Misc

Ports in use

sudo lsof -i :5432

Open ports

ssl -tunlp

Telnet

Is a CLI tool for connecting to TCP servers

Firewall

For more on this see: UFW (Uncomplicated Firewall)

# UFW activate 
sudo ufw enable

# Port 11355 
sudo ufw allow 11355/tcp


sudo ufw allow 11355/udp

# Check rules 
sudo ufw status

# Check rules in more detail 
sudo ufw status verbose