[Bug 1010724] Re: No IPv6 nameservers in Ubuntu 12.04

[Thomas Hood]

There is no evidence in the report of a bug in resolvconf.

If dnsmasq is not responding at ::1 then this may be because dnsmasq has
been started with the "--bind-interfaces" and "--listen-
address=127.0.0.1" options which is the case, for example, when dnsmasq
is controlled by NetworkManager.  Please provide the output of "ps
-elf|grep dnsmasq".

When I run the standalone dnsmasq with the aforementioned options,
dnsmasq does not respond to either of the following commands

    dig aaaa -6 google.com
    dig @::1 aaaa -6 google.com

but it does respond correctly to the following command.

    dig @127.0.0.1 aaaa -6 google.com

Wireshark confirms that in the first case ("dig aaaa -6 google.com"),
dig tries to contact ::1 rather than 127.0.0.1, even though its man page
says "If no server argument is provided, dig consults /etc/resolv.conf
and queries the name servers listed there."

So it looks as if there is a bug in dig and a bug in network-manager.

The bug in dig is that when "nameserver 127.0.0.1" is listed in
/etc/resolv.conf, "dig aaaa -6 google.com" doesn't query 127.0.0.1 but
::1, contrary to what its man page says.

The bug in network-manager is that it starts dnsmasq such that the
latter doesn't listen on ::1.

To fix the latter bug it may suffice for NM to invoke dnsmasq with an
additional option  "--listen-address=::1".  With this option added to
the other two all the "dig", "host" and "ping" commands I've mentioned
in this and in my previous comment work properly.

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https://bugs.launchpad.net/bugs/1010724

Title:
  NM fails to start dnsmasq such that it listens on ::1

Status in “network-manager” package in Ubuntu:
  New

Bug description:
  I have IPv6 activated on Ubuntu 12.04 LTS and I receive an IPv6
  address through DHCPv6. However, requests sent through IPv6 fail. For
  example:

  strainu at emily:~$ dig aaaa -6 google.com

  ; <<>> DiG 9.8.1-P1 <<>> aaaa -6 google.com
  ;; global options: +cmd
  ;; connection timed out; no servers could be reached

  But:

  strainu at emily:~$ dig aaaa google.com

  ; <<>> DiG 9.8.1-P1 <<>> aaaa google.com
  ;; global options: +cmd
  ;; Got answer:
  ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60426
  ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 4

  ;; QUESTION SECTION:
  ;google.com.			IN	AAAA

  ;; ANSWER SECTION:
  google.com.		94	IN	AAAA	2a00:1450:400d:805::1000

  
  Looking into /etc/resolv.conf, I see:

  strainu at emily:~$ cat /etc/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
  search lan

  And with netstat:

  strainu at emily:~$ netstat -ln
  Active Internet connections (only servers)
  Proto Recv-Q Send-Q Local Address           Foreign Address         State      
  tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN     
  tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN     
  tcp6       0      0 ::1:631                 :::*                    LISTEN     
  udp        0      0 127.0.0.1:53            0.0.0.0:*                          
  udp        0      0 0.0.0.0:68              0.0.0.0:*                          
  udp        0      0 0.0.0.0:5353            0.0.0.0:*                          
  udp        0      0 0.0.0.0:38399           0.0.0.0:*                          
  udp6       0      0 :::47973                :::*                               
  udp6       0      0 :::5353                 :::*          

  Apparently, the local dnsmasq server does not listen on IPv6, which is
  wrong. The server should also listen on ::1:53, to allow IPv6-only
  connections. Alternatively, the resolvconf package should write the
  actual DNS server received through DHCPv6 in /etc/resolv.conf

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: resolvconf 1.63ubuntu14
  ProcVersionSignature: Ubuntu 3.2.0-24.39-generic 3.2.16
  Uname: Linux 3.2.0-24-generic x86_64
  ApportVersion: 2.0.1-0ubuntu8
  Architecture: amd64
  Date: Sat Jun  9 02:27:02 2012
  InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
  PackageArchitecture: all
  SourcePackage: resolvconf
  UpgradeStatus: Upgraded to precise on 2012-05-28 (11 days ago)

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