Iptables

iptables command line utility allows to modify Linux kernel firewall rules.

Basic commands

• sudo iptables -L
• iptables-save and iptables-restore

Activities

1. Read iptables Ubuntu howto: https://help.ubuntu.com/community/IptablesHowTo
2. Read archlinux documentation: https://wiki.archlinux.org/index.php/iptables
3. Read Stackoverflow iptables questions: https://stackoverflow.com/questions/tagged/iptables?tab=Votes
4. Review your current iptables configuration

See also

• iptables ufw firewalld nftables firewall-cmd ipfw (FreeBSD) PF (OpenBSD), netsh advfirewall
• nftables
• firewall-cmd
• Palo Alto firewalls: PAN-OS
• Port knocking, fail2ban fwknop, DenyHosts

https://serverfault.com/a/608976