Subject:
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Re: Cracking down on unauthorized image links
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Newsgroups:
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lugnet.admin.general
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Date:
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Fri, 4 Jun 1999 22:26:19 GMT
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Viewed:
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1041 times
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In lugnet.admin.general, lehman@javanet.com (Todd Lehman) writes:
> In lugnet.admin.general, david_nospam@sork.com (D Sorkin) writes:
> > Instead of frustrating both the image pirates and their prospective
> > customers, why not turn this situation to your advantage? Suppose that
> > each time an HTTP request is made for an unauthorized image, you serve
> > up a substitute image containing an advertisement in place of the
> > original. The substitute image could be mostly text in a limited number
> > of colors (does this reduce the size of a JPEG image much, or does it
> > only work for GIFs?), but with the same dimensions as the original (in
> > case the embedded image link includes HEIGHT and WIDTH paramaters).
> > [...]
By the way: David, there is no way that an HTTP server can know the size of
an image that a client/browser is expecting. That is, the HEIGHT and WIDTH
attributes of the <IMG> tag are known only to the client/browser and to the
originator of the HTML document.
So in fact (unfortunately) it is not even possible to scale the image to an
appropriate viewing size at the server end, even if bandwidth and CPU
weren't an issue. But if an image is simple enough, the client can do its
crude job of scaling it, and it'll still be readable enough.
> [...]
> My real concern with making accidentally broken links is the browser's
> cache. If someone visits the a page for a set, and they do View Image from
> their browser, and they cut & paste the image's URL into their own page,
> then it's very likely that when they view their own page to test the link,
> the image will actually show up (because it's still in their browser's
> cache)! One way around this is to include a no-cache pragma in the HTTP
> headers whenever the images are served, but then that creates an additional
> drag on both the server and clients.
Well, wouldn't you know it -- already now just in the past day, there are
new links from eBay to the new image URLs. None of these new links work, of
course, but at the time, they probably all appeared to work to the person
making the link, because of browser caching.
I took David's suggestion of displaying a placeholder image in lieu of a
broken image link. But I made it a simple static image, 200x200 pixels.
The image depicts a sad face and gives a URL to go to for more information:
http://www.lugnet.com/oops.gif
http://www.lugnet.com/oops.html
This is about the best I can do, short of going overboard and figuring out a
way to automatically send email to offenders.
I'm able to look at the HTTP server logs, BTW, to see where the unauthorized
links are coming from, without ever having to go scan other sites. Here are
some recent ones, for example:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=113058082
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=113315714
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=113461949
(Note: these URLs probably won't work after about a week, or may already
have been fixed by the time you view them.)
--Todd
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Message has 1 Reply:
 | | Re: Cracking down on unauthorized image links
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| (...) Well, couldn't you have several JPEGs of various dimensions ready to go, along with a database of the dimensions of the original images, and then feed the one whose dimensions are closest to those of the requested image? Actually, it probably (...) (25 years ago, 4-Jun-99, to lugnet.admin.general)
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Message is in Reply To:
| | Re: Cracking down on unauthorized image links
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| (...) That's an intriguing idea. I've seen similar sorts of things where a static (maybe 2KB) image is plopped up in place of the real image, and it typically gets scaled by modern browsers and looks all chunky and like that. But you're talking (...) (25 years ago, 4-Jun-99, to lugnet.admin.general)
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