PowerBuilder

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.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Tunnel
string ls_SshHostname
integer li_SshPort
integer li_MaxWaitMs
integer li_UseTls
oleobject loo_Channel
integer li_BigEndian
oleobject loo_Dt
integer li_BLocalTime

li_Success = 0

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

loo_Tunnel = create oleobject
li_rc = loo_Tunnel.ConnectToNewObject("Chilkat.Socket")
if li_rc < 0 then
    destroy loo_Tunnel
    MessageBox("Error","Connecting to COM object failed")
    return
end if

ls_SshHostname = "sftp.example.com"
li_SshPort = 22

// Connect to an SSH server and establish the SSH tunnel:
li_Success = loo_Tunnel.SshOpenTunnel(ls_SshHostname,li_SshPort)
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

// Authenticate with the SSH server via a login/password
// or with a public key.
// This example demonstrates SSH password authentication.
li_Success = loo_Tunnel.SshAuthenticatePw("mySshLogin","mySshPassword")
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

// 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
li_MaxWaitMs = 4000
li_UseTls = 0
loo_Channel = create oleobject
li_rc = loo_Channel.ConnectToNewObject("Chilkat.Socket")

li_Success = loo_Tunnel.SshNewChannel("time-c.nist.gov",37,li_UseTls,li_MaxWaitMs,loo_Channel)
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    return
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
// 1 or 0 to indicate success.  If successful, the integer
// is obtained via the ReceivedInt property.
li_BigEndian = 1
li_Success = loo_Channel.ReceiveInt32(li_BigEndian)
if li_Success = 0 then
    Write-Debug loo_Channel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    return
end if

loo_Dt = create oleobject
li_rc = loo_Dt.ConnectToNewObject("Chilkat.CkDateTime")

loo_Dt.SetFromNtpTime(loo_Channel.ReceivedInt)

// Show the current local date/time
li_BLocalTime = 1
Write-Debug "Current local date/time: " + loo_Dt.GetAsRfc822(li_BLocalTime)

// Close the SSH channel.
li_Success = loo_Channel.Close(li_MaxWaitMs)
if li_Success <> 1 then
    Write-Debug loo_Channel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Dt
    return
end if

// 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.
li_Success = loo_Tunnel.SshNewChannel("time-a.nist.gov",37,li_UseTls,li_MaxWaitMs,loo_Channel)
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Dt
    return
end if

// Review the LastErrorText to see that the connection was made via the SSH tunnel:
Write-Debug loo_Tunnel.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.
li_Success = loo_Channel.Close(li_MaxWaitMs)
if li_Success <> 1 then
    Write-Debug loo_Channel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Dt
    return
end if

// Finally, close the SSH tunnel.
li_Success = loo_Tunnel.SshCloseTunnel()
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Dt
    return
end if

Write-Debug "TCP SSH tunneling example completed."


destroy loo_Tunnel
destroy loo_Channel
destroy loo_Dt