How to Start SSH in Linux?

Secure Shell (SSH) is a powerful protocol that enables secure communication between two systems over an insecure network. It plays a crucial role in remote server management, allowing users to access and control their Linux systems with confidence. In this guide, we will walk you through the process of starting SSH in Linux, providing step-by-step instructions and valuable insights to help you get started.

Setting the Stage: Why SSH?

Before we dive into the nitty-gritty of starting SSH, let's briefly understand why SSH is essential. SSH ensures secure communication by encrypting the data exchanged between the client and server, making it a preferred choice for remote access, file transfers, and command execution.

Checking SSH Installation:

First and foremost, ensure that SSH is installed on your Linux system. Open your terminal and type the following command:

sudo apt-get install openssh-server   # For Ubuntu/Debian

sudo yum install openssh-server       # For CentOS/RHEL

Starting SSH Service:

Once installed, you need to start the SSH service. Use the following command:

sudo service ssh start                # For systems using SysV init

sudo systemctl start ssh              # For systems using systemd

Enabling SSH on System Boot:

To ensure that SSH starts automatically on system boot, run:

sudo service ssh enable               # For SysV init systems

sudo systemctl enable ssh             # For systems using systemd

Configuring SSH:

SSH can be configured to enhance security and customize its behavior. The configuration file is usually located at /etc/ssh/sshd_config. Open it using a text editor:

sudo nano /etc/ssh/sshd_config

Here, you can tweak settings such as port number, authentication methods, and more. Save the changes and restart the SSH service:

sudo service ssh restart              # For SysV init systems

sudo systemctl restart ssh            # For systems using systemd

Logging In Using SSH:

Now that SSH is up and running, let's connect to a remote server. Use the following command, replacing username and hostname with your credentials:

ssh username@hostname

You'll be prompted for your password. Once entered correctly, you'll have secure access to the remote system.

More Examples:

• Specifying Port Number:
  If your SSH service uses a non-default port (other than 22), specify it with the -p option:

  ssh -p 2222 username@hostname
  

• Key-Based Authentication:
  Enhance security by using key-based authentication. Generate a key pair with:

  ssh-keygen -t rsa
  

  Then, copy the public key to the remote server:

  ssh-copy-id username@hostname
  

Congratulations! You've successfully learned how to start SSH in Linux, ensuring secure and efficient remote communication. Experiment with the various configurations and options available to tailor SSH to your specific needs. Now, go ahead and explore the world of secure shell access with confidence.