THE ARCHIPELAGO

What this is. Behind a proxy, an app learns who you are from a header the proxy adds, and anyone who can reach the app directly could write that header themselves. So each app keeps a list of the proxies it believes. This page sets those lists side by side.

What goes wrong. Too open, and anything on the network can claim to be anyone. Too strict, and every visitor looks like the proxy, so one lockout locks out everyone. It shows who an app believes, not who can reach it; the map's roads answer that.