Web Filtering via SmartFilter

Ricky Chan

Why do we need a Web Filter?

Until recently, the Internet has always been conceived as an educational tool. It is now rapidly evolving as an unrestricted and uncontrolled sources of content such as sex, obscenity and pornography, criminal skills and gambling. As an educational institution, it is our duty to protect our students and to ensure that the best of the Internet is utilised without the risk of exposing them to inappropriate materials or potentially illegal or harmful contents. Controls are now in place to confine student access to appropriate Internet resources by adopting Web filter software such as SmartFilter which controls students' access to the World Wide Web through a control list. The SmartFilter Control List offers a continuously updated database of 27 categories (such as Criminal Skills, Drugs, Sex, etc.) that we have the option to block, with decisions made on a category-by-category basis.

How does SmartFilter work?

SmartFilter is a server-based solution that is tailored to "enterprise" use because it is implemented as a gateway, independent of products on the desktop, which in turn can be enforced to block undesirable sites. Server-based solution is more scalable, manageable, and cost-effective in the long run. A major advantage of SmartFilter is that it can be installed as an add-on package on the University's Squid proxy server. To enable Web filtering on a computer, one can simply change the proxy setting of a Web browser (e.g. Netscape) to point to the Squid proxy server with SmartFilter installed. The configuration setting of the SmartFilter and Squid proxy server in the CityU is shown in Figure 1 below.

Currently the SmartFilter control list contains more than 60,000 categorised entries, sub-sites, and URLs. Initially, the CSC will restrict the URLs belonging to the categories: Criminal Skills, Drugs, Extreme, Gambling and Sex. The "Criminal Skills" category contains URLs that offer instructions, or identification of methods to promote, encourage, or provide the skills to commit illegal, criminal activities. These include such examples as bomb making instructions, lockpicking, computer hacking, rapes and so on. The "Drugs" category contains the URLs that provide information on purchase and use of illegal or recreational drugs. The "Extreme" category encompasses URLs that contain information that is extremely violent, gory, or horrific in nature and may be related to sex, bodily function, obscenity, or perverse activities. The "Gambling" category contains URLs that encourage betting money or other items on the outcomes of games, contests, etc. It includes sites that offer gaming, bookmaker odds, lottery pages, and bingo. The "Sex" category contains URLs that refer to, discuss, or show pornography, pictures or videos of sex, nudity, and soft and hard core pornography, child pornography and the like.

Setting up SmartFilter

If your department wishes to block students’ access to inappropriate Web pages, you can set up a SmartFilter Squid proxy server for this purpose. A SmartFilter Squid proxy server consists of three major components: a computer, SmartFilter software and Squid proxy server software. SmartFilter and Squid software support both Solaris and Linux platforms, so one can select either SunSparc workstation or PC as the computer hardware. Squid proxy server is a freeware on the Internet and is commonly used by our University, JUCC and other universities in Hong Kong. SmartFilter, on the other hand, is a commercial software and its price is based on the number of users. If you are interested in setting up a SmartFilter Squid proxy server, please feel free to contact Mr. Ricky Chan at x7450 or simply send an e-mail to cc@cityu.edu.hk.

Computing Services Centre City University of Hong Kong ccnetcom@cityu.edu.hk