Visual Basic 6.0

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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Visual Basic 6.0

Dim success As Long
success = 0

'  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.

Dim sshJump As New ChilkatSsh

'  Connect and authenticate to the jump host first.
Dim sshPort As Long
sshPort = 22
success = sshJump.Connect("jump.example.com",sshPort)
If (success = 0) Then
    Debug.Print sshJump.LastErrorText
    Exit Sub
End If

'  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.
Dim password As String
password = "mySshPassword"

success = sshJump.AuthenticatePw("myJumpLogin",password)
If (success = 0) Then
    Debug.Print sshJump.LastErrorText
    Exit Sub
End If

'  Set up the tunnel and connect to the target SSH server through the jump host.
Dim tunnel As New ChilkatSshTunnel
tunnel.DestHostname = "db.internal.example.com"
tunnel.DestPort = 5432

success = tunnel.ConnectThroughSsh(sshJump,"ssh.internal.example.com",sshPort)
If (success = 0) Then
    Debug.Print tunnel.LastErrorText
    Exit Sub
End If

'  Authenticate to the target SSH server (its own credentials).
success = tunnel.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    Debug.Print tunnel.LastErrorText
    Exit Sub
End If

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

Dim waitForThreadExit As Long
waitForThreadExit = 1
success = tunnel.CloseTunnel(waitForThreadExit)
If (success = 0) Then
    Debug.Print tunnel.LastErrorText
    Exit Sub
End If

sshJump.Disconnect