After I found out `UFW` was too limited in terms of functionalities, I tried several firewall roles out there but none satisfied the requirements I had:
- Support virtually all iptables rules from the start
- Allow granular rules addition/overriding for specific hosts
- Easily inject variables in the rules
- Allow rules ordering
- Simplicity (not having to learn how role variables would generate the rules)
- Persistence (reload the rules at boot)
This role is an attempt to solve these requirements.
It supports **ipv4** and **ipv6*** on Debian and RedHat distributions.
*ipv6 support was brought up thanks to [@maloddon](https://github.com/maloddon). It is currently in early stages and knowledgable people should review the [default rules](https://github.com/mikegleasonjr/ansible-role-firewall/blob/master/defaults/main.yml). ipv6 rules are not configured by default. If you which to use them, don't forget to set `firewall_v6_configure` to `true`.
Requirements
------------
* Ansible 2.2.1.0
*`iptables` (installed by default on all official Debian and RedHat distributions)
Installation
------------
`$ ansible-galaxy install mikegleasonjr.firewall`
Role Variables
--------------
`defaults/main.yml`:
```
firewall_v4_configure: true
firewall_v6_configure: false
firewall_v4_default_rules:
001 default policies:
- -P INPUT ACCEPT
- -P OUTPUT ACCEPT
- -P FORWARD DROP
002 allow loopback:
- -A INPUT -i lo -s 127.0.0.0/8 -d 127.0.0.0/8 -j ACCEPT
003 allow ping replies:
- -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
- -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
100 allow established related:
- -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
200 allow ssh:
- -A INPUT -p tcp --dport ssh -j ACCEPT
999 drop everything:
- -P INPUT DROP
firewall_v4_group_rules: {}
firewall_v4_host_rules: {}
firewall_v6_default_rules:
001 default policies:
- -P INPUT ACCEPT
- -P OUTPUT ACCEPT
- -P FORWARD DROP
002 allow loopback:
- -A INPUT -i lo -s ::1/128 -d ::1/128 -j ACCEPT
003 allow ping replies:
- -A INPUT -p icmpv6 --icmpv6-type echo-request -j ACCEPT
- -A OUTPUT -p icmpv6 --icmpv6-type echo-reply -j ACCEPT
100 allow established related:
- -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
200 allow ssh:
- -A INPUT -p tcp --dport ssh -j ACCEPT
999 drop everything:
- -P INPUT DROP
firewall_v6_group_rules: {}
firewall_v6_host_rules: {}
```
The keys to the `*_rules` dictionaries (`001 default policies`, `002 allow loopback`, ...) can be anything. They are only used for rules **ordering** and **overriding**. On rules generation, the keys are sorted alphabetically. That's why I chose here the 001s and 999s.
Those defaults will generate the following script to be executed on the host (for ipv4):
```
#!/bin/sh
# Ansible managed: <redacted>
# flush rules & delete user-defined chains
iptables -F
iptables -X
iptables -t raw -F
iptables -t raw -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
# 001 default policies
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP
# 002 allow loopback
iptables -A INPUT -i lo -s 127.0.0.0/8 -d 127.0.0.0/8 -j ACCEPT
# 003 allow ping replies
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
# 100 allow established related
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
# 200 allow ssh
iptables -A INPUT -p tcp --dport ssh -j ACCEPT
# 999 drop everything
iptables -P INPUT DROP
```
As you can see, you have complete control over the rules syntax.
`$ iptables -L -n` on the host then shows...
```
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmptype 8
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22
Chain FORWARD (policy DROP)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmptype 0
```
Now that takes care of the default rules. What about overriding?
You can change the rules for specific hosts and groups instead of re-defining everything. Rules in `firewall_v4_host_rules` will be merged with `firewall_v4_group_rules`, and then the result will be merged back with the defaults. Same thing for ipv6.
This allows 3 levels of rules definition and overriding. I simply chose the names to match how the variable precedence works in Ansible (`all` -> `group` -> `host`). See the example playbook below to see rules overriding in action.
Example Playbook (ipv4)
----------------
```
- hosts: all
roles:
- mikegleasonjr.firewall
```
in `group_vars/all.yml` you could define the default rules for all your hosts:
```
firewall_v4_default_rules:
001 default policies:
- -P INPUT ACCEPT
- -P OUTPUT ACCEPT
- -P FORWARD DROP
002 allow loopback:
- -A INPUT -i lo -j ACCEPT
003 allow ping replies:
- -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
- -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
100 allow established related:
- -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
200 allow ssh limiting brute force:
- -I INPUT -p tcp -d {{ hostvars[inventory_hostname]['ansible_eth1']['ipv4']['address'] }} --dport 22 -m state --state NEW -m recent --set
- -I INPUT -p tcp -d {{ hostvars[inventory_hostname]['ansible_eth1']['ipv4']['address'] }} --dport 22 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j DROP
999 drop everything:
- -P INPUT DROP
```
in `group_vars/webservers.yml` you would open up port 80:
```
firewall_v4_group_rules:
400 allow web traffic:
- -A INPUT -p tcp --dport http -j ACCEPT
```
in `host_vars/secureweb.yml` you would want to open https as well and remove ssh logins:
```
firewall_v4_host_rules:
400 allow web traffic:
- -A INPUT -p tcp --dport http -j ACCEPT # need to redefine this one as well because the whole key is overwritten
- -A INPUT -p tcp --dport https -j ACCEPT
200 allow ssh limiting brute force: []
```
To "delete" rules, you just assign an empty list to an existing dictionary key.
To summarize, rules in `firewall_v4_host_rules` will overwrite rules in `firewall_v4_group_rules`, and then rules in `firewall_v4_group_rules` will overwrite rules in `firewall_v4_default_rules`.
You can play with the rules and see the generated script on the host at the following location: `/etc/iptables.v4.generated` and `/etc/iptables.v6.generated`.
Dependencies
------------
none
License
-------
BSD
Contributing
-------
A vagrant environment has been provided to test the role on different distributions. Add your tests in `tests.yml` and...
```
$ vagrant up
$ vagrant provision
```
Author Information
------------------
Mike Gleason jr Couturier (mikegleasonjr@gmail.com)
