PHP

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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<?php

use Chilkat2\Ssh;

// 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.

$ssh = new Ssh();

$sshPort = 22;
try {
    $ssh->Connect('ssh.example.com', $sshPort);

    // 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.
    $password = 'mySshPassword';

    $ssh->AuthenticatePw('mySshLogin', $password);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// The target name is resolved by the SSH server, not by this computer, so it must be
// reachable from the server's network.
$targetHostname = 'db.internal.example.com';
$targetPort = 5432;
$channelNum = $ssh->OpenDirectTcpIpChannel($targetHostname, $targetPort);
if ($channelNum < 0) {
    echo $ssh->LastErrorText, "\n";
    exit;
}

echo 'Opened direct-tcpip channel: ', $channelNum, "\n";

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

$ssh->Disconnect();