Dart

SSH Tunnel Per-Client Logging and Client Identifier

Demonstrates the ClientLogDir and ClientIdentifier properties. When ClientLogDir is set, a separate log file is created for each tunnel client; ClientIdentifier is the SSH client-identification string sent during the handshake.

Note: The log paths are relative to the application's current working directory. Absolute paths may also be used.

Background: When many clients share one tunnel, a single combined log is hard to follow, so ClientLogDir gives each connection its own file — the fastest way to diagnose one misbehaving client. ClientIdentifier sets the version string the server sees; overriding the default is occasionally needed for compatibility with servers that key behavior off the client identification, or simply to label your application in server logs.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the SshTunnel per-client logging properties ClientLogDir and ClientIdentifier.

  final tunnel = CkSshTunnel();

  // When ClientLogDir is set, a separate log file is created for each tunnel client in this
  // directory, which is useful for troubleshooting individual connections.
  tunnel.clientLogDir = 'qa_output/client_logs';

  // The SSH client-identification string sent to the SSH server during the handshake.
  tunnel.clientIdentifier = 'SSH-2.0-MyTunnelApp_1.0';

  tunnel.destHostname = 'db.internal.example.com';
  tunnel.destPort = 5432;

  final sshPort = 22;
  try {
    tunnel.connect('ssh.example.com', sshPort);
  } on ChilkatException catch (e) {
    print(e.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.
  final password = 'mySshPassword';

  try {
    tunnel.authenticatePw('mySshLogin', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final listenPort = 1080;
  try {
    tunnel.beginAccepting(listenPort);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Tunnel running; each client is logged in ${tunnel.clientLogDir}');

  final waitForThreadExit = true;
  try {
    tunnel.closeTunnel(waitForThreadExit);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }
}