Lock Down SSH and Set Up a Firewall

What you will build

A server that only accepts SSH from your IP and web traffic from anywhere.

Starting point: you only need a Vultr account. This challenge is self-contained, so you can do it without having done any other.

The minimum

• Deploy your own fresh Ubuntu 24.04 instance with an SSH key for this challenge
• A non-root user with sudo
• Key-only SSH, root login disabled
• A Vultr Firewall group allowing only ports 22 and 80/443 as needed
• SSH restricted to your own IP

sudo sshd -T | grep -E 'permitrootlogin|passwordauthentication'

Keep a second SSH session open while you edit sshd_config so a mistake does not lock you out.