From owner-freebsd-hackers Tue Dec 26 11:21:44 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id LAA13028 for hackers-outgoing; Tue, 26 Dec 1995 11:21:44 -0800 (PST) Received: from iaehv.IAEhv.nl (root@iaehv.IAEhv.nl [192.87.208.2]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id LAA13023 for ; Tue, 26 Dec 1995 11:21:38 -0800 (PST) Received: from oasis.IAEhv.nl by iaehv.IAEhv.nl (8.6.12/1.63) id UAA29614; Tue, 26 Dec 1995 20:21:33 +0100 X-Disclaimer: iaehv.nl is a public access UNIX system and cannot be held responsible for the opinions of its individual users. Received: by oasis.IAEhv.nl (8.7.3/1.63) id UAA05384; Tue, 26 Dec 1995 20:19:10 +0100 (MET) From: volf@oasis.IAEhv.nl (Frank Volf) Message-Id: <199512261919.UAA05384@oasis.IAEhv.nl> Subject: Freebsd IP alias and BIND To: freebsd-hackers@freebsd.org, bind-users@vix.com Date: Tue, 26 Dec 1995 20:19:10 +0100 (MET) X-Mailer: ELM [version 2.4 PL25] Content-Type: text Sender: owner-hackers@freebsd.org Precedence: bulk Hi and merry Xmas to you all, This message is sent to both freebsd-hackers and bind-users because I haven't figured out yet whether to blame FreeBSD, bind ore myself. I know this (or similar) problem have been the topic of bind-users before, but as far as I know there has not been a fix for it. THE SETUP: FreeBSD 2.05 box (pentium 90) and bind-4.9.3beta32. The FreeBSD box has a IP address (192.87.208.2) and an IP alias (194.151.64.2). The alias is used because we are in process of moving to a new IP netblock and we want both the old and the new nameserver addresses to be valid in the transition period. THE PROBLEM: When a query is sent to the IP alias two responses are generated: one response with the real IP address as the source address, the other one with the alias address as the source address: 17:02:20.146789 192.87.209.4.53 > 194.151.64.2.53: 52731+ NS? tue.nl. (24) 17:02:20.148820 192.87.208.2.53 > 192.87.209.4.53: 52731* 3/0/3 NS kweetal.tue.nl. (144) 17:02:20.150752 194.151.64.2.53 > 192.87.209.4.53: 52731* 3/0/3 NS ns1.surfnet.nl. (144) On a UNIX system runing BIND, the bogus response triggers the "response from unexpected source" message, but has no other effects. Some dialin software however (older versions of trumpet winsocket if I recall correctly) do not handle this correctly and cause the nameserver request to timeout if the wrong response is received first. THE CAUSE: I'm not sure. Since you can see in the tcpdump that the responses are different (round robin is turned on), it seems that bind gets or processes the incoming UDP package twice. I however don't know, if this is caused by bind or by the FreeBSD kernel. THE SOLUTION: Please tell me :-) Regards, Frank ---------------------------------------------------------------------------- Frank Volf - Internet Access Eindhoven - Digitale Stad Eindhoven ---------------------------------------------------------------------------- || volf@oasis.IAEhv.nl - use for personal mail || || volf@IAEhv.nl - use for Internet Access Eindhoven related mail || || volf@dse.dse.nl - use for Digital City of Eindhoven related mail || ---------------------------------------------------------------------------- IAE Public Access Unix System - Dial +31.40.2439436 and login as new. ----------------------------------------------------------------------------