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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.

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llSuccess = .F.

//  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.

loSshJump = createobject("CkSsh")

//  Connect and authenticate to the jump host first.
lnSshPort = 22
llSuccess = loSshJump.Connect("jump.example.com",lnSshPort)
if (llSuccess = .F.) then
    ? loSshJump.LastErrorText
    release loSshJump
    return
endif

//  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.
lcPassword = "mySshPassword"

llSuccess = loSshJump.AuthenticatePw("myJumpLogin",lcPassword)
if (llSuccess = .F.) then
    ? loSshJump.LastErrorText
    release loSshJump
    return
endif

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

llSuccess = loTunnel.ConnectThroughSsh(loSshJump,"ssh.internal.example.com",lnSshPort)
if (llSuccess = .F.) then
    ? loTunnel.LastErrorText
    release loSshJump
    release loTunnel
    return
endif

//  Authenticate to the target SSH server (its own credentials).
llSuccess = loTunnel.AuthenticatePw("mySshLogin",lcPassword)
if (llSuccess = .F.) then
    ? loTunnel.LastErrorText
    release loSshJump
    release loTunnel
    return
endif

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

llWaitForThreadExit = .T.
llSuccess = loTunnel.CloseTunnel(llWaitForThreadExit)
if (llSuccess = .F.) then
    ? loTunnel.LastErrorText
    release loSshJump
    release loTunnel
    return
endif

loSshJump.Disconnect()


release loSshJump
release loTunnel