SSH (Secure Shell) is an encrypted protocol which allows connections between client system and a servers. You can connect to your system remotely, perform administrative tasks and access files. Also, you can transfer files securely via scp and sftp. In this tutorial we will show you how to enable SSH on an Ubuntu 20.04 system.
Enabling SSH on Ubuntu
If you have installed fresh Ubuntu, remote access via SSH is denied. You have to enable it for remote access. It is very easy with simple steps.
To install and enable SSH on your Ubuntu system, follow the below steps as root or user with sudo privileges:
1. First update the package index list and install the openssh-server package:
sudo apt update
sudo apt install openssh-server
It will prompt you to enter password, enter your password and hit Enter to continue to installation.
2. SSH service will start automatically, once the installation is finished. Verify SSH Service by checking status:
sudo systemctl status ssh
You should get output as following:
● ssh.service - OpenBSD Secure Shell server
Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enab
Active: active (running) since Sun 2020-05-31 12:27:57 UTC; 1 day 13h ago
Process: 890 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Main PID: 914 (sshd)
...You can quit by pressing q to the command prompt.
3. If you system is secured with firewall then you should allow SSH port.
sudo ufw allow ssh
At this point SSH is installed and you can connect to your Ubuntu system via SSH from any remote system. By default, Linux and macOS systems have SSH clients pre-installed. You can connect from a Windows machine by using an SSH client such as PuTTY.
Connecting to the SSH Server
To connect to your Ubuntu machine over network you can use the ssh command followed by the username and the IP address as following:
ssh USERNAME@IP_ADDRESS
Here, you should replace with your real username and ip address of the remote host.
For example, username is tecnstuff and ip address is 53.168.3.125 then you should run command as below:
ssh tecnstuff@53.168.3.125
It will show a message when you connecting first time:
The authenticity of host '53.168.3.125 (53.168.3.125)' can't be established. ECDSA key fingerprint is SHA256:cybd23mAJuNuBDunE++yowF7lgAs5a2bLFiO3qmLDPD. Are you sure you want to continue connecting (yes/no)?
Type yes and you will be asked to enter password:
Warning: Permanently added '53.168.3.125' (ECDSA) to the list of known hosts. tecnstuff@53.168.3.125's password:
On success, it will show default Ubuntu welcome message:
Welcome to Ubuntu 20.04 LTS (GNU/Linux 5.4.0-26-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
...This means you are now connected to remote system.
Disabling SSH on Ubuntu
If you would like to disable the SSH server on your Ubuntu system, just stop the SSH service by typing:
sudo systemctl disable --now ssh
Again, to re-enable it, type:
sudo systemctl enable --now ssh
Conclusion
This tutorial shown how to install and enable SSH on your Ubuntu 20.04 system. Now you can make remote session from your any client machine and do further admin tasks.
You can improve your remote machine security by changing the default SSH port, which will reduce the risk of automated attacks. To know more about SSH server read the official SSH manual page.
If you have any questions or feedback, please leave a comment below.