Hi, We're currently running 6 different 100-200Mbit relay/guard nodes, and are looking at some issues moving on towards high performant exit nodes.
There are some administrative issues ( needing another IP block due to the RIPE registration, our ISP doesn't want their name on the exit nodes that we are responsible for ) which are generally minor ( are being resolved anyhow ) and then the big stumbling block.
Right now, with iptables modifications ( raw tables hacks to disable conntrack, bucket increases, following the general best practices ) our firewall is running at high amounts of CPU, but coping. However, once we start introducing Exit Nodes into this equation, things turn sour.
So, since we do not want to trust only routing level separation between Exit Nodes and internal networks, we're going to have to invest into new hardware that can cope with this. Before this, we tried Ingate firewalls, and they weren't capable of coping with the load of guard nodes.
( The traditional "linux box in front" doesn't quite cut it due to networking hardware in most cases. )
So, in summary, when you get to the point of actively dealing with 8-900Mbps of Tor traffic ( on top of normal users and others) what hardware is needed to cope with firewalling?
Regards, D.S. Ljungmark