Learn how to install Secure SHell “SSH” in Ubuntu and learn how to enable SSH Service in Ubuntu 16.10. Ubuntu users can configure OpenSSH Server “sshd_config file” and edit connection settings.
SSH (“Secure SHell”) is a protocol for securely accessing one computer from another. Despite the name, SSH allows you to run command line and graphical programs, transfer files, and even create secure virtual private networks over the Internet.
OpenSSH (OpenBSD Secure Shell) is a suite of security-related network-level utilities based on the Secure Shell (SSH) protocol, which help to secure network communications via the encryption of network traffic over multiple authentication methods and by providing secure tunneling capabilities.
Install OpenSSH in Ubuntu
To use SSH, you will need to install an SSH client on the computer you connect from, and an SSH server on the computer you connect to. The most popular Linux SSH client and Linux SSH server are maintained by the OpenSSH project.
To install OpenSSH in Ubuntu, simply open terminal from App Launcher or via Ctrl+Alt+T keys. When it opens, run command:
sudo apt install openssh-server
Once SSH is installed, it will automatically start SSH service.
Edit OpenSSH in Ubuntu
Ubuntu users can edit the sshd_config configuration file in the /etc/ssh directory. This is done to configure the options related to SSH. Please note that sshd_config is the configuration file for the OpenSSH server and ssh_config is the configuration file for the OpenSSH client.
Before you edit the configuration file, make a backup of the sshd_config file by copying it to the home directory, or making a read-only copy in /etc/ssh by running the following command:
sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.factory-defaults
sudo chmod a-w /etc/ssh/sshd_config.factory-defaults
Once the sshd_config file is backed up, edit the configuration file by using the command given below:
sudo gedit /etc/ssh/sshd_config
Editing the sshd_config file, Ubuntu users can disable password authentication, disable forwarding, specify which accounts can use SSH and limit the rate at which one IP address can establish new SSH connections.
Once the sshd_config file is edited, restart the SSH service via command:
sudo service ssh restart
Now since the SSH service is restarted, check that your SSH daemon is running:
ps -A | grep sshd