[Bug 1990542] [NEW] initrd starts dhclient on interfaces that are not supposed to get an IP address

[Valentijn Sessink]

Public bug reported:

After trying several setups, I think this is a bug. If not - I can't
find how to fix things.

Setup: Ubuntu 22.04, with ubuntu-minimal installed (which depends on
isc-dhcp-client). A network with a bridge interface. This can be
anything, even an old /etc/network/interfaces file will do. For
simplicity, the following netplan setup is used:

network:
    version: 2
    ethernets:
        enp4s0:
          wakeonlan: true
            dhcp4: no
            dhcp6: no
    bridges:
      br0:
        interfaces: [enp4s0]
        dhcp4: yes
        dhcp6: yes
        parameters:
          stp: false
          forward-delay: 0


What happens:
Starting this machine will, during initrd phase, make dhclient fetch an IP address for enp4s0. Then netplan takes over and fetches an address for br0. If both enp4s0 and br0 have the same IP address from the DHCP-server, the machine will not be reachable.

What should happen:
enp4s0 should not get an IP address, as the netplan-configuration clearly says.

A workaround is to remove isc-dhcp-client (which, in turn, removes meta-
package ubuntu-minimal) and run update-initramfs -k all -u; afterwards,
the dhclient in initrd is (obviously) not there anymore.

** Affects: initramfs-tools (Ubuntu)
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to initramfs-tools in Ubuntu.
https://bugs.launchpad.net/bugs/1990542

Title:
  initrd starts dhclient on interfaces that are not supposed to get an
  IP address

Status in initramfs-tools package in Ubuntu:
  New

Bug description:
  After trying several setups, I think this is a bug. If not - I can't
  find how to fix things.

  Setup: Ubuntu 22.04, with ubuntu-minimal installed (which depends on
  isc-dhcp-client). A network with a bridge interface. This can be
  anything, even an old /etc/network/interfaces file will do. For
  simplicity, the following netplan setup is used:

  network:
      version: 2
      ethernets:
          enp4s0:
            wakeonlan: true
              dhcp4: no
              dhcp6: no
      bridges:
        br0:
          interfaces: [enp4s0]
          dhcp4: yes
          dhcp6: yes
          parameters:
            stp: false
            forward-delay: 0

  
  What happens:
  Starting this machine will, during initrd phase, make dhclient fetch an IP address for enp4s0. Then netplan takes over and fetches an address for br0. If both enp4s0 and br0 have the same IP address from the DHCP-server, the machine will not be reachable.

  What should happen:
  enp4s0 should not get an IP address, as the netplan-configuration clearly says.

  A workaround is to remove isc-dhcp-client (which, in turn, removes
  meta-package ubuntu-minimal) and run update-initramfs -k all -u;
  afterwards, the dhclient in initrd is (obviously) not there anymore.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/1990542/+subscriptions