php下获取客户端ip地址的函数

function getip() { 
$IP=getenv('REMOTE_ADDR'); 
$IP_ = getenv('HTTP_X_FORWARDED_FOR'); 
if (($IP_ != "") && ($IP_ != "unknown")) $IP=$IP_; 
return $IP; 
}

下面这个比较好的

function getIP() 
{ 
if (isset($_SERVER)) { 
if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) { 
$realip = $_SERVER['HTTP_X_FORWARDED_FOR']; 
} elseif (isset($_SERVER['HTTP_CLIENT_IP'])) { 
$realip = $_SERVER['HTTP_CLIENT_IP']; 
} else { 
$realip = $_SERVER['REMOTE_ADDR']; 
} 
} else { 
if (getenv("HTTP_X_FORWARDED_FOR")) { 
$realip = getenv( "HTTP_X_FORWARDED_FOR"); 
} elseif (getenv("HTTP_CLIENT_IP")) { 
$realip = getenv("HTTP_CLIENT_IP"); 
} else { 
$realip = getenv("REMOTE_ADDR"); 
} 
} 
return $realip; 
}