3 ms·
> Networking isn't my strength, so I don't know where, or what part of the my local network decides that 192.x.x.x can't be routed, and so doesn't. It's a stan
by RiverCrochet 3y ago
> Networking isn't my strength, so I don't know where, or what part of the my local network decides that 192.x.x.x can't be routed, and so doesn't.
It's a standard that is "enforced" in two places I think:
* Place 1: ISPs configure their carrier-grade routers to drop it if they receive it.
Technically, there really is nothing stopping an ISP from actually routing it, just like there is nothing preventing you from assigning an already-assigned address like one of Google's to a NIC in your LAN.
But ...
* Place 2: Internet registries won't give out IP blocks in these ranges. So no ISP can make an AS that has routes for these addresses.
Technically again, there really is nothing stopping a registry from assigning something in the block. Imagine if someone bribed a registry to give them out. These assignments are basically what makes the global BGP table that is the "top layer" routing information for the Internet.
But:
A) all registries would have to cooperate at once for it to be globally reachable - ARIN, RIPE, APNIC, AFRNIC, and LACNIC - and current geopolitics would almost guarantee that wouldn't happen. IPv4 space is scarce and valuable, so they'd really fight over it, and
B) everyone is already using it for private IP space anyway, so even if you hosted something on a publicly accessible 192.168.1.1, no one would be able to reach it due to existing configs and assumptions, so it would be pointless.
- bluGill 3y ago> So no ISP can make an AS that has routes for these addresses. A lot of ISPs are using these addresses internally as part of a carrier grade NAT since there are not enough IPv4 addresses to go around. So they do give them out, they just don't route them except through their NAT system, and they wouldn't want to route them as any effort would break their system. Of course some ISPs have more IPs free than others.
- iscoelho 3y agoThis is not correct. RFC6598 defines CGNAT IP space as 100.64.0.0/10 (https://datatracker.ietf.org/doc/html/rfc6598 https://datatracker.ietf.org/doc/html/rfc6598). RFC1918 (private IP space) is a different allocation.
- cesarb 3y ago> RFC6598 defines CGNAT IP space as 100.64.0.0/10 That's a relatively recent RFC; there are ISPs which have been using CGNAT for longer than that, and they do use RFC1918 addresses for their CGNAT (for instance, I know of one which used something in the 10.x.x.x range for CGNAT, which works in practice since most domestic networks use something in the 192.168.x.x range).
- iscoelho 3y agoI'm familiar with CGNAT mostly on Cellular Networks. VZW (debatably largest CGNAT in USA?) uses RFC6598. I'd be surprised (but not too surprised honestly) if the other ones haven't cleaned up the skeletons in their routers yet.
- ArchOversight 3y agoSquatting on DoD IP space was also the norm for an ISP I worked at...
- iscoelho 3y agoSome people just want to watch the world burn.