You don't need to, but it's a nice side effect for people who don't know what a firewall is.
I'd wager most home networks are protected only by the fact that they use NAT. ISPs are getting better about shipping routers with firewalls on by default, but it's still not there.
I'd wager most home networks are protected only by the fact that they use NAT. ISPs are getting better about shipping routers with firewalls on by default, but it's still not there.