Why? What's the (supposed) fear?
Disclaimer: I have never worked for Amazon but I can add some input from the assorted medium to large companies I have been employed with. I won't mention any names. This is for someone I know reads my comments wink wink
I am not justifying it, just adding some of the bits I experienced. There are many security devices that do not have the same capabilities on IPv6 as IPv4 yet. Some enterprise IoT devices only support IPv4. Adding to this some network engineers don't want to step outside of their comfort zone and tooling/scripts to generate configurations automagically do not yet support IPv6. As the company grows they hire less Sr. Network Engineers and some of the new people depend on but do not understand the automation. e.g. someone wrote some API and they retired or changed companies. Some tooling may remain stagnant for some time. It's also a heavy lift to retrofit some enterprise environments for smaller changes so people fear the outages they will induce implementing IPv6. In some companies it is a major change just to migrate customers to a new load balancer endpoint. There may also be hundreds of undocumented things due to employee churn and lack of change control running that when broken will cause extended outages. And then there is internal politics and finger pointing...
Again, not justifying it, rather I think there are too many moving bits and complexity that people have added over the decades and they are paralyzed by fear and risking the loss of their paycheck. And then there is the embarrassment that comes from having to acknowledge that nobody knows the current state of an environment and that embarrassment can go all the way up the organizational chain.
That is based on my experience of being brought into companies with the speicifc task of, "Hey, make this simpler, reduce outages." It's rarely strictly a technical challenge but rather having to navigate politics, personality types and individual sub-org leaders that have had independent control of their environment for a long time. The more I think about it this could be a topic in and of itself how companies induce self inflicted bloat as they grow.
Having NAT and a firewall gives you a better illusion of privacy. Sure you can track devices from the outside world, but its pretty hard.
If you have v6 configured in a certain way, then your IP address is basically a UUID for your machine. Plus you can't really just stop ICMP anymore so you can trivially ping it (caveats apply)
In the early days of IPv4 many big companies did not NAT IPv4. I was at a company that did this. Our workstations all had routable public IPv4 addresses. There are still some companies that do this. One of these was a company that had 20 managers and VP's on a call when I just wanted to give their network engineer a CIDR block and a pre-shared secret for a network VPN. I suspect they will be using public IPv4 addresses internally forever. And I doubt they will ever sell their /8's unless people comment on their Vogon poetry.
Amazon is probably one of the exceptions as they have so many geographically disperse configurations it would be harder to continue using RFC1918 address space. Not impossible, just difficult. I can think of a few other big companies that do manufacturing that are spread out around the world that would probably run into walls with RFC1918 at some point. I've seen some of them take over public address space for internal routing which then breaks access to some things on the internet thus requiring double/triple NATs. 1/8 assorted, 25/8 MoD, 26/8 DISA are a few I've seen.
A lot of big universities did this and even still do this to a large degree. They got huge IPv4 allocations early and there was no scarcity.
Eh… If I was a company that wanted to use IP addresses to fingerprint users, IPv4 vs IPv6+privacy extensions both seem identical to me. Multiple requests from the same IPv4 address mean “someone, perhaps more than one person, from the same household/wifi”. Whereas multiple IPv6+privacy requests from the same /64 prefix means the same thing.
ie. You just consider the first 64 bits of the IP and can assume the same amount of information you already would assume from the IPv4 address. Just ignore the trailing 64 bits because it’s expected that they’ll be randomized/shuffled even from the same client.
I don't know how companies are doing it but they are able to track your IPv6 changed daily or not.
Not saying this is what you should do, just a common rationalization.
Pretty sure that's enough time to test it in development...
I'm curious how people do it btw, if you have tips to share, I'm all hear. Do you simply rate limit IP ranges? Even limiting per /64, it's still potentially quite a lot of /64 to track.
It's possible that cloud providers assign smaller ranges to their customers, so you may need to allocate more bits for granularity in that case; on the other hand, one might naively assume that cloud providers are more responsive to abuse reports than ISP's.
Cox & Spectrum only hand out /56. I'd hate to be banned because my neighbor did something bad and we happen to be in the same /48.
> Do you simply rate limit IP ranges? Even limiting per /64, it's still potentially quite a lot of /64 to track.
Yes you'd limit by /64 or slightly larger.
The live set of IPs shouldn't be very big.
If you go the extra mile and simultaneously track /64, /56, and /48 with moderately increasing thresholds, you'll probably end up causing less collateral damage when you block someone than with IPv4.
People see a 10.x and instantly know it can't be reached from the public internet. IPv6 is much harder. For internal-only stuff there is the fd00::/8 block, which AWS actually does use, but there is no equivalent range for outgoing-only connections.
There are some annoying operational issues around it as well, common one: DNS hostnames for devices that only do SLAAC
If your network card breaks you switch it out, and you make sure your IPv4 settings apply to the new card.
If you fully rely on IPv6 you'll get a new address.
And if your devices self-update DNS then you have to make sure they pick the right address, as there can be many due to privacy extensions.
Lastly, combining privacy extensions plus hosting stuff is hard, as you don't know on which address a certain port is bound.