[Bug 1713226] Re: systemd-networkd messes up networking

[Dimitri John Ledkov]

Is this on upgrades to artful? or clean-install / clean-bring up of
artful?

Note that artful will no longer have ifupdown installed on clean-install, and thus /etc/network/interfaces changes for clean-installs will have no effect at all. And one should instead use netplan e.g. $ sudo netplan ifupdown-migrate
to move the system over to networkd.

The router advertisement vs networkmanager is interesting case. In
practice networkd should not have configured the interface imho, if it
was not told to manage it via netplan configuration. Or e.g.
NetworkManager should still consider interface for management, even if
it has acquired RA ipv6.

** Also affects: nplan (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: network-manager (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1713226

Title:
  systemd-networkd messes up networking

Status in network-manager package in Ubuntu:
  New
Status in nplan package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  New

Bug description:
  Since systemd-234-2ubuntu8 systemd-networkd is enabled by default.

  This causes problems existing configurations
  ex1: if the network has ipv6 enables (the host recieves a router advertisement), networkmanager does not configure the network anymore so you get only ipv6 and no ipv4 connections (since systemd-networkd seems to bring only the link up)

  ex2: if you use systemd-nspawn and configured static ip addresses in
  /etc/network/interfaces, systemd-networkd adds a dhcp obtained address
  on the host0 adapter and a 169.254 address

  For the average user both is not expected, so my solution was
  systemctl disable systemd-networkd, but since you seem to insist
  having this enabled, it must be made sure systemd-networkd does not
  touch existing configurations.

  My suggestion is:
  1) if /etc/network/interfaces contains anything other than lo -> do not enable systemd-networkd
  2) if network-manager is enabled, systemd-networkd must be disabled and vice versa

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