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How to block Known Agents Browser

Operated by Known Agents. Known Agents Browser is an automated agent operated by Known Agents.

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 ~* "(Known Agents Browser)") {
    return 403;
}

Apache

In .htaccess or the vhost.

Apache
BrowserMatchNoCase "Known Agents Browser" 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 "Known Agents Browser")

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 (['Known Agents Browser'] as $needle) {
        if (stripos($agent, $needle) !== false) {
            status_header(403);
            exit('Blocked: Known Agents Browser');
        }
    }
});

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.

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