Outdated: This post references REGISTER_GLOBALS, which was deprecated in PHP 5.3 and removed in PHP 5.4. Use $_SERVER['REMOTE_ADDR'] exclusively. Note that behind a reverse proxy or load balancer, you may need to check headers like X-Forwarded-For instead.

Sometimes you want to get the visitor’s IP address (e.g to show it to him or for logging purposes). This simple snippet does the job:

$ip = $_SERVER['REMOTE_ADDR'];

Also, if you have REGISTER_GLOBALS turned on on your server, you can use the shorter version:

$ip = @$REMOTE_ADDR;

Then you can easily use the variable called $ip for your needs.