Re: [Dnsmasq-discuss] DHCP Relay across VLANs
Hi Chris, Thank you for the note. I was able to get the LEDE build environment working and recompiled dnsmasq with the patch. The patch, when applied to v2.77, worked and DHCP relay is working as expected in my use case. Thanks for the help! Ray -Original Message- From: Chris Novakovic [mailto:ch...@chrisn.me.uk] Sent: Thursday, September 14, 2017 6:40 PM To: Ray Ramadorai Cc: dnsmasq-discuss@lists.thekelleys.org.uk Subject: Re: [Dnsmasq-discuss] DHCP Relay across VLANs On 15/09/2017 01:26, Ray Ramadorai wrote: > Software versions working case: > > Kernel: Linux Openwrt 3.18.23 #1 SMP Sun Jan 31 15:32:38 CET 2016 > x86_64 GNU/Linux > > DNSMasq: Dnsmasq version 2.73 Copyright (c) 2000-2015 Simon Kelley > > Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP > no-DHCPv6 no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC > loop-detect inotify > > > > Software versions NOT working case: > > Kernel: Linux LEDE 4.4.71 #0 SMP Wed Jun 7 19:24:41 2017 x86_64 > GNU/Linux > > Dnsmasq version 2.77 Copyright (c) 2000-2016 Simon Kelley > > Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP > no-DHCPv6 no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC no-ID > loop-detect inotify DHCP relay was broken by a commit shortly before 2.76 was released [1], and this breakage was itself recently fixed by a commit that'll eventually make it into 2.78 [2]. If you're able to compile dnsmasq yourself, could you check that [2] fixes the problem you're seeing? [1] http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=ff325644c7afae2588 583f935f4ea9b9694eb52e [2] http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=1649f709e7351f0c6b bfedc5bd32744b330e2bcd ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
[Dnsmasq-discuss] DHCP Relay across VLANs
I recently was trying to transition from OpenWRT to LEDE and ran into a problem with DHCP relay not working correctly after the transition. I have taken debug about as far as I can and am looking for some help going forward. Some details on network and configuration: Network A (VLAN82) 192.168.42.0/24 Host: DHCP Server 192.168.42.4 Host: Relay 192.168.42.41 on interface (eth0.82) Network B (VLAN85) 192.168.85.0/24 Host: DHCP Client MAC: (00:0c:29:ed:03:a5) Host: Relay 192.168.85.2 on interface (eth0.85) dnsmasq.conf on the Relay host: dhcp-authoritative domain-needed localise-queries read-ethers bogus-priv expand-hosts local-service domain=lan server=/lan/ dhcp-leasefile=/tmp/dhcp.leases resolv-file=/tmp/resolv.conf.auto stop-dns-rebind rebind-localhost-ok dhcp-broadcast=tag:needs-broadcast addn-hosts=/tmp/hosts conf-dir=/tmp/dnsmasq.d user=dnsmasq group=dnsmasq dhcp-relay=192.168.85.2,192.168.42.4 The platform is a set of virtual machines running on x86 hardware. Software versions working case: Kernel: Linux Openwrt 3.18.23 #1 SMP Sun Jan 31 15:32:38 CET 2016 x86_64 GNU/Linux DNSMasq: Dnsmasq version 2.73 Copyright (c) 2000-2015 Simon Kelley Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP no-DHCPv6 no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC loop-detect inotify Software versions NOT working case: Kernel: Linux LEDE 4.4.71 #0 SMP Wed Jun 7 19:24:41 2017 x86_64 GNU/Linux Dnsmasq version 2.77 Copyright (c) 2000-2016 Simon Kelley Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP no-DHCPv6 no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC no-ID loop-detect inotify In the working case the normal 4 packet DHCP handshake occurs as expected and the relay passes the packets between the DHCP server and the client. In the failing case the client request packet gets from the client to the relay and then on to the dhcp server via the relay. The response from the dhcp server makes it back to the relay, but then the corresponding packet from the relay to the client never gets sent. Though I see the packet come back from the server it is not clear that DNSMasq sees the packet. I can attach TCP dumps as needed. Any help in further debug steps to determine if dnsmasq is not seeing the response from the DHCP server or is not sending the packet and why would be very helpful. I also came across this bug that looks similar but I am not sure has been reported upstream: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1686192 Thanks Ray Ramadorai ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss