iptables

 http://163.20.160.24/~pc/modules/tadnews/index.php?nsn=58

https://stevenitlife.blogspot.com/2020/01/k8s-cluster.html

https://mileslin.github.io/2019/05/%E7%9E%AD%E8%A7%A3-Docker-%E7%9A%84%E9%A0%90%E8%A8%AD%E7%B6%B2%E8%B7%AF%E8%A8%AD%E7%BD%AE/

http://linux.vbird.org/linux_server/0250simple_firewall.php

https://blog.jangmt.com/2015/09/centos7-firewalld-iptables.html

https://www.itread01.com/content/1541339230.html

https://blog.gtwang.org/linux/centos-7-firewalld-command-setup-tutorial/

https://www.hwchiu.com/iptables-1.html

https://www.digitalocean.com/community/tutorials/how-to-list-and-delete-iptables-firewall-rules