JavaScript

Connect an SSH Tunnel Through a Jump Host

Demonstrates the Chilkat SshTunnel.ConnectThroughSsh method, which connects to an SSH 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 SSH hostname and port.

Background: This chains the tunnel through a "jump host" (bastion): the application reaches a gateway server, then tunnels onward to an SSH server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SshTunnel — still requiring its own authentication and BeginAccepting — whose transport is routed through the first connection.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

JavaScript

var success = false;

//  Demonstrates the SshTunnel.ConnectThroughSsh method, which connects to an SSH 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 SSH hostname and port.

var sshJump = new CkSsh();

//  Connect and authenticate to the jump host first.
var sshPort = 22;
success = sshJump.Connect("jump.example.com",sshPort);
if (success == false) {
    console.log(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.
var password = "mySshPassword";

success = sshJump.AuthenticatePw("myJumpLogin",password);
if (success == false) {
    console.log(sshJump.LastErrorText);
    return;
}

//  Set up the tunnel and connect to the target SSH server through the jump host.
var tunnel = new CkSshTunnel();
tunnel.DestHostname = "db.internal.example.com";
tunnel.DestPort = 5432;

success = tunnel.ConnectThroughSsh(sshJump,"ssh.internal.example.com",sshPort);
if (success == false) {
    console.log(tunnel.LastErrorText);
    return;
}

//  Authenticate to the target SSH server (its own credentials).
success = tunnel.AuthenticatePw("mySshLogin",password);
if (success == false) {
    console.log(tunnel.LastErrorText);
    return;
}

//  After authenticating, call BeginAccepting to start listening for local connections to forward.

var waitForThreadExit = true;
success = tunnel.CloseTunnel(waitForThreadExit);
if (success == false) {
    console.log(tunnel.LastErrorText);
    return;
}

sshJump.Disconnect();