https://www.certdepot.net/rhel7-get-started-firewalld/ https://www.linuxjournal.com/content/understanding-firewalld-multi-zone-configurations https://computingforgeeks.com/install-and-use-firewalld-on-ubuntu-18-04-ubuntu-16-04/

1iptables -A INPUT -p tcp -s 114.191.33.88 --dport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT 2iptables -A OUTPUT -p tcp --sport 22 -m conntrack --ctstate ESTABLISHED -j ACCEPT

1sudo firewall-cmd --add-rich-rule 'rule family="ipv4" source address="192.168.10.9" service name="ssh" accept' --permanent 2sudo firewall-cmd --remove-service ssh --permanent ## needed, otherwise ssh will still be allowed for all 3sudo systemctl reload firewalld See details in …

https://www.linux.com/learn/introduction-uncomplicated-firewall-ufw

1root@xxx:/var/log# ufw status 2Status: active 34To Action From 5-- ------ ---- 622 LIMIT Anywhere 780 ALLOW Anywhere 8443 ALLOW Anywhere 9??41908/tcp ALLOW Anywhere 10Anywhere ALLOW 115.85.11.98 1125/tcp ALLOW Anywhere 124444/tcp ALLOW Anywhere 134444/udp ALLOW Anywhere 1422 (v6) LIMIT Anywhere (v6) 1580 (v6) ALLOW …