Opening ports on your VPS firewall (ufw) and common ports

On a VPS you decide which ports are open. The control panel does not filter incoming traffic to your VPS, so the firewall inside the server is what protects it. On Ubuntu Server the simplest firewall is ufw, which is installed but usually not active on a new server.

Before you start#

Open ports with ufw#

# show the current state
sudo ufw status verbose

# allow SSH first, then the ports you need
sudo ufw allow 22/tcp
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp

# switch the firewall on
sudo ufw enable

For UDP services add /udp, for example sudo ufw allow 19132/udp. A port range needs the protocol: sudo ufw allow 27015:27030/udp. ufw applies each rule to IPv4 and IPv6.

Close a port again#

sudo ufw status numbered
sudo ufw delete 3            # number from the list
sudo ufw delete allow 80/tcp # or by rule

A port is open in ufw but still not reachable? Check that the service runs and listens on the public address: sudo ss -tulpn lists all listening ports. A service bound to 127.0.0.1 only accepts connections from the server itself.

Common ports#

Locked out or need the console? See Managing your VPS.