Dart

Connect to an SSH Server Through Another (Jump Host)

Demonstrates the Chilkat Ssh.ConnectThroughSsh method, which connects to a second SSH server through an already connected and authenticated Ssh object. The first argument is the first (jump-host) Ssh object, and the second and third are the destination hostname and port.

Background: This is SSH chaining through a "jump host" (bastion): the application connects to a reachable gateway, then tunnels onward to a target that is only accessible from inside the network. Each hop is authenticated separately with its own credentials. The result is a normal Ssh object for the target that happens to be routed through the first connection.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the Ssh.ConnectThroughSsh method, which connects to a second SSH server through
  // an already connected and authenticated Ssh object (a jump host).  The 1st argument is the
  // first Ssh object, and the 2nd and 3rd are the destination hostname and port.

  final sshJump = CkSsh();

  // Connect and authenticate to the first SSH server (the jump host).
  final sshPort = 22;
  try {
    sshJump.connect('jump.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 {
    sshJump.authenticatePw('jumpUser', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Connect to the target SSH server through the jump host.
  final sshTarget = CkSsh();
  try {
    sshTarget.connectThroughSsh(sshJump, 'target.example.com', sshPort);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Authenticate to the target server (separate credentials).
  try {
    sshTarget.authenticatePw('targetUser', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Connected to the target through the jump host.');

  sshTarget.disconnect();
  sshJump.disconnect();
}