garden-gnome

This is a node.js application for redirecting only OS "does this device have internet" probes to an information portal. It mimics the functionality of a "captive portal" without blocking/redirecting background traffic and traffic that is going to non-probe urls.

Installation

System dependencies

• dnsmasq

sudo apt-get install dnsmasq

• netfilter

• Pretty much guaranteed to be present in linux.

Install node.js packages:

npm install

Permissions

garden-gnome uses netfilter to add and remove iptables rules. In order to do that, it must have the proper permissions.

From https://github.com/diosney/node-netfilter/blob/master/README.md#requirements:

To properly execute the provided methods the application that uses the module must have the proper sudo privileges. One way to do it could be by adding a custom user to the system:

sudo adduser --no-create-home garden-gnome

then add its permissions at /etc/sudoers file:

garden-gnome ALL= NOPASSWD: /sbin/iptables, /sbin/ip6tables, /sbin/ipset

garden-gnome also must write to /etc/dnsmasq.d/garden-gnome.conf (or a config filename of your choosing). /etc/dnsmasq.d has root permissions, so as a root level user you must create a /etc/dnsmasq.d/garden-gnome.conf file with garden-gnome (or your user for running the portal) as the owner.

Settings

Copy and tweak settings file

cp settings.js.example settings.js

Usage

Usage: ./index.js

Options:
  --ip: Proxy listen IP address (default: 127.0.0.1)
  --port: Proxy listen port (default: 5080)
  --dnsLookupPeriod: Amount of time before refreshing dns cache. (in sec) (default: 60).
  --inInterface: Interface to redirect from (default: all).

Defaults and other settings can be overwritten in the settings.js file.

You likely want to daemonize this. TODO: Add info about systemd or others?

Details

garden-gnome captures internet detection probes to the following urls:

• apple.com/library/test/success.html
• captive.apple.com/library/test/success.html
• www.ibook.info/library/test/success.html
• www.itools.info/library/test/success.html
• www.airport.us/library/test/success.html
• www.thinkdifferent.us/library/test/success.html
• www.appleiphonecell.com/library/test/success.html
• clients3.google.com/generate_204

and redirects them to our portal web page. On the portal page, taking an action (clicking on a link), will prevent that user from seeing the portal again until a specified amount of time passes.

All other traffic will be ignored. This is all traffic except traffic on port 80 to the hosts shown above.

License

GPLv3

Copyright 2015 Maxb