B3 dnsmasq ignores DHCP requests since 2.6.0.3 [SOLVED]

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Cheeseboy
Posts: 789
Joined: 08 Apr 2007, 12:16

B3 dnsmasq ignores DHCP requests since 2.6.0.3 [SOLVED]

Post by Cheeseboy » 07 Oct 2016, 05:33

Dear all,

I've been away for a while due to health issues.
I'm absolutely delighted to see that the forum is still alive!

My problem:
Since applying the 2.6.0.3 standard update (viewtopic.php?f=22&t=5851) and apt-get upgrade, B3s dnsmasq seem to have stopped serving DHCP requests. The only way I can get network access from my clients is to enter details manually, ignoring DHCP.

I can see dnsmasq listening on port 53 and 67:

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sudo netstat -anp | grep dnsmasq
tcp        0      0 0.0.0.0:53              0.0.0.0:*               LISTEN      6640/dnsmasq    
tcp6       0      0 :::53                   :::*                    LISTEN      6640/dnsmasq    
udp        0      0 0.0.0.0:53              0.0.0.0:*                           6640/dnsmasq    
udp        0      0 0.0.0.0:67              0.0.0.0:*                           6640/dnsmasq    
udp6       0      0 :::53                   :::*                                6640/dnsmasq    
unix  2      [ ]         DGRAM                    43740    6640/dnsmasq 
Note that there is IPv6 stuff in there that I have never seen before on my B3.
Thinking that might have been the cause of the problem, I've tried to disable all IPv6, but to no avail.

My NICs all seem to sport a IPv6 address now. Here is ifconfig output.

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br0       Link encap:Ethernet  HWaddr 00:0b:6b:7d:5b:1b  
          inet addr:192.168.10.1  Bcast:192.168.10.255  Mask:255.255.255.0
          inet6 addr: fe80::20b:6bff:fe7d:5b1b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:27889953 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22962071 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:3745661175 (3.4 GiB)  TX bytes:4100007216 (3.8 GiB)

eth0      Link encap:Ethernet  HWaddr 00:22:02:00:15:4a  
          inet addr:46.59.60.204  Bcast:46.59.61.255  Mask:255.255.254.0
          inet6 addr: fe80::222:2ff:fe00:154a/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1500  Metric:1
          RX packets:20158753 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25725956 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3587417914 (3.3 GiB)  TX bytes:4142391012 (3.8 GiB)
          Interrupt:11 

eth1      Link encap:Ethernet  HWaddr 00:22:02:00:15:4b  
          inet6 addr: fe80::222:2ff:fe00:154b/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:31504326 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25984869 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:498169527 (475.0 MiB)  TX bytes:296273231 (282.5 MiB)
          Interrupt:15 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:5792 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5792 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:545833 (533.0 KiB)  TX bytes:545833 (533.0 KiB)

mon.wlan0 Link encap:UNSPEC  HWaddr 00-0B-6B-7D-5B-1B-01-00-00-00-00-00-00-00-00-00  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1293406 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:32 
          RX bytes:240426395 (229.2 MiB)  TX bytes:0 (0.0 B)

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:192.168.222.1  P-t-P:192.168.222.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

wlan0     Link encap:Ethernet  HWaddr 00:0b:6b:7d:5b:1b  
          inet6 addr: fe80::20b:6bff:fe7d:5b1b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:54992 errors:0 dropped:0 overruns:0 frame:0
          TX packets:105761 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:32 
          RX bytes:8160874 (7.7 MiB)  TX bytes:34541203 (32.9 MiB)

I have also noticed that DHCP fails for incoming OpenVPN connections.

Please forgive me if I have missed something obvious or have not included relevant information, it's been a long time since...

Many thanks in advance,

Cheeseboy
Last edited by Cheeseboy on 07 Oct 2016, 13:37, edited 2 times in total.

Gordon
Posts: 1390
Joined: 10 Aug 2011, 03:18

Re: B3 dnsmasq ignores DHCP requests since 2.6.0.3

Post by Gordon » 07 Oct 2016, 10:24

Why do you have a bridge interface if you have no wireless? The IPv6 protocols will have been introduced by the bridge module which has a fixed dependency on, and thus autoloads, the ipv6 module. You should verify your network settings. Be careful not to lock yourself out (firewall) when correcting any wrong settings.

Cheeseboy
Posts: 789
Joined: 08 Apr 2007, 12:16

Re: B3 dnsmasq ignores DHCP requests since 2.6.0.3

Post by Cheeseboy » 07 Oct 2016, 10:56

Hi Gordon,

Sorry, copy/paste mishap.
I have edited my original post with the full ifconfig -a output.
I have wifi and a tun interface for OpenVPN.

I thought perhaps something weird had happened with my iptables configuration, but it looks like it used to do, and I can reach the TCP and UDP ports with nc.
The DHCP clients however use broadcast on 255.255.255.255... No idea how to test that.

Any ideas appreciated as always!

Cheers,

Cheeseboy

Cheeseboy
Posts: 789
Joined: 08 Apr 2007, 12:16

Re: B3 dnsmasq ignores DHCP requests since 2.6.0.3

Post by Cheeseboy » 07 Oct 2016, 13:35

Hi again,

After a lot of desperate measures like recompiling dnsmasq with COPTS=-DNO_IPV6 and others, I noticed this in /etc/dnsmasq.d/bubba.conf:

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no-dhcp-interface=br0,tun0
The file had a new datestamp (from when I ran the upgrade).
Unfortunately I had no backup to compare it with, but commenting the line out has restored service as normal.

Cheers,
Cheeseboy

Gordon
Posts: 1390
Joined: 10 Aug 2011, 03:18

Re: B3 dnsmasq ignores DHCP requests since 2.6.0.3 [SOLVED]

Post by Gordon » 08 Oct 2016, 10:22

Ah yes, that would do it.

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