B4X

SSH Tunnel with Dynamic Port Forwarding

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Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can use for establishing connections through an SSH tunnel. B4X

Dim success As Boolean = False

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

success = False

Dim tunnel As ChilkatSshTunnel
tunnel.Initialize("tunnel")

Dim sshHostname As String = "sftp.example.com"
Dim sshPort As Int = 22

'  Connect to an SSH server and establish the SSH tunnel:
success = tunnel.Connect(sshHostname, sshPort)
If success <> True Then
    Log(tunnel.LastErrorText)
    Return
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
    Log(tunnel.LastErrorText)
    Return
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
    Log(tunnel.LastErrorText)
    Return
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, 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.

'  For this example, let's do a simple HTTPS request:
Dim url As String = "https://www.ethereum.org/"

Dim http As ChilkatHttp
http.Initialize("http")

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

http.SendCookies = True
http.SaveCookies = True
http.CookieDir = "memory"

'  Do the HTTPS page fetch (through the SSH tunnel)
Dim html As String = http.QuickGetStr(url)
If http.LastMethodSuccess <> True Then
    Log(http.LastErrorText)
    Return
End If


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


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