[mirimir]

OnionShare is a good choice.[0]

However, Tor is vulnerable to traffic analysis. And running a server, adversaries can easily modulate/fingerprint the traffic, which facilitates traffic analysis. If you can see the signal, and have taps on major AS, you can drill down to the server.

0) https://onionshare.org/

[bouncycastle]

A way I would pinpoint a hidden server would be to monitor different data center regions / networks for outages or congestion, while at the same time looking at the hidden server's ping reply. The response times alone can reveal a lot of information. Once I have the data center, I'm sure the data center admins can see which servers are using Tor, and help with pinpointing it further. No need for taps.

[mirimir]

Yeah, that too :(

One can route Tor traffic for .onion servers through VPNs, or even through nested VPN chains. That makes it a little harder, because the hosting provider can't easily tell that it's Tor traffic. Also, one can run a private obfsproxy, which isn't listed or indexed by Tor.