Category: PHP

Okay, this is a very crude way to block bots, spiders and crawlers by their user-agent, but so far, this has been very, very efficient.

Even when one chooses ” yes “, the question will be repeated. This is not a problem, because no one in their right mind is going to add “bot”, “spider” or “crawler” as their user-agent.

So here’s the PHP script that I rammed into a certain website to prevent it from being DDOSsed by (malicious) bots.

<?php

// Emergency bypass
// goto end;

/////////////////////////////////////////////////////////////
// (c) FoxSAIn 2023, Free to use.
/////////////////////////////////////////////////////////////

// Function to check if the user agent appears to be a bot or spider.
// Enter the bots you would like to block in a list as shown below.
function isBot()
{
    $user_agent = $_SERVER["HTTP_USER_AGENT"];
    $bot_keywords = [
        "bytespider",
        "amazonbot",
        "mj12bot",
        "YandexBot",
        "SemrushBot",
        "AhrefsBot"
    ];

    foreach ($bot_keywords as $keyword) {
        if (stripos($user_agent, $keyword) !== false) {
            return true;
        }
    }

    return false;
}

// Check if the visitor is a bot or spider
if (isBot()) {
    // This visitor appears to be a bot or spider, so display a choice.
    // Check if the choice form is submitted
    if (isset($_POST["submit"])) {
        // Check the choice made by the visitor
        $choice = isset($_POST["choice"]) ? $_POST["choice"] : "";

        if ($choice === "yes") {
            // User selected "Yes," block access
            echo "Access denied. If you believe this is an error, please contact us by writing the word support before the at sign, followed by 4-stroke.net";
        } elseif ($choice === "no") {
            // User selected "No," proceed to end
            goto end;
        }
    } else {
        // Output the message to the user and make the choice mandatory
        echo "Your user agent suggests you might be a bot, spider, or crawler. Are you one of these three?";

        // Output the radio button choices within a form
        echo '</p>
<form method="post" action="">';
        echo ' <label><input type="radio" name="choice" value="yes" required>Yes</label>';
        echo ' <label><input type="radio" name="choice" value="no">No</label>';
        echo ' <button type="submit" name="submit">Proceed</button>';
        echo "</form>
<p>";
    }

    // Exit to prevent further processing
    exit();
}
end:
// Original website code starts from here.
/////////////////////////////////////////////////////////////
?>