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

<?php $deny = array("111.111.111", "222.222.222", "333.333.333");
if (in_array ($_SERVER['REMOTE_ADDR'], $deny)) {
   header("location: https://example.com/");
   exit();
} ?>

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 behind the scenes.

Usage

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., *). Also you may want to change the redirect location. Currently it is set to https://example.com/, so feel free to change that to whatever URL is desired.

After making any changes, upload the file to your server. 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, or perhaps send them to the blackhole.

Jeff Starr
About the Author
Jeff Starr = Web Developer. Security Specialist. WordPress Buff.
WP Themes In Depth: Build and sell awesome WordPress themes.

109 responses to “How to Block IP Addresses with PHP”

  1. THANK YOU FOR THE CODE!
    I got some problems with spam from a specific IP. You helpt me a lot!
    Thanx again!

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Perishable Press is operated by Jeff Starr, a professional web developer and book author with two decades of experience. Here you will find posts about web development, WordPress, security, and more »
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