Security is not a product, but a process. These guides cover defense-in-depth strategies for Linux systems including system hardening, authentication, encryption, auditing, and security tools.
System Hardening
Linux System Hardening
intermediateComprehensive guide to hardening Linux systems against attacks.
SSH Security Hardening
beginnerSecure SSH configuration and best practices for remote access.
Kernel Security Hardening
advancedKernel parameters and configurations for enhanced security.
Service Hardening
intermediateSecure configuration of common system services.
Authentication
PAM Configuration
advancedPluggable Authentication Modules configuration and security.
SSH Key Management
beginnerSecure SSH key generation, deployment, and management.
LDAP Authentication
advancedCentralized authentication with LDAP and Active Directory integration.
Two-Factor Authentication
intermediateImplementing TOTP and other 2FA methods for Linux systems.
Encryption
GPG/PGP Encryption
intermediateGNU Privacy Guard for file encryption and email signing.
LUKS Disk Encryption
intermediateFull disk encryption with LUKS for Linux systems.
SSL/TLS Certificates
intermediateSSL/TLS certificate management, best practices, and implementation.
File Encryption
beginnerEncrypt individual files and directories with various tools.
Auditing
Linux Audit System (auditd)
advancedConfigure the Linux audit framework for security monitoring.
Log Analysis and Management
intermediateCentralized logging, analysis, and security monitoring.
Intrusion Detection Systems
advancedHost and network-based intrusion detection with OSSEC, Snort, and Suricata.
File Integrity Monitoring
intermediateMonitor file changes with AIDE, Tripwire, and other FIM tools.
Tools
nmap Network Scanner
intermediateNetwork discovery and security auditing with nmap.
Lynis Security Auditing
beginnerAutomated security auditing and hardening suggestions with Lynis.
fail2ban Intrusion Prevention
beginnerProtect services from brute-force attacks with fail2ban.
ClamAV Antivirus
beginnerOpen-source antivirus for Linux servers and mail gateways.
Security Principles
- +Defense in Depth - Multiple layers of security controls
- +Least Privilege - Minimum permissions necessary
- +Fail Secure - Default to secure state on failure
- +Zero Trust - Never trust, always verify
- +Audit Everything - Log and monitor all activity
- +Keep Updated - Patch vulnerabilities promptly