Thread: ServerAndClient via Ip

Hey,
Iam trying to connect a server with a client via public ip, but it is always is unable to connect.
When I try it with using localhost (in the same network) its working fine.

I already forwarded my ports in my router and firewall, but it will not connect when I use my
public ip address.

Error

Exception in thread "main" java.net.ConnectException: Connection timed out: connect
	at java.net.DualStackPlainSocketImpl.connect0(Native Method)
	at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
	at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
	at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
	at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
	at java.net.PlainSocketImpl.connect(Unknown Source)
	at java.net.SocksSocketImpl.connect(Unknown Source)
	at java.net.Socket.connect(Unknown Source)
	at java.net.Socket.connect(Unknown Source)
	at java.net.Socket.<init>(Unknown Source)
	at java.net.Socket.<init>(Unknown Source)
	at main.ClientMain.main(ClientMain.java:10)

Client

public class ClientMain {
	public static void main(String[] args) throws IOException {
		Socket client = new Socket("localhost", 4545);
 
		DataOutputStream output = new DataOutputStream(client.getOutputStream());
		output.writeUTF("Message from the client.");
 
		DataInputStream input = new DataInputStream(client.getInputStream());
		System.out.println(input.readUTF());
 
		client.close();
	}
}

Server

public class ServerMain {
	public static void main(String[] args) throws IOException {
		ServerSocket server = new ServerSocket(4545);
 
		while(true) {
			System.out.println("Waiting for client on port " + server.getLocalPort() + ".");
			Socket client = server.accept();
 
			System.out.println("Client connected from " + client.getInetAddress() + ".");
 
			DataInputStream input = new DataInputStream(client.getInputStream());
			System.out.println(input.readUTF());
 
			DataOutputStream output = new DataOutputStream(client.getOutputStream());
			output.writeUTF("Message from the server.");
 
			client.close();
		}
	}
}

Thanks for help!

Originally Posted by Norm

Is there a Firewall blocking the connection?

I dont think so. The ports are forwarded in my router and my firewall.
Is there any port wich is automatically forwarded, so that I could test it?

Originally Posted by Norm

The only thing I can suggest is double check the firewall.

In my firewall are 2 rules for the port 4545 (in/out).

When I try it via ip I use this code:

public class ClientMain {
	public static void main(String[] args) throws IOException {
		Socket client = new Socket("81.198.251.108", 4545);  //This is just an example ip
 
		DataOutputStream output = new DataOutputStream(client.getOutputStream());
		output.writeUTF("Message from the client.");
 
		DataInputStream input = new DataInputStream(client.getInputStream());
		System.out.println(input.readUTF());
 
		client.close();
	}
}

Is that correct?

Originally Posted by Norm

Is anything printed on your server's console?

Nope, there is just the text from the regular start. ("Waiting for client on port 4545.")

Originally Posted by Norm

If the code works with the localhost address, then I'd suspect the problem is outside of the programs.
I don't have any experience with configuring routers or firewalls.

Socket client = new Socket("81.198.251.108", 4545);

Just putting in the ip in there is correct or?