Objective-C

Connect to an SFTP Server Through a Jump Host

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

Background: This is the "jump host" (bastion) pattern: the application connects to a reachable gateway, then tunnels onward to an SFTP server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SFtp object — still requiring its own authentication and InitializeSftp — that happens to be routed through the first connection.

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Objective-C

#import <CkoSsh.h>
#import <NSString.h>
#import <CkoSFtp.h>

BOOL success = NO;

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

CkoSsh *sshJump = [[CkoSsh alloc] init];

//  Connect and authenticate to the jump host first.
int port = 22;
success = [sshJump Connect: @"jump.example.com" port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",sshJump.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";

success = [sshJump AuthenticatePw: @"myJumpLogin" password: password];
if (success == NO) {
    NSLog(@"%@",sshJump.LastErrorText);
    return;
}

//  Connect to the SFTP server through the jump host.
CkoSFtp *sftp = [[CkoSFtp alloc] init];
success = [sftp ConnectThroughSsh: sshJump hostname: @"sftp.internal.example.com" port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  Authenticate to the SFTP server (its own credentials), then initialize SFTP.
success = [sftp AuthenticatePw: @"mySshLogin" password: password];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

success = [sftp InitializeSftp];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

NSLog(@"%@",@"Connected to the SFTP server through the jump host.");

[sftp Disconnect];
[sshJump Disconnect];