Use php to detect proxy

Able to detect most IPs accessed through proxy servers.
//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 '
REMOTE_ADDR';
print $ip;

if (($v=="")&&($f=="")&&($c=="")&&($o=="")){
print "
not through proxy";
}
else {
print "
through proxy";
print '
http_via: ';print $v;
print '
http_x_forwarded_for: ';print $f;
print '< ;br>http_xroxy_connection: ';print $c;
print '
http_pragma: ';print $o;
}
?>