tor 2006-03-16 klockan 17:54 +0100 skrev Christoph Haas: > Just one hint: Squid is bad at checking the content of HTTP objects. Unless > you use another proxy that can handle content better you will need to rely > on what the web server is sending you. The Content-Diposition header might > work here but is IMHO rather made for MIME parts of email messages rather > than being used in HTTP communication. It's used for almost every download service, as it instructs the browser to save the object to disk rather than trying to display it and by what name the object should be saved. Without the content-disposition header the browsers guesses what should be done with the object based on the content-type, content and prior experience of the users preferences, and what name it should have based on the URL. But no, it isn't an official HTTP header. But the HTTP standard does document the defacto common practise about using this header, and all major browser vendors have selected to implement it. > But whatever header field you check: you are always relying on the web > server administrators classification of files. True, but as most focus on making the user experience relatively good making these kinds of hints is in fact quite good for "normal" sites. The evil sites is not much you can do about, except blocking them when found and educating your users on acceptable usew of internet etc. But determined users or web masters will always find ways around nearly any block you make. The without doubt most important step to take when starting to filter Internet content and restricting access is to make sure there is a clear policy on acceptable internet usage, and that your users are aware of the policy and the penalties of not obeying the policy. Without this in place all you accomplish is annoyed users and a war for finding ways around whatever block/filter you set up. With this in place even very simple blocking/filtering methods becomes very effective as all the blocking/filtering method then needs to do is to act as a gentle reminder that there is limits on what is considered acceptable so people not unintentionally stray off too far from the policy. The "bad" users who intentionally violate the policy has to be hunted down manually in either case by keeping statistics and regularily auditing the Internet usage. Here statistics from the block/filter is again quite valueable as it can provide one hint on which users needs to be investigated more closely as users often getting caught in the block/filter probably isn't acting in a good manner. But it should not be the only method used. Regards Henrik
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