Is it standard to check for proxies with getenv and is it effective?
<p>Hey quick question, I am wondering</p>

<ol>
<li>Do big sites use php's <strong>getenv</strong> function to prevent proxy users from registering or signing in?</li>
<li>Is it effective in deterring hackers from creating a bunch of accounts for abusive purposes if it is used?</li>
</ol>
