Linux Security HOWTO

1. Introduction
1.1. New Versions of this Document
1.2. Feedback
1.3. Disclaimer
1.4. Copyright Information
2. Overview
2.1. Why Do We Need Security?
2.2. How Secure Is Secure?
2.3. What Are You Trying to Protect?
2.4. Developing A Security Policy
2.5. Means of Securing Your Site
2.5.1. Host Security
2.5.2. Network Security
2.5.3. Security Through Obscurity
2.6. Organization of This Document
3. Physical Security
3.1. Computer locks
3.2. BIOS Security
3.3. Boot Loader Security
3.4. xlock and vlock
3.5. Detecting Physical Security Compromises
4. Local Security
4.1. Creating New Accounts
4.2. Root Security
5. Files and Filesystem Security
5.1. Umask Settings
5.2. File Permissions
5.3. Integrity Checking with Tripwire Tripwire
5.4. Trojan Horses
6. Password Security and Encryption
6.1. PGP and Public-Key Cryptography
6.2. SSL, S-HTTP, HTTPS and S/MIME
6.3. Linux IPSEC Implementations
6.4. ssh (Secure Shell) and stelnet
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
6.11.1. X11
6.11.2. SVGA
6.11.3. GGI (Generic Graphics Interface project)
7. Kernel Security
7.1. 2.0 Kernel Compile Options
7.2. 2.2 Kernel Compile Options
7.3. Kernel Devices
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. SATAN, ISS, and Other Network Scanners
8.5.1. Detecting Port Scans
8.6. sendmail, qmail and MTA's
8.7. Denial of Service Attacks
8.8. NFS (Network File System) Security.
8.9. NIS (Network Information Service) (formerly YP).
8.10. Firewalls
8.11. IP Chains - Linux Kernel 2.2.x Firewalling
8.12. VPN's - Virtual Private Networks
9. Security Preparation (before you go on-line)
9.1. Make a Full Backup of Your Machine
9.2. Choosing a Good Backup Schedule
9.3. Backup Your RPM or Debian File Database
9.4. Keep Track of Your System Accounting Data
9.5. Apply All New System Updates.
10. What To Do During and After a Breakin
10.1. Security Compromise Underway.
10.2. Security Compromise has already happened
10.2.1. Closing the Hole
10.2.2. Assessing the Damage
10.2.3. Backups, Backups, Backups!
10.2.4. Tracking Down the Intruder.
11. Security Sources
11.1. FTP Sites
11.2. Web Sites
11.3. Mailing Lists
11.4. Books - Printed Reading Material
12. Glossary
13. Frequently Asked Questions
14. Conclusion
15. Acknowledgements