BEFW project

Dynamic Host-Based Firewall

Intro

BEFW is a couple of golang-written tools that are eligible to maintain dynamic firewall rules across the datacenter(s). The approach is based on the service discovery concept: if we know there's a service, we can protect it. If we know there's a client for the service, we can allow him to connect to. BEFW is using consul service catalog to store services ( with their tcp/udp ports ) and is using consul key-value storage to store services clients. It's just a bit smarter than curl localhost:8200/v1/agent/services|perl -e '<script>'|iptables-restore, but 'a bit' is significant here.

Requirements

• Any modern Linux distro with iptables & ipset support.
• You must have at least one consul cluster with acl support enabled.
• You must have consul agent on every node that runs befw.
• We provide the only PuppetDB orchestration provider. You may need to develop yourth.

How to build

go install github.com/wgnet/befw/cmd/befw-cli
go install github.com/wgnet/befw/cmd/befw-firewalld
go install github.com/wgnet/befw/cmd/befw-sync

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Deployment scheme

BEFW is not only tools but the approach too. If you build dynamic firewall from scratch, you may use our deployment guide.

Consul cluster

1. Install regular consul cluster ( or federated cluster ) with N ( N % 2 == 1) servers and M agents. Each server must have consul agent running.
2. Push some data and enjoy

ACLs

To protect your firewall configuration from unauthorized changes you need to create at least 3 acl sets on your consul cluster. To enable ACL support please read this article.

anonymous ACL

Allows anyone to read data from firewall ( usable for monitoring, metrics & UI for end users). Example.

node/agent ACL

Allows node/agent to read firewall configuration and register services. Example.

Commit/Master ACL

Allows 3pc software to write firewall configuration and purge expired data. Example.

Configuration

We use single consul datacenter to store firewall KV and we call it dc. You should specify this datacenter into configuration file. We use multiple consul datacenters ( one per site ) to store services & local KVs. You may use single-dc configuration, specify it's name as dc though.

Default firewall rules

3. Change default iptables template

Service

4. Install & launch befw-firewalld service on every agent node
5. Edit sample configuration and place it to /etc/befw.conf
6. Place sample service to services dir and see what will happen

Puppet/Hiera/PuppetDB

We use puppet to do items 3-6 and below as we have a huge puppet installation. Skip this if you don't. Puppet provides a great way to enumerate services on every node. You can just add something like that in every role/application-definition class:

file { "/etc/befw.service.d/${title}.json":
    ensure  => file,
    content => "<-- json here -->",
}

This will provide your services in consul automagically. Just a few patches once will save your time forever. See samples for more information.

befw-sync

Here, in Wargaming, we also use hiera & puppetdb to provide both services & clients for our services. The idea is that if we can collect & commit something to puppetdb ( like 'i_need_this_service_to_work'), that we can just grab it from puppetdb and store into consul. befw-sync does this job, looking into puppetdb for a corresponding resource and grabbing parameters to push to consul KV storage. See sample config to get into, but we doubt it is useful if you don't have such huge puppet installation on your world.

Managing rules

Adding new service

• Place a service file to services directory or
• Post a http request to local consul agent ( v1/agent/register ) or
• Allow consul-supported software ( like vault ) to manage it on its own

N.B. use tag 'befw' to generate rules for this service. Use tags 'port/protocol' ( like '80/tcp' ) to specify additional ports for the service.

Adding new rules

• Place ip/network and expiry value to KV storage on dc datacenter or
• Place alias and expiry value to KV storage on dc datacenter or
• Place a new data to alias definition to KV storage on dc datacenter

N.B. You can specify world, dc or node level while placing the rules.

Examples

consul.KV().Put("befw/$service$/service_tcp_443/192.168.1.1/30", time.now()+2*week)
consul.KV().Put("befw/$service$/dc/service_tcp_443/192.168.1.1/30", time.now()+2*week)
consul.KV().Put("befw/$service$/dc/nodename/service_tcp_443/192.168.1.1/30", time.now()+2*week)
consul.KV().Put("befw/$service$/service_tcp_443/$trusted$", -1) // <0 never expires
consul.KV().Put("befw/$alias$/$trusted$/192.168.1.1.30", time.now()+1*hour)

Tools

pusher is a very primitive python (2.7) tool to manage befw manually. Please avoid using it in production. Usage: ./pusher.py list|add|rm|clist|cadd|crm [opts] Config file: ~/.pusher.conf

host=localhost
port=8500
dc=consul
token=2375a28a-75ec-4b5f-a30f-3e68f8239a0a

Example usage:

# no clients for service
$ ./pusher.py clist myown_tcp_5672
[+] DC= dc , Node= node
# adding new one for level 3 ( node )
$ ./pusher.py cadd myown_tcp_5672 127.0.0.1 3
[+] DC= dc , Node= node
Added 127.0.0.1 to befw/dc/node/myown_tcp_5672/127.0.0.1 with expiry=1554896188
# yes we have it on KV now
$ ./pusher.py clist myown_tcp_5672
[+] DC= dc , Node= node
befw/dc/node/myown_tcp_5672/
 *127.0.0.1
# deleteting 127.0.0.1 from all levels
$ ./pusher.py crm myown_tcp_5672 127.0.0.1
[+] DC= dc , Node= node
Deleting befw/myown_tcp_5672/127.0.0.1
Deleting befw/dc/myown_tcp_5672/127.0.0.1
Deleting befw/dc/node/myown_tcp_5672/127.0.0.1
# no clients found
$ ./pusher.py clist myown_tcp_5672
[+] DC= dc , Node= node
$

Changelog

See CHANGELOG.

Known issues

See ISSUES.

Contributing

See CONTRIB.