Date: Mon, 12 Jan 2015 01:04:58 -0500 From: grarpamp grarpamp@gmail.com To: tor-relays@lists.torproject.org

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On Fri, Jan 9, 2015 at 10:26 PM, Drake Wilson drake@dasyatidae.net wrote: eric gisse wrote: Plus the logic starts to get warped when you wonder "So do you BadExit every node that runs on an ISP that caches traffic?"

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As far as http caching, it would be relatively fine IF the cache truly did good practice, and IF the site truly did good design for the cache to follow. However those two necessary truths are often false, whether by AND or XOR context. So to be true, a cache shouldn't be deployed, but in the interest of bandwidth they are, more commonly at small end-tier user access ISPs (including exits) for that purpose.

I'd suggest best practice is for

• users to use https to bypass
• caches to insert their tagline in http headers so

users can bitch to the owner.

• Tor exits? Well, they're volunteer paid diversity, so which is

more valuable to you? The IF's above, or TCP truth at potential cost to diversity?

I prefer TCP truth, but if I was a constrained operator I'd do my best research into setting up a quality cache. Provided caching images of ill repute on disk were not an overriding concern.

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I can imagine two strategies to avoid caching images on-disk:

1. Use an in-memory cache 2. Don't cache images

While these strategies might not technically/legally offer much more protection (IANAL):

1. If the cache disappears as soon as the machine shuts down, it's much harder to prove the possession of anything illegal. (However, the proxy headers, live imaging, or an insecure/subverted server might give away what was being cached.)

2. And if images aren't being cached, while textual material could still be illegal, it's less likely to be specifically targeted by law enforcement.

In my opinion, if you use HTTP over the internet, you are essentially consenting to caching, inspection, or worse. And most people know that by now. And if you use HTTP over Tor, you should be much more aware of this.

teor

teor2345 at gmail dot com pgp 0xABFED1AC https://gist.github.com/teor2345/d033b8ce0a99adbc89c5

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