v2.3, 22 January 2004
Abstract
This document is a general overview of security issues that face the administrator of Linux systems. It covers general security philosophy and a number of specific examples of how to better secure your Linux system from intruders. Also included are pointers to security-related material and programs. Improvements, constructive criticism, additions and corrections are gratefully accepted. Please mail your feedback to both authors, with "Security HOWTO" in the subject.
Table of Contents
- 1. Introduction
- 2. Overview
- 3. Physical Security
- 4. Local Security
- 5. Files and File system Security
- 6. Password Security and Encryption
- 6.1. PGP and Public-Key Cryptography
- 6.2. SSL, S-HTTP and S/MIME
- 6.3. Linux IPSEC Implementations
- 6.4.
ssh(Secure Shell) andstelnet - 6.5. PAM - Pluggable Authentication Modules
- 6.6. Cryptographic IP Encapsulation (CIPE)
- 6.7. Kerberos
- 6.8. Shadow Passwords.
- 6.9. "Crack" and "John the Ripper"
- 6.10. CFS - Cryptographic File System and TCFS - Transparent Cryptographic File System
- 6.11. X11, SVGA and display security
- 7. Kernel Security
- 8. Network Security
- 8.1. Packet Sniffers
- 8.2. System services and tcp_wrappers
- 8.3. Verify Your DNS Information
- 8.4. identd
- 8.5. Configuring and Securing the Postfix MTA
- 8.6. SATAN, ISS, and Other Network Scanners
- 8.7. sendmail, qmail and MTA's
- 8.8. Denial of Service Attacks
- 8.9. NFS (Network File System) Security.
- 8.10. NIS (Network Information Service) (formerly YP).
- 8.11. Firewalls
- 8.12. IP Chains - Linux Kernel 2.2.x Firewalling
- 8.13. Netfilter - Linux Kernel 2.4.x Firewalling
- 8.14. VPNs - Virtual Private Networks
- 9. Security Preparation (before you go on-line)
- 10. What To Do During and After a Breakin
- 11. Security Sources
- 12. Glossary
- 13. Frequently Asked Questions
- 14. Conclusion
- 15. Acknowledgments