Comment 1 for bug 1447715

A quick update -- This seems to be a timing issue, i.e. dhclient trying to bind to the DHCPv6 port (UDP 546) on a link-local address when the interface is not ready, but I am not sure. What I do know is that the following patch to isc-dhcp-client 4.3.1 works around the problem:

--- a/common/socket.c
+++ b/common/socket.c
@@ -170,6 +170,11 @@
   if ((info->flags & INTERFACE_STREAMS) == INTERFACE_UPSTREAM) {
    *do_multicast = 0;
   }
+
+ /*
+ * Wait a little before calling bind(). See LP #1447715.
+ */
+ sleep(5);
   break;
 #endif /* DHCPv6 */

With this patch dhclient -6 waits 5 seconds before attempting to bind(), and that allows me to obtain an IPv6 address from the DHCPv6 server.

A machine running ArchLinux and network-manager 1.0 does not have this problem of dhclient quitting after failing to bind(). Ubuntu 15.04 uses network-manager 0.9.10.0 so this might be a problem with Network Manager after all. We will have to wait and see until Ubuntu has Network Manager 1.0. In the meantime, I am all see with the above "workaround".

Cheers,

Eloy Paris.-