Reference

http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/_User-Authentication-HOWTO.html The User-Authentication HOWTO describes how user and group information is stored and used for authentication.

http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/Shadow-Password-HOWTO.html The Shadow-Password HOWTO delves into the murky depths of shadow passwords and even discusses why you might not want to use them.

http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/_Security-HOWTO.html A must-read HOWTO, the Security HOWTO is a good overview of security issues. Especially applicable to this chapter are sections on creating accounts, file permissions, and password security.

http://www.secinf.net/unix_security/Linux_Administrators_Security_Guide/ A general guide, the Linux System Administrator's Security Guide has interesting sections on limiting and monitoring users.

http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/Config-HOWTO.html How can you customize some user-specific settings? The Config HOWTO Software Configuration gives some advice.

http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/Path.html How can one know the true path? The Path HOWTO sheds light on this issue. You need to understand paths if you want to guide the users to their data and applications.

http://www.courtesan.com/sudo/ The SUperuser DO command is a powerful and elegant way to delegate authority to regular users for specific commands.

http://www.kernel.org/pub/linux/libs/pam/index.html The Pluggable Authentication Modules suite contains complex and highly useful applications that provide additional security and logging for passwords. PAM is installed by default in Ubuntu. It isn't necessary to understand the intricacies of PAM to use it effectively.