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Introduction to Linux Security

Security in Linux is a multi-layered approach designed to protect data, resources, and users from unauthorized access or malicious activities. While Linux is inherently designed with security in mind, misconfigurations or out-of-date software can introduce vulnerabilities.

Core Security Principles​

  1. Principle of Least Privilege: Users and processes should only be granted the minimum permissions required to perform their specific tasks. Never run applications as the root user unless absolutely necessary.
  2. Defense in Depth: Employ multiple layers of security. If one layer fails (e.g., a firewall is bypassed), another layer (e.g., file permissions or AppArmor/SELinux) should provide backup protection.
  3. Keep Systems Updated: Security patches are constantly released. Regularly update your system to close known vulnerabilities.

Common Attack Vectors​

  • Brute Force & Dictionary Attacks: Automated scripts attempting to guess passwords.
  • Exploiting Outdated Software: Attackers leveraging known bugs in old software versions.
  • Social Engineering: Tricking users into revealing credentials or running malicious scripts.

Best Practices​

  • Always use strong, unique passwords.
  • Disable direct root login via SSH.
  • Keep only essential services running. Shut down or uninstall what you do not use.