Summary

This chapter introduced UNIX security from a user’s perspective. You were introduced to set user ID and set group ID permissions and how they are used, and you were introduced to setuid programs. You learned about access code lists and role-based access control. You saw how /etc/passwd and /etc/shadow files work, and how HP-UX handles passwords. You were shown how to use UNIX utilities for file encryption, and you learned about the relative security of encryption using these utilities. You also learned about PGP and GPG and how to use them to send secure e-mail and how to sign messages.

Other security concerns, such as Trojan horses, viruses, worms, unattended terminals, and logout procedures, were described. You were offered a checklist of security concerns for users and a brief description of the restricted shell, when it is used, and its limitations. Finally, you read about levels of operating system security and how this applies to UNIX.

Chapter 13 discusses security from a system administrator’s point of view. Chapter 17 discusses security for networking, including TCP/IP networking and mail.