I have a problem implementing socket connection between an android client (on physical device) and python server (on my pc). When the client tries to connect to the server, I get an error of ConnectionRefused. But if I try to connect in localhost with telnet, it works. If I run telnet from the android device the connection is refused. I lookup the tcpdump and i find out that the client sends a request of starting connection, but the server sends back a reset request.
Here the code:
server python:
import socket
bind_ip = socket.gethostname()
bind_port = 5000
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((bind_ip, bind_port))
server.listen(5)
print("[*] Listening on %s:%d" % (bind_ip, bind_port))
while True:
client, addr = server.accept()
print("[*] Accepted connection from: %s:%d" % (addr[0], addr[1]))
android client activity:
public class Test2Activity extends BaseActivity implements View.OnClickListener{
Button mButton;
EditText mStringEdit;
EditText mIpEdit;
final int port = 5000;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
setContentView(R.layout.activity_test2_layout);
super.onCreate(savedInstanceState);
mButton = findViewById(R.id.send_button);
mStringEdit = findViewById(R.id.string_edit_text);
mIpEdit = findViewById(R.id.ip_edit_text);
mButton.setOnClickListener(this);
}
@Override
public void onClick(View view) {
sendData();
}
private void sendData() {
if (mIpEdit.getText().toString().equals("")) {
Toast.makeText(this, "Server ip not setted yet!", Toast.LENGTH_SHORT).show();
}
if (!mStringEdit.getText().toString().equals("")) {
if (Client.getInstance().sendText(mStringEdit.getText().toString()) == 0) {
Toast.makeText(this, "Somethings goes wrong!", Toast.LENGTH_SHORT).show();
}
}
new Thread(new Runnable() {
@Override
public void run() {
try {
InetAddress address = InetAddress.getByName(mIpEdit.getText().toString());
Socket socket = new Socket(address, port);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}
and finally tcpdump info:
12:20:41.903480 ARP, Request who-has robinho-laptop tell android-c49064c93c3f654e.station, length 28
12:20:41.903508 ARP, Reply robinho-laptop is-at 7c:5c:f8:7f:3e:c4 (oui Unknown), length 28
12:20:41.911749 IP android-c49064c93c3f654e.station.41439 > robinho-laptop.5000: Flags [S], seq 3327241168, win 14600, options [mss 1460,sackOK,TS val 40845430 ecr 0,nop,wscale 6], length 0
12:20:41.911791 IP robinho-laptop.5000 > android-c49064c93c3f654e.station.41439: Flags [R.], seq 0, ack 3327241169, win 0, length 0
Here android logcat:
E/DataScheduler: isDataSchedulerEnabled():false
W/System.err: java.net.ConnectException: failed to connect to localhost/::1 (port 50000): connect failed: ECONNREFUSED (Connection refused)
W/System.err: at libcore.io.IoBridge.connect(IoBridge.java:130)
W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
W/System.err: at java.net.Socket.startupSocket(Socket.java:566)
W/System.err: at java.net.Socket.<init>(Socket.java:226)
W/System.err: at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
W/System.err: at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:631)
W/System.err: at java.net.Socket.<init>(Native Method)
W/System.err: at utils.connection.Client$1.run(Client.java:42)
W/System.err: at java.lang.Thread.run(Thread.java:841)
W/System.err: Caused by: libcore.io.ErrnoException: connect failed: ECONNREFUSED (Connection refused)
W/System.err: at libcore.io.Posix.connect(Native Method)
W/System.err: at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85)
W/System.err: at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
W/System.err: at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:631)
W/System.err: at libcore.io.BlockGuardOs.connect(Native Method)
W/System.err: at libcore.io.IoBridge.connectErrno(IoBridge.java:176)
W/System.err: at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
W/System.err: at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:631)
W/System.err: at libcore.io.IoBridge.connectErrno(Native Method)
W/System.err: at libcore.io.IoBridge.connect(IoBridge.java:128)
W/System.err: ... 9 more
W/System.err: java.net.ConnectException: failed to connect to laptop.station/192.168.1.6 (port 5000): connect failed: ECONNREFUSED (Connection refused)
W/System.err: at libcore.io.IoBridge.connect(IoBridge.java:130)
W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
W/System.err: at java.net.Socket.startupSocket(Socket.java:566)
W/System.err: at java.net.Socket.<init>(Socket.java:226)
W/System.err: at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
W/System.err: at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:631)
W/System.err: at java.net.Socket.<init>(Native Method)
W/System.err: at ui.activities.Test2Activity$1.run(Test2Activity.java:62)
W/System.err: at java.lang.Thread.run(Thread.java:841)
W/System.err: Caused by: libcore.io.ErrnoException: connect failed: ECONNREFUSED (Connection refused)
W/System.err: at libcore.io.Posix.connect(Native Method)
W/System.err: at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85)
W/System.err: at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
W/System.err: at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:631)
W/System.err: at libcore.io.BlockGuardOs.connect(Native Method)
W/System.err: at libcore.io.IoBridge.connectErrno(IoBridge.java:176)
W/System.err: at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
W/System.err: at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:631)
W/System.err: at libcore.io.IoBridge.connectErrno(Native Method)
W/System.err: at libcore.io.IoBridge.connect(IoBridge.java:128)
W/System.err: ... 9 more
Anyone can explain me this issue ?
You probably bind your socket to a wrong ip.
From https://pymotw.com/2/socket/tcp.html
Many servers have more than one network interface, and therefore more than one IP address. Rather than running separate copies of a service bound to each IP address, use the special address INADDR_ANY to listen on all addresses at the same time. Although socket defines a constant for INADDR_ANY, it is an integer value and must be converted to a dotted-notation string address before it can be passed to bind(). As a shortcut, use the empty string '' instead of doing the conversion.
server_address = ('', 5000)
sock.bind(server_address)