How to Block IP Addresses with PHP

[ Image: Skeletor Blocks a Move ] Figuratively speaking, hunting down and killing spammers, scrapers, and other online scum remains one of our favorite pursuits. Once we have determined that a particular IP address is worthy of banishment, we generally invoke the magical powers of htaccess to lock the gates. When htaccess is not available, we may summon the versatile functionality of PHP to get the job done.

This method is relatively straightforward. Simply edit, copy and paste the following code example into the top of any PHP for which you wish to block access:

$deny = array("111.111.111", "222.222.222", "333.333.333");
if (in_array ($_SERVER['REMOTE_ADDR'], $deny)) {
} ?>

The code basically creates an array of the IP addresses that you wish to block, and then checks incoming addresses against the array. If the incoming (i.e., remote) address matches against any value in the array, the function will deny access with a redirect header to the specified URL, which in this case is the majestic Google home page. It all happens quickly, quietly, and without any fuss.

Thus, when using this code in your pages, simply replace the “dummy” IP addresses (i.e., "111.111.111", "222.222.222", ...) with those that you wish to block (e.g., "123.456.789", "123.456.*", "123.*", ...). Yes, PHP understands wildcard operators (i.e., *). After editing the array of IP addresses, upload the file to your server and relax. If you would like to verify this method, simply lookup your own IP address, add it to the array, and try loading the target page. That’s all there is to it — “grab, gulp, and go”.

Using this method, you may also wish to create a customized page to which blocked addresses are redirected, perhaps to explain the situation, provide contact information, or display a macro shot of your greasy bum. If you customize, remember to change the redirect URL (i.e., to that of your custom page.

See also: Block Multiple IP Addresses with PHP