How to Setup and Use SSH on Ubuntu Server

Secure Shell (SSH) is a cryptographic network protocol that allows users to securely access a remote computer or a server over an unsecured network. For webmasters and system administrators, SSH is an invaluable tool, offering a secure method to manage and configure servers, transfer files, and even run remote commands. Ubuntu, a popular Linux distribution, comes with SSH capabilities that can be easily set up and utilized.

In this comprehensive guide, we’ll walk you through the process of setting up and using SSH on an Ubuntu system. Whether you’re connecting to a remote server or setting up your own, understanding SSH is crucial.

Let’s get started.

Step 1: Installing OpenSSH Server

First, update your package list to ensure you get the latest version:

sudo apt update

Install the OpenSSH server package:

sudo apt install openssh-server

Once installed, the SSH service will start automatically. You can check its status with:

sudo systemctl status ssh

For example:

root@geeks:~# sudo systemctl status ssh
● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
   Active: active (running) since Sun 2023-10-22 13:16:26 UTC; 19h ago

Step 2: Configuring SSH

To configure SSH, you’ll need to edit its main configuration file:

sudo nano /etc/ssh/sshd_config

Some key configurations to consider:

• Port: By default, SSH uses port 22. You can change this for security reasons.
• PermitRootLogin: It’s recommended to set this to “no” to prevent root login.
• PasswordAuthentication: If set to “no”, users must use SSH keys to log in.

After making changes, save the file and exit.

Restart the SSH service to apply the changes:

sudo systemctl restart ssh

Step 3: Connecting to SSH

From another computer, you can connect to your Ubuntu system using the following command:

ssh username@your_server_ip

Replace “username” with your Ubuntu username and “your_server_ip” with the IP address of your Ubuntu system.

Step 4: Using SSH Key Authentication

On the client machine, generate an SSH key pair:

ssh-keygen

Copy the public key to the Ubuntu server:

ssh-copy-id username@your_server_ip

Now, you can log in to the server without a password.

Commands Mentioned

• sudo apt update – Updates the package list.
• sudo apt install openssh-server – Installs the OpenSSH server.
• sudo systemctl status ssh – Checks the status of the SSH service.
• sudo nano /etc/ssh/sshd_config – Edits the SSH configuration file.
• sudo systemctl restart ssh – Restarts the SSH service.
• ssh username@your_server_ip – Connects to the server via SSH.
• ssh-keygen – Generates an SSH key pair.
• ssh-copy-id username@your_server_ip – Copies the public key to the server.

FAQ

1. What is the default port for SSH?

   The default port for SSH is 22. However, for security reasons, it’s often recommended to change this to a non-standard port.

2. How can I enhance SSH security?

   To enhance SSH security, consider changing the default port, disabling root login, using SSH key authentication, and implementing a firewall to restrict access.

3. What’s the difference between OpenSSH and SSH?

   SSH is a protocol, while OpenSSH is a free, open-source implementation of the SSH protocol. OpenSSH includes both the server and client software.

4. Why might I be unable to connect via SSH?

   There could be several reasons, including incorrect IP address, SSH service not running on the server, firewall restrictions, or incorrect login credentials.

5. Is it safe to use SSH over the internet?

   Yes, SSH is designed to be secure and encrypts all data transmitted over the network. However, it’s essential to follow best practices, like using strong passwords or SSH keys and regularly updating the software.

Conclusion

SSH is a powerful and essential tool for anyone managing servers or remote systems. With its encryption capabilities, it ensures that data transmitted between the client and server remains confidential and tamper-proof. By following this guide, you’ve equipped yourself with the knowledge to set up, configure, and use SSH on an Ubuntu system effectively.

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Furthermore, it’s crucial to stay updated with the latest security practices and patches for SSH. Regularly checking for updates and being aware of any vulnerabilities can help you maintain a secure environment.

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