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 rules are not configured by default. If you which to use them, don't forget to set firewall_v6_configure to true.
- Ansible 2.4.0.0
iptables(installed by default on all official Debian and RedHat distributions)
$ ansible-galaxy install mikegleasonjr.firewall
defaults/main.yml:
---
firewall_v4_configure: true
firewall_v6_configure: false
firewall_v4_flush_rules:
- -F
- -X
- -t raw -F
- -t raw -X
- -t nat -F
- -t nat -X
- -t mangle -F
- -t mangle -X
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_flush_rules:
- -F
- -X
- -t raw -F
- -t raw -X
- -t nat -F
- -t nat -X
- -t mangle -F
- -t mangle -X
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, except the flush rules, 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
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.
- 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.
none
BSD
A vagrant environment has been provided to test the role on different distributions. Add your tests in tests.yml and...
$ vagrant up
$ vagrant provision
Mike Gleason jr Couturier (mikegleasonjr@gmail.com)
Other roles from the same author: