just remove asyncmap 0 from your config file. This gives a slight performance hit, but with the wonderful resourcefullness of some ISPs, what can you do... Origional message follows: This gets a 10.0 on my weird-o-meter. I have a FreeBSD 4.7-RELEASE machine sitting at a client which dials in and collects their mail via POP3, and sends outgoing mail via a smarthost which points to an SMTP server at their ISP. This machine has worked fine since late last year, but started giving a strange problem this week. When connected to their ISP, SAIX, the machine can ping any live internet IP and it can traceroute to anywhere, but, it can not talk to any DNS server. Any traffic to port 53 UDP simply seems to dissapear. The same with firewalling enabled as normal, or even with ipfw add 1 allow ip from any to any When connected to any other ISP we have tried dialing, all works perfectly. When dialed from another FreeBSD box with the same username/password, the SAIX connection works perfectly. Yet, this single machine absolutely flat out refuses to talk to any name server while connected to SAIX, firewalling, no firewalling, no difference. I have tried running tcpdump -i ppp0 udp port 53 in an attempt at capturing these packets, nothing, I also looked at rl0 just for interest's sake, nothing. I have run out of ideas, what am I missing? PS: Please CC me in the reply, I get so much list mail I might miss a reply there. -- Willie Viljoen Freelance IT Consultant 214 Paul Kruger Avenue, Universitas Bloemfontein 9321 South Africa +27 51 522 15 60 +27 82 404 03 27 (mobile) will@unfoldings.net