I'm trying to set up a server/client connection in Java.
I've connected my PC directly to the DSL, and it works fine through Windows 10 firewall. I reconnect to my TP-Link Archer C9 router with Virtual Server set for port 4023 and 4024. I get a SocketTimeoutException on the Client Side.
And Wireshark gives me a bunch of TCP Retransmissions saying 'hello server' after the handshake from the Client, when I filter for port 4023:
Server code:
public class ServerTester {
public static void main(String[] args) {
try {
final int PORT = 4023;
ServerSocket server = new ServerSocket(PORT, 100, null);
System.out.println("Waiting for clients...");
while (true)
{
Socket s = server.accept();
System.out.println("Client connected from " + s.getLocalAddress().getHostName());
ServerClient chat = new ServerClient(s);
Thread t = new Thread(chat);
t.start();
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
Server Client:
public class ServerClient implements Runnable {
private Socket socket;
public ServerClient(Socket s) {
socket = s;
}
@Override
public void run() {
try {
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
System.out.println("ObjectInputStream from inputStream created");
ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
System.out.println("ObjectOutputStream created");
String input = (String) ois.readObject();
System.out.println("received: " + input);
oos.writeObject("hello yourself!");
oos.flush();
input = (String) ois.readObject();
System.out.println(input);
oos.writeObject("this is my second message");
oos.flush();
ois.close();
oos.close();
socket.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
Client Code:
public class ClientTester {
private final static int PORT = 4023;
private final static int LOCAL_PORT = 4024;
private final static String HOST = //removed for this post;
public static void main(String[] args) throws IOException {
try {
Socket s = new Socket(HOST, PORT, InetAddress.getByName(HOST), LOCAL_PORT);
s.setSoTimeout(5000);
System.out.println("You connected to " + HOST);
ClientClient client = new ClientClient(s);
Thread t = new Thread(client);
t.start();
}
catch (Exception noServer)
{
System.out.println("The server might not be up at this time.");
System.out.println("Please try again later.");
noServer.printStackTrace();
}
}
}
Client Client:
public class ClientClient implements Runnable {
private Socket socket;
public ClientClient(Socket s)
{
socket = s;
}
@Override
public void run() {
try {
ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
System.out.println("ObjectOutputStream from inputStream created");
oos.writeObject("hello server");
oos.flush();
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
System.out.println("ObjectInputStream from inputStream created");
String input = (String) ois.readObject();
System.out.println(input);
oos.writeObject("here is my second message to the server");
oos.flush();
input = (String) ois.readObject();
System.out.println(input);
oos.close();
ois.close();
socket.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
The server console says:
run:
Waiting for clients...
Client connected from Ben
The client console says:
run:
You connected to //removed for post
ObjectOutputStream from inputStream created
java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:170)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at java.io.ObjectInputStream$PeekInputStream.read(ObjectInputStream.java:2320)
at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2333)
at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2804)
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:802)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
at clienttester.ClientClient.run(ClientClient.java:33)
at java.lang.Thread.run(Thread.java:745)
Can my router's firewall be the culprit? It seems like it is allowing back and forth communication until the ObjectInputStream is being created.
Then is it a stupid Java error I'm making? As I said earlier, it works when I remove the router from the system. I'm completely baffled.
This is my first question, from a longtime leacher. Thanks for all your help Stack Overflow!
Sorry for the brief reply, I'm on a mobile, but the problem is that your while loop is in the wrong place. Socket.accept is a blocking operation for a client connection. The client connection is made, then closed,and the code is done. I'll try to expand on the answer when i get to a desktop.