我最近使用本教程将全新安装的 CentOS 7 升级到 CentOS 8：
https://www.tecmint.com/upgrade-centos-7-to-centos-8/
我没有安装额外的软件，只有基本安装。升级后，我尝试做的第一件事就是只打开 SSH 和 HTTP 的大门，所以我启用并启动了 firewalld：
systemctl enable firewalld
systemctl start firewalld
systemctl status firewalld
? firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-12-24 11:05:50 -02; 10min ago
Docs: man:firewalld(1)
Main PID: 7620 (firewalld)
Tasks: 2 (limit: 17886)
Memory: 22.1M
CGroup: /system.slice/firewalld.service
??7620 /usr/libexec/platform-python -s /usr/sbin/firewalld --nofork --nopid
dez 24 11:05:49 renie.cc systemd[1]: Stopped firewalld - dynamic firewall daemon.
dez 24 …