Internet Filtering: Client-based vs. Server-based
The original filtering solutions were client-based -- programs that ran
on individual workstations. They typically use keyword filtering or
small URL databases, or combinations of both. They tend to have high
support costs, are difficult to update, are often easy to disable,
and generally aren't very effective.
Server-based solutions started being used in about 1994. These are
usually implemented as servers that run on the network between
workstations and the Internet. They are easier to maintain and update
than client-based solutions and are difficult to disable or circumvent.
Their primary disadvantage is that they don't offer as much end-user
control over the filtering parameters.
Hybrid solutions are just starting to come into use recently. These
combine the flexibility of client software with the ease-of-maintenance
and power of servers. When implemented properly they can partially
overcome the disadvantages of client software because they are simpler
and need less maintenance, and can be integrated into existing client