System Security

Dive deep into Linux security principles. Learn how to protect your systems, manage user access, configure firewalls, and implement robust security measures.

User Authentication

  • User and group management
  • Password policies
  • SSH key-based authentication
  • Multi-factor authentication

Example Commands

useradd newuserpasswd usernamesudo usermod -aG groupname usernamessh-keygen -t rsa

File Permissions

  • Advanced permission management
  • Access Control Lists (ACLs)
  • Special permission bits
  • Securing sensitive files

Example Commands

chmod u+s executable (setuid)setfacl -m u:username:rwx filechattr +i file (immutable)find / -perm -4000 (find setuid files)

Firewall Configuration

  • Introduction to iptables
  • UFW (Uncomplicated Firewall)
  • Configuring network security
  • Port management

Example Commands

sudo ufw enablesudo ufw allow 22/tcpsudo iptables -Lnetstat -tuln (list listening ports)

Encryption and Privacy

  • Disk encryption
  • File and directory encryption
  • GPG for email and file encryption
  • SSL/TLS basics

Example Commands

gpg -c file.txt (encrypt)cryptsetup luksFormat /dev/sdbopenssl enc -aes-256-cbc -in filessh-keygen -t ed25519
Previous: File System ManagementNext: Server Administration

Security Best Practices

Proactive Measures

  • Keep systems updated
  • Use strong, unique passwords
  • Implement least privilege principle
  • Regular security audits

Network Security

  • Use VPN
  • Disable unnecessary services
  • Configure intrusion detection
  • Use fail2ban

Remember: Security is an ongoing process, not a one-time setup.