This quick guide walks you through installing and enabling OpenSSH on Ubuntu 22.04 or 20.04, starting with an `apt update` followed by `apt install openssh-server`. Once the package is installed, you activate the daemon at boot with `systemctl enable --now ssh`, then optionally harden security settings in `/etc/ssh/sshd_config`, such as disabling root login and ensuring pubkey authentication is enabled. The tutorial also covers firewall configuration by allowing the OpenSSH rule in UFW and provides commands to verify that the service is active, including checking status and testing a local SSH connection. Finally, it lists common troubleshooting steps for issues like missing connections, key authentication failures, or unwanted password prompts, so you can resolve typical hiccups quickly.

Installing and Enabling OpenSSH on Ubuntu 22.04 or 20.04

Want a quick, reliable way to jump into your machine from anywhere?

This guide walks you through the exact steps to get OpenSSH up and running on Ubuntu 22.04 LTS or 20.04 LTS, plus a few sanity checks that will save you hours of frustration later.

1. Grab the package

sudo apt update
sudo apt install openssh-server

apt update pulls fresh metadata; without it, apt install might grab an old copy or fail entirely.

The package name is openssh-server—the client (ssh) comes pre‑installed on most Ubuntu installs.

2. Make the daemon stick around

sudo systemctl enable --now ssh

enable tells systemd to start SSH automatically at boot, while --now launches it immediately so you can test right away.

If you skip this step, every reboot will kill your ability to remote in until you remember to hand‑run the service.

3. Harden the defaults (optional but recommended)

Open /etc/ssh/sshd_config in your favorite editor:

sudo nano /etc/ssh/sshd_config

• Find #PermitRootLogin prohibit-password and change it to

PermitRootLogin no – you’ll never need a root password over SSH.

• Ensure PubkeyAuthentication yes is enabled so key‑based logins work.

I ran into an odd issue after a kernel upgrade where this line was commented out by default; once I uncommented it, my keys started working again.

After editing, reload the service:

sudo systemctl reload ssh

Reloading applies changes without dropping any active connections.

4. Open the firewall to SSH traffic

If you’re running UFW (Uncomplicated Firewall), allow the standard port with:

sudo ufw allow OpenSSH

UFW blocks everything by default, so this one rule is all you need for a secure, accessible server.

5. Confirm it’s alive and reachable

systemctl status ssh

You should see “Active: active (running)” in green.

Try connecting from the same machine to double‑check:

ssh localhost

If that works, you’re good to go from any other host on your network.

6. Common hiccups and quick fixes

• No connection? Check /var/log/auth.log for “Connection closed by …” messages; they often point to a firewall or mis‑configured sshd_config.
• Key authentication fails? Make sure your public key is in $HOME/.ssh/authorized_keys on the remote host and has 600 permissions.

I once saw this issue after a fresh install where the folder was left at 755, and SSH refused every key.

• Password prompts still appear? If you accidentally set PasswordAuthentication yes, remove or comment that line to enforce keys only.

That’s it—OpenSSH is now installed, enabled, and ready for secure remote work.