Routing and bandwidth problem

[Tim Alberts]

>          4. Optional: Provide each tenant with an FTP-served directory on
> the server which can *only* be accessed from their network. So if they pull
> down the confidential something or their wife's nude pictures, other
> tenants cannot get at that information.

You should try ProFTPd (http://www.proftpd.org/).  There configuration is 
similar to apache where you can create virtual FTP servers for each IP 
address.  I've been using this program for years on my office network and it 
is always running perfect.