Newbie: How can I restrict user access to net or sites

[Adam Niemirowski <adam qcom com>]

Hello all,

Forgive me if this has been addressed.  However, I just setup 6.2 for a 
e-mail server / net access and I need to restrict some users from having 
access to the net.  All they need is e-mail access.  BTW, I have no ftp, 
telnet running if that makes a difference.

Other users need access to the net but some abuse the access and hang out 
at sites that they have no reason during work.  Can I restrict access to 
certain sites?

Is there a way to maybe partition out bandwidth?

Futher, what log files are the best to follow what is happening or is there 
a software package that does that?

sorry for all the questions at once, but I need some advice.

Thanks,
Adam