After using the alien package manager to convert RPM packages into DEB packages, the installation of Authentication Services completes successfully, but no users can log in.
原因
alien is a program that converts between Red Hat rpm, Debian deb, Stampede slp, Slackware, tgz, and Solaris pkg file formats.
alien should not be used to replace necessary system packages, like init, libc, or other essential things for the functioning of your system. In this case, alien fails to properly convert the Authentication Services RPM packages to DEB format, breaking the way PAM modules are configured in Ubuntu.
対策
Do not use alien to convert packages to DEB format. Make sure you always use the recommended .DEB packages for your Ubuntu platform.