Netty server remote connection

Question

Netty server, Fedora. I just can't connect to the server from remote host and no listening socket is displayed via netstat util. However I can establish the connection running client and server on the same machine. That's simply like that:

port = System.getProperty(PORT_PROPERTY);
Preconditions.checkNotNull(port, "Network error, port property is not set");
hostAddress = new InetSocketAddress(Integer.valueOf(port));
...
serverChannel = bootstrap.bind(hostAddress);

I've tried initializing hostAddress with the port only, localhost IP, 0.0.0.0 IP, and IP of my network. Nothing helps. What could be the root of problem?

Answer 1

Here's some suggestions that should help disagnosing the problem:

• For clarity (until you resolve this), stick to using

new InetSocketAddress("0.0.0.0", Integer.valueOf(port))

since this will ensure you bind to all interfaces.

• Invoke the JVM with -Djava.net.preferIPv4Stack=true to force the JVM into IPV4. I have found it easier to muck with these issues when in IPV4 since is it less complicated than V6.

• Get the PID of the JVM and then issue a netstat like this:

sudo netstat -ap --numeric-ports | grep <PID>

This should display all sockets for your JVM instance. (Please post this output if you're still not able to connect remotely. Also post the output of ifconfig )