Smoothwall Corporate Guardian is a web access and content filtering solution, implemented in software and designed to protect networks with an existing firewall.

However, rather than simply filter URLs and check against blacklists, the software also uses a technology called Dynamic Content Analysis (DCA) to categorise content on-the-fly.

As such, it doesn’t just block objectionable material but can also screen out viruses, spyware and other malicious code.

Getting started is a doddle with no software dependencies as the supplied CD contains everything required, including a security-hardened Linux operating system.

All you have to do is pop the disc into a suitable PC, boot it up and answer a few network questions. The hard disk is then wiped clean and the new Linux OS and Smoothwall software installed.

Alternatively, you can do as we did to test the product and install Corporate Guardian on a virtual machine hosted on a VMWare, or other virtual server.

Once installed remote browser-based management is the order of the day with a fairly intuitive, if busy, interface to be mastered. And it’s worth noting that there’s quite a bit to do if you want to take advantage of all that Smoothwall software has to offer. Plus, you may also have to make client changes.

Two modes of operation are supported with so-called transparent mode, where the Smoothwall server simply becomes the default internet gateway, the easiest option calling only for a couple of DHCP tweaks.

However, to take advantage of authentication and other advanced features it’s better to reconfigure client browsers to use Corporate Guardian as a web proxy, something you can do with a script if many users are involved.

We took the proxy route and by following the quick-start guide had a working web proxy blocking access to adult, gambling and a range of other sites in about 10 minutes.

We were then able to assign the blocking rules to specific groups, authenticating users and controlling access via their network logon. This option requires an LDAP (Lightweight Directory Access Protocol) server, such as Active Directory, although authentication against a local user list is also supported.

We also found customising the message displayed when content is blocked to be quite easy and were impressed by the comprehensive logging and reporting facilities, further enhanced in version 5.0 with a clutch of new reports and support for Crystal Reports.

Also new in the 5.0 release are controls to screen out active code, such as Java and ActiveX applets, and scan for viruses, using either a built-in ClamAV engine or other ICAP-compatible scanner.

Time-based controls have also been added, plus rules to manage HTTPS access to, for example, block Skype and phishing sites that use this protocol, as well as SSL proxy sites designed to bypass web filters.

On the downside we encountered a few problems when testing Corporate Guardian, most of which were quickly resolved by changing our rule settings.

However, if the software has one weak point it’s the number of options available. As we found, it’s easy to get things wrong and either block access to the wrong people or allow unfettered access to those who shouldn’t have it.

That aside, once you get to grips with it the Smoothwall software works well. Plus you don’t need expensive hardware to host it which, with affordable licensing, will appeal to small businesses looking to control what users can see and do on the web.