Well, an ISP does do that, but so does an end user's network. So if I put a Tor node on an ethernet ("PHYSICAL infrastructure") and then connect that to an ISP ("other PHYSICAL networks"), that doesn't make for a real good way to differentiate between an ISP, a commercial ISP customer who gets routed IP networks via BGP, or an end user who has an ethernet behind a NAT gateway.
I was speaking of TOR as a service. The service is not provided inherent of= the infrastructure to pass packets. It's more similar to a tunneling proto= col service.
So if we can choose convenient definitions for the sake of discussing the issue, this is a pointless discussion, because you'll use your preferred definitions and I'll use mine, and we'll both be right by that logic. Tunnels and VPN's are a fact of life on the modern internet, though. Those could be considered services. Or they could be considered part of the infrastructure.
From my point of view, they're just a way to attach to the Internet in order to gain specific characteristics (a secure pathway, or IPv6, or whatever). When you look at it like that, Tor looks suspiciously similar to that, in that it's just a way to attach to the Internet in order to gain anonymity - a characteristic. The traffic flows through a Tor node in much the same way as traffic flows through a NAT gateway, being modified a bit in the process.
The person hosting the endpoint on their infrastructure would be the servic= e point and they are the ones acting as protector and as such should take o= n the responsibility as such. I can feel lawyers rubbing their hands togeth= er as I type.
You could say the same thing about Internet Service Providers. But ISP's have cried foul at that for years, and even got significant protections embodied in law. ... JG -- Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net "We call it the 'one bite at the apple' rule. Give me one chance [and] then I won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN) With 24 million small businesses in the US alone, that's way too many apples.