[Bug 1877271] Re: networkd does not enable ipv6 when requested

[Dan Streetman]

root at lp1877271-e:~# dpkg -l systemd|grep systemd
ii  systemd        242-7ubuntu3.7 amd64        system and service manager
root at lp1877271-e:~# echo 1 > /proc/sys/net/ipv6/conf/eth0/disable_ipv6 
root at lp1877271-e:~# ip -6 a show eth0
root at lp1877271-e:~# systemctl restart systemd-networkd
root at lp1877271-e:~# ip -6 a show eth0
root at lp1877271-e:~# 


root at lp1877271-e:~# dpkg -l systemd|grep systemd
ii  systemd        242-7ubuntu3.9 amd64        system and service manager
root at lp1877271-e:~# echo 1 > /proc/sys/net/ipv6/conf/eth0/disable_ipv6 
root at lp1877271-e:~# ip -6 a show eth0
root at lp1877271-e:~# systemctl restart systemd-networkd
root at lp1877271-e:~# ip -6 a show eth0
112: eth0 at if113: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000 link-netnsid 0
    inet6 2001:db8::100/64 scope global tentative 
       valid_lft forever preferred_lft forever
    inet6 fe80::216:3eff:fe7d:babb/64 scope link tentative 
       valid_lft forever preferred_lft forever


** Tags removed: verification-needed verification-needed-eoan
** Tags added: verification-done verification-done-eoan

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https://bugs.launchpad.net/bugs/1877271

Title:
  networkd does not enable ipv6 when requested

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed

Bug description:
  [impact]

  if networkd is configured with ipv6 address but the 'disable_ipv6'
  sysctl is enabled, networkd does not enable it and set the ipv6
  configuration.

  [test case]

  [Match]
  Name=ens3

  [Network]
  DHCP=ipv4
  LinkLocalAddressing=ipv6
  Address=2001:db8::100/64

  manually disable ipv6 for the interface:

  ubuntu at lp1859862-b:~$ echo 1 | sudo tee /proc/sys/net/ipv6/conf/ens3/disable_ipv6
  1

  the interface should not contain any ipv6 addresses:

  ubuntu at lp1859862-b:~$ ip -6 a show ens3
  ubuntu at lp1859862-b:~$

  restart networkd; it should enable ipv6 as ipv6 addresses are
  configured, but it does not:

  ubuntu at lp1859862-b:~$ sudo systemctl restart systemd-networkd
  ubuntu at lp1859862-b:~$ ip -6 a show ens3
  ubuntu at lp1859862-b:~$

  [regression potential]

  any regression would likely result in failure to configure ipv6
  addresses/routes.

  [scope]

  this is needed only for Eoan.

  this is fixed by commit 57ad76074670d4859e808a6aabd69fd6e58514c5,
  which is included starting in v243, so this is fixed in Focal and
  later.

  this bug was introduced by a series of patches starting at
  54a1a535bd60f13964bbddd8f381601e33e8e56f, which is included starting
  in v243, but was also pulled into Debian v242-4, and so included in
  Eoan.  This bug is not present in earlier versions so is not needed in
  Xenial or Bionic.

  [other info]

  this is a follow on for the fix in bug 1859862.

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