(Perl) 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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use chilkat();

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

$tunnel = chilkat::CkSocket->new();

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

# Connect to an SSH server and establish the SSH tunnel:
$success = $tunnel->SshOpenTunnel($sshHostname,$sshPort);
if ($success != 1) {
    print $tunnel->lastErrorText() . "\r\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 != 1) {
    print $tunnel->lastErrorText() . "\r\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 = 0;
# channel is a Socket
$channel = $tunnel->SshOpenChannel("time-c.nist.gov",37,$useTls,$maxWaitMs);
if ($tunnel->get_LastMethodSuccess() == 0) {
    print $tunnel->lastErrorText() . "\r\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
# 1 or 0 to indicate success.  If successful, the integer
# is obtained via the ReceivedInt property.
$bigEndian = 1;
$success = $channel->ReceiveInt32($bigEndian);
if ($success != 1) {
    print $channel->lastErrorText() . "\r\n";

    exit;
}

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

# Show the current local date/time
$bLocalTime = 1;
print "Current local date/time: " . $dt->getAsRfc822($bLocalTime) . "\r\n";

# Close the SSH channel.
$success = $channel->Close($maxWaitMs);
if ($success != 1) {
    print $channel->lastErrorText() . "\r\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 Socket
$channel = $tunnel->SshOpenChannel("time-a.nist.gov",37,$useTls,$maxWaitMs);
if ($tunnel->get_LastMethodSuccess() == 0) {
    print $tunnel->lastErrorText() . "\r\n";
    exit;
}

# Review the LastErrorText to see that the connection was made via the SSH tunnel:
print $tunnel->lastErrorText() . "\r\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 != 1) {
    print $channel->lastErrorText() . "\r\n";

    exit;
}

# Finally, close the SSH tunnel.
$success = $tunnel->SshCloseTunnel();
if ($success != 1) {
    print $tunnel->lastErrorText() . "\r\n";
    exit;
}

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