Ok, so i need your help guys, i want to create a seedbox on my spare PC running ubuntu
its basically a HTPC, so i will be using it via remote in all probabilities.

so what i need to do is:

1. have usernames and passwords for login purposes, more than one.


2. be able to log into the torrent client and add/modify their torrent


3. logout

but i need to impose restrictions such as:

1. no one can access settings


2. no one can make changes to stuff added by some other ID

in short, what i aim for is making that machine into a multi user seedbox.
it has 2 GB of RAM and A TB of HDD space

any torrent client is welcome so long as it will do the job.
any idea on how we can do it?