Failed to start firewalld.service: Unit is masked.
出现这个提示说明防火墙被锁，用了这条命令 systemctl mask firewalld
解锁命令：systemctl unmask firewalld
Failed to start firewalld.service: Unit is masked.
出现这个提示说明防火墙被锁，用了这条命令 systemctl mask firewalld
解锁命令：systemctl unmask firewalld