In #190215, Reinhard Mueller suggests that su logs successufl/unsuccessful logins through syslog.
He suggests the following matrix: successful unsuccessful non-root user LOG_INFO LOG_NOTICE root user LOG_NOTICE LOG_WARNING The user on the left being the user *after* the su (or the user which was failed to become). Though this is in general a good suggesiton, imho., this does not follow PAM behaviour where successful authentication is logged as LOG_INFO and unsuccessful is logged as LOG_NOTICE. I suggest keeping this and thus implementing the following simple matrix: successful unsuccessful any user LOG_INFO LOG_NOTICE My patch to sulog.c for this is ready and waits for comments ? --