[Bug 1624320] Re: systemd-resolved appends 127.0.0.53 to resolv.conf alongside existing entries

[Richard Pillay]

Another vote to bump up the priority on this.

Just lost 2 days to this bug, mostly because the behavior is so stupidly
borked that I never suspected that Ubuntu would be the cause. Can you
imagine how stupid it is that the only machines on the network affected
are the Ubuntu Desktops and Ubuntu Servers. Can you imagine how
embarrassing it that even Windows machines follow the standards better
than a Linux machine.

And the absolutely mind-boggling thing is that this is affecting every
release from 16.04 to 19.04 and still it is not considered important
enough to fix.

It is absolutely ridiculous that it would be considered more important
to keep behavior that supports a few edge cases of software that wants
to do their own DNS resolution in spite of the fact that it breaks the
world-wide standards of DNS resolution and ignore DHCP-provided DNS
addresses.

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https://bugs.launchpad.net/bugs/1624320

Title:
  systemd-resolved appends 127.0.0.53 to resolv.conf alongside existing
  entries

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  systemd-resolved, or more precisely the hook script
  /lib/systemd/system/systemd-resolved.service.d/resolvconf.conf, causes
  resolvconf to add 127.0.0.53 to the set of nameservers in
  /etc/resolv.conf alongside the other nameservers.  That makes no sense
  because systemd-resolved sets up 127.0.0.53 as a proxy for those other
  nameservers.  The effect is similar to bug 1624071 but for
  applications doing their own DNS lookups.  It breaks any DNSSEC
  validation that systemd-resolved tries to do; applications will
  failover to the other nameservers, bypassing validation failures.  And
  it makes failing queries take twice as long.

  /etc/resolv.conf should have only 127.0.0.53 when systemd-resolved is
  active.

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