[Dnsmasq-discuss] Repeated assignment, ignored dhcp-host, and failed DNS lookup
Let me preface by saying that I've been using dnsmasq for a couple of years, without known problems until today. Today, after having been away for a week, I tried to connect with an internal server as I've done many, many times, but DNS lookup failed. So, on the server that's running dnsmasq, I typed (where m1330c is the server in question), and the response was: Server: 127.0.0.1 Address: 127.0.0.1#53 Non-authoritative answer: *** Can't find m1330c: No answer Now, let me point out that m1330c has a wireless interface and a wired interface. And both of these are specified in the dnsmasq.conf with preferred addresses, in the format: dhcp-host=11:22:33:44:55:66,m1330c,192.168.0.6 dhcp-host=11:22:33:44:55:67,m1330cw,192.168.0.7 I get the same nslookup response for m1330cw Upon review of the messages log, I found that different addresses are being assigned (.14 and .15, respectively)... and not only that, but the assignment is being made every 50-some seconds. This has been set-it-and-forget-it for me, and I don't remember a lot of the details I went through for the initial configuration, but I do know that it was working, and now has stopped, but without configuration changes. A reboot of the server running dnsmasq did not resolve the issue. There are a few devices on the network. Three have hard-coded addresses (in /etc/hosts), and nslookup shows accurate information for them. Those with DHCP-based addresses all return can't find ... messages. Final bit of information: It appears that the repeat-ip-serving for m1330c/w has been going on for months, but did not seem to impact operation. But it seems to happen only to these two interfaces (a Windows 7 server, but not the only one in the net). To summarize: nslookup does not return IP address of DHCP-based servers dhcp-host entries in /etc/dnsmasq.conf are ignored, or at least are not as expected Repeated assignment of IP address to two interfaces Following are the messages from dnsmasq since time of boot. What might I be missing? Oct 8 10:46:46 stora-1 dnsmasq[2046]: started, version 2.62 cachesize 150 Oct 8 10:46:46 stora-1 dnsmasq[2046]: compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP DHCPv6 no-Lua TFTP no-conntrack Oct 8 10:46:46 stora-1 dnsmasq-dhcp[2046]: DHCP, IP range 192.168.0.10 -- 192.168.0.109, lease time 7d Oct 8 10:46:46 stora-1 dnsmasq-tftp[2046]: TFTP root is /home/tftpd Oct 8 10:46:46 stora-1 dnsmasq[2046]: reading /etc/resolv.conf Oct 8 10:46:46 stora-1 dnsmasq[2046]: using nameserver 65.32.5.112#53 Oct 8 10:46:46 stora-1 dnsmasq[2046]: using nameserver 65.32.5.111#53 Oct 8 10:46:46 stora-1 dnsmasq[2046]: read /etc/hosts - 258 addresses Oct 8 10:46:58 stora-1 dnsmasq[2046]: reading /etc/resolv.conf Oct 8 10:46:58 stora-1 dnsmasq[2046]: using nameserver 65.32.5.112#53 Oct 8 10:46:58 stora-1 dnsmasq[2046]: using nameserver 65.32.5.111#53 Oct 8 10:46:58 stora-1 dnsmasq[2046]: ignoring nameserver 127.0.0.1 - local interface Oct 8 10:47:35 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.14 00:21:9b:cb:e6:dd Oct 8 10:47:35 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.14 00:21:9b:cb:e6:dd M1330C Oct 8 10:47:35 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.15 00:21:5c:6a:03:ef Oct 8 10:47:35 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.15 00:21:5c:6a:03:ef m1330cw Oct 8 10:48:35 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.14 00:21:9b:cb:e6:dd Oct 8 10:48:35 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.14 00:21:9b:cb:e6:dd M1330C Oct 8 10:48:36 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.15 00:21:5c:6a:03:ef Oct 8 10:48:36 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.15 00:21:5c:6a:03:ef m1330cw Oct 8 10:49:37 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.14 00:21:9b:cb:e6:dd Oct 8 10:49:37 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.14 00:21:9b:cb:e6:dd M1330C Oct 8 10:49:37 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.15 00:21:5c:6a:03:ef Oct 8 10:49:37 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.15 00:21:5c:6a:03:ef m1330cw Oct 8 10:50:41 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.14 00:21:9b:cb:e6:dd Oct 8 10:50:41 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.14 00:21:9b:cb:e6:dd M1330C Oct 8 10:50:41 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.15 00:21:5c:6a:03:ef Oct 8 10:50:41 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.15 00:21:5c:6a:03:ef m1330cw Oct 8 10:51:42 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.14 00:21:9b:cb:e6:dd Oct 8 10:51:42 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.14 00:21:9b:cb:e6:dd M1330C Oct 8 10:51:42 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.15 00:21:5c:6a:03:ef Oct 8 10:51:42 stora-1 dnsmasq-dhcp[2046]: DHCPACK(eth0) 192.168.0.15 00:21:5c:6a:03:ef m1330cw Oct 8 10:53:35 stora-1 dnsmasq-dhcp[2046]: DHCPINFORM(eth0) 192.168.0.14
Re: [Dnsmasq-discuss] Repeated assignment, ignored dhcp-host, and failed DNS lookup
Hi, Simon: I have all the logs going back to June, 2011. (That represents about 70,000 lines of dnsmasq-related messages.) What would you like to see from those? The m1330c/w system was on a different network yesterday morning, and moved back to this network in the evening. Absolutely possible that it is hanging on to its prior lease, though I didn't think those survived a boot after a network switch. You would absolutely know, though, and I take it from your response that that's probably what happened. I'll refresh the lease this PM if not back to normal by then. How would I know if a rogue DHCP server has appeared on the net? I'm assuming you're on the right track since the answer to the remaining question is: /var/lib/misc/dnsmasq.leases is empty Dennis -Original Message- From: dnsmasq-discuss-boun...@lists.thekelleys.org.uk [mailto:dnsmasq-discuss-boun...@lists.thekelleys.org.uk] On Behalf Of Simon Kelley Sent: Monday, October 08, 2012 12:04 PM To: dnsmasq-discuss@lists.thekelleys.org.uk Subject: Re: [Dnsmasq-discuss] Repeated assignment, ignored dhcp-host, and failed DNS lookup On 08/10/12 16:43, Lovelady, Dennis E. wrote: To summarize: nslookup does not return IP address of DHCP-based servers dhcp-host entries in /etc/dnsmasq.conf are ignored, or at least are not as expected Repeated assignment of IP address to two interfaces Following are the messages from dnsmasq since time of boot. What might I be missing? The log is expected, and not necessarily a problem. The DHCPINFORM transaction is the host asking for configuration information, which dnsmasq supplies in the DHCPACK. It's possible for dnsmasq to reply to DHCPINFORM messages even if a host doesn't actually have a DHCP lease with it. Questions: Are there leases for .0.14 and .0.15 in the dnsmasq leases file? Is there any way to get logs going further back? Is there any chance that a rogue DHCP server has turned up on your network? Has the host in question been attached to another network where it could have picked up a different DHCP lease? My guess is that the .14 and .15 leases don't exist in dnsmasq and the host has picked them up elsewhere. by now, the DHCP leases on .0.14 and .0.15 may have expired, and the host will fail to renew them and cycle through the DHCP process, getting the correct addresses. If not then taking the interfaces down and then back up, or rebooting the host, should do that. Cheers, Simon. ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss BR_ FONT size=2BR DTCC DISCLAIMER: This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error, please notify us immediately and delete the email and any attachments from your system. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email./FONT ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
[Dnsmasq-discuss] How to add local configuration to Network Manager initiated dnsmasq in Ubuntu 12.04
I have run dnsmasq with local configuration for quite a while now to provide local DNS services on my home LAN. I am now upgrading my machines to [xl]ubuntu 12.04 and in this version dnsmasq is run automatically by Network Manager. A default installation just puts the following in resolv.conf:- # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 127.0.0.1 How can I customize the dnsmasq configuration in a way that won't get broken by future upgrades? The NM dnsmasq runs as follows:- chris$ ps -ef | grep dnsmasq nobody1341 1090 0 17:40 ?00:00:00 /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/var/run/sendsigs.omit.d/network-manager.dnsmasq.pid --listen-address=127.0.0.1 --conf-file=/var/run/nm-dns-dnsmasq.conf --cache-size=0 --proxy-dnssec Since the config file is specified as --conf-file=/var/run/nm-dns-dnsmasq.conf it's difficult to do anything that won't get lost at upgrade time. -- Chris Green ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] Repeated assignment, ignored dhcp-host, and failed DNS lookup
How would I know if a rogue DHCP server has appeared on the net? I'm assuming you're on the right track since the answer to the remaining question is: You can do a packet capture on the computer getting the wrong addresses (use wireshark for example) while running ipconfig /renew Look at the source MAC address of the DHCPOFFER packets and compare to the MAC address of your dnsmasq computer's NIC. ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] Repeated assignment, ignored dhcp-host, and failed DNS lookup
On 08/10/12 17:30, Lovelady, Dennis E. wrote: Hi, Simon: I have all the logs going back to June, 2011. (That represents about 70,000 lines of dnsmasq-related messages.) What would you like to see from those? The m1330c/w system was on a different network yesterday morning, and moved back to this network in the evening. Absolutely possible that it is hanging on to its prior lease, though I didn't think those survived a boot after a network switch. You would absolutely know, though, and I take it from your response that that's probably what happened. I'll refresh the lease this PM if not back to normal by then. A lease will survive a client reboot, but I'd expect a reboot to cause a system to at least confirm a lease. Could you look through your dnsmasq logs to see what, if anything dnsmasq logged about this machine when it booted up on this network? How would I know if a rogue DHCP server has appeared on the net? I'm assuming you're on the right track since the answer to the remaining question is: I don't think it's likely, at the moment. My guess is that the DHCP server is at the same IP address on both the networks, and when the machine came back up, it sent the DHCPINFORM to the DHCP server address, then took the response as confirmation that the lease was still valid. This is a bit of a gray area, but the client isn't strictly allowed to do that: it should send a DHCPREQUEST. (strictly, it should entry INIT-REBOOT state) /var/lib/misc/dnsmasq.leases is empty That makes sense: dnsmasq will still reply to DHCPINFORM without a lease, and the DHCPINFORM won't create a lease. Once the lease expires at the client end, or you force it too, then stuff should re-sync. If rebooting the client caused it to send only DHCPINFORM requests, then we have some grounds to complain to Microsoft. Simon. ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
[Dnsmasq-discuss] Trivial error in sample dnsmasq.conf file
I believe the line: #dhcp-boot=net:red,pxelinux.red-net should be #dhcp-boot=tag:red,pxelinux.red-net And, since I have noticed someone has gone to the trouble of fixing other minor typos: # Include a another lot of configuration options. should be # Include another lot of configuration options. ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] How to add local configuration to Network Manager initiated dnsmasq in Ubuntu 12.04
Did you edit /etc/NetworkManager/NetworkManager.conf? The line should say dns=dnsmasq - Jay Sent from my iPhone On Oct 8, 2012, at 14:04, Chris Green c...@isbd.net wrote: I have run dnsmasq with local configuration for quite a while now to provide local DNS services on my home LAN. I am now upgrading my machines to [xl]ubuntu 12.04 and in this version dnsmasq is run automatically by Network Manager. A default installation just puts the following in resolv.conf:- # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 127.0.0.1 How can I customize the dnsmasq configuration in a way that won't get broken by future upgrades? The NM dnsmasq runs as follows:- chris$ ps -ef | grep dnsmasq nobody1341 1090 0 17:40 ?00:00:00 /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/var/run/sendsigs.omit.d/network-manager.dnsmasq.pid --listen-address=127.0.0.1 --conf-file=/var/run/nm-dns-dnsmasq.conf --cache-size=0 --proxy-dnssec Since the config file is specified as --conf-file=/var/run/nm-dns-dnsmasq.conf it's difficult to do anything that won't get lost at upgrade time. -- Chris Green ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
