Make a query parameter to control opt-in/opt-out
Add a parameter that lets an admin choose whether a permission cookie is required before the proxy badge starts serving clients.
This also requires designing some kind of information/permission page, with yse/no buttons, that sets a cookie when you click yes. The permission page should also be able to stand on its own for direct linking, in case people want a link to promote opt-in.
https://lists.torproject.org/pipermail/tor-talk/2012-October/025891.html
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