This is a simple guide to show you how to enable Secure Shell (SSH) service in Ubuntu.

SSH is a secure communication protocol that lets you remotely access network computers. Withing this secure data communication you can do lot of things like remote command-line login, remote command execution etc.

You could easily enable this service via OpenSSH, which is a free version of the SSH connectivity tools developed by the OpenBSD Project.

To to do that, press Ctrl + Alt + T on your keyboard to open the terminal. When it opens, issue the following commands below to install openssh-server.

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

Once you installed, use your SSH client to connect to your computer using the default port 22.

Example attempt:

ssh gayan@192.168.0.102

Configure ssh server settings

You can also configure ssh-server settings by editing the sshd_config file in the /etc/ssh directory.

sshd_config is the configuration file for the OpenSSH server. ssh_config is the configuration file for the OpenSSH client. Make sure not to get them mixed up.

If you are about to change the settings, make a backup of your sshd_config file by copying it to your home directory, or by making a read-only copy in /etc/ssh by doing:

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.factory-defaults
sudo chmod a-w /etc/ssh/sshd_config.factory-defaults

Once you’ve backed up your sshd_config file, you can make changes with any text editor, for example;

sudo gedit /etc/ssh/sshd_config

For example if you wish to change the connection port, then change the port

shown to whatever you want and save the file. But remember to use the

new port number every time you want to connect to your system via SSH.

You can apply the changes by saving the file then doing:

sudo restart ssh

More references:

• SSH/OpenSSH/Configuring
• Askubuntu - How to accept ssh connections?