[Bug 1764853] Re: winbind returns PAM_AUTHINFO_UNAVAIL on first login after reboot

[Andreas Hasenack]

Please attach these logs from when the login failure happens:
- /var/log/auth.log
- /var/log/syslog
- /var/log/samba/log*

I configured a VM with your smb.conf, joined a windows 2016 AD server
via net ads join -k and AD users can login just fine immediately after a
reboot.

I also used your netplan file, and I have no /etc/network/interfaces or
interfaces.d/* content. I didn't upgrade from xenial, though, this was a
fresh bionic install.

Since this is a VM I provisioned with uvt-kvm, there are a few differences from a normal desktop install:
- I did "apt install ubuntu-desktop" after provisioning the vm
- I removed the cloud-init package after provisioning
- my dns and dhcp server is not the AD server, although I used its DNS server temporarily when doing "net ads join" so that the server could be found

I could try a fresh bionic *desktop* install, I know it could configure
networking a bit differently, or even install a xenial desktop and then
upgrade, but let's start with the logs I requested above.

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https://bugs.launchpad.net/bugs/1764853

Title:
  winbind returns PAM_AUTHINFO_UNAVAIL on first login after reboot

Status in samba package in Ubuntu:
  Incomplete

Bug description:
  The following issue exists only on Ubuntu 18.04

  I've upgraded ubuntu from 17.10 and noticed that winbind does not work well.
  90% of the time I reboot my system I'm getting PAM_AUTHINFO_UNAVAIL when trying to log in with a domain account.
  clicking login again on the login screen most of the time succeeds (so the password is correct)

  I've checked if it works if I wait 10 minutes before logging in, no success, so it is not a timing issue.
  Also I've checked if winbind is working (log in with ssh using a local account)
  getent passwd xy and wbinfo -K user%pwd both work always.

  Now my workaround is putting
  winbind request timeout = 3
  in smb.conf, since the PAM_AUTHINFO_UNAVAIL is returned about 60sec after trying to login. This workaround solves nothing, it only makes logging in faster. (But now it fails mostly two times, but waiting 6 seconds is better than 60)

  To me it seems like deadlock, but I was unable to track it since it
  happens only on the first login. Then I would have to reboot
  (restarting winbind does not trigger it twice, also removing all
  caches in /run/samba does not trigger it twice)

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