Linux System Security: An Introduction to Basic Protection Strategies

Linux security requires attention to basic configurations; neglecting them can lead to risks like weak passwords and open ports. The core protective strategies are as follows: **Account Security**: Disable shared root access, use strong passwords (including uppercase, lowercase, numbers, and symbols), and **mandatorily use SSH key-based login** (generate a key pair locally, copy the public key to the server's `authorized_keys`, set permissions, and disable password authentication). Delete default/test accounts; use regular users with `sudo` for privilege elevation in daily operations. **File Permissions**: Follow the principle of least privilege. Set home directories to `700` (only the owner can operate), regular files to `644` (owner can read/write, others can read), and system files to `600`; avoid high-privilege settings like `777`. **Firewall**: Only open necessary ports (e.g., SSH 22, Web 80/443); default to blocking others. Use `iptables` or `firewalld` for configuration, and disable outdated services like Telnet. **System Updates**: Regularly perform `yum update`/`apt upgrade`, and restart after updates. Disable insecure services like Telnet to prevent vulnerability exploitation. **Log Monitoring**: Use tools like `journalctl`, `last`, and `auth.log` to monitor... (Note: The original text was truncated at "关注" and the translation reflects the uncompleted content as-is.)