阻止空白HTTP_X_FORWARDED_FOR流量

Question

当HTTP_X_FORWARDED_FOR空白/空htaccess时，是否可以屏蔽流量？

我试过这两个：

RewriteEngine On
RewriteCond %{HTTP:X-FORWARDED-FOR} ^.{0}$
RewriteRule .* - [F]

和

RewriteEngine On
RewriteCond %{HTTP:X-FORWARDED-FOR} ^$
RewriteRule .* - [F]