I am new to Linux and also new on the job. My boss told me to set up a linux server for the company capable of securing our wireless network apart from the wireless passkey. He wants everyone to be behind the server. I have set up DHCP and Source NAT. We can access the internet through the server but i have not yet met his needs of other security features using the linux server. Is it possible for staff to have their individual accounts on the network through the server and how? does it cover central login and authentication too? What other set up must be done on the server apart including using iptables firewall.
Note: All workstations are on Windows OS

Although my experience has been with openSuSe we may usefully try together to keep this thread productive.