stream_get_transports — Retrieve list of registered socket transports
Returns an indexed array containing the name of all socket transports available on the running system.
Example #1 Using stream_get_transports()
$xportlist = stream_get_transports();
Output will be similar to the following. Note: there may be more or fewer transports in your version of PHP.
Array (  => tcp  => udp  => unix  => udg )