pam unix

 Feb 06 12:35:55 SERVER_NAME sshd[1851658]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=xx.228.54.xx  user=USERNAME

 Feb 05 14:35:55 SERVER_NAME passwd[29180]: pam_unix(passwd:chauthtok): password changed for root

Aug 16 13:34:59 master_server sudo: pam_unix(sudo:auth): auth could not identify password for [yourusername]

Solution: add this line to /etc/pam.d/sudo
auth       sufficient   pam_permit.so

See also

• PAM, libpam_cracklib, pam_tally2, /etc/pam.d/, /etc/pam.d/sshd, pam_oath, pam_sss, /etc/pam.d/login, pam_unix, pam_krb5