charcoal

Web API based Squid URL Redirector

Copyright Unmukti Technology Pvt Ltd. All rights reserved.

Licensed under GNU Affero General Public License Version 3. See LICENSE file for more details.

Why the name charcoal?

Activated charcoal is used as sediment filter for water.

Internet data is water for users, while Network Administrators would like to filter out the sediments that use up the bandwidth unnecessarily, are harmful, and do not align with business priorities.

Why a web API based filter?

To make lives of adminstrators a bit easy. Instead of spending time and energy on periodically updating the blacklists from multiple sources, maintaining them, they should focus on getting things done. While we manage the blacklists.

It also helps a great deal if you have to manage 10s or 100s of locations. Managing blacklists and policies across them is a real pain.

Charcoal helps you create and implement policies across distributed networks in a jiffy.

How does it all fit together?

Charcoal has 2 components

• Server

  • WebGUI for managing the rules (CRUD)
    • Perl Catalyst
    • Postgresql
    • Twitter Bootstrap
  • API Server for enforcing the rules
    • Perl
    • Postgresql
    • Memcached

• Client

It is a squid helper which runs on your squid server.

It receives requests from squid and consults with the API server for the policy to be applied.

If the API server tells it to let the request pass, it is ALLOWED.

And if API server finds that this user is not allowed to access this destination at this hour with this User-Agent while trying to use the method POST to upload a file of type audio/mp3, it tells the helper to redirect the user to a block page.

All this happens within a few milliseconds.

System requirements

Client

Squid helper is written in Perl and is currently running on following systems:

• OpenWRT / LEDE Project on

  • PCEngines ALIX
  • PCEngines APU
  • PCEngines APU2
  • Routerboard RB951Ui-2HnD

• PfSense on x86 and AMD64 (ALIX & APU/APU2 included)

It can run on any POSIX compliant Unix system which has:

• Perl >= 5.14.x
  • IO::Socket

Server

Server hardware sizing depends on the size of the deployment and number of requests per second.

Squid Versions supported

Squid-2.x is supported in compatibility mode with -c argument to the helper. While Squid-3.x is supported natively. We will add support for Squid-4.x soon.

Setup and configuration