Setup SSH on Ubuntu

SSH (Secure Shell) is a protocol that allows secure remote access to a computer over an unsecured network. Today, I will guide you through the best practices for setting up SSH on an Ubuntu system.

Step 1: Install OpenSSH Server


sudo apt-get update
sudo apt-get install -y openssh-server

Step 2: Start and Enable SSH service


sudo systemctl enable ssh
sudo systemctl start ssh
sudo systemctl status ssh # check if SSH is running

Step 3: Configure SSH settings

To enhance security, you can modify the SSH configuration file by searching the following settings:

PasswordAuthentication no: Disable password authentication to use key-based authentication.
PermitRootLogin no: Disable root login via SSH.
AllowUsers your_username: Restrict SSH access to specific users.
AllowGroups your_group: Restrict SSH access to specific groups.


sudo nano /etc/ssh/sshd_config

/etc/ssh/sshd_config


PasswordAuthentication no
PermitRootLogin no
AllowUsers user1 user2 user3
AllowGroups sshusers

Step 4: Restart SSH service


sudo systemctl restart ssh

Step 5: Configure Firewall

Configuring firewall is very important to secure your server. By default, Ubuntu uses UFW (Uncomplicated Firewall) and when you enable it, SSH connections are blocked. To allow SSH connections, run the following command:


sudo ufw allow ssh
sudo ufw enable
sudo ufw status


kc@kcserver:~$ sudo ufw status
Status: active
 
To                         Action      From
--                         ------      ----
22/tcp                     ALLOW       Anywhere                  
22/tcp (v6)                ALLOW       Anywhere (v6)

Step 6: Reboot the server

The final step is to reboot the server to ensure all changes take effect.


sudo reboot