There are 2 types of bans.
Autobans. Isn't what it sounds like, it means someone pressed the ban button, but it's automatically carried out, as opposed to be manually entered. Though there is a mod or two running scripts because of the spammers. This results in the message You were banned by a forum moderator, email xxx. Both global mods and admins use this, so it isn't a guarantee it was a moderator, just more likely. I use autoban instead of manual bans for permanent bans because it's faster and more efficient. All bans in the modlog are autobans, and permanent.
Autobans ban the account involved only, you can still log in and do everything normally, just can't post or pm. It also adds units of evil to the IPs used, a new account created using these IPs will need to pay a fee. Units of evil increase with additional bans. Nuking is essentially an autoban+deletion of posts.
Manual bans are only available to admins, and are generally configured the same way as above, though it's possible to increase the scope of the ban to include things like registering from certain emails/providers, ips, subnets, hostnames, etc. Can also add multiple accounts to the same ban. It's also possible to prevent banned users from logging in at all using the banned account, this will prevent them from being able to read the forum and access pm's too though, so I rarely use it. These result in the customized reason for the ban+duration, insubstantial posts or whatever.
New accounts do not face any automatic restrictions beyond units of evil, a human needs to verify it. IPs alone are generally not conclusive evidence.
It is true that they can easily make new account and start posting again but they'll have to build everything from zero. Remember that this behaviour (ban evading) is not allowed and the new account will immediately gets perma-banned too if the Staff know about it.
So anyone with a copy of TOR can easily evade ban if they have alts and use different IPs on each?
Varying degrees of easy, being anonymous isn't as easy as people think it is, but yes. I would rather people be able to protect their privacy, even if it means it makes my duties more difficult, or impossible.
