Good Afternoon JungleGeorge --
While several ISP's do have multiple proxy servers between their clients and the web, most do not. We can also tell when a proxy server is being used, so obviously we don't ban those people. Most cable networks (comcast, road runner, etc.) use dynamic addresses with endless leases, so until the power goes out or the user unplugs the modem, the IP stays the same. DSL modems also get their own public addresses most of the time, but each time they connect the lease is renewed, thus getting a new IP. Generally, only the last octet changes, so it isn't a problem. When we see two user names logging in from a unique static IP address over and over again, that pretty much gives them away.
Scanning MAC addresses is a good idea, but it suffers from the same problems, it is just as unrealiable as tracking IP addresses. MAC addresses can be spoofed, just like IP's. In fact, you can spoof a mac address using the same software you would to connect to a site via a proxy server. Nothing is 100% reliable in the computer world, I'm sure you can agree with that.
Koiphen.com isn't a fortress, it doesn't need to be. We could implement all kinds of security, but all it would do is cause more problems for the good people. Nothing is completely secure on the internet, it just works at levels. The higher the level the more motivated someone would have to be. We are all here to talk about the koi, we don't want to waste hours each day analyzing network logs.
It's all about the hobby folks! Happy Holidays from Koiphen.com!
-Justin Pennington