How to Set Up SSH Server on Ubuntu

Learn how to install, configure and secure SSH server on Ubuntu with this step-by-step guide covering installation, key-based authentication, and essential security configurations.

Installing SSH Server

To enable remote access to your Ubuntu machine, you'll first need to install the OpenSSH server package. Here's how to do it:

sudo apt update
sudo apt install openssh-server

Verifying Installation

After installation, verify that SSH service is running with these commands:

sudo systemctl status ssh
sudo systemctl enable ssh
sudo systemctl start ssh

Basic SSH Connection

From your client machine, you can now connect using:

ssh username@server_ip

Setting Up Key-based Authentication

For enhanced security, set up SSH keys instead of password authentication:

1. Generate SSH Key Pair

ssh-keygen -t ed25519

2. Copy Public Key to Server

ssh-copy-id username@server_ip

Enhancing Security

After setting up key-based authentication, disable password authentication by editing the SSH configuration:

sudo nano /etc/ssh/sshd_config

Modify these settings:

PasswordAuthentication no
ChallengeResponseAuthentication no

Finally, restart the SSH service:

sudo systemctl restart ssh

Testing

Test your new SSH setup by trying to connect from your client machine. You should now be able to log in using your SSH key without a password prompt.