php怎么能得到客户的ip地址？

 1   
 2//echo "$d_time";   
 3//补充一下，有时候$REMOTE_ADDR;并不一定是你真是的ip   
 4//用HTTP_X_FORWARDED_FOR更真实一些   
 5print $ip = getenv('HTTP_X_FORWARD_FOR');   
 6print $host = gethostbyaddr($ip);   
 7//下面就是得到的别人防问你的ip   
 8if (getenv(HTTP_X_FORWARDED_FOR)) {   
 9print $ip = getenv('HTTP_X_FORWARD_FOR');   
10print $host = gethostbyaddr($ip);   
11} else {   
12print $ip = getenv('REMOTE_ADDR');   
13print $host = gethostbyaddr($ip);   
14}