alt Hacker News> NAT and firewall are two completely separate things that can exist independently of each other.
This is kind of like saying that web browsers don't have to have a graphical interface. Or that a web browser doesn't necessarily support HTTPS. It's correct, but not practically correct.
The reality is that essentially all NAT software you'll actually encounter will be integrated into a stateful firewall because the two systems share so many functions that most projects and products that do one will also do the other. If you have a system with NAT set up and there is no packet filtering, it's most often because you've intentionally gone and disabled all the packet filtering, not because you need separate software for it.
It is important to understand that NAT doesn't have any inherent security to it, but criticizing people for talking like NAT is a feature built into firewalls when NAT is overwhelmingly a feature built into firewalls is a pretty unfair reading when we're talking about general deployments. Even with the technical audience of HN, we're not discussing carrier grade NAT here or other highly specialized or exceptional deployments.
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> when NAT is overwhelmingly a feature built into firewalls
This is just not correct. NAT and firewall are simply orthogonal concepts and can and often are deployed separately. A simple example is your average small SOHO router, which usually has NAT but quite a lot of them lack a firewall.
SNAT absolutely has intrinsic features that are utilized for security purposes.
This isn't to disagree with your main point. Many people in this topic have an oddly narrow definition "firewall" that tends to fall along the lines of "whatever makes me right and you wrong".
A statefull SNAT implementation itself has most of the characteristics of a "firewall".