[Bug 1352255] Re: Impossible to configure network interface with only IPv6 address

Thu Oct 9 16:36:41 UTC 2014

I did a fair amount of debug information including recreation with a
cloud image at lp:~smoser/+junk/lp-1377005 . I'll copy the final comment
here.

ok. so, i now know what happens, and why adding anything before the ipv6 address "fixes" the problem.
boot happens like this:
 * system boot
 * net-device-added fires network-interface.conf
 * net-device-added runs ifup --allow auto
 * ifup --allow auto reads /etc/network/interfaces *in order*
 * after the *first* stanza is brought up, /etc/network/if-up.d/upstart is invoked
 * /etc/network/if-up.d/upstart finds all interfaces to be up and emits static-network-up
 * /etc/init/failsafe.conf is stopped, freeing procps.conf to start
 * procps.conf runs sysctl on files in /etc/sysctl.d/*.conf
    which includes /etc/sysctl.d/10-ipv6-privacy.conf

ipv6-privacy.conf ends up killing the existing addresses.

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Title:
  Impossible to configure network interface with only IPv6 address

Status in “ifupdown” package in Ubuntu:
  Confirmed

Bug description:
  As it says on the tin.
  I'm unable to configure my Ubuntu 14.04 VM to have only an IPv6 address on boot-up.
  Dual stack works fine.

  My /etc/networking/interfaces looks like this:

  # This file describes the network interfaces available on your system
  # and how to activate them. For more information, see interfaces(5).

  # The loopback network interface
  auto lo
  iface lo inet loopback

  # The primary network interface
  auto eth0
  iface eth0 inet6 static
          address 2001:610:188:444::55
          netmask 64
          gateway 2001:610:188:444::1
          autoconf 0
          privext 0
          accept_ra 0
          dns-search terena.org
          dns-domain terena.org
          dns-nameservers 2001:610:1:800a:192:87:106:106

  After boot-up there is only a link-local address:

  root at trusty-test:~# ifconfig                                                                        
  eth0      Link encap:Ethernet  HWaddr 00:50:56:95:42:ab                                             
            inet6 addr: fe80::250:56ff:fe95:42ab/64 Scope:Link                                        
            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1                                        
            RX packets:101 errors:0 dropped:0 overruns:0 frame:0                                      
            TX packets:22 errors:0 dropped:0 overruns:0 carrier:0                                     
            collisions:0 txqueuelen:1000                                                              
            RX bytes:6644 (6.6 KB)  TX bytes:2132 (2.1 KB)                                            

  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:65536  Metric:1                                                  
            RX packets:240 errors:0 dropped:0 overruns:0 frame:0                                      
            TX packets:240 errors:0 dropped:0 overruns:0 carrier:0                                    
            collisions:0 txqueuelen:0                                                                 
            RX bytes:18192 (18.1 KB)  TX bytes:18192 (18.1 KB)                                        

  However, if I manually ifdown/ifup the interface, then things start working:

  root at trusty-test:~# ifdown eth0                                                                     
  root at trusty-test:~# ifconfig                                                                        
  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:65536  Metric:1                                                  
            RX packets:240 errors:0 dropped:0 overruns:0 frame:0                                      
            TX packets:240 errors:0 dropped:0 overruns:0 carrier:0                                    
            collisions:0 txqueuelen:0                                                                 
            RX bytes:18192 (18.1 KB)  TX bytes:18192 (18.1 KB)                                        

  root at trusty-test:~# ifup eth0                                                                       
  Waiting for DAD... Done                                                                             
  root at trusty-test:~# ifconfig                                                                        
  eth0      Link encap:Ethernet  HWaddr 00:50:56:95:42:ab                                             
            inet6 addr: fe80::250:56ff:fe95:42ab/64 Scope:Link                                        
            inet6 addr: 2001:610:188:444::55/64 Scope:Global                                          
            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1                                        
            RX packets:894 errors:0 dropped:0 overruns:0 frame:0                                      
            TX packets:652 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:1000
            RX bytes:168407 (168.4 KB)  TX bytes:95052 (95.0 KB)

  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:65536  Metric:1
            RX packets:288 errors:0 dropped:0 overruns:0 frame:0
            TX packets:288 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:0
            RX bytes:21792 (21.7 KB)  TX bytes:21792 (21.7 KB)

  FYI, I have many 12.04 LTS VMs that work fine with the same configuration.

  Many thanks!!!

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