php获取客户端IP地址的几种方法

$iipp=$_SERVER["REMOTE_ADDR"];
echo $iipp;
?>

///////////////////////////////////////////////

$user_IP = ($_SERVER["HTTP_VIA"]) ? $_SERVER["HTTP_X_FORWARDED_FOR"] : $_SERVER["REMOTE_ADDR"];
$user_IP = ($user_IP) ? $user_IP : $_SERVER["REMOTE_ADDR"];

echo $user_IP;
?>

///////////////////////////////////////////////

function get_real_ip(){
$ip=false;
if(!empty($_SERVER["HTTP_CLIENT_IP"])){
$ip = $_SERVER["HTTP_CLIENT_IP"];
}
if (!empty($_SERVER[HTTP_X_FORWARDED_FOR])) {
$ips = explode (", ", $_SERVER[HTTP_X_FORWARDED_FOR]);
if ($ip) { array_unshift($ips, $ip); $ip = FALSE; }
for ($i = 0; $i < count($ips); $i++) {
if (!eregi ("^(10|172.16|192.168).", $ips[$i])) {
$ip = $ips[$i];
break;
}
}
}
return ($ip ? $ip : $_SERVER[REMOTE_ADDR]);
}

echo get_real_ip();
?>

///////////////////////////////////////////////

//php获取ip的算法
if ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"])
{
$ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"];
}
elseif ($HTTP_SERVER_VARS["HTTP_CLIENT_IP"])
{
$ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"];
}
elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"])
{
$ip = $HTTP_SERVER_VARS["REMOTE_ADDR"];
}
elseif (getenv("HTTP_X_FORWARDED_FOR"))
{
$ip = getenv("HTTP_X_FORWARDED_FOR");
}
elseif (getenv("HTTP_CLIENT_IP"))
{
$ip = getenv("HTTP_CLIENT_IP");
}
elseif (getenv("REMOTE_ADDR"))
{
$ip = getenv("REMOTE_ADDR");
}
else
{
$ip = "Unknown";
}
echo "你的IP:".$ip ;
?>

///////////////////////////////////////////////

if(getenv(HTTP_CLIENT_IP)) {
$onlineip = getenv(HTTP_CLIENT_IP);
} elseif(getenv(HTTP_X_FORWARDED_FOR)) {
$onlineip = getenv(HTTP_X_FORWARDED_FOR);
} elseif(getenv(REMOTE_ADDR)) {
$onlineip = getenv(REMOTE_ADDR);
} else {
$onlineip = $HTTP_SERVER_VARS[REMOTE_ADDR];
}
echo $onlineip;
?>