Add ip-address/hostname to database

Problem/Motivation

Hello. I'd like to use the flag module for anonymous users to vote for movies.
As the winner get's a price, i'd like to have some control against "delete cookies / flag again".

Proposed resolution

I thought adding the hostname / ip-address to the flagging-table in the database.
Then I would have an insight into possible frauds.

I have no idea how to do that.

Thanks for ideas.