(VB.NET) SSH Tunnel Inside another SSH Tunnel

Demonstrates how to create a TCP/IP socket connection through an SSH tunnel that is dynamic port forwarded through another SSH tunnel.

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

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

' This example requires Chilkat version 9.5.0.50 or greater.
Dim tunnel As New Chilkat.SshTunnel


Dim sshHostname As String = "www.ssh-serverA.com"
Dim sshPort As Integer = 22

' Connect to an SSH server and establish the SSH tunnel:
Dim success As Boolean = tunnel.Connect(sshHostname,sshPort)
If (success <> True) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


' Authenticate with the SSH server via a login/password
' or with a public key.  
' This example demonstrates SSH password authentication.
success = tunnel.AuthenticatePw("mySshLogin","mySshPassword")
If (success <> True) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If



' Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
' with dynamic port forwarding:
tunnel.DynamicPortForwarding = True

' We may optionally require that connecting clients authenticate with our SOCKS proxy server.
' To do this, set an inbound username/password.  Any connecting clients would be required to 
' use SOCKS5 with the correct username/password.
' If no inbound username/password is set, then our SOCKS proxy server will accept both
' SOCKS4 and SOCKS5 unauthenticated connections.

tunnel.InboundSocksUsername = "chilkat123"
tunnel.InboundSocksPassword = "password123"

' Start the listen/accept thread to begin accepting SOCKS proxy client connections.
' Listen on port 1080.
success = tunnel.BeginAccepting(1080)
If (success <> True) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If



' Now that a background thread is running a SOCKS proxy server that forwards connections
' through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
' such as HTTP, POP3, SMTP, IMAP, FTP, Socket, etc.  The protocol may use SSL/TLS because the SSL/TLS
' will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
' connections may be routed through the SSH tunnel.

Dim tunnelB As New Chilkat.Socket

' Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
tunnelB.SocksHostname = "localhost"
tunnelB.SocksPort = 1080
tunnelB.SocksVersion = 5
tunnelB.SocksUsername = "chilkat123"
tunnelB.SocksPassword = "password123"

' Open a new SSH tunnel through the existing tunnel (via what we treat as a SOCKS5 proxy,
' but it is actually a dynamic port-forwarded SSH tunnel).
success = tunnelB.SshOpenTunnel("www.ssh-serverB.com",22)
If (success <> True) Then
    Debug.WriteLine(tunnelB.LastErrorText)
    Exit Sub
End If


' Authenticate with ssh-serverB.com
success = tunnelB.SshAuthenticatePw("uname","pwd")
If (success <> True) Then
    Debug.WriteLine(tunnelB.LastErrorText)
    Exit Sub
End If



' OK, the SSH tunnel (within a tunnel) is setup.  Now open a channel within the tunnel.
' Once the channel is obtained, the Socket API may
' be used exactly the same as usual, except all communications
' are sent through the channel in the SSH tunnel.
' Any number of channels may be created from the same SSH tunnel.
' Multiple channels may coexist at the same time.

' Connect to an NIST time server and read the current date/time
Dim channel As Chilkat.Socket
Dim maxWaitMs As Integer = 4000
Dim useTls As Boolean = False
channel = tunnelB.SshOpenChannel("time-c.nist.gov",37,useTls,maxWaitMs)
If (tunnelB.LastMethodSuccess = False) Then
    Debug.WriteLine(tunnelB.LastErrorText)
    Exit Sub
End If


' The time server will send a big-endian 32-bit integer representing
' the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
' The ReceiveInt32 method will receive a 4-byte integer, but returns
' True or False to indicate success.  If successful, the integer
' is obtained via the ReceivedInt property.
Dim bigEndian As Boolean = True
success = channel.ReceiveInt32(bigEndian)
If (success <> True) Then
    Debug.WriteLine(channel.LastErrorText)

    Exit Sub
End If


Dim dt As New Chilkat.CkDateTime
dt.SetFromNtpTime(channel.ReceivedInt)

' Show the current local date/time
Dim bLocalTime As Boolean = True
Debug.WriteLine("Current local date/time: " & dt.GetAsRfc822(bLocalTime))

' Close the SSH channel.
success = channel.Close(maxWaitMs)
If (success <> True) Then
    Debug.WriteLine(channel.LastErrorText)

    Exit Sub
End If







' Stop the background listen/accept thread:
Dim waitForThreadExit As Boolean = True
success = tunnel.StopAccepting(waitForThreadExit)
If (success <> True) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If



' Close the SSH tunnel (would also kick any remaining connected clients).
success = tunnel.CloseTunnel(waitForThreadExit)
If (success <> True) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If