This is a method to check if a host name is accessible i.e it is online, by using PHP. With fsocketopen() a connection will be created, if it fails false will be returned otherwise it will return a pointers.
In this script 192.168.0.1 gets pinged on port 80 the conditional statement will output simple statements based on the fsocketopen() response. Errors are suppressed with the @.
<?php if (@fsockopen("192.168.0.1", 80) === false) { echo "Down"; } else { echo "Up"; }
If a connection was not rejected it will output Up otherwise the output will be Down.