This is specifically important for any configuration that wants to have both a IPv4 address and DHCPv6 IPv6 address on a single interface, and uses ifupdown for interface management, and wants independent control of the 4 and 6 address. Meaning, to be able to add or remove an interface's IPv6 DHCPv6 address, while leaving the interface up and still configured with its IPv4 address. The ifupdown program does not have any mechanism for controlling IPv4 and IPv6 addresses on a single interface separately, so interface aliases are the most convenient way to keep using ifupdown and be able to control the addresses separately. An example ifupdown configuration might be:
auto eth0 iface eth0 inet manual pre-down ifdown eth0:1 pre-down ifdown eth0:2 auto eth0:1 iface eth0:1 inet dhcp auto eth0:2 iface eth0:2 inet6 dhcp That configuration will start dhcp for both IPv4 and IPv6 addresses on eth0 at boot, and will allow running 'sudo ifdown eth0:1' to remove the IPv4 address only, while leaving the IPv6 address, or 'sudo ifdown eth0:2' to remove the IPv6 address only, while leaving the IPv4 address. Or, 'sudo ifdown eth0' will remove both addresses and take down the physical interface. Since this configuration uses an interface alias for DHCPv6, the current isc-dhcp-client fails, and requires the patch from the attached debdiffs to work. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to isc-dhcp in Ubuntu. https://bugs.launchpad.net/bugs/1693819 Title: dhclient DHCPv6 does not work with interface alias Status in isc-dhcp package in Ubuntu: New Status in isc-dhcp source package in Trusty: New Status in isc-dhcp source package in Xenial: New Status in isc-dhcp source package in Yakkety: New Status in isc-dhcp source package in Zesty: New Status in isc-dhcp source package in Artful: New Bug description: [Impact] The isc-dhcp-client dhclient program does not work with interface alias names, e.g. eth0:1. It fails immediately. [Test Case] On trusty through artful, find an interface that is connected to a network that has a DHCPv6 server on it. First verify it can get a DHCPv6 address, e.g.: $ sudo dhclient -6 -v ens7 that should successfully set up a DHCPv6 address on the interface. Then release the interface: $ sudo dhclient -6 -v -r ens7 Now, try again but use the interface alias, e.g.: $ sudo dhclient -6 -v ens7:1 It should succeed, but it will fail with: no link-local IPv6 address for ens7:1 [Regression Potential] Changing how isc-dhcp handles (enumerates/lists/compares) interface names may lead to isc-dhcp using the wrong interface or failing to find the correct interface to use. However, if the only change is to strip the alias part from the interface during comparison, the possibility of error should be small, since all interface aliases point back to the same physical interface. [Other Info] This bug exists in the upstream isc-dhcp; the ISC has no public bug tracker, and only accepts bug reports via private email, which has been sent. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/isc-dhcp/+bug/1693819/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
