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Open a direct-tcpip Channel (SSH Port Forwarding)

Demonstrates the Chilkat Ssh.OpenDirectTcpIpChannel method, which opens a direct-tcpip channel through the SSH server to a target host and port. The first argument is the target hostname and the second is the target port. It returns the channel number, or -1 on failure.

Background: This is SSH local port forwarding at the API level: the channel carries ordinary TCP traffic to a service that may be reachable only from the SSH server's network — a database, an internal web app, a message broker. The key detail is that the server resolves the target name, not your machine, so it must resolve and be reachable there. Supplying a numeric IPv4 address avoids remote DNS resolution entirely.

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Local $bSuccess = False

;  Demonstrates the Ssh.OpenDirectTcpIpChannel method, which opens a direct-tcpip channel
;  through the SSH server to a target host and port.  The 1st argument is the target hostname
;  and the 2nd is the target port.  It returns the channel number, or -1 on failure.

$oSsh = ObjCreate("Chilkat.Ssh")

Local $iSshPort = 22
$bSuccess = $oSsh.Connect("ssh.example.com",$iSshPort)
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

;  Normally you would not hard-code the password in source.  You should instead obtain it
;  from an interactive prompt, environment variable, or a secrets vault.
Local $sPassword = "mySshPassword"

$bSuccess = $oSsh.AuthenticatePw("mySshLogin",$sPassword)
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

;  The target name is resolved by the SSH server, not by this computer, so it must be
;  reachable from the server's network.
Local $sTargetHostname = "db.internal.example.com"
Local $iTargetPort = 5432
Local $iChannelNum = $oSsh.OpenDirectTcpIpChannel($sTargetHostname,$iTargetPort)
If ($iChannelNum < 0) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

ConsoleWrite("Opened direct-tcpip channel: " & $iChannelNum & @CRLF)

;  The channel now carries ordinary TCP data to the target, tunneled over SSH.

$oSsh.Disconnect