Using php to detect proxy

Able to detect most of the visit through a proxy server ip.

<?php
$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>http_xroxy_connection: ;print $c;
print <br>http_pragma: ;print $o;
}
?>