tldr/pages/linux/iptables.md

iptables

Program that allows configuration of tables, chains and rules provided by the Linux kernel firewall. More information: https://www.netfilter.org/projects/iptables/.

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

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

• Set chain [P]olicy rule:

sudo iptables --policy {{chain}} {{rule}}

• [A]ppend rule to chain policy for IP:

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

• [A]ppend rule to chain policy for IP considering [p]rotocol and port:

sudo iptables --append {{chain}} --source {{ip}} --protocol {{protocol}} --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}}

• [D]elete chain rule:

sudo iptables --delete {{chain}} {{rule_line_number}}

• Save iptables configuration of a given [t]able to a file:

sudo iptables-save --table {{tablename}} > {{path/to/iptables_file}}

• Restore iptables configuration from a file:

sudo iptables-restore < {{path/to/iptables_file}}