About content filters
From Second Life Wiki
This article explains content filtering in general, and its relation to gaining access to the Second Life® virtual world. There are several different software methods for stopping incoming internet content that users may find objectionable. Firewalls, for example, typically work by blocking internet traffic based on ports, protocols and IP addresses. Another technique relies on identifying objectionable content. Content filtering works by blocking internet traffic based on keywords, domain names and whole classes of media such as streaming video, as well as various other creative methods invented by the producers of content filtering solutions. Unfortunately, some of these content filters categorize Second Life as a "game". This can end up disabling all access to the Second Life virtual world for business, education and non-profit organizations who are using such content filters to block more obviously objectionable material. Should you find access to the Second Life website or virtual world hindered in any way at work or school, but have no problems at home, you may want to investigate whether a content filter is the cause. In those cases, please contact the manufacturer of those products for further technical support. While we do not have a comprehensive list of these content filters, one that has blocked access to Second Life recently is 8e6 Technologies. They have their own Knowledge Base article describing how to resolve blockage of Second Life. It can be found at http://www.8e6.com; select Support > Knowledge Base from the navigation bar at the top of the page, and search for "Second Life". A firewall may also be responsible for your access difficulties, in which case the following firewall-related articles may be helpful:
