Visual FoxPro

SSH Tunnel Inside another SSH Tunnel

See more SSH Tunnel Examples

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

LOCAL lnSuccess
LOCAL loTunnel
LOCAL lcSshHostname
LOCAL lnSshPort
LOCAL loTunnelB
LOCAL loChannel
LOCAL lnMaxWaitMs
LOCAL lnUseTls
LOCAL lnBigEndian
LOCAL loDt
LOCAL lnBLocalTime
LOCAL lnWaitForThreadExit

lnSuccess = 0

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

loTunnel = CreateObject('Chilkat.SshTunnel')

lcSshHostname = "www.ssh-serverA.com"
lnSshPort = 22

* Connect to an SSH server and establish the SSH tunnel:
lnSuccess = loTunnel.Connect(lcSshHostname,lnSshPort)
IF (lnSuccess = 0) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    CANCEL
ENDIF

* Authenticate with the SSH server via a login/password
* or with a public key.  
* This example demonstrates SSH password authentication.
lnSuccess = loTunnel.AuthenticatePw("mySshLogin","mySshPassword")
IF (lnSuccess = 0) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    CANCEL
ENDIF

* Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
* with dynamic port forwarding:
loTunnel.DynamicPortForwarding = 1

* 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.

loTunnel.InboundSocksUsername = "chilkat123"
loTunnel.InboundSocksPassword = "password123"

* Start the listen/accept thread to begin accepting SOCKS proxy client connections.
* Listen on port 1080.
lnSuccess = loTunnel.BeginAccepting(1080)
IF (lnSuccess = 0) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    CANCEL
ENDIF

* 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.

loTunnelB = CreateObject('Chilkat.Socket')

* Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
loTunnelB.SocksHostname = "localhost"
loTunnelB.SocksPort = 1080
loTunnelB.SocksVersion = 5
loTunnelB.SocksUsername = "chilkat123"
loTunnelB.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).
lnSuccess = loTunnelB.SshOpenTunnel("www.ssh-serverB.com",22)
IF (lnSuccess = 0) THEN
    ? loTunnelB.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    CANCEL
ENDIF

* Authenticate with ssh-serverB.com
lnSuccess = loTunnelB.SshAuthenticatePw("uname","pwd")
IF (lnSuccess = 0) THEN
    ? loTunnelB.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    CANCEL
ENDIF

* 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
loChannel = CreateObject('Chilkat.Socket')
lnMaxWaitMs = 4000
lnUseTls = 0
lnSuccess = loTunnelB.SshNewChannel("time-c.nist.gov",37,lnUseTls,lnMaxWaitMs,loChannel)
IF (lnSuccess = 0) THEN
    ? loTunnelB.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loChannel
    CANCEL
ENDIF

* 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
* 1 or 0 to indicate success.  If successful, the integer
* is obtained via the ReceivedInt property.
lnBigEndian = 1
lnSuccess = loChannel.ReceiveInt32(lnBigEndian)
IF (lnSuccess = 0) THEN
    ? loChannel.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loChannel
    CANCEL
ENDIF

loDt = CreateObject('Chilkat.CkDateTime')
loDt.SetFromNtpTime(loChannel.ReceivedInt)

* Show the current local date/time
lnBLocalTime = 1
? "Current local date/time: " + loDt.GetAsRfc822(lnBLocalTime)

* Close the SSH channel.
lnSuccess = loChannel.Close(lnMaxWaitMs)
IF (lnSuccess = 0) THEN
    ? loChannel.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loChannel
    RELEASE loDt
    CANCEL
ENDIF

* Stop the background listen/accept thread:
lnWaitForThreadExit = 1
lnSuccess = loTunnel.StopAccepting(lnWaitForThreadExit)
IF (lnSuccess = 0) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loChannel
    RELEASE loDt
    CANCEL
ENDIF

* Close the SSH tunnel (would also kick any remaining connected clients).
lnSuccess = loTunnel.CloseTunnel(lnWaitForThreadExit)
IF (lnSuccess = 0) THEN
    ? loTunnel.LastErrorText
    RELEASE loTunnel
    RELEASE loTunnelB
    RELEASE loChannel
    RELEASE loDt
    CANCEL
ENDIF

RELEASE loTunnel
RELEASE loTunnelB
RELEASE loChannel
RELEASE loDt