proxyserver uses php to detect proxy

Finally wrote something useful!
Able to detect most IPs accessed through proxy servers.
<?php
//beiji.com 2000.6.17
$ip = getenv("REMOTE_ADDR");
$v = getenv("HTTP_VIA");
$ f = getenv("HTTP_X_FORWARDED_FOR");
$c = getenv("HTTP_XROXY_CONNECTION");
$o = getenv("HTTP_PRAGMA");
print '<br>REMOTE_ADDR';
print $ip;
if ((( $v=="")&&($f=="")&&($c=="")&&($o=="")){
print "<br>not through proxy";
}
else {
print "<br>through proxy";
print '<br>http_via: ';print $v;
print '<br>http_x_forwarded_for: ';print $f;
print '<br&gt ;http_xroxy_connection: ';print $c;
print '<br>http_pragma: ';print $o;
}
?>

The above introduces proxyserver to use PHP to detect proxy, including the content of proxyserver. I hope it will be helpful to friends who are interested in PHP tutorials.