I recently purchased an old (but still functional) Dell Server, and then put Ubuntu Server edition onto it. It has been my first time with it and I have having loads of fun learning the command line stuff.

The reason I bought the server was to use it as an SSH Tunnel for my friends and I. I got the OpenSSH Server running on it and have managed to connect to it from other computers (Windows) using Putty. I haven't tried connecting to the server from outside of the network, but I'm guessing you just forward the port for the server and type in the external IP of the network instead of the internal IP. Please correct me if I am wrong.

I am just testing it with the computers at home, and have made 3 accounts (for my friends), these account don't have admin access so they can't do anything (that my friend's are capable of doing) but tunnel.

I know this has been a bit long winded, but here are my 2 questions:

1) Is there anyway to monitor (from my admin account) what is going on? I mean, who is currently logged on, who is consuming the most bandwidth being used by each user, the amount of data downloaded from each user, etc. (I know this is a lot, but so far the possibilities of Ubuntu seem limitless, so it's worth asking!)

2) Is there any way of controlling my friends? I mean, if I find out they are viewing inappropriate websites, etc, can I ban them? Or limit their bandwidth if they are slowing the connection down?

Thanks in advance, and any advise, whether is pertain to these questions or not would be much appreciated,