356 lines
14 KiB
Markdown
356 lines
14 KiB
Markdown
# Nftables
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1. [Overview](#overview)
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2. [Role Variables](#role-variables)
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* [OS Specific Variables](#os-specific-variables)
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* [Rules Dictionaries](#rules-dictionaries)
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3. [Example Playbook](#example-playbook)
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4. [Known Issue](#known-issue)
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5. [Configuration](#configuration)
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6. [Development](#development)
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7. [License](#license)
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8. [Author Information](#author-information)
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## Overview
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A role to manage Nftables rules and packages.
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Highly inspired by [Mike Gleason firewall role][mikegleasonjr firewall github] (3 levels of rules definition and template), thanks ! I hope i haven't complexify his philosophy… ^^
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## Role Variables
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* **nft_enabled** : Enable or disable support for Nftables [default : `true`].
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* **nft_pkg_state** : State of new `nftables` package(s) [default : `present`].
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* **nft_old_pkg_list** : The list of useless packages to remove (such as Iptables,…) [default : `iptables`].
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* **nft_old_pkg_state** : State of old package(s) [default : `absent`].
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* **nft_old_pkg_manage** : If old package(s) should be managed with this role [default : `true`].
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* **nft_conf_dir_path** : Directory to store the differents Nftables configuration files [default : `/etc/nftables.d`].
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* **nft_main_conf_path** : Main configuration file loaded by systemd unit [default : `/etc/nftables.conf`].
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* **nft_main_conf_content** : Template used to generate the previous main configuration file [default : `etc/nftables.conf.j2`].
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* **nft_input_conf_path** : Input configuration file include in main configuration file [default : `{{ nft_conf_dir_path }}/filter-input.nft`].
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* **nft_input_conf_content** : Template used to generate the previous input configuration file [default : `etc/nftables.d/filter-input.nft.j2`].
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* **nft_output_conf_path** : Output configuration file include in main configuration file [default : `{{ nft_conf_dir_path }}/filter-output.nft`].
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* **nft_output_conf_content** : Template used to generate the previous output configuration file [default : `etc/nftables.d/filter-output.nft.j2`].
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* **nft_define_conf_path** : Vars definition file include in main configuration file [default : `{{ nft_conf_dir_path }}/defines.nft`].
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* **nft_define_conf_content** : Template used to generate the previous vars definition file [default : `etc/nftables.d/defines.nft.j2`].
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* **nft_sets_conf_path** : Sets and maps definition file include in main configuration file [default : `{{ nft_conf_dir_path }}/sets.nft`].
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* **nft_sets_conf_content** : Template used to generate the previous sets and maps definition file [default : `etc/nftables.d/sets.nft.j2`].
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* **nft_global_default_rules** : Set default rules for `global` chain. Other chains will jump to `global` before apply their specific rules.
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* **nft_global_rules** : You can add `global` rules or override those defined by **nft_global_default_rules** for all hosts.
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* **nft_global_group_rules** : You can add `global` rules or override those defined by **nft_global_default_rules** and **nft_global_rules** for a group.
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* **nft_global_host_rules** : Hosts can also add or override all previours rules.
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* **nft__custom_content** : Custom content (tables, include,…) to add in Nftables configuration [default : `''`].
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* **nft_input_default_rules** : Set default rules for `input` chain.
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* **nft_input_rules** : You can add `input` rules or override those defined by **nft_input_default_rules** for all hosts.
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* **nft_input_group_rules** : You can add `input` rules or override those defined by **nft_input_default_rules** and **nft_input_rules** for a group.
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* **nft_input_host_rules:** : Hosts can also add or override all previous `input` rules.
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* **nft_output_default_rules** : Set default rules for `output` chain.
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* **nft_output_rules** : You can add `output` rules or override those defined by **nft_output_default_rules** for all hosts.
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* **nft_output_group_rules** : You can add `output` rules or override those defined by **nft_output_default_rules** and **nft_output_rules** for a group.
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* **nft_output_host_rules** : Hosts can also add or override all previous `output` rules.
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* **nft__nat_table_manage** : If the nat table should be managed [default : `False`].
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* **nft__nat_default_prerouting_rules** : Set default rules for `prerouting` chain of **nat** table.
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* **nft__nat_prerouting_rules** : Set rules for `prerouting` chain of **nat** table for all hosts in the Ansible inventory.
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* **nft__nat_group_prerouting_rules** : Set rules for `prerouting` chain of **nat** table for hosts in specific Ansible inventory group.
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* **nft__nat_host_prerouting_rules** : Set rules for `prerouting` chain of **nat** table for specific hosts the Ansible inventory.
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* **nft__nat_prerouting_conf_path** : Prerouting configuration file include in the main configuration [default : `{{ nft_conf_dir_path }}/nat-prerouting.nft`].
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* **nft__nat_prerouting_conf_content** : Template used to generate the previous prerouting configuration file [default : `etc/nftables.d/nat-prerouting.nft.j2`].
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* **nft__nat_default_postrouting_rules** : Set default rules for `postrouting` chain of **nat** table.
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* **nft__nat_postrouting_rules** : Set rules for `postrouting` chain of **nat** table for all hosts in the Ansible inventory.
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* **nft__nat_group_postrouting_rules** : Set rules for `postrouting` chain of **nat** table for hosts in specific Ansible inventory group.
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* **nft__nat_host_postrouting_rules** : Set rules for `postrouting` chain of **nat** table for specific hosts the Ansible inventory.
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* **nft__nat_postrouting_conf_path** : postrouting configuration file include in the main configuration [default : `{{ nft_conf_dir_path }}/nat-postrouting.nft`].
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* **nft__nat_postrouting_conf_content** : Template used to generate the previous postrouting configuration file [default : `etc/nftables.d/nat-postrouting.nft.j2`].
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* **nft_define_default** : Set default vars available in all rules.
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* **nft_define** : You can add vars or override those defined by **nft_define_default** for all hosts.
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* **nft_define_group** : You can add vars or override those defined by **nft_define_default** and **nft_define** for a group.
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* **nft_define_host** : You can add or override all previous vars.
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* **nft_service_manage** : If `nftables` service should be managed with this role [default : `true`].
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* **nft_service_name** : `nftables` service name [default : `nftables`].
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* **nft_service_enabled** : Set `nftables` service available at startup [default : `true`].
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* **nft__service_protect** : If systemd unit should protect system and home [default : `true`].
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* **nft__fail2ban_service** : If the Nftables service should also restart the Fail2ban service [default : `False`].
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* **nft_merged_groups** : If variables from the hosts Ansible groups should be merged [default : `false`].
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* **nft_merged_groups_dir** : The dictionary where the nftables group rules, named like the Ansible groups, are located in [default : `vars/`].
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* **nft_debug** : Toggle more verbose output on/off. [default: 'false'].
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### OS Specific Variables
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Please see default value by Operating System file in [vars][vars directory] directory.
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* **nft_pkg_list** : The list of package(s) to provide `nftables`.
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### Rules Dictionaries
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Each type of rules dictionaries will be merged and rules will be applied in the alphabetical order of the keys (the reason to use 000 to 999 as prefix). So :
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* **nft_*_default_rules** : Define default rules for all nodes. You can define it in `group_vars/all`.
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* **nft_*_rules** : Can add rules and override those defined by **nft_*_default_rules**. You can define it in `group_vars/all`.
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* **nft_*_group_rules** : Can add rules and override those defined by **nft_*_default_rules** and **nft_*_rules**. You can define it in `group_vars/webservers`.
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* If 'nft_merged_groups' is set to true, multiple group rules from the ansible groups will also be merged together.
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* **nft_*_host_rules** : Can add rules and override those define by **nft_*_default_rules**, **nft_*_group_rules** and **nft_*_rules**. You can define it in `host_vars/www.local.domain`.
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`defaults/main.yml`:
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``` yml
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# rules
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nft_global_default_rules:
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005 state management:
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- ct state established,related accept
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- ct state invalid drop
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nft_global_rules: {}
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nft_merged_groups: false
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nft_merged_groups_dir: vars/
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nft_global_group_rules: {}
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nft_global_host_rules: {}
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nft_input_default_rules:
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000 policy:
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- type filter hook input priority 0; policy drop;
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005 global:
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- jump global
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010 drop unwanted:
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- ip daddr @blackhole counter drop
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015 localhost:
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- iif lo accept
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210 input tcp accepted:
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- tcp dport @in_tcp_accept ct state new accept
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nft_input_rules: {}
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nft_input_group_rules: {}
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nft_input_host_rules: {}
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nft_output_default_rules:
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000 policy:
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- type filter hook output priority 0; policy drop;
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005 global:
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- jump global
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015 localhost:
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- oif lo accept
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050 icmp:
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- ip protocol icmp accept
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- ip6 nexthdr icmpv6 counter accept
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200 output udp accepted:
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- udp dport @out_udp_accept ct state new accept
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210 output tcp accepted:
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- tcp dport @out_tcp_accept ct state new accept
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nft_output_rules: {}
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nft_output_group_rules: {}
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nft_output_host_rules: {}
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# define nft vars
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nft_define_default:
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broadcast and multicast:
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desc: 'broadcast and multicast'
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name: badcast_addr
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value: '{ 255.255.255.255, 224.0.0.1, 224.0.0.251 }'
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input tcp accepted:
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name: in_tcp_accept
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value: '{ ssh }'
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output tcp accepted:
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name: out_tcp_accept
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value: '{ http, https, hkp }'
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output udp accepted:
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name: out_udp_accept
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value: '{ bootps, domain, ntp }'
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nft_define: {}
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nft_define_group: {}
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nft_define_host: {}
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# sets and maps
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nft_set_default:
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blackhole:
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- type ipv4_addr;
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- elements = $badcast_addr
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in_tcp_accept:
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- type inet_service; flags interval;
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- elements = $in_tcp_accept
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out_tcp_accept:
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- type inet_service; flags interval;
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- elements = $out_tcp_accept
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out_udp_accept:
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- type inet_service; flags interval;
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- elements = $out_udp_accept
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nft_set: {}
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nft_set_group: {}
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nft_set_host: {}
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```
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Those default will generate the following configuration :
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```
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#!/usr/sbin/nft -f
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# Ansible managed
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# clean
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flush ruleset
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include "/etc/nftables.d/defines.nft"
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table inet filter {
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chain global {
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# 000 state management
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ct state established,related accept
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ct state invalid drop
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}
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include "/etc/nftables.d/sets.nft"
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include "/etc/nftables.d/filter-input.nft"
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include "/etc/nftables.d/filter-output.nft"
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}
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```
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And you can get all rules and definitons by displaying the ruleset on the host : `$ nft list ruleset` :
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```
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table inet filter {
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set blackhole {
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type ipv4_addr
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elements = { 255.255.255.255, 224.0.0.1, 224.0.0.251}
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}
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set out_tcp_accept {
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type inet_service
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flags interval
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elements = { http, https, hkp}
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}
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set out_udp_accept {
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type inet_service
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flags interval
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elements = { domain, bootps, ntp}
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}
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chain global {
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ct state established,related accept
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ct state invalid drop
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}
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chain input {
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type filter hook input priority 0; policy drop;
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jump global
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ip daddr @blackhole counter packets 0 bytes 0 drop
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iif "lo" accept
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tcp dport @in_tcp_accept ct state new accept
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}
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chain output {
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type filter hook output priority 0; policy drop;
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jump global
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oif "lo" accept
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ip protocol icmp accept
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udp dport @out_udp_accept ct state new accept
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tcp dport @out_tcp_accept ct state new accept
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}
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}
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```
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## Example Playbook
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* Manage Nftables with defaults vars :
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``` yml
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- hosts: serverXYZ
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roles:
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- role: ipr-cnrs.nftables
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```
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* Override some of the default defined sets:
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``` yml
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- hosts: serverXYZ
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vars:
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- nft_define:
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input tcp accepted:
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desc: Custom SSH port and torrent
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name: in_tcp_accept
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value: '{ 2201, 6881 }'
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input udp accepted:
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desc: torrent
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name: in_udp_accept
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value: '{ 6881 }'
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roles:
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- role: ipr-cnrs.nftables
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```
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* Use default rules with allow incoming ICMP and count dropped input packets :
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`group_vars/first_group` :
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``` yaml
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nft_input_group_rules:
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020 icmp:
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- ip protocol icmp icmp type echo-request ip length <= 84 counter limit rate 1/minute accept
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999 count policy packet:
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- counter
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```
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* Use merged group rules from multiple ansible groups:
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``` yml
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- hosts: serverXYZ
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vars:
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nft_merged_groups: true
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nft_merged_groups_dir: vars/
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roles:
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- role: ipr-cnrs.nftables
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```
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And put the rules inside the "vars" folder named after your ansible groups of the server:
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`vars/first_group` :
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``` yaml
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nft_input_group_rules:
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020 icmp:
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- ip protocol icmp icmp type echo-request ip length <= 84 counter limit rate 1/minute accept
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999 count policy packet:
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- counter
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```
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`vars/second_group` :
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``` yaml
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nft_input_group_rules:
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021 LAN:
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- iif eth0 accept
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```
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These rulesets from the two groups will be merged if the host has the two groups as ansible roles.
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## Known Issue
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* The 10 minutes delay at the first run is finally fixed by allowing the host to reset SSH connection (flags `rst, psh | ack`) (see #1).
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## Configuration
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This role will :
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* Install `nftables` on the system.
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* Enable `nftables` service by default at startup.
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* Generate a default configuration file which include all following files and loaded by systemd unit.
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* Generate input and output rules files include called by the main configuration file.
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* Generate vars in a file and sets and maps in another file.
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* (re)Start `nftables` service at first run.
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* Reload `nftables` service at next runs to avoid to let the host without firewall rules due to invalid syntax.
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## Development
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This source code comes from our [Gogs instance][nftables source] and the [Github repo][nftables github] exist just to be able to send the role to Ansible Galaxy…
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But feel free to send issue/PR here :)
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Thanks to this [hook][gogs to github hook], Github automatically got updates from our [Gogs instance][nftables source] :)
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## License
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[WTFPL][wtfpl website]
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## Author Information
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Jérémy Gardais
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* Source : [on IPR's Gogs][nftables source]
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* [IPR][ipr website] (Institut de Physique de Rennes)
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[gogs to github hook]: https://stackoverflow.com/a/21998477
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[nftables source]: https://git.ipr.univ-rennes1.fr/cellinfo/ansible.nftables
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[nftables github]: https://github.com/ipr-cnrs/nftables
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[wtfpl website]: http://www.wtfpl.net/about/
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[ipr website]: https://ipr.univ-rennes1.fr/
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[mikegleasonjr firewall github]: https://github.com/mikegleasonjr/ansible-role-firewall
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