OpenSSH Server Hardening Check List

Hardening an OpenSSH server is crucial for securing remote access to your Linux system. Here's a checklist to help you secure your OpenSSH server:

1.Keep OpenSSH Up to Date:

   → Regularly update the OpenSSH server to the latest version to patch known vulnerabilities.

   → Keep your operating system up to date as well.

2.Implement Two→Factor Authentication (2FA):

   → Implement two→factor authentication for an extra layer of security.

3.Change Default Port:

   → Consider changing the default SSH port (usually 22) to a non→standard port to deter automated attacks.

4.Configure SSH Idle Timeout:

   → Set an idle session timeout to automatically log out inactive users.

5.Enable SSH Logging:

   → Enable SSH session logging and regularly review the logs for security incidents.

6.Use SSH Keys with Passphrases:

   → Disable password→based authentication and use SSH keys for authentication.

   → Generate strong SSH keys (at least 2048 bits) and protect the private key with a passphrase.

7.Implement Firewall Rules:

   → Use firewall rules to restrict SSH access to trusted IP addresses or networks.

8.Monitor SSH Logs:

   → Regularly review SSH logs for suspicious activity.

   → Consider using tools like `Fail2ban` or `DenyHosts` for blocking repeated failed login attempts.

9.Disable Password→Based SSH Login:

   → Disable password→based authentication in your SSH server configuration (`PasswordAuthentication no`).

10.Disable Unused SSH Features (i.e., SSHv1):

    → Disable any unused or outdated SSH features in the SSH server configuration.

11.Regularly Audit SSH Server Configuration:

    → Perform regular security audits of your SSH server configuration to identify and fix vulnerabilities.

12.Disable User SSH Passwordless Connection Requests:

    → Ensure that users cannot establish passwordless SSH connections to the server.

13.Disable SSH Root Logins:

    → Disable direct root logins in the SSH server configuration (`PermitRootLogin no`).

14.Configure a Limit for Password Attempts:

    → Configure a limit for the number of password login attempts to prevent brute→force attacks.

15.Disable X11 Forwarding:

    → Unless needed, consider disabling X11 forwarding in the SSH server configuration (`X11Forwarding no`).

16.Use Public Key Authentication:

    → Promote the use of public key authentication among users.