Хост указан просто, решил скрыть.
Задал так:
send (SOCK, "POST /index.php? HTTP/1.0\r\n$host\r\nn=1b2de2499e5f93e00a5a90e79a9da4b1 \n\n", 0);
Вот теперь что пишет:

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>400 Bad Request</title>
</head><body>
<h1>Bad Request</h1>
<p>Your browser sent a request that this server could not understand.<br />
Request header field is missing ':' separator.<br />
<pre>
n=1</pre>
</p>
<hr>
<address>Apache Server at localhost Port 80</address>
</body></html>