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> If not for NAT, we'd all need a firewall

You still need a firewall regardless of NAT. Otherwise, every time you take your computer outside of your home, you're no longer protected. Any attacker or compromised device on your hotel, airport, or coffee shop wifi network would have direct access to your machine.

by baron3dl12 hours ago|

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I think about this frequently. IMO, geographic sparsity is the biggest difference. Every malcontent on the planet just can't reach my door, and the physical reality of movement through space means they can't reach my door, AND every other door on the planet, in the same way they can reach every IP, or practically every IP.

There's probably a field of study with vocabulary and accompanying proofs of significant rigor that prove or disprove this. Maybe they'll stop by our little subthread and clear it up.

by ElectricalUnion8 hours ago|

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> If not for NAT, we'd all need a firewall

A NAT implementation could broadcast any "WAN" side incoming packets to all link local clients (aka: put everyone in the DMZ). The only thing preventing that is a stateful firewall.

by api10 hours ago|

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Uhh... you can have a firewall without NAT, including one at the perimeter.

This is a very common misunderstanding. NAT and firewalls are separate concepts. You can also have NAT with no meaningful firewall -- a port remapping NAT that allows anything through.

Most IPv6 networks are firewalled but there's no NAT.

by tptacek4 hours ago|

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I think this is not really a good way to divide up the space. It's obviously true that there are non-NAT firewalls. But NAT was introduced as a firewalling technique. In the first decade of firewalls, there was a whole taxonomy of different kinds of firewalls: application layer gateways, packet filters, "stateful" packet filters, and, yes, NAT.