php $_SERVER['HTTP_X_FORWARDED_FOR'] vs REMOTE_ADDR

PHP $ _ SERVER[ # 039；HTTP _ X _ FORWARDED _ FOR # 039]vs REMOTE _ addr PHP $ _ SERVER[ # 039；HTTP _ X _ FORWARDED _ FOR # 039php中VS Remote _ Addr: $ _ server介绍[ # 039；HTTP _ X _ FORWARDED _ FOR # 039] vs REMOTE_ADDR两者有什么区别？网上说HTTP_X_FORWARDED_FOR可以伪造(甚至造成SQL注入