获取用户IP地址的权威方式[重复]

Question

Possible Duplicate:
Function to get user ip address

<?PHP

$ipaddress = $_SERVER["REMOTE_ADDR"];

echo "Your IP is $ipaddress!";

?>

I was told this way of getting ip address has issues such as being able to fool. Is there a better way to gather ip address? looking for tutorials of better way to get ip address?

Answer 1

$_SERVER['REMOTE_ADDR'] is the only reliable IP address you'll get - it's extracted directly from the TCP stack and is where the current connection was established from. This means if the user is connecting via a proxy, you'll get the proxy's address, not the user's.

Any of the other header-based ones are unreliable, as HTTP headers are trivial to forge. You can use the information from them, if you'd like, as long as you don't TRUST it.