SSH (Secure Shell)

SSH is a secure protocol for remotely managing Linux systems. It allows you to execute commands on remote servers, transfer files, and manage systems securely.

Connecting to a Remote Machine

• Command:

  ssh user@remote-host
  

• Replace user with your username and remote-host with the server's IP or domain.

Troubleshooting Connection Issues:

1. Authentication Failures:
2. Ensure the correct username and password.

3. Check for missing or incorrect SSH keys.

4. Firewall or Port Issues:

   • Verify that port 22 (default SSH) is open on the remote machine:

     ss -tuln | grep 22
     

Copying Files Securely

scprsync

• Command:

  scp file.txt user@remote-host:/path/to/destination
  

• Command:

  rsync -av file.txt user@remote-host:/path/to/destination
  

Troubleshooting Example:

• If file transfers fail, ensure scp or rsync is installed on both systems.
• Verify permissions on target directories.

Key Management

Generate SSH KeysCopy Public Key to Remote Server

See the SSH Keys instructions on how to properly setup your SSH Keys.

• Command:

  ssh-keygen -t rsa
  

• Command:

  ssh-copy-id user@remote-host
  

Troubleshooting Example:

• If key authentication fails:
• Verify the public key is present in ~/.ssh/authorized_keys on the remote server.
• Check permissions for ~/.ssh (should be 700) and authorized_keys (should be 600).

By mastering SSH, you'll be equipped to manage remote systems securely and efficiently.