Ubuntu 24.04 SSH Client: How To Install and Use SSH

What is SSH and What is it Used For?

SSH (Secure Shell) is a cryptographic network protocol used to securely connect to remote machines over an unsecured network. It provides a secure method for communication between two systems, typically allowing a user to log in to another computer, transfer files, and execute commands on a remote system.

Common SSH Use Cases:

• Remote Access: SSH is commonly used for remote login to servers or other computers, particularly in system administration and software development.
• Secure File Transfer: Using scp or sftp, users can securely transfer files between machines.
• Remote Command Execution: You can use SSH to execute commands on a remote machine, making it an essential tool for automating tasks and managing servers.

To use the SSH client on Ubuntu, you typically use the ssh command, which is included in the OpenSSH client package. Here’s how to ensure it’s installed and use it:

Step 1: Install OpenSSH Client (if not already installed)

In most cases, the OpenSSH client comes pre-installed with Ubuntu. To check if it’s installed or to install it, run:

$ sudo apt update
$ sudo apt install openssh-client

Step 2: Check the SSH Service is Running

$ sudo systemctl status ssh

Step 3: Use SSH to Connect to a Remote Server

Once the SSH client is installed, you can connect to a remote server using the following command:

$ ssh username@remote_host

Replace username with the remote system’s username, and remote_host with the remote system’s IP address or domain name.

For example:

$ ssh user@example.com

Step 4: Add Custom SSH Options (optional)

You can customize the SSH connection by adding options like:

• Port number (if SSH is running on a non-standard port):

$ ssh -p 2222 username@remote_host

• Using an identity file (e.g., private key):

$ ssh -i /path/to/private_key username@remote_host

Step 5: SSH Configuration (optional)

You can also configure default settings for SSH connections by editing ~/.ssh/config file. Here’s an example configuration:

Host myserver
  HostName example.com
  User username
  Port 2222
  IdentityFile ~/.ssh/private_key

This allows you to simply type ssh myserver to connect to the specified host with custom options.

Step 6: Check SSH Version

To check the installed version of the SSH client:

$ ssh -V

This will give you the OpenSSH version currently running on your system.

This should be enough to get you started with SSH on Ubuntu 24.04 (or any other version). If you are looking to learn more about how you can use SSH, take a look at how to set up a homelab to practice penetration testing.