Basic setup for DigitalOcean VPS

Create another user

Since you want to login as this user then switch to root via su , we have to create another user with:

sudo adduser username

Edit sshd_config: new port + block root login

sudo nano /etc/ssh/sshd_config

Set Port 2222 (or your chosen port) and PermitRootLogin no, removing any leading #. Save and exit, then validate with:

sudo sshd -t

no output = valid

Disable ssh.socket

Ubuntu defaults to socket-based SSH activation, which ignores your Port setting entirely. Disable it so sshd runs standalone and actually respects sshd_config:

sudo systemctl stop ssh.socket
sudo systemctl disable ssh.socket

Then

sudo systemctl enable ssh.service
sudo systemctl start ssh.service

Verify only the new port is listening

sudo ss -tlnp | grep ssh

Should show only your new port, one PID

Lock down the firewall — allow ports before enabling

Allow what you need:

sudo ufw allow 2222/tcp
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp

Then

sudo ufw default deny incoming
sudo ufw default allow outgoing

Then enable the ufw:

sudo ufw enable

Check the ufw status and ports:

sudo ufw status

Test everything from a brand new terminal

From a completely fresh terminal:

ssh -p 2222 username@server_ip

Should work, then switch to root via su:

su -

Confirm these all fail:

ssh root@server_ip
ssh -p 2222 root@server_ip
ssh username@server_ip

That it​​​​!