Networking Task: Configuring firewalld, ufw, or iptables

Goal

Apply basic firewall policies to limit exposure and isolate traffic.

firewalld

firewall-cmd --get-active-zones
firewall-cmd --permanent --zone=public --add-service=ssh
firewall-cmd --reload

ufw (Ubuntu)

ufw default deny incoming
ufw default allow outgoing
ufw allow ssh
ufw enable

iptables (legacy)

iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -j DROP

Best Practices

• Use firewalld for RHEL/Alma systems
• Avoid mixing multiple firewall tools
• Backup rules

Tools

• firewall-cmd, ufw, iptables-save, nft (modern replacement)