Linux Shadow Password HOWTO

Michael H. Jackson, mhjack@tscnet.com

1. Introduction.

• 1.1 Changes from the previous release.
• 1.2 New versions of this document.
• 1.3 Feedback.

2. Linux Shadow Support History

• 2.1 Original Shadow Code
• 2.2 Linux Distributions
• 2.3 Linux-PAM (Pluggable Authentication Modules for Linux) project.
• 2.4 Older Shadow Packages

3. Why shadow your passwd file?

• 3.1 Why you might NOT want to install the Shadow Suite.
• 3.2 Format of the /etc/passwd file
• 3.3 Format of the shadow file
• 3.4 Review of crypt(3).

4. Getting the Shadow Suite.

• 4.1 Where to get the Shadow Suite.
• 4.2 What is included with the Shadow Suite.

5. Compiling the programs.

• 5.1 Unpacking the archive.
• 5.2 Configuring with the config.h file
• 5.3 Making backup copies of your original programs.
• 5.4 Running make

6. Installing

• 6.1 Have a boot disk handy in case you break anything.
• 6.2 Removing duplicate man pages
• 6.3 Running make install
• 6.4 Running pwconv
• 6.5 Renaming npasswd and nshadow

7. Other programs you may need to upgrade or patch

• 7.1 Slackware adduser program
• 7.2 The wu_ftpd Server
• 7.3 Standard ftpd
• 7.4 pop3d (Post Office Protocol 3)
• 7.5 xlock
• 7.6 xdm
• 7.7 sudo
• 7.8 imapd (E-Mail pine package)
• 7.9 pppd (Point-to-Point Protocol Server)

8. Putting the Shadow Suite to use.

• 8.1 Adding, Modifying, and deleting users
• 8.2 The passwd command and passwd aging.
• 8.3 The login.defs file.
• 8.4 Group passwords.
• 8.5 Consistency checking programs
• 8.6 Dial-up passwords.

9. Adding shadow support to a C program

• 9.1 Header files
• 9.2 libshadow.a library
• 9.3 Shadow Structure
• 9.4 Shadow Functions
• 9.5 Example

10. Frequently Asked Questions.

11. Copyright Message.

12. Miscellaneous and Acknowledgments.