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tldr/pages/linux/iptables.md
2025-03-13 04:41:47 +02:00

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# 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 {{[-vnL --line-numbers|--verbose --numeric --list --line-numbers]}}`
- Set chain policy rule:
`sudo iptables {{[-P|--policy]}} {{chain}} {{rule}}`
- Append rule to chain policy for IP:
`sudo iptables {{[-A|--append]}} {{chain}} {{[-s|--source]}} {{ip}} {{[-j|--jump]}} {{rule}}`
- Append rule to chain policy for IP considering protocol and port:
`sudo iptables {{[-A|--append]}} {{chain}} {{[-s|--source]}} {{ip}} {{[-p|--protocol]}} {{tcp|udp|icmp|...}} --dport {{port}} {{[-j|--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 {{[-t|--table]}} {{nat}} {{[-A|--append]}} {{POSTROUTING}} {{[-s|--source]}} {{192.168.0.0/24}} {{[-j|--jump]}} {{MASQUERADE}}`
- Delete chain rule:
`sudo iptables {{[-D|--delete]}} {{chain}} {{rule_line_number}}`