From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1FuyU4-0007rb-8R for garchives@archives.gentoo.org; Mon, 26 Jun 2006 21:19:04 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.7/8.13.6) with SMTP id k5QLGshR009814; Mon, 26 Jun 2006 21:16:54 GMT Received: from evil.uchicago.edu (evil.uchicago.edu [128.135.17.55]) by robin.gentoo.org (8.13.7/8.13.6) with ESMTP id k5QLGpNe001066 for ; Mon, 26 Jun 2006 21:16:52 GMT Received: from localhost (localhost [127.0.0.1]) (uid 1000) by evil.uchicago.edu with local; Mon, 26 Jun 2006 16:16:51 -0500 id 001BBDAE.44A04EC3.00002B60 Date: Mon, 26 Jun 2006 16:16:51 -0500 From: mjinks@uchicago.edu To: gentoo-embedded@lists.gentoo.org Subject: [gentoo-embedded] dhcp across segments with dnsmasq? Message-ID: <20060626211651.GB13974@uchicago.edu> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-embedded@gentoo.org Reply-to: gentoo-embedded@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Disclaimer: This message contains no useful information. User-Agent: Mutt/1.5.11 X-Archives-Salt: 86b1cd00-d884-449f-99ae-ff5e23293dea X-Archives-Hash: 148fa8446326760ba8afa79811482bad We have a big old Dell running RedHat, which does nothing (any more) but serve DHCP for a number of labs around our campus. We thought it would be an ideal candidate for replacement with a home-rolled GNAP machine using dnsmasq's DHCP service. It seemed to work well in testing, but when we dropped in the replacement system we found that machines on remote VLANs could no longer get addresses. The campus network runs on Cisco switches, controlled by another group. I'm pretty much Cisco-ignorant myself, but my undertanding is that the VLANs which serve our DHCP clients have been configured to propagate DHCP requests beyond the local segment and on to our centrally-located DHCP server, and this works fine with the old machine. A little tcpdumping shows some differences between the old (RedHat) box and the new (GNAP) system. In this example, "msfc-ri-v17.uchicago.edu" is the router which serves our DHCP client; "dell-test-03.uchicago.edu" is the DHCP client; and "bonzai.uchicago.edu" houses the DHCP server. tcpdump is running on bonzai: 14:42:27.985373 msfc-ri-v17.uchicago.edu.bootps > bonzai.uchicago.edu.bootps: (request) hops:1 xid:0x20dcf2e1 secs:4 flags:0x8000 G:msfc-ri-v17.uchicago.edu ether 0:f:1f:dc:f2:e1 [|bootp] 14:42:27.986066 bonzai.uchicago.edu.bootps > msfc-ri-v17.uchicago.edu.bootps: (reply) hops:1 xid:0x20dcf2e1 secs:4 flags:0x8000 Y:dell-test-03.uchicago.edu S:bonzai.uchicago.edu G:msfc-ri-v17.uchicago.edu ether 0:f:1f:dc:f2:e1 [|bootp] (DF) Now here's an example of the same case, except that the hardware acting as bonzai.uchicago.edu is now our GNAP machine: 01:06:27.601181 IP msfc-ri-v17.uchicago.edu.bootps > bonzai.uchicago.edu.bootps: BOOTP/DHCP, Request [|bootp] The GNAP box doesn't issue a response, apparently because it can't see that the request is coming from one of its listed DHCP clients. So, does anybody know what might be going on here? I don't think that dnsmasq is (necessarily) the culprit, since tcpdump shows more information in the case of the packets dumped on the RedHat machine. Is this a difference, maybe, in the uclibc network handling? Do I need to tweak my kernel? Am I just crazy? Thanks for any thoughts. --Michael -- gentoo-embedded@gentoo.org mailing list