iptables

Configure tables, chains and rules of the Linux kernel IPv4 firewall. Use ip6tables to set rules for IPv6 traffic. See also: iptables-save, iptables-restore. More information: https://manned.org/iptables.

• View chains, rules, packet/byte counters and line numbers for the filter table:

sudo iptables --verbose --numeric --list --line-numbers

• Set chain Policy rule:

sudo iptables --policy chain rule

• Append rule to chain policy for IP:

sudo iptables --append chain --source ip --jump rule

• Append rule to chain policy for IP considering protocol and port:

sudo iptables --append chain --source ip --protocol tcp|udp|icmp|... --dport port --jump rule

• Add a NAT rule to translate all traffic from the 192.168.0.0/24 subnet to the host’s public IP:

sudo iptables --table nat --append POSTROUTING --source 192.168.0.0/24 --jump MASQUERADE

• Delete chain rule:

sudo iptables --delete chain rule_line_number