Re:Most 16-year-olds don't have servers in their rooms
by hunter2_ on Friday December 22, 2023 @09:15PM
(#38741029)
> the WAN IP on your router will match the "what is my ip" website, but the problem is that it will also match many other people's routers
That's interesting. So the ISP is directing packets at the various customer routers using some other identifier than the WAN IP the router sees? MAC address or something?
Re:Most 16-year-olds don't have servers in their rooms
by dwattttt on Friday December 22, 2023 @10:30PM
(#38741370)
I don't specifically know, but typical NAT can use stateful flow information, i.e. "a UDP packet originated from inside the NAT to external IP/port X, packets from that external IP/port should be routed to the originating NAT/customer" (see https://en.m.wikipedia.org/wiki/UDP_hole_punching)
Re:Most 16-year-olds don't have servers in their rooms
by LilBytes on Saturday December 23, 2023 @02:23AM
(#38742334)
Some ISPs use MAC address filtering.
HFC (Hybrid Fiber Coaxial) and FttN (Fiber to the Node) are such examples. The rest of them if you don't have a static IP or an internet routable address, use NAT (Network Address Translation) and in some even more exotic environments they use Port Address Translating (PAT), but it's been many years since I've seen PAT in any way at commercial, residential or enterprise setups in ISP space.
But PAT is quite common in the reverse and forward proxy space.
My layman understanding is that the WAN IP on your router will match the "what is my ip" website, but the problem is that it will also match many other people's routers.
Basically imagine your home router and NAT has been moved into the ISP and is serving thousands of end users as well as you... you can't just configure the ISP's CGNAT to forward port 80 to you alone.
I'm not sure if there is a definitive way to know if you are behind CGNAT, however its definitely the case on all mobile networks.