Get IP of Websocket on known port

Question

I have built a websocket in C++ (using boost::beast). It is going to serve a website (client) with a JSON string if requested. When designing my setup I made a disastrous mistake: I forgot that the client web browser (that is running on a separate device from the server) will not know the IP address of the server. It will know the port that the server is listening on.

I should specify: Both (server and client) are running in a local network.

So I have two clumsy ideas to resolve this. I would be very happy to hear your input – I am sure there will be a more elegant way to fix my problem.

1. Send some kind of broadcast message “Very specific string” into the network. My server will know that it is been looked for and will respond with its IP, so that the connection can be established. This post seems to indicate that this approach will not be possible.

2. Have the user input the (known) IP address of the device that is running the server. I would really like to avoid this last resort solution.

Unfortunately, I cannot run node.js on the device that is hosting the websocket server.

Answer 1

I might not be understanding the problem. Why aren't you capable of knowing the IP of the server? Is it due because it changes? Is it because it's a server you don't know? Maybe the solution is not about finding the IP rather than knowing beforehand the server IP address.

I could recommend checking out this post to find out the IP address in your local network. If you at least know the servername of the server that could be helpful.

Answer 2

@E.Soria Thank you for your answer! I was not precise enough.

The problem was, that the server is running on a device that is going to be part of our customer’s network. The customer will define the IP address for the device, which means that I need some way of getting the address of the server.

But I might have found another solution (as you might already be able to tell I am very new to networking, so this just may be wrong): I will host the website on the same device that is hosting the server and supplying the data. Then I can just establish a websocket connection through javascript like this: let socket = new WebSocket(ws://127.0.0.1:8080); and have the website read data from the server. This seems to be very straightforward and I am a little embarrassed that I did not think of this before. I just had not really understood how the internet works :) As long as the user who wants to see the website knows where it is hosted, he/she can just connect to the website and will see anything that I put on there.