[Bug 715152] Re: ntp wont run on IPv6 only host unless lo has 127.0.0.1 address

[James Page]

Minimal patch to fix running with no IPv4

** Description changed:

+ IMPACT:
+ Ubuntu instances running in pure IPv6 environments (including 127.0.0.1) cannot run ntp as it dies when scanning for available interfaces.
+ 
+ FIX:
+ IPv6/IPv4 scanning has been improved in later releases; patch created from later release to resolve this issue (directly attached to this bug report).
+ 
+ TESTING:
+ 1) On a working system with IPv4 & IPV6:
+   sudo apt-get install ntp
+   netstat -a | grep ntp
+ Ports should be mapped for both udp and udp6
+ 
+ 2) Disable IPv4
+ Add the following line to /etc/network/interfaces to disable 127.0.0.1:
+ 
+ iface lo inet loopback
+     post-up ip addr del 127.0.0.1/8 dev lo
+ 
+ And remove the line(s) relating to IPv4 configuration of other network
+ interfaces (looks like iface eth* inet dhcp|static*)
+ 
+ 3) Reboot server
+ 
+ 4) NTP service will not be running; messages in /var/log/syslog relating to startup of daemon; however no daemon running
+    ps -aef | grep ntp
+    netstat -a | grep ntp
+ 
+ IMPACT:
+ Patch is relatively minimal and comes from later release.
+ 
+ >>>> ORIGINAL BUG REPORT <<<<<
+ 
  Binary package hint: ntp
  
  Lucid host running IPv6 only, with network configured like this:
  
  root at svn:~# ifconfig
  eth0      Link encap:Ethernet  HWaddr 00:50:56:86:00:15
-           inet6 addr: 2001:610:148:dead:cafe:babe:0:29/64 Scope:Global
-           inet6 addr: fe80::250:56ff:fe86:15/64 Scope:Link
-           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
-           RX packets:3164 errors:0 dropped:0 overruns:0 frame:0
-           TX packets:2075 errors:0 dropped:0 overruns:0 carrier:0
-           collisions:0 txqueuelen:1000
-           RX bytes:1516490 (1.5 MB)  TX bytes:387497 (387.4 KB)
+           inet6 addr: 2001:610:148:dead:cafe:babe:0:29/64 Scope:Global
+           inet6 addr: fe80::250:56ff:fe86:15/64 Scope:Link
+           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
+           RX packets:3164 errors:0 dropped:0 overruns:0 frame:0
+           TX packets:2075 errors:0 dropped:0 overruns:0 carrier:0
+           collisions:0 txqueuelen:1000
+           RX bytes:1516490 (1.5 MB)  TX bytes:387497 (387.4 KB)
  
  lo        Link encap:Local Loopback
-           inet6 addr: ::1/128 Scope:Host
-           UP LOOPBACK RUNNING  MTU:16436  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:0
-           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
- 
+           inet6 addr: ::1/128 Scope:Host
+           UP LOOPBACK RUNNING  MTU:16436  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:0
+           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
  
  Now ntpd wont start:
  
  ./../libisc/ifiter_ioctl.c:567: REQUIRE(iter->pos < (unsigned int) iter->ifc.ifc_len) failed.
  Aborted
  
  After adding an IPv4 loopback address to lo interface:
  
  ip addr add 127.0.0.1 dev lo
  
  ntpd is able to start.
  
  According to http://bugs.ntp.org/show_bug.cgi?id=397 this might be
  related to libisc.

** Patch added: "fix-noipv4.patch"
   https://bugs.launchpad.net/ubuntu/+source/ntp/+bug/715152/+attachment/2016103/+files/fix-noipv4.patch

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https://bugs.launchpad.net/bugs/715152

Title:
  ntp wont run on IPv6 only host unless lo has 127.0.0.1 address