Wanting a firewall is good, you can have that on v4 or v6. However, after you add 3 simple firewall rules, NAT provides no additional security. Drop state=I

Wanting a firewall is good, you can have that on v4 or v6. However, after you add 3 simple firewall rules, NAT provides no additional security. Drop state=INVALID Allow state=EATABLISHED,RELATED Drop all You're now just as secure as if you had a typical NAT setup, but without the decades of kludges that is NAT.