容易被忽略的HTTP_X_FORWARDED_FOR攻击

function getIP() {
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’];
}
return $realip;
}

这个是网上常见获取ip函数

其中x-forword-fox的值是可以被自定义改写的.

在firefox下通过Moify Headers插件或者用php的fsockopen()函数等方法来改写.

如果你需要将IP写入数据库并打开的错误输出,那么将HTTP_X_FORWARDED_FOR的值改成192.168.0.1′ or 1= 是可能会产生sql注射.

同样$_SERVER[“HTTP_USER_AGENT”],$_SERVER[“HTTP_ACCEPT_LANGUAGE”],$_SERVER[‘HTTP_REFERER’] 等http变量入库时也需做过滤

改进的获取ip函数

if(getenv(‘HTTP_CLIENT_IP’) && strcasecmp(getenv(‘HTTP_CLIENT_IP’), ‘unknown’)) {
$OnlineIP = getenv(‘HTTP_CLIENT_IP’);
} elseif(getenv(‘HTTP_X_FORWARDED_FOR’) && strcasecmp(getenv(‘HTTP_X_FORWARDED_FOR’), ‘unknown’)) {
$OnlineIP = getenv(‘HTTP_X_FORWARDED_FOR’);
} elseif(getenv(‘REMOTE_ADDR’) && strcasecmp(getenv(‘REMOTE_ADDR’), ‘unknown’)) {
$OnlineIP = getenv(‘REMOTE_ADDR’);
} elseif(isset($_SERVER[‘REMOTE_ADDR’]) && $_SERVER[‘REMOTE_ADDR’] && strcasecmp($_SERVER[‘REMOTE_ADDR’], ‘unknown’)) {
$OnlineIP = $_SERVER[‘REMOTE_ADDR’];
}
preg_match(“/[\d\.]{7,15}/”, $OnlineIP, $match);
$OnlineIP = $match[0] ? $match[0] : ‘unknown’;
unset($match);

参考:

http://www.jb51.net/article/37690.htm

http://zhangxugg-163-com.iteye.com/blog/1663687