The answer to my question maybe is not that hard but anyways, I do not know what to do. So, I just got in a new job in a Univerisity and I found out that the network (the LAN) is full of public IP addresses. Seriously, the whole LAN (probably more than 150 hosts) has it' own internet IP address and I don't know how to manage it. I have a very good experience using iptables (Linux firewall) in a NAT'ed environment. But then how should I proceed in an environment where all my LAN is working with a bunch of public IP addresses? Should I just use the "forward" rules and ignore the NAT rules or is there any other issue in such environment which I should take care? Can I add a firewall between the router and the LAN in order to produce packet filtering for these public IP addresses in my LAN or will this just not work? Thanks!