Pam_unix sshd authentication failure even though the login works?

pasta_paul

I have a server that is configured with winbind and samba to provide active directory authentication. The active directory integration works fine however whenever I authenticate I see the following errors: Errors Authentication: May 11 00:25:29 SERVER sshd[28119]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=x.x.x.x user=USERNAME Sudo: May 11 01:33:14 SERVER sudo: pam_unix(sudo:auth): authentication...

Originally asked by Jay on Stack Exchange (unix) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

I'm no PAM expert, but that would probably be happening because the pam_unix authentication module (local user database: /etc/password and /etc/shadow ) is being consulted before the pam_winbind module (Samba/Active Directory). I am looking at the auth lines in your /etc/pam.d/system-auth , and assuming that system-auth is connected to password-auth (which /etc/pam.d/sshd references). When logging in as an AD user, pam_unix would not find the user locally, and so PAM would log an authentication failure for that module. Because pam_unix is marked as sufficient , not finding the user locally isn't considered a complete failure, and so PAM advances to the next module, eventually reaching...

Full answer by tangle: https://unix.stackexchange.com/a/674949 (CC BY-SA 4.0).

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