(PHP Extension) TCP Socket through SSH Tunnel (Port Forwarding)

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.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

$tunnel = new CkSocket();

$sshHostname = 'sftp.example.com';
$sshPort = 22;

// Connect to an SSH server and establish the SSH tunnel:
$success = $tunnel->SshOpenTunnel($sshHostname,$sshPort);
if ($success != true) {
    print $tunnel->lastErrorText() . "\n";
    exit;
}

// Authenticate with the SSH server via a login/password
// or with a public key.
// This example demonstrates SSH password authentication.
$success = $tunnel->SshAuthenticatePw('mySshLogin','mySshPassword');
if ($success != true) {
    print $tunnel->lastErrorText() . "\n";
    exit;
}

// 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

$maxWaitMs = 4000;
$useTls = false;
// channel is a CkSocket
$channel = $tunnel->SshOpenChannel('time-c.nist.gov',37,$useTls,$maxWaitMs);
if ($tunnel->get_LastMethodSuccess() == false) {
    print $tunnel->lastErrorText() . "\n";
    exit;
}

// 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
// true or false to indicate success.  If successful, the integer
// is obtained via the ReceivedInt property.
$bigEndian = true;
$success = $channel->ReceiveInt32($bigEndian);
if ($success != true) {
    print $channel->lastErrorText() . "\n";

    exit;
}

$dt = new CkDateTime();
$dt->SetFromNtpTime($channel->get_ReceivedInt());

// Show the current local date/time
$bLocalTime = true;
print 'Current local date/time: ' . $dt->getAsRfc822($bLocalTime) . "\n";

// Close the SSH channel.
$success = $channel->Close($maxWaitMs);
if ($success != true) {
    print $channel->lastErrorText() . "\n";

    exit;
}

// 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.
// channel is a CkSocket
$channel = $tunnel->SshOpenChannel('time-a.nist.gov',37,$useTls,$maxWaitMs);
if ($tunnel->get_LastMethodSuccess() == false) {
    print $tunnel->lastErrorText() . "\n";
    exit;
}

// Review the LastErrorText to see that the connection was made via the SSH tunnel:
print $tunnel->lastErrorText() . "\n";

// 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.
$success = $channel->Close($maxWaitMs);
if ($success != true) {
    print $channel->lastErrorText() . "\n";

    exit;
}

// Finally, close the SSH tunnel.
$success = $tunnel->SshCloseTunnel();
if ($success != true) {
    print $tunnel->lastErrorText() . "\n";
    exit;
}

print 'TCP SSH tunneling example completed.' . "\n";

?>