Installing OpenSSH on Ubuntu 18.04

OpenSSH is a suite of secure networking utilities based on the Secure Shell (SSH) protocol, which provides a secure way to communicate between computers over an unsecured network. It enables remote logins, file transfers, and other secure network services over an encrypted channel.

Step 1: Update Package List

Before installing OpenSSH, it is recommended to update the package list and upgrade any existing packages.

sudo apt update
sudo apt upgrade

Step 2: Install OpenSSH Server

To install OpenSSH server, run the following command:

sudo apt install openssh-server

Step 3: Verify OpenSSH Installation

Once the installation is complete, you can verify the OpenSSH server status:

sudo systemctl status ssh

If the service is active and running, you should see a green "active (running)" message in the output.

Step 4: Configure OpenSSH (Optional)

You may want to customize the OpenSSH server's configuration based on your requirements. The main configuration file is located at /etc/ssh/sshd_config. Make sure to backup the file before making any changes.

After modifying the configuration file, reload the SSH service for changes to take effect:

sudo systemctl reload ssh

Step 5: Adjust Firewall Settings (Optional)

If your system has a firewall enabled, you need to allow SSH connections. By default, OpenSSH uses TCP port 22. To allow incoming SSH connections, use the following command:

sudo ufw allow OpenSSH

Step 6: Connect to OpenSSH Server

Once OpenSSH server is installed and running, you can remotely connect to your Ubuntu machine using an SSH client, such as OpenSSH, PuTTY, or Bitvise SSH Client.

Use the command below to connect to your Ubuntu machine from another computer:

ssh username@your_ubuntu_server_ip

Replace username with your username and your_ubuntu_server_ip with the IP address or hostname of your Ubuntu server.

Learn more about OpenSSH.