servicewall 0.4.2

the desktop firewall that adapts to different network connections

ServiceWall

What to expect

ServiceWall is a firewall intended for laptops and all devices that connect to several different networks. It will drop incoming requests, excepted for those that you allow. Each service you allow in will be remembered either :

• for the network you're connected to (the realm's ruleset), or
• for unregistered networks (the default ruleset)

At the moment the default ruleset is : accept ssh and DHCP incoming connections. ssh connections are accepted from anywhere, whereas DHCP ones are only accepted on the local network (connected to the same gateway as you). All new rules will be limited to this local network.

It won't remember the network you're connected to until you change the default ruleset. Once you do, it writes down an identifier for the network realm, together with the default ruleset plus the rule you added. Now when you connect to another network, it will put this identified ruleset aside, and try to find a ruleset for the new network. If it can't find any, it'll fallback to the default ruleset. When you connect to the identified network back, it will automagically bring back the rules you chose (magic here involves a network dispatcher telling it network changes).

The default ruleset also has a few basic stateful rules : accept icmp requests, accept all from the localhost loop, accept already established connections, drop invalid packets, and log anything dropped.

What not to expect

This firewall works on incoming traffic ; it won't be very useful on a server needing to forward anything.

At the moment, you can't expect it to let any traffic come in from out of the local network realm either (excepted ssh, which is is a kind of "special" rule). At the moment, you can't either change the default ruleset on the command line ; you would have to manually edit /etc/servicewall/realms.json for that.

So basically, if your device is not a laptop you use as a personal device, this software shouldn't be really fitted.

Installation

Dependencies

Required dependencies are python 3, iptables, systemd, and either NetworkManager or systemd-networkd enabled. If you run a linux on a laptop, you should be all set.

There are python packages needed as well, but if you use a decent install method like pip, they should be managed all right. Those are :

• optional : python-argcomplete
• build-time : python-setuptools
• python-iptables
• python-netifaces
• python-argparse

You might really wish to have python-argcomplete for the command-line completion to work. This can really prove handy when you're looking for a service to allow.

Install

Once you have the required dependencies, install the package with :

# pip install servicewall

For those using Arch linux, there is a PKGBUILD script for this, coming soon into AUR. Give it a try !

Usage

The firewall is disabled by default. To enable it now and at boot-time :

# braise enable

(you indeed get the corresponding disable). Once started, the default behaviour is to drop all that come in, excepted for ssh from anywhere and DHCP from the local network. All that go out is allowed.

To have details on the status, use :

# braise status

ServiceWall works with service definitions provided by jhansonxi. They link a service to ports it needs. To allow a specific service, do :

# braise allow service "Service Name"

which will add this service to this realm's definition. If you connect to internet in another place, the rules for this place will be put aside, and brought back when you connect to it again. You can move back with braise disallow service ...

Don't know what's the exact name of the service you want to allow ? You'll need to :

# braise show services

The list is quite long. Once you want exhaustive informations on a single service, do

# braise show service "Service Name"

And if you wonder which services use to use port 80, do

# braise show port 80

These rules are stored together with a string identifying the network you're connected to, in a dictionary called realm_defs. To interrogate it, do :

# braise show realms

And in the end, the firewall logs all that it drops ; there's a log processor tool included ; try it with

# braise show logs

or

# braise show logs since NUMBER_OF_SECONDS

Copyright

This software is copyrighted under the GNU Version 3 license.