Send a message via TCP with NC between two PCs connected to a LAN

obtain the private IP of said computer

ipconfig getifaddr en0

A PC sends a message via FTP to a private IP and port.

The PC to which the message is sent listens to a port and receives messages.

send message

nc :private_ip :port

listen in port

nc -l :port

An example made with a Java application that sends “Hola” when I execute the /send endpoint

In a terminal I am connected to another PC via SSH

java code:

• 192.168.0.7 is a private IP
• “Hola” is the message to send
• 15000 is the port of the PC to send the message

    public void sendDefaultMessage() {
        int port = 0;
        try {
            port = CommonFunctions.getPort();
            Node node = new Node(port);
            node.sendMessage("Hola", "192.168.0.7", 15000);
        } catch (IOException e) {
            System.out.println("Connection error: " + e.getMessage());
        } catch (Exception e) {
            System.out.println("Unexpected error: " + e.getMessage());
        }
    }

    public void sendMessage(String message, String ipAdress, int port) throws Exception {
        ObjectOutputStream outputStream = new ObjectOutputStream(socket.getOutputStream());
        outputStream.writeObject( message );
        socket.close();
    }