(VB.NET) TCP or TLS over Multiple Hop SSH to Remote Server

Demonstrates how to use the Chilkat Socket API to connect to a remote server (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => DestinationServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

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' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim ssh1 As New Chilkat.Ssh

' Connect directly to the 1st SSH server.
Dim success As Boolean = ssh1.Connect("serverssh1.com",22)
If (success <> True) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If


' Authenticate using login/password:
success = ssh1.AuthenticatePw("ssh1Login","ssh1Password")
If (success <> True) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If



' Connect through the 1st SSH connection to reach a 2nd SSH server.
' Note: Any number of SSH connections may be simultaneously tunneled through a single
' existing SSH connection.
Dim ssh2 As New Chilkat.Ssh
success = ssh2.ConnectThroughSsh(ssh1,"serverssh2.com",22)
If (success <> True) Then
    Debug.WriteLine(ssh2.LastErrorText)
    Exit Sub
End If



' Authenticate with ssh2...
success = ssh2.AuthenticatePw("ssh2Login","ssh2Password")
If (success <> True) Then
    Debug.WriteLine(ssh2.LastErrorText)
    Exit Sub
End If




Dim socket As New Chilkat.Socket

' Tell the socket object to connect to our destination server though the ssh2 tunnel (which itself is routed through ssh1).
' The connection looks like this:  ApplicationSocket(TLS) => ServerSSH1 => ServerSSH2 => DestinationServer
success = socket.UseSsh(ssh2)
If (success <> True) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


' Connect using TLS to www.chilkatsoft.com
' We could also tunnel a bare TCP connection by specifying port 80 with useTls = False.
Dim useTls As Boolean = True
Dim maxWaitMillisec As Integer = 20000
success = socket.Connect("www.chilkatsoft.com",443,useTls,maxWaitMillisec)
If (success <> True) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


' Once the multiple hop SSH tunneled connection is setup,  the socket programming
' is identical to the normal case where we have a direct connection.

' Tell the socket object that all text is to be sent in the utf-8 encoding,
' and the text received is assumed to be utf-8.
socket.StringCharset = "utf-8"

' Send an HTTP HEAD request:
success = socket.SendString("HEAD / HTTP/1.1" & vbCrLf & "Host: www.chilkatsoft.com" & vbCrLf & vbCrLf)
If (success <> True) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


' Wait a maximum of 4 seconds while no data is forthcoming:
socket.MaxReadIdleMs = 4000


' Get the 1st response line, which should be "HTTP/1.1 200 OK"
Dim responseStatusLine As String = socket.ReceiveToCRLF()
If (socket.LastMethodSuccess <> True) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("StatusLine: " & responseStatusLine)

' Now get the 1st line of the response header:
Dim responseHeaderLine As String = socket.ReceiveToCRLF()
If (socket.LastMethodSuccess <> True) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("HeaderLine: " & responseHeaderLine)

' Now read the remainder of the response header by reading until a double CRLF is seen:
Dim remainderOfHeader As String = socket.ReceiveUntilMatch(vbCrLf & vbCrLf)
If (socket.LastMethodSuccess <> True) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("Remainder: " & remainderOfHeader)


' Close the connection with the server.  This closes the tunnel through ssh2.
' Wait a max of 20 seconds (20000 millsec)
success = socket.Close(20000)



' Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
' The connection with ssh1 is still alive, and may be used for more connections.
ssh2.Disconnect()


ssh1.Disconnect()