It is always a mystery how people just randomly misinterpret what I write. At literally no point did I mention port mapping.
I am pointing out how the problem NAT “solves” is just dynamic address configuration. They have implemented a N+K bit address where the N-bit prefix is routed and allocated using IP and the low K-bits are routed and allocated like a custom fever dream.
You can just do it all the same way instead of doing it differently and worse for the low bits.
To be clear, the router should rewrite zero bits in the packet under the scheme I am describing just like how routers have no need to rewrite any bits when routing to a specific globally-routable IP address.
You get a lease for a /N+K address. /N routes to your router which routes the last K bits just like normal as if it had a /N-M to a /N route. This is a generic description of homogenous hierarchical routing.
If I understand it correctly, you're suggesting formalizing a way to make parts of the (host-specific) port canonically part of the network-wide address, no?
This still sounds like a very bad mixing of layers, even if done in a perfectly standardized and uniform way.
> It is always a mystery how people just randomly misinterpret what I write.
If this is intended literally and not as a general complaint: My main problem of understanding your suggestion is that I don't know what you mean by "IP+NAT address". NAT is a translation scheme, not an address.
Maybe it would be clearer if you could provide an example?
I did provide a example:
> You get a lease for a /N+K address. /N routes to your router which routes the last K bits just like normal as if it had a /N-M to a /N route.
> This still sounds like a very bad mixing of layers, even if done in a perfectly standardized and uniform way.
No, I am describing a generalization of IP to arbitrary concatenated routing prefixs.
NAT has the same problems as if we lived in a alternate world where we decomposed IPv4 into 4 8-bit layers and then used a different protocol for each layer. That is obviously stupid because the subdivision of a /8 into /16s and a /16 into /24s is fractally similar. You can just use the same protocol 4 times. Or even better, use one protocol (i.e IP) that just handles arbitrary subdivision.
In the IPv4 (no NAT) world your application has a 49-bit address. Your router is running a DHCPv4 server and allocates your computer a /32 and your computer is “running” a DHCPvPort server that allocates a 17-bit prefix to your applications.
In the IPv4+NAT world your application has a 49-bit address. Your router is “running” a DHCPv4+Port server and allocates your applications a /49, but only tells them their /32 and then rewrites the packets because the applications do not know their address because the stupid router did not tell them.
In good world your application has a 49-bit address. Your router is “running” a DHCPv4+Port server and allocates your applications a /49 and tells them their /32 prefix and 17-bit segment. No packet rewriting is necessary.
Your router could also choose to allocate your computer a /32 subnet and leave DHCPvPort to your computer. Or it could give your computer a /31 if you have 8 interfaces. Or a /34 as a /32 subnet with 2-bit port prefix. Each node routes as much or as little routing prefix as it understands/cares about.
This is a generalization of IP that can handle arbitrary-length, arbitrarily-concatenated routing in a completely uniform manner and all the pieces are basically already there, just over-specialized.
The original SOCKS proxy specification was something like this. You'd LD_PRELOAD a library that would make the application think it was running directly on the proxy server, and it supported both connecting outbound and listening.
I didn’t see it as mysterious. 25 years ago, the problem as stated went through lots of consensus to become IPv6. It took a few years for SLAAC to emerge. But we don’t need it to be homogeneous; the router advertises different feature levels via ICMPv6.
NAT allocates ports. If you reserve a port, that's old good port forwarding.