pamtester -v auth pknopf authenticate
pamtester: invoking pam_start(auth, pknopf, ...)
pamtester: performing operation - authenticate
Password:
pamtester: Authentication failure

Feb 06 13:22:17 PAULS-ARCH unix_chkpwd[31998]: check pass; user unknown
Feb 06 13:22:17 PAULS-ARCH unix_chkpwd[31998]: password check failed for user (pknopf)
Feb 06 13:22:17 PAULS-ARCH pamtester[31997]: pam_unix(auth:auth): authentication failure; logname= uid=1000 euid=1000 tty= ruser= rhost=  user=pknopf