C# 控制台应用程序通过互联网配对

Question

I want to build a C# chat like app, where you can enter a string into the Client console and receive it in the Server console.

What I mean: User B executes the Client Program on his Computer, which is anywhere else than at User A. The Client Program connects over TCP to the Server Program, which has User A opened on his Computer. When User B enters a string in the Program and press enter, User A should receive the string over Internet.

I have something like that:

Server:

static void Main(string[] args)
{

    Console.WriteLine("Start Server ...");


    IPAddress b = IPAddress.Any;
    TcpListener Server = new TcpListener(b, 5550);
    Server.Start();
    Console.WriteLine("Server started.");

    Console.WriteLine("Wait for Connection...");
    TcpClient Client = Server.AcceptTcpClient();
    Console.WriteLine("Succeeded");

    Stream MessageStream = Client.GetStream();

    while (true)
    {
        byte[] message = new byte[4096];
        int bytesRead;
        try
        {
            bytesRead = MessageStream.Read(message, 0, 4096);

            ASCIIEncoding encoder = new ASCIIEncoding();
            Console.WriteLine(encoder.GetString(message, 0, bytesRead));
        }

        catch (IOException)
        {
            break;
        }
    }

    Client.Close();
    Server.Stop();
}

Client:

static void Main(string[] args)
{
    IPAddress IP = IPAddress.Parse("192.168.2.140");
    TcpClient Client = new TcpClient();
    Client.Connect(IP, 5550);

    Stream MessageStream = Client.GetStream();
    Console.WriteLine("Success");

    ASCIIEncoding encoder = new ASCIIEncoding();

    Console.WriteLine("Enter Text here");

    var input = Console.ReadLine();
    if(input != null)
    {
        byte[] buffer = encoder.GetBytes(input);

        MessageStream.Write(buffer, 0, buffer.Length);
        MessageStream.Flush();
    }

    Console.ReadLine();
}

When I execute the Client on my PC and the Server on my Laptop, it works fine, but how does it work with outside-of-my-local-network-Computers?

When I replaced
IPAddress IP = IPAddress.Parse("192.168.2.140"); with the WAN IP, which I get from canihazip.com, it doesn't want to connect.

EDIT:

Port-Forwarding is activated i guess

The Problem is: It works in the local Network at my home as i want, it connects, i can write a text, which shows up in the server-application. But when i ask some of my friends to try this, they cant connect to my server..

Answer 1

You need to go to your router's admin interface, and forward connections on certain ports from the internet to the IP address of the system behind the network. That will be entirely dependent on your router and quick google search will tell you what you need to know.

Update from OP edit:

So from there, you access it via the public ip with the public port, and set your system to listen on the LAN port. Another effective thing to help will be to use a free dynamic dns service, such as duckdns.com whom I've used before and found to be good and easy enough, to get an actual name that will always map to your public ip address which - if you're not purchasing a static ip address from your ISP - is dynamic and will changein the future.