Linux Security HOWTO
Kevin Fenzi, kevin-securityhowto@tummy.com
& Dave Wreski, dave@linuxsecurity.com
v1.3.1, 11 February 2002
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.
- 1.1. New Versions of this Document
- 1.2. Feedback
- 1.3. Disclaimer
- 1.4. Copyright Information
- 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
- 2.6. Organization of This Document
- 3.1. Computer locks
- 3.2. BIOS Security
- 3.3. Boot Loader Security
- 3.4. xlock and vlock
- 3.5. Security of local devices
- 3.6. Detecting Physical Security Compromises
- 4.1. Creating New Accounts
- 4.2. Root Security
- 5.1. Umask Settings
- 5.2. File Permissions
- 5.3. Integrity Checking
- 5.4. Trojan Horses
- 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) 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
- 7.1. 2.0 Kernel Compile Options
- 7.2. 2.2 Kernel Compile Options
- 7.3. Kernel Devices
- 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
- 9.1. Make a Full Backup of Your Machine
- 9.2. Choosing a Good Backup Schedule
- 9.3. Testing your backups
- 9.4. Backup Your RPM or Debian File Database
- 9.5. Keep Track of Your System Accounting Data
- 9.6. Apply All New System Updates.
- 10.1. Security Compromise Underway.
- 10.2. Security Compromise has already happened
- 11.1. LinuxSecurity.com References
- 11.2. FTP Sites
- 11.3. Web Sites
- 11.4. Mailing Lists
- 11.5. Books - Printed Reading Material