173.164.206.181 is a Tor relay node and not a Tor exit node, as it appears from http://torstatus.blutmagie.de/router_detail.php?FP=25871bf90689b270bb6fe873f9c72760ab026dd1. However, it is blocked automatically by TorBlock as an exit node. The operator states that he has never run a Tor exit node on that IP before. Could you check on how this IP managed to be affected by TorBlock?
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Severity: major