Visual FoxPro

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 lnSuccess
LOCAL loSsh
LOCAL lnSshPort
LOCAL lcPassword
LOCAL lcTargetHostname
LOCAL lnTargetPort
LOCAL lnChannelNum

lnSuccess = 0

*  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.

loSsh = CreateObject('Chilkat.Ssh')

lnSshPort = 22
lnSuccess = loSsh.Connect("ssh.example.com",lnSshPort)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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.
lcPassword = "mySshPassword"

lnSuccess = loSsh.AuthenticatePw("mySshLogin",lcPassword)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  The target name is resolved by the SSH server, not by this computer, so it must be
*  reachable from the server's network.
lcTargetHostname = "db.internal.example.com"
lnTargetPort = 5432
lnChannelNum = loSsh.OpenDirectTcpIpChannel(lcTargetHostname,lnTargetPort)
IF (lnChannelNum < 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

? "Opened direct-tcpip channel: " + STR(lnChannelNum)

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

loSsh.Disconnect()

RELEASE loSsh