For those of you with this handy technology, the mobile phone, in the United States: you have an IPv6 address without NAT. Some of you even exist on a network using 464XLAT to tunnel IPv4 in IPV6, because it's a pure IPV6 network (T-Mobile). These mobile phone providers do not let the gazillion consumer smartphones act as servers for obvious reasons.
This is all to underscore the author's point: NAT may necessitate stateful tracking, but firewalls without translation has been deployed at massive scale for one of the most numerous types of device in existence.
This is all to underscore the author's point: NAT may necessitate stateful tracking, but firewalls without translation has been deployed at massive scale for one of the most numerous types of device in existence.