connecting two android devices via TCP sockets

Question

I've been trying to connect two Android devices (2.1) via TCP sockets. The vital part of the code:

Server: ServerSocket serverSocket = new ServerSocket(SERVERPORT);

Client: Socket socket = new Socket(serverAddr, SERVERPORT);

The weird thing is I can make it work if the client is an emulator, but the same code fails if running both of them on real devices. The failure in the client side is:

 
java.net.SocketException: No route to host
     at org.apache.harmony.luni.platform.OSNetworkSystem.connectSocketImpl(Native
 Method)
     at org.apache.harmony.luni.platform.OSNetworkSystem.connect(OSNetworkSystem.
java:114)
     at org.apache.harmony.luni.net.PlainSocketImpl.connect(PlainSocketImpl.java:
245)
     at org.apache.harmony.luni.net.PlainSocketImpl.connect(PlainSocketImpl.java:
220)
     at java.net.Socket.startupSocket(Socket.java:780)
     at java.net.Socket.(Socket.java:314)

I tried with WIFI and mobile net too, they were in the same subnet both times, INTERNET permission is given, the server is addressed through its real 192.168.. IP.
I am planning to change the socket implementation with setCustomSocketImplFactory().
The problem is crucial in the process of implementing MSRP protocol to Android.
Can anyone give me some advice?

What do you mean by real IP if the programs are running on two mobile phones ? — user409393
I've just tried to say that the problem is not that I use 10.0.2.15 IP for the real devices — Diepie

Brad Fitzpatrick Brad Fitzpatrick · Accepted Answer · 2010-12-09T01:40:29

Very few mobile phones have publicly routable IP addresses. Most are behind NAT.

You may want to consider using C2DM instead:

http://code.google.com/android/c2dm/

connecting two android devices via TCP sockets

1 Answers