Xbase++ Requires Chilkat v11.0.0+

TCP Socket through SSH Tunnel (Port Forwarding)

See more Socket/SSL/TLS Examples

Demonstrates using Chilkat Socket to communicate to a TCP service through an SSH tunnel. This example will connect to an NIST time server and (using the old Time Protocol (RFC 868)), will read the current GMT time.

Note: This is not necessarily a recommended means for getting the current date/time. The most commonly used time protocol is the Network Time Protocol (RFC-1305). The intent of this example is to show how TCP communications can occur through an SSH tunnel.

Xbase++

LOCAL nSuccess
LOCAL oTunnel
LOCAL cSshHostname
LOCAL nSshPort
LOCAL nMaxWaitMs
LOCAL nUseTls
LOCAL oChannel
LOCAL nBigEndian
LOCAL oDt
LOCAL nBLocalTime

nSuccess := 0

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

oTunnel := CreateObject("Chilkat.Socket")

cSshHostname := "sftp.example.com"
nSshPort := 22

//  Connect to an SSH server and establish the SSH tunnel:
nSuccess := oTunnel:SshOpenTunnel(cSshHostname, nSshPort)
IF (nSuccess == 0)
    ? oTunnel:LastErrorText
    oTunnel:destroy()
    RETURN
ENDIF

//  Authenticate with the SSH server via a login/password
//  or with a public key.
//  This example demonstrates SSH password authentication.
nSuccess := oTunnel:SshAuthenticatePw("mySshLogin", "mySshPassword")
IF (nSuccess == 0)
    ? oTunnel:LastErrorText
    oTunnel:destroy()
    RETURN
ENDIF

//  OK, the SSH 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
nMaxWaitMs := 4000
nUseTls := 0
oChannel := CreateObject("Chilkat.Socket")
nSuccess := oTunnel:SshNewChannel("time-c.nist.gov", 37, nUseTls, nMaxWaitMs, oChannel)
IF (nSuccess == 0)
    ? oTunnel:LastErrorText
    oTunnel:destroy()
    oChannel:destroy()
    RETURN
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.
nBigEndian := 1
nSuccess := oChannel:ReceiveInt32(nBigEndian)
IF (nSuccess == 0)
    ? oChannel:LastErrorText
    oTunnel:destroy()
    oChannel:destroy()
    RETURN
ENDIF

oDt := CreateObject("Chilkat.CkDateTime")
oDt:SetFromNtpTime(oChannel:ReceivedInt)

//  Show the current local date/time
nBLocalTime := 1
? "Current local date/time: " + oDt:GetAsRfc822(nBLocalTime)

//  Close the SSH channel.
nSuccess := oChannel:Close(nMaxWaitMs)
IF (nSuccess != 1)
    ? oChannel:LastErrorText
    oTunnel:destroy()
    oChannel:destroy()
    oDt:destroy()
    RETURN
ENDIF

//  It is possible to create a new channel from the existing SSH tunnel for the next connection:
//  Any number of channels may be created from the same SSH tunnel.
//  Multiple channels may coexist at the same time.
nSuccess := oTunnel:SshNewChannel("time-a.nist.gov", 37, nUseTls, nMaxWaitMs, oChannel)
IF (nSuccess == 0)
    ? oTunnel:LastErrorText
    oTunnel:destroy()
    oChannel:destroy()
    oDt:destroy()
    RETURN
ENDIF

//  Review the LastErrorText to see that the connection was made via the SSH tunnel:
? oTunnel:LastErrorText

//  Close the connection to time-a.nist.gov.  This is actually closing our channel
//  within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection.
nSuccess := oChannel:Close(nMaxWaitMs)
IF (nSuccess != 1)
    ? oChannel:LastErrorText
    oTunnel:destroy()
    oChannel:destroy()
    oDt:destroy()
    RETURN
ENDIF

//  Finally, close the SSH tunnel.
nSuccess := oTunnel:SshCloseTunnel()
IF (nSuccess == 0)
    ? oTunnel:LastErrorText
    oTunnel:destroy()
    oChannel:destroy()
    oDt:destroy()
    RETURN
ENDIF

? "TCP SSH tunneling example completed."

oTunnel:destroy()
oChannel:destroy()
oDt:destroy()