- Connection Validation

  # test target port available, v for verbose, z for no data sending
  nc -vz 192.168.1.2 8080    

  # test a port range
  nc -v -v -w3 -z 192.168.1.2 8080-8083

- Server / Client Test

  # Start this in your server
  nc -l -p 8080

  # Start this in your client
  nc 192.168.1.2 8080

- UDP Validation

  # For server
  nc -u -l -p 8080

  # For client
  nc -u 192.168.1.2 8080

- File Transfer

  # For server
  nc -l -p 8080 > image.jpg

  # For client
  nc 192.168.1.2 8080 < image.jpg