There are lots of programs that small businesses (libraries, internet cafes, etc) can install on local computers to enforce their rules and terms of service when using free resources. These aren't ideal as they require constant updates, and can readily be circumvented. A lot of this stems from three intertwined requirements - preventing over-usage, decreasing liability (illegal internet activity, comply with gov't regulation, etc), while enabling the greatest level of internet access possible.
Assuming the computer cannot be trusted, a proxy appears to be a logical choice. A transparent proxy is nice in that it requires no configuration on the end machine, and would also apply to users that bring their own machines.
- What are good, free proxy servers that can be configured as transparent proxies?
- Is a proxy server good for metering and rate limiting usage, or is different software better for this?
- Are there free/open blacklists available for preventing the usual "bad" access (other proxies, child porn, etc)?