IPv6
Internet Protocol v6
Internet Protocol version 6 (IPv6) is the current version of the Internet Protocol (IP). The IETF developed it to solve IPv4 address exhaustion, which has since become reality: IANA handed out its last IPv4 blocks in 2011, and the regional registries followed soon after. IPv6 is no longer a future technology but a deployed one, carrying more than 40% of the traffic reaching Google by the mid-2020s. IPv6 uses a 128-bit address, in theory allowing 2128 (about 3.4×1038) addresses, although a number of ranges are reserved or excluded from ordinary use. That is vastly more than the roughly 4.3 billion addresses of 32-bit IPv4. The two protocols are not interoperable on the wire, so hosts generally run both at once (dual stack) during the long transition.
Setup IPv6 NAT on OpenWrt Router
Introduction This tutorial is a HowTo for setting up IPv6 NAT (NAT66) on an OpenWrt router. Why would anyone want NAT on IPv6, when the whole point of the protocol was to give every device a globally routable address? In my case the campus network (China Education and Research Network, CERNET) authenticates per device and only assigns an IPv6 address to a device that has logged in. Every other device behind the router is left without connectivity. NAT66 works around this: the router authenticates once, then masquerades all LAN traffic behind that single authenticated IPv6 address, so every device on the network reaches the IPv6 Internet through it.