Dart

Get SSH Server Authentication Methods

Demonstrates getting the authentication methods advertised by an SSH server. Connect first but do not authenticate, then call GetAuthMethods, which returns a lowercase, comma-separated list such as publickey,password,keyboard-interactive.

Important: Querying the authentication methods intentionally disconnects from the server, so reconnect before authenticating.

Background: Knowing what a server accepts lets a client choose the right authentication path rather than guessing — for example, falling back to keyboard-interactive when password authentication is not offered, or failing fast with a clear message when only public-key is allowed. It is also useful diagnostically when authentication fails for reasons that are not obvious from the error text.

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Dart

import 'package:chilkat/chilkat.dart';

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

  // Demonstrates getting the authentication methods advertised by an SSH server.

  final ssh = CkSsh();

  final port = 22;

  // The server must be connected, but not yet authenticated.
  try {
    ssh.connect('ssh.example.com', port);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Returns a lowercase, comma-separated list, such as:
  //     publickey,password,keyboard-interactive
  final String authMethods;
  try {
    authMethods = ssh.getAuthMethods();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Authentication methods supported by this server: $authMethods');

  // IMPORTANT: Querying the authentication methods intentionally disconnects from the server.
  // Reconnect before authenticating.
  try {
    ssh.connect('ssh.example.com', port);
  } 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 {
    ssh.authenticatePw('mySshLogin', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('SSH authentication successful.');

  ssh.disconnect();
}