Objective-C

Continue SSH Tunnel Keyboard-Interactive Authentication

Demonstrates the Chilkat SshTunnel.ContinueKeyboardAuth method, which submits a response to a keyboard-interactive prompt. The only argument is the response text; for a request with multiple prompts, an XML response is supplied instead. It returns XML indicating the next prompt or the final result.

Background: This is the second half of the exchange started by StartKeyboardAuth. A server may issue several rounds of prompts, so a robust client loops: submit answers, read the returned XML, and continue until it sees success or failure. On success, BeginAccepting still must be called before the tunnel forwards traffic.

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Objective-C

#import <CkoSshTunnel.h>
#import <NSString.h>

BOOL success = NO;

//  Demonstrates the SshTunnel.ContinueKeyboardAuth method, which submits a response to a
//  keyboard-interactive prompt.  The only argument is the response.  For multiple prompts, an XML
//  response is supplied instead.

CkoSshTunnel *tunnel = [[CkoSshTunnel alloc] init];

//  The tunnel forwards accepted local connections to this destination through the SSH server.
tunnel.DestHostname = @"db.internal.example.com";
tunnel.DestPort = [NSNumber numberWithInt:5432];

//  Connect to the SSH server.  This performs the TCP/proxy connection and SSH handshake, but
//  does not authenticate yet.
int sshPort = 22;
success = [tunnel Connect: @"ssh.example.com" port: [NSNumber numberWithInt: sshPort]];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}

//  Begin keyboard-interactive authentication to receive the server's prompt(s).
NSString *infoRequestXml = [tunnel StartKeyboardAuth: @"mySshLogin"];
if (tunnel.LastMethodSuccess == NO) {
    NSLog(@"%@",tunnel.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.
NSString *password = @"mySshPassword";

//  Submit the response (typically the password).  The returned XML indicates the next prompt or
//  the final result.
NSString *result = [tunnel ContinueKeyboardAuth: password];
if (tunnel.LastMethodSuccess == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}

NSLog(@"%@",result);

BOOL waitForThreadExit = YES;
success = [tunnel CloseTunnel: waitForThreadExit];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}