How to block Cloudflare Custom Hostname Verification

Cloudflare Custom Hostname Verification service.

nginx

In the server block, then reload.

nginx

# In the server block. 403 rather than 444: a closed connection tells the
# operator nothing, and an agent that gets a status code can log it.
if ($http_user_agent ~* "(Cloudflare Custom Hostname Verification)") {
    return 403;
}

Apache

In .htaccess or the vhost.

Apache

BrowserMatchNoCase "Cloudflare Custom Hostname Verification" bad_bot

<RequireAll>
    Require all granted
    Require not env bad_bot
</RequireAll>

Cloudflare

Security → WAF → Custom rules.

Cloudflare

# Security → WAF → Custom rules, action: Block
(http.user_agent contains "Cloudflare Custom Hostname Verification")

WordPress

A child theme's functions.php, or a small plugin.

WordPress

// functions.php of a child theme, or a small plugin. Runs before WordPress
// builds the page, so a blocked agent costs one PHP process and no queries.
add_action('init', function () {
    $agent = $_SERVER['HTTP_USER_AGENT'] ?? '';

    foreach (['Cloudflare Custom Hostname Verification'] as $needle) {
        if (stripos($agent, $needle) !== false) {
            status_header(403);
            exit('Blocked: Cloudflare Custom Hostname Verification');
        }
    }
});

A rule on the user agent is a rule on a string it chose

The server rules match on a header the requester sets, which stops the agent that says who it is and not the one that copies somebody else's name. Botscope verifies identity against DNS and published address ranges, records which check decided each request, and shows you the ones that lied.

See what actually reached you Check your robots.txt first

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