Q&A: Web filtering

Tim Lloyd is the Founder and Managing Director of CensorNet, a company that develops Internet security products that filter and remove offensive material found online. In this interview he discusses Web filtering.

When someone mentions Web filtering, people usually think about Big Brother and wonder if it should be deployed in the enterprise at all. On the other hand, employers want to minimize malware problems and having employees focus on work during all office hours doesn’t hurt as well. In your opinion, what are the pros and cons in having Web filtering in a company?
I think the pros far outway the cons these days. A few years ago, companies were concerned about pornography and the surrounding legal ramifications of having images downloaded and stored on the network. Now the concerns are broader, covering security issues such as malware and phishing, timewasting, Web 2.0 tools and bandwidth usage. Companies need to embrace the Web more than ever to grow their businesses but there has to be a balance – a completely blocked policy frustrates staff and denies the business any value from online activities (such as HR using Facebook to review potential employees, your sales manager using LinkedIn to identify new prospects and the marketing team using Twitter to promote your brand). A completely open policy leaves the business feeling exposed and out of control.

I believe an effective Web filter will allow the business to find the right balance. One of the cons that people talk about is the impact on performance – that Web access will slow down if you install a filter. The reality is that with the computing power available today and the ability to manage more effectively streaming audio/video and use of bandwidth, the overall network performance should increase with the installation of a Web filter.

On what basis does your software filter websites? How are those lists compiled? Who decides what should be filtered?
Our software uses four techniques to filter Web sites. On the first pass, it looks at the URL and decides whether it is known to us and is in our database – which contains approximately 65 million sites in 70 categories. If it is, the database will return a category for the URL e.g. Pornography, Shopping, Travel, Violence, etc, and based on the rules the administrator has configured the site will either be blocked, allowed or passed on to the next module for further inspection. If passed on, the second step would be to analyse the page content in real time using sophisticated AI algorithms which have been trained to identify specific types of content. Currently our real-time raters cover 16 categories and 15 languages. If the real-time raters cannot determine the type of site, it is passed on to the Image Analysis engine which will inspect any pictures on the Web site and determine if they are acceptable or not. If they are deemed unacceptable they will be replaced with a safe symbol before display in the browser. Finally, if configured by the administrator, the site will also be subject to file type, anti-virus and MIME type scanning.

The lists are compiled by spidering the Web using the real-time raters to automatically categorise as much as possible and then using human categorisation to verify and categorise what’s left. It is a constantly evolving database and generally on a daily basis between 50,000 and 100,000 Web sites are added, removed and updated.

Ultimately it is the administrator that decides what should be filtered. We have designed our product to be as flexible as possible and it can enforce an extremely strict filtering policy or an extremely passive one. Some customers just want to report on activity and not block anything, whilst others want fine grained control specifying different access levels for different groups of users. We have some cool features such as Advisory Mode – whereby a user can override a block if they deem it suitable for their work remit, with full logging of course. Another feature is Time Quota, where the administrator can set up a floating time period in which users can visit non-work related sites (Shopping, Travel, etc) – once the time is used up the sites are blocked until the next day. It is all geared up to support the wishes of the company’s management team and policy on Web use.

What’s the core difference in deploying a software content filtering solution versus an appliance-based solution?
The core difference is that you are supplying your own hardware and therefore you have to run through the installation process yourself. If you buy an appliance it is pre-installed and ready to plug in and go. We offer all options to give the customer choice. A lot of them already have a policy to buy HP or IBM servers and an SLA which they trust, so if they can just install the software themselves it is a preferred option.

How do your products compare to a free solution like OpenDNS?
I suppose it is the same old adage that you get what you pay for. OpenDNS is not a very secure or necessarily accurate solution. It works on matching domain names using the DNS system. It is fine if you just want to block sites but I think companies demand more these days – it is not just about blocking it’s now about managing Web access. All the things we talked about in the first question.

With a myriad of vendors offering Web filtering solutions, what do you see as your strengths in the market? How are you building on these advantages?
You’re right, there are a lot of competitors out there. Our strengths come in the flexibility of the product, the service we can offer and the affordability – especially with the software only option. We are also one of the first vendors to release a VMware Certified Virtual Appliance for Web filtering & content management. This is proving extremely popular as more businesses are moving towards a virtualisation policy to reduce cost, save energy and to simplify server management.

We are trying to get the message out that companies need to regain control of the Web. It has tremendous advantages and simply blocking web sites is no longer the way to go. Employees can be more productive when they have access to the Web and they can use new Web 2.0 and social networking tools as part of their work. So why block them? With our software you can create a balance that doesn’t hinder the employee but at the same time satisifes HR and management concerns about Web usage.

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