Android™
Android™
Open a direct-tcpip Channel (SSH Port Forwarding)
See more SSH Examples
Demonstrates the Chilkat Ssh.OpenDirectTcpIpChannel method, which opens a direct-tcpip channel through the SSH server to a target host and port. The first argument is the target hostname and the second is the target port. It returns the channel number, or -1 on failure.
Background: This is SSH local port forwarding at the API level: the channel carries ordinary TCP traffic to a service that may be reachable only from the SSH server's network — a database, an internal web app, a message broker. The key detail is that the server resolves the target name, not your machine, so it must resolve and be reachable there. Supplying a numeric IPv4 address avoids remote DNS resolution entirely.
Chilkat Android™ Downloads
// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;
import android.app.Activity;
import com.chilkatsoft.*;
import android.widget.TextView;
import android.os.Bundle;
public class SimpleActivity extends Activity {
private static final String TAG = "Chilkat";
// Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
boolean success = false;
// Demonstrates the Ssh.OpenDirectTcpIpChannel method, which opens a direct-tcpip channel
// through the SSH server to a target host and port. The 1st argument is the target hostname
// and the 2nd is the target port. It returns the channel number, or -1 on failure.
CkSsh ssh = new CkSsh();
int sshPort = 22;
success = ssh.Connect("ssh.example.com",sshPort);
if (success == false) {
Log.i(TAG, ssh.lastErrorText());
return;
}
// Normally you would not hard-code the password in source. You should instead obtain it
// from an interactive prompt, environment variable, or a secrets vault.
String password = "mySshPassword";
success = ssh.AuthenticatePw("mySshLogin",password);
if (success == false) {
Log.i(TAG, ssh.lastErrorText());
return;
}
// The target name is resolved by the SSH server, not by this computer, so it must be
// reachable from the server's network.
String targetHostname = "db.internal.example.com";
int targetPort = 5432;
int channelNum = ssh.OpenDirectTcpIpChannel(targetHostname,targetPort);
if (channelNum < 0) {
Log.i(TAG, ssh.lastErrorText());
return;
}
Log.i(TAG, "Opened direct-tcpip channel: " + String.valueOf(channelNum));
// The channel now carries ordinary TCP data to the target, tunneled over SSH.
ssh.Disconnect();
}
static {
System.loadLibrary("chilkat");
// Note: If the incorrect library name is passed to System.loadLibrary,
// then you will see the following error message at application startup:
//"The application <your-application-name> has stopped unexpectedly. Please try again."
}
}