Comment 0 for bug 1689854

[Impact]

When using isc-dhcp-client on a Trusty system, with multiple interfaces configured to use DHCPv6, not all the DHCPv6 clients will receive the server responses on some of the interfaces. This results in not all DHCPv6 interfaces being configured.

[Test Case]

Set up a DHCPv6 server with multiple interfaces (3-4 is enough) and configure it to serve DHCPv6 on all the interfaces (as separate subnets). The server release does not matter. Set up a client system with the same number of interfaces, connected/bridged to the server interfaces. The client must be a Trusty system. Configure (with ifupdown via /etc/network/interfaces) all the interfaces to use DHCPv6, and reboot. Keep rebooting until one or more of the DHCPv6 interfaces fails to get an address; it should not take more than a few reboots. After a failure, even manual ifdown/ifup on the failed interface will not get a DHCPv6 address.

[Regression Potential]

As this changes how the isc-dhcp-client binds to IPv6 sockets, this could cause problems when the client tries to bind, send, or receive, with this or other operations.

[Other Info]

This is fixed upstream already, and the patch is included in Xenial and later releases. This patch is needed only in the Trusty release.