Comment on IPv6 & Opnsense & Not Exposing Machine-Specific IPv6s to Corpos
Overspark@feddit.nl 1 week agoNAT is not a firewall and it’s not that great for privacy either, it’s not hard to fingerprint individual devices behind NAT. There are no cases where NAT is better than the alternatives, except when you’re out of public IP’s, which isn’t an issue with IPv6.
So you’re much better off by not trying to reinvent the wheel and using IPv6 the way it was intended. Use privacy extensions for privacy. Use proper firewall rules for security. Revel in the fact that NAT isn’t fucking up your inbound connections. Do not under any circumstances force the horrible kludge that is NAT into your IPv6 network.
glizzyguzzler@piefed.blahaj.zone 1 week ago
I gather people talk like NAT is a rung of hell, but I guess it works because I never think of it. Maybe it becomes shittastic at multiple NATs? With one router it seems straight forward to have port forwarding.
I do not understand why I want better inbound connections - but maybe if I get hit with a cgnat then I’ll understand?
Overspark@feddit.nl 1 week ago
Yeah multiple NAT is a lot worse, but normal NAT has a lot of corner cases too that most people just don’t run into that often. For example if two computers behind NAT want to listen on the same port, that just doesn’t work.
NAT is a “good enough” solution that tricked a whole generation of people growing up with it into thinking it’s a good thing. While in reality the best case is that you don’t run into issues and the worst case is that performance is horrible and you can’t do the things you want to do. The only people that benefit from it are lazy ISPs, not their users.
glizzyguzzler@piefed.blahaj.zone 1 week ago
I see now that a limitation I just understood for IPv4 (expose one port from one device only on the router) isn’t a thing for IPv6 working without NAT, every device on a LAN can be given a world wide routable address and expose the same port. Interesting, in my home I don’t think I’d ever run into that, but I can see issues like that pile up quick in big deployments.
Thanks for taking the time to explain all of this in detail!
Overspark@feddit.nl 1 week ago
You’re welcome, great to see how you’re taking all the comments on board!
There are more subtle problems with NAT as well. Say that PC-A opens a connection from port 1234 (to something on the internet), and PC-B opens a connection from port 1234 too. Now the router has to translate the PC-B connection to coming from port 1235 to distinguish them from each other. But if PC-C then wants to open a listening port on 1235 it won’t work because the port is already in use, even though you can’t see anything using that port!
NAT is full of ridiculous corner cases like that, which normal users aren’t very likely to notice. But once you start self-hosting things or trying to get something like older multiplayer games working the problems pile up fast if you’re unlucky.