How to log user's IP in RoR?

[Pawel Stawicki]

Hello,

I want to log users who enter my site and what they are doing.
Registration and login is not required, so what is left is IP.
(something like wikipedia, you can edit without logging in, and then
there is your IP in log). How to get this IP in Ruby on Rails?

And if you know some nice tutorial about logging in ruby I would also
appreciate

Regards
Pawel Stawicki