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Open Source Gateway, Content Filtering and Firewall for School

We have just switched broadband providers and hit a problem that the content filtering that they provided remotely did not really meet our needs. There main issues were with WiFi, BYOD devices and number of proxy exceptions needed to make Google Apps work.

  • For BYOD, users had to input the proxy and an unrealistic number of exceptions.
  • Our WiFi system did not work correctly with the content filter.
  • Without a load of exceptions, Google Docs did not work correctly on any device and as we use Google Apps this was sort of important.

This forced me to look at alternative solutions. We had been using ClearOS 5.2 for DNS and a few other things for some time and a knew it could do content filtering. So I setup a test VM (running on ESXi) of ClearOS 6.4 Community. The content filter on this seemed to work well and the proxy ran in transparent mode - so no pesky proxy settings or exceptions.

For a production system, more system resources were needed. This involved buying a dedicated (at least for now) box to run Clear OS 6.4 Professional on. This box currently has 8Gb and runs a hex core Xeon processor on an ESXi 5.1 platform. Clear OS Professional works by a subscription at various levels. We went for the basic level that gives content filter updates, software updates, antivirus update and so on. Was only $260 a year. Much less than other commercial systems.

Its early days - but the system seems to perform well on a 200Mb leased line with several hundred concurrent users. Offsite access for staff is given via the 1 to 1 NAT plugin that maps an external IP address to a local terminal server.

Some screen shots

Dashboard - show load on the system and resources used. There is also a real-time bandwidth monitor.
Filtering - there are a wide range of filtering options. There are configurable Blacklists and Phrase lists and well as exceptions and banned sites. You can also block the download of certain types of file extensions if you want. The overall sensitivity of the system is also configurable.
Web Proxy - we have this configured to transparent so that no proxy settings are needed. You can configure the system cache that speeds up access to frequently visited sites. You can also set bypasses for IP addresses - we have a couple of machines that need to go straight out to the net.

There is lots more you can do. For example, there is an active directory plugin than then allows you to set filtering levels by AD security group membership. This is a paid for extension so have not go there yet.

For us - at least at least at the moment, it seems to work well, allows everything to work as it should and does not cost the Earth (or nothing at all - but you do need to pay if you want filter updates).

In terms of installing it - if you run ESXi (you will need internal and external Vnics configured) its really fairly straightforward. There are some online guides, but essentially you will need two NICs. One for the internet and one connected to your internal network. You will also need IP/DNS settings from your ISP to configure the outward facing NIC. Once you have setup the networking, you can browse to the server at https://ipaddress(or DNS name)of server:81 login and it will take you through the rest.

Might post more details when I have time.

Update: we have found for good performance under load that we had to turn off the squid proxy disk cache. This can be done by putting in the line:
deny cache all
into the the squid.conf file. You can also delete reference to the location the the squid cache.

Your need to do this will depend on the number of users and the speed of your local disks.

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