[Web4lib] the efficacy of filtering software

[John Fitzgibbon]

Hi,

I just wish to use the mailing list as a sounding board to test if my
understanding of how filtering software works is correct.

Filtering software companies use software to retrieve web pages as
search engines do. The retrieved web page is scanned for blocked
keywords. If the page contains any of the blocked keywords, the address
of the web site is added to a list of blocked sites.

This so-called black list is being updated all the time. The list is
downloaded onto the user's PC from time to time and whenever an http
request is made, this list is first checked to determine if the request
will be permitted.

Because the Web is vast and ever changing it is not feasible to keep the
black list up to date

Filtering software will fail to block a large number of pornographic
sites.

Filtering software may, therefore, give parents a false sense of
security; it may give them a mistaken belief that all pornographic sites
are blocked.

Is my analysis correct? If a number of sexual swear words are entered
into a search engine, what proportion of the sites returned is not
blocked by the main filtering software? Would it be one site per ten
i.e. one site on every result page would be accessible or would it be
much less than this?

Are there any studies on this?

Is it the case that filtering software which is based on black lists can
successfully block innocent children from stumbling across porn but do
not stop people who are determinedly hunting for porn from finding it?

I would welcome any feedback.

Regards
John

John Fitzgibbon

p: 00 353 91 562471
f: 00 353 91 565039
w: http://www.galwaylibrary.ie 

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