Objective-C

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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Objective-C

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

BOOL success = NO;

//  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.

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

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

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

//  Authenticate to the target server (separate credentials).
success = [sshTarget AuthenticatePw: @"targetUser" password: password];
if (success == NO) {
    NSLog(@"%@",sshTarget.LastErrorText);
    return;
}

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

[sshTarget Disconnect];
[sshJump Disconnect];