Can't create a TCP/IP connection over Internet

Question

Problem with TCP/IP and PORT Forwarding

I disabled the Firewall
setup DMZ to my local IP
ran a C# console app which listens for incoming connections from port 8659 (SERVER):

static void Main(string[] args)
{
    // port to listen to
    int connPort = 8659;
    // the  local endPoint
    var localEP = new IPEndPoint(IPAddress.Any, connPort);
    // creating the socket
    using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
    {
        // binding the socket to the local endPoint
        socket.Bind(localEP);
        // listening for incoming connections
        socket.Listen(10);
        // logging
        Debug.WriteLine("waiting for client ...");
        // grab the first client
        var client = socket.Accept();
        // logging
        Debug.WriteLine("client connected !");
        var jsonContent = "this is json test";
        // sending the json content as a json response
        client.Send(Encoding.ASCII.GetBytes("HTTP/1.1 200 OK\n" +
            "Content-Type: text/plain\n" +
            $"Content-Length: {jsonContent.Length}\n" +
            "\n" + jsonContent));
    } // end of using
    Console.ReadLine();
} // end of main

tried to connect to the server with another app (CLIENT) using the public IP:

static void Main(string[] args)
{
    var host = Dns.GetHostEntry(Dns.GetHostName());
    // the ip address of the interface connected to internet
    var ip = host.AddressList[1];
    // my public IP ( dynamic ) not yet static, just a test
    var ServerIP = IPAddress.Parse("197.119.200.25");
    // the server endpoint
    var serverEP = new IPEndPoint(ServerIP, 8659);
    // the endpoint to use to connect to the server
    var localEP = new IPEndPoint(ip, 8658);
    // creating the socket
    var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    // bind the socket to the endpoint
    socket.Bind(localEP);
    // connect to the server endpoint
    socket.Connect(serverEP);
} // end of mainc

Client threw:

System.Net.Sockets.SocketException: 'A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 197.119.200.25:8659'

So my question is why isn't my server app reachable by the machine's public IP?

I don't know if it's my ISP blocking Ports or I have another problem that I'm not aware of!

Most likely you need to enable port forwarding on your router — damian, Oct 11 '19 at 19:56
Does your DMZ sit behind a legit firewall or just some home router. Its like @damian said you might need to enable port forwarding if its a home router or if its a firewall like a cisco pix or something you will need to setup some allows inbound for the ports. — Bearcat9425, Oct 11 '19 at 20:00
@damian, isn't DMZ enough to do the trick?, if it makes it better i tried port forwarding and nothing changed. my computer is connected to a router that uses 4G to connect to internet. — Abdelkarim bettayeb, Oct 11 '19 at 20:30
How do you know that `host.AddressList[1];` is the address for your public interface? — Anon Coward, Oct 11 '19 at 21:27
@anoncoward it contains 192.168.0.117 which is my ethernet local IP ( checked with ipconfig command ) — Abdelkarim bettayeb, Oct 11 '19 at 21:38
Fair enough, if I remove that line and the two lines that depend on it (my public IP is in a different location in the array), your code works for me, so I'd assume it's some networking issue. — Anon Coward, Oct 11 '19 at 21:40
@anoncoward are you sure you used your public IP with the client app? — Abdelkarim bettayeb, Oct 11 '19 at 21:42
Yep. I tested on the Internet, with the client and server running on different machines. — Anon Coward, Oct 11 '19 at 21:48
Seems to bee simple configuration issue. Check the port forwarding on your router. Or maybe, your provider disalows to use some kind of port. — Andreas Schmidt, Oct 11 '19 at 21:50
@AndreasSchmidt, yep i tried DMZ and PORT forwarding none of them worked, do you know any method that i could use to determine whether my ISP is blocking ports or not? — Abdelkarim bettayeb, Oct 11 '19 at 21:55
@AndreasSchmidt none of the ports you suggested worked for me. — Abdelkarim bettayeb, Oct 14 '19 at 05:08
As i mentionned before i setup both DMZ and PORT forwarding, none of them works — Abdelkarim bettayeb, Oct 15 '19 at 16:33

Can't create a TCP/IP connection over Internet

Problem with TCP/IP and PORT Forwarding

0 Answers0