tcpwrap_check

Performs a tcpwrap check (PECL tcpwrap:0.1-1.0)
bool tcpwrap_check ( string daemon, string address [, string user [, bool nodns]] )

If your /etc/hosts.deny file contains:

php: 127.0.0.1

And your code looks like:

<?php
if (!tcpwrap_check('php', $_SERVER['REMOTE_ADDR'])) {

  die('You are not welcome here');

}
?>

tcpwrap_check