Question

How do i go about making my Java app run an HTTP server on some socket (e.g 172.16.1.10:8080) and make it so that when another computer on the network connects to a domain (e.g http://myjavadomain.com) it gets redirected to the socket?

Answer 1

If you want to run a fully fledged HTTP server then you will probably want to use some external library. For instance, Tomcat is written in Java, but there is also SUN’s httpserver package. If it’s just a simple socket server you’re after, you can use the built-in classes from the java.net package:

ServerSocket server = new ServerSocket(8080);

while (running) {
    Socket socket = server.accept();
    handleConnection(socket);
}

This will listen for incoming socket connections on port 8080 and create a new Socket whenever a client connects. You can then communicate with the client through the Socket‘s InputStream and OuputStream, which you would probably do in a separate Thread, so that your ServerSocket can continue listening for incoming connections from other clients.

As for the second part of your question: by default, a web browser will connect to port 80, and there are several ways you could do port forwarding. One possible solution using iptables is given on this website:

iptables -t nat -I PREROUTING --src 0/0 --dst 172.16.1.10 -p tcp --dport 80 -j REDIRECT --to-ports 8080

But the easiest solution would be to just specify the port number directly when connecting to your machine, e.g.

http://myjavadomain.com:8080

This is assuming that your DNS is configured so that it resolves myjavadomain.com to 172.16.1.10 already.