I make an dhcp server on CentOS, and i apply a mac filter for my clients. Now, with a small number of clients (max 10) ,is not that hard, but what I will do with 2000 clients? My idea was to create a list (ex. "macfilter.lst") and this list, to be updated after a database. I have tow questions. First: How do i create a filter in IPTABLES that takes info`s from a file (file hosted on server) Second: Any idea about how to write a script, that update a file after a database?? Thanks so much for your help.