centos7 Failed to start firewalld.service: Unit is masked.

centos7 啟動防火牆失敗：Failed to start firewalld.service: Unit is masked.   ---- 剛yum安裝了iptables

解決：

執行”systemctl start firewalld”啟動，出現”Failed to start firewalld.service: Unit is masked.”錯誤。繼續找解決方法，然后輸入”systemctl unmask firewalld.service”。

解決CentOS7出現的”Failed to start firewalld.service”問題
然后再啟動”systemctl start firewalld”即可解決問題沒有報錯。