Another one would be
Coyote Linux. And you're still confusing technologies. RADIUS (and by deduction, FreeRADIUS) have
nothing to do with how a firewall works.
What you want is a firewall (only allow connections from certain IPs to certain ports) / gateway (communicate between different networks and allow a certain amount of connections between them).
You would need RADIUS if you'd have a modem/DSL pool, which your customers/employees use to connect to you and you'd want to authenticate them. While the two technologies are often used together, they're doing two different things.