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New examples usecases (mostly for playbooks)

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Jeremy Gardais 2021-03-09 17:55:55 +01:00
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13
CHANGELOG.md
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@ -1,9 +1,16 @@
## v1.X.Y ## v1.X.Y
### Fix ### Added
* New examples usecases (mostly for playbooks) in README.md.
### Removed
* Remove everything related to **in_udp_accept** (see conversation in PR #13).
Cause it was empty by default and the role currently doesn't manage it very
well. Take a look to new examples in README.md to find your preferred solution
(re-adding it, new simple/multi-ports filter rule,…).
### Fixed
* Ansible-lint: Fix line longer than 160 chars. * Ansible-lint: Fix line longer than 160 chars.
* Remove everything related to in_udp_accept (see conversation in PR #13).
Cause it was empty by default and the role currently doesn't manage it well.
## v1.7.0 ## v1.7.0

347
README.md
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@ -1,21 +1,24 @@
# Nftables # Nftables
1. [Overview](#overview) 1. [Overview](#overview)
2. [Role Variables](#role-variables) 1. [Role Variables](#role-variables)
* [OS Specific Variables](#os-specific-variables) * [OS Specific Variables](#os-specific-variables)
* [Rules Dictionaries](#rules-dictionaries) * [Rules Dictionaries](#rules-dictionaries)
3. [Example Playbook](#example-playbook) 1. [Examples](#examples)
4. [Known Issue](#known-issue) * [With playbooks](#with-playbooks)
5. [Configuration](#configuration) * [With group_vars and host_vars](#with-group_vars-and-host_vars)
6. [Development](#development) 1. [Configuration](#configuration)
7. [License](#license) 1. [Development](#development)
8. [Author Information](#author-information) 1. [License](#license)
1. [Author Information](#author-information)
## Overview ## Overview
A role to manage Nftables rules and packages. A role to manage Nftables rules and packages.
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… ^^ 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… (I'm pretty sure, i now did complexify it :D) ^^
## Role Variables ## Role Variables
@ -241,17 +244,189 @@ table inet filter {
} }
``` ```
## Example Playbook ## Examples
* Manage Nftables with defaults vars : ### With playbooks
<details>
<summary>Manage Nftables with defaults vars (<i>click to expand</i>)</summary>
<!-- have to be followed by an empty line! -->
``` yml ``` yml
- hosts: serverXYZ - hosts: serverXYZ
roles: roles:
- role: ipr-cnrs.nftables - role: ipr-cnrs.nftables
``` ```
</details>
* Override some of the default defined sets: <details>
<summary>Add a new <b>simple</b> filter rule for incoming traffic (eg. 1 port for UDP/torrent) (<i>click to expand</i>)</summary>
``` yml
- hosts: serverXYZ
vars:
nft_input_rules:
400 input torrent accepted:
- udp dport 6881 ct state new accept
roles:
- role: ipr-cnrs.nftables
```
* **nft_input_group_rules** or **nft_input_host_rules** variables can
also be used.
* The weight (`400`) allow to order all merged rules (from
<b>nft_input_*rules</b> dictionaries).
* The text following the weight (`input torrent accepted`) is a small
description that will be added as a comment in **nft_input_conf_path** file
on the remote host.
</details>
<details>
<summary>Add a new <b>multi-ports</b> filter rule for incoming traffic (eg. TCP/http, https, http-alt,…) (<i>click to expand</i>)</summary>
``` yml
- hosts: serverXYZ
vars:
nft_input_rules:
400 input http accepted:
- tcp dport { 80, 443, 8080-8082 } ct state new accept
roles:
- role: ipr-cnrs.nftables
```
* **nft_input_group_rules** or **nft_input_host_rules** variables can
also be used.
* The weight (`400`) allow to order all merged rules (from
<b>nft_input_*rules</b> dictionaries).
* The text following the weight (`input http accepted`) is a small
description that will be added as a comment in **nft_input_conf_path** file
on the remote host.
* In this case, brackets are useful and define a anonymous set. For a single
element (port, IP address,…), brackets are overkill and the singleton
definition is enought.
</details>
<details>
<summary>Add a new rule with a variable (<i>click to expand</i>)</summary>
Nftables variables can be useful if you define somes generic rules for all hosts
with such variables (called with **$**) and override variable's value for some
groups or hosts.
``` yml
- hosts: serverXYZ
vars:
- nft_define_group:
input http accepted:
desc: HTTP and HTTPS
name: in_http_accept
value: '{ 80, 443 }'
nft_input_group_rules:
400 input http accepted:
- tcp dport $in_http_accept ct state new accept
roles:
- role: ipr-cnrs.nftables
```
1. Add a new variable with **define** for HTTP ports.
1. Add a new rule for incoming traffic and use the previous defined variable.
1. Result of `nft list ruleset` on the remote host will be :
``` bash
table inet filter {
…
chain input {
…
tcp dport { http, https } ct state new accept
…
}
…
}
```
* No mention of `$in_http_accept` variable.
* **nft_define** or **nft_define_host** variables can also be used.
* **nft_input_rules** or **nft_input_host_rules** variables can also be used.
* The weight (`400`) allow to order all merged rules (from
<b>nft_input_*rules</b> dictionaries).
* The text following the weight (`input http accepted`) is a small description
that will be added as a comment in **nft_input_conf_path** file on
the remote host.
</details>
<details>
<summary>Add a new rule with a named set (<i>click to expand</i>)</summary>
Quite similar to Nftables variables, **named set** can be useful if you define
somes generic rules and sets (eg. for all hosts) and override only the set in
some case (eg. for a group or some hosts).
In addition to variables, it is possible to add content to named sets on the
fly from the host without completely rewrite the rule.
``` yml
- hosts: serverXYZ
vars:
nft_set_group:
in_udp_accept:
- type inet_service; flags interval;
- elements = { 6881-6887, 6889 }
nft_input_group_rules:
200 input udp accepted:
- udp dport @in_udp_accept ct state new accept
roles:
- role: ipr-cnrs.nftables
```
1. Add a new named set with <b>nft_set_group</b> dictionary (eg. for torrent ports).
1. Add a new rule for incoming traffic and use the previous defined set.
1. On the remote host, if you try to add a port to this set : `nft add element inet filter in_udp_accept \{ 6999 \}`
1. Result of `nft list ruleset` on the remote host will now be :
``` bash
table inet filter {
…
set in_udp_accept {
type inet_service
flags interval
elements = { 6881-6887, 6889, 6999 }
}
chain input {
…
udp dport @in_udp_accept ct state new accept
…
}
…
}
```
* **nft_set** or **nft_set_host** variables can also be used.
* **nft_input_rules** or **nft_input_host_rules** variables can also be used.
* The weight (`200`) allow to order all merged rules (from
<b>nft_input_*rules</b> dictionaries).
* The text following the weight (`input upd accepted`) is a small description
that will be added as a comment in **nft_input_conf_path** file on
the remote host.
</details>
<details>
<summary>Override a default rule with 2 new rules (<i>click to expand</i>)</summary>
``` yml
- hosts: serverXYZ
vars:
nft_input_host_rules:
050 icmp:⏎
- ip protocol icmp ip saddr != 192.168.0.0/24 counter drop⏎
- ip protocol icmp icmp type echo-request ip length <= 84 counter limit rate 10/minute accept
roles:
- role: ipr-cnrs.nftables
```
1. Get rule description from `defaults/main.yml` file (eg. `050 icmp`).
1. Drop any ICMP request that doesn't come from 192.168.0.0 network.
1. Ensure the request is less or equal to 84 bytes and set up a limit
to 10 requests per minute.
* **nft_input_rules** or **nft_input_group_rules** variables can also be used.
* The weight (`050`) allow to order all merged rules (from
<b>nft_input_*rules</b> dictionaries).
* The text following the weight (`icmp`) is a small description that
will be added as a comment in **nft_input_conf_path** file on
the remote host.
</details>
<details>
<summary>Override some of the default defined sets (<i>click to expand</i>)</summary>
``` yml ``` yml
- hosts: serverXYZ - hosts: serverXYZ
@ -261,15 +436,76 @@ table inet filter {
desc: Custom SSH port and torrent desc: Custom SSH port and torrent
name: in_tcp_accept name: in_tcp_accept
value: '{ 2201, 6881 }' value: '{ 2201, 6881 }'
input udp accepted:
desc: torrent
name: in_udp_accept
value: '{ 6881 }'
roles: roles:
- role: ipr-cnrs.nftables - role: ipr-cnrs.nftables
``` ```
1. Get item name (eg. `input tcp accepted`) and variable name
(eg. `in_tcp_accept`) from `defaults/main.yml` file.
1. Set a new value (eg. `'{ 2201, 6881 }'`).
1. You can add a `desc` attribute that will be set as a comment in
**nft_input_conf_path** file on the remote host.
* **nft_define_group** or **nft_define_host** variables can also be used.
</details>
* Use default rules with allow incoming ICMP and count dropped input packets : <details>
<summary>Override all default rules (eg. for outgoing traffic) (<i>click to expand</i>)</summary>
If the default rules are too permissive, if you already override most of them,…
In some case, i guess, it can be interesting to redefine the default variable :
``` yml
- hosts: serverXYZ
vars:
nft_output_default_rules:
000 policy:
- type filter hook output priority 0; policy drop;
005 state management:
- ct state established,related accept
- ct state invalid drop
015 localhost:
- oif lo accept
050 my rule for XXX hosts and services:
- tcp dport 2000 ip saddr { xxx.xxx.xxx.xxx, yyy.yyy.yyy.yyy } ct state new accept
250 reset-ssh: # allow the host to reset SSH connections to avoid 10 min delay from Ansible controller
- tcp sport ssh tcp flags { rst, psh | ack } counter accept
roles:
- role: ipr-cnrs.nftables
```
* At least, don't forget to :
1. set a default `policy`.
1. manage already `established` state.
1. accept `rst, psh | ack` flags for **ssh** to avoid a 10 minutes delay at
the first run of this Nftables role (see #1).
* Then add your own rules with the wanted weight to order all merged rules (from
<b>nft_output_*rules</b> dictionaries) and descriptions.
</details>
<details>
<summary>Remove a default rule (<i>click to expand</i>)</summary>
``` yml
- hosts: serverXYZ
vars:
nft_output_host_rules:
210 output tcp accepted:
-
roles:
- role: ipr-cnrs.nftables
```
1. Get rule description from `defaults/main.yml` file (`210 output tcp accepted`).
1. The default policy for outgoing traffic (**drop**) will now be applied to
ports defined in **out_tcp_accept** variable. Be sure of what you are doing.
1. The rule will no longer be present in `nft list ruleset` result, just a
comment will remain (`210 output tcp accepted`) in **nft_output_conf_path**
file on the remote host.
* **nft_output_rules** or **nft_output_group_rules** variables can also be used.
* The weight (`210`) allow to order all merged rules (from
<b>nft_output_*rules</b> dictionaries).
</details>
### With group_vars and host_vars
<details>
<summary>Use default rules and allow, for <b>first_group</b>, incoming ICMP and count both ICMP and default policy (<b>drop</b>) packets (<i>click to expand</i>)</summary>
`group_vars/first_group` : `group_vars/first_group` :
@ -280,62 +516,61 @@ nft_input_group_rules:
999 count policy packet: 999 count policy packet:
- counter - counter
``` ```
</details>
* Use merged group rules from multiple ansible groups: <details>
<summary>Use merged group rules from multiple ansible groups (<i>click to expand</i>)</summary>
``` yml 1. Enable to merge group's variables :
- hosts: serverXYZ ``` yml
vars: - hosts: serverXYZ
nft_merged_groups: true vars:
nft_merged_groups_dir: vars/ nft_merged_groups: true
roles: nft_merged_groups_dir: vars/
- role: ipr-cnrs.nftables roles:
``` - role: ipr-cnrs.nftables
```
And put the rules inside the "vars" folder named after your ansible groups of the server: 1. Put extra rules inside the "vars" folder named after your ansible groups for serverXYZ :
* `vars/first_group` :
`vars/first_group` : ``` yaml
nft_input_group_rules:
``` yaml 020 icmp:
nft_input_group_rules: - ip protocol icmp icmp type echo-request ip length <= 84 counter limit rate 1/minute accept
020 icmp: 999 count policy packet:
- ip protocol icmp icmp type echo-request ip length <= 84 counter limit rate 1/minute accept - counter
999 count policy packet: ```
- counter * `vars/second_group` :
``` ``` yaml
nft_input_group_rules:
`vars/second_group` : 021 LAN:
- iif eth0 accept
``` yaml ```
nft_input_group_rules: 1. These rulesets, from the two groups, will be merged if the host is a member
021 LAN: of these groups.
- iif eth0 accept </details>
```
These rulesets from the two groups will be merged if the host has the two groups as ansible roles.
## Known Issue
* 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).
## Configuration ## Configuration
This role will : This role will :
* Install `nftables` on the system. * Install `nftables` on the system.
* Enable `nftables` service by default at startup. * Enable `nftables` service by default at startup.
* Generate a default configuration file which include all following files and loaded by systemd unit. * Generate a default configuration file which include all following files and
loaded by systemd unit.
* Generate input and output rules files include called by the main configuration file. * Generate input and output rules files include called by the main configuration file.
* Generate vars in a file and sets and maps in another file. * Generate vars in a file and sets and maps in another file.
* (re)Start `nftables` service at first run. * (re)Start `nftables` service at first run.
* Reload `nftables` service at next runs to avoid to let the host without firewall rules due to invalid syntax. * Reload `nftables` service at next runs to avoid to let the host without firewall
rules due to invalid syntax.
## Development ## Development
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… This source code comes from our [Gitea instance][nftables source] and the
[Github repo][nftables github] exist just to be able to send the role to Ansible
Galaxy…
But feel free to send issue/PR here :) But feel free to send issue/PR here :)
Thanks to this [hook][gogs to github hook], Github automatically got updates from our [Gogs instance][nftables source] :) Thanks to this [hook][gogs to github hook], Github automatically got updates from our [Gitea instance][nftables source] :)
## License ## License
@ -344,7 +579,7 @@ Thanks to this [hook][gogs to github hook], Github automatically got updates fro
## Author Information ## Author Information
Jérémy Gardais Jérémy Gardais
* Source : [on IPR's Gogs][nftables source] * Source : [on IPR's Gitea][nftables source]
* [IPR][ipr website] (Institut de Physique de Rennes) * [IPR][ipr website] (Institut de Physique de Rennes)
[gogs to github hook]: https://stackoverflow.com/a/21998477 [gogs to github hook]: https://stackoverflow.com/a/21998477