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No ISPs don't need to do NAT but you can if you like. You also don't have to do NAT with IPv4 if you only have one device or get a subnet from your ISP. It's ju
by bauruine 4y ago
No ISPs don't need to do NAT but you can if you like. You also don't have to do NAT with IPv4 if you only have one device or get a subnet from your ISP. It's just done because we don't have enough v4 addresses.
They can do subnet to customer correlation. The IPv6 is randomly generated by your device if you use SLAAC. But if your ISP is an adversary you have pretty much lost anyway. If they provide you with a router they can see all devices in your network (MAC and hostname) and they could also map certain devices to certain port ranges and sell that too.
- pbhjpbhj 4y agoI'm sorry, you've misconstrued the question. The context is the privacy extension to IPv6 under RFC 4941. So, my question was would ISPs need to do NAT in order to provide that extension -- I only skimmed the RFC but there was no other obvious way to me for it to be provided that wouldn't fall to an adversarial ISP because it appears they must do NAT to make that work? AIUI ISPs provide a fixed prefix to customers. So I'd need to look how SLAAC would work if it uses a random IPv6 address; surely your ISP only has allowance to use a limited set of numbers that are allocated to them by IANA or whoever.
- bauruine 4y agoThey they don't need NAT that is simply called routing. The ISP sends every packet that is in your assigned /64 to your routers IP address. It's called prefix delegation [0] Yes they get a /32 by default (at least in RIPE) larger allocations need justification. But there are 2^32 /64 subnets in a /32 so every ISP gets a complete IPv4 internet of /64 they can assign to their customers at will. Your devices assigns itself a random IP address from that /64 network your ISP gave you via prefix delegation. [0] https://en.wikipedia.org/wiki/Prefix_delegation https://en.wikipedia.org/wiki/Prefix_delegation