Dart

SSH Tunnel with Dynamic Port Forwarding

See more SSH Examples

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can use for establishing connections through an SSH tunnel. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example assumes the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final tunnel = CkSshTunnel();

  final sshHostname = 'sftp.example.com';
  final sshPort = 22;

  // Connect to an SSH server and establish the SSH tunnel:
  try {
    tunnel.connect(sshHostname, sshPort);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Authenticate with the SSH server via a login/password
  // or with a public key.  
  // This example demonstrates SSH password authentication.
  try {
    tunnel.authenticatePw('mySshLogin', 'mySshPassword');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
  // with dynamic port forwarding:
  tunnel.dynamicPortForwarding = true;

  // We may optionally require that connecting clients authenticate with our SOCKS proxy server.
  // To do this, set an inbound username/password.  Any connecting clients would be required to 
  // use SOCKS5 with the correct username/password.
  // If no inbound username/password is set, then our SOCKS proxy server will accept both
  // SOCKS4 and SOCKS5 unauthenticated connections.

  tunnel.inboundSocksUsername = 'chilkat123';
  tunnel.inboundSocksPassword = 'password123';

  // Start the listen/accept thread to begin accepting SOCKS proxy client connections.
  // Listen on port 1080.
  try {
    tunnel.beginAccepting(1080);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Now that a background thread is running a SOCKS proxy server that forwards connections
  // through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
  // such as HTTP, POP3, SMTP, IMAP, FTP, etc.  The protocol may use SSL/TLS because the SSL/TLS
  // will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
  // connections may be routed through the SSH tunnel.

  // For this example, let's do a simple HTTPS request:
  final url = 'https://www.ethereum.org/';

  final http = CkHttp();

  // Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
  http.socksHostname = 'localhost';
  http.socksPort = 1080;
  http.socksVersion = 5;
  http.socksUsername = 'chilkat123';
  http.socksPassword = 'password123';

  http.sendCookies = true;
  http.saveCookies = true;
  http.cookieDir = 'memory';

  // Do the HTTPS page fetch (through the SSH tunnel)
  final String html;
  try {
    html = http.quickGetStr(url);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Stop the background listen/accept thread:
  final waitForThreadExit = true;
  try {
    tunnel.stopAccepting(waitForThreadExit);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Close the SSH tunnel (would also kick any remaining connected clients).
  try {
    tunnel.closeTunnel(waitForThreadExit);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }
}