Just because an IP doesn't answer to someone - especially coming from the general internet - doesn't mean it's not in use. This should be obvious to anyone even with the tiniest amount of understanding of TCP/IP networking and IT in general. Hence the authors of such a 'scan' aren't that credible to me. Unless 'scan' is something totally different.
Of course, some of these machines actually might have valid justification for squatting on a public IPv4 address. Perhaps their firewalls are configured to drop all packets except those from a handful of "trusted" IP addresses, so a random scanner on the Internet gets no response.
But I doubt that such cases account for the majority of "seemingly unused" IPv4 blocks. What's more likely is that some large organization was assigned a massive block of IPs 20-30 years ago and never found much use for them. IBM owns 9/8. Xerox owns 13/8. HP owns 15/8. Apple owns 17/8. Ford owns 19/8. Several pharmaceutical and chemical companies also own an /8 each, as do some universities. Do they really need 16.7 million public IPv4 addresses? Of course not. But I wouldn't be surprised if they started to sell bits and pieces of their blocks once the price per IP goes up enough.
That's a horrible hack and those people are wrong. Separate your concerns; addresses for addressing, firewalls for firewalling. Using private addresses adds extra complications; what if someone's home network uses the same range and they want to connect to your VPN? What if you merge with another company that's using the same range? What if you want to use FTP or SIP or any other protocol that uses the internet the way it was intended to connect to a server in a different office, are your packets going to make it through or not? You'll observe that private addresses have been deliberately left out of IPv6, for good reason.
B) I agree there are inconveniences and complications with using private addresses in ipv4. But it seems to be necessary thrift in the ipv4 world of rapidly expiring address space; using public routable ipv4 addresses for machines which do not communicate with the public internet is perhaps a luxury we can not afford, even in cases where to do otherwise is inconvenient or complicated.
I imagine the only reason you would use a IPv6 private address is if you didn't have allocated global ones. It's just replacing no chance of collision with some chance of collision.
Yes, but they were a late addition, postdating IPv6 by 10 years, and aren't meant to be used lightly.
IPv6 is designed for easy & automatic renumbering so there's less need to hold on to a specific prefix as an "island of stability".
Just gotta make sure OSPF, (E/I)BGP and L2/L3 drop these ranges though.
Why? A router could still offer private IPv4 and encapsulate IPv4 packets in IPv6. The carrier can decapsulate IPv6 packets and perform NAT.
In fact, this is how my home cable connection works (per DS-Lite [1]). Our modem/router only gets an IPv6 address, but IPv4-only devices work fine.
SNI removes the requirement from HTTPS websites to host one domain per IP. This is done by having hostname part of the initial handshake.
Many websites or at least most (hopefully all) webapps these days serve over https, at least the ones that require user input like login. So there's the need for at least one public IP per site.
With SNI these could be all served from the same IP.
Now imagine CDN services like AWS CloudFront -- to support sites with SSL certificates you must use one IP per cert in EACH region or whatever the distribution granularity is.
Now this my friends is why AWS CloudFront asks $600/mo for each custom SSL cert domain and with SNI custom SSL it costs $0/mo.
As soon as all the 99.9% browsers/clients support SNI we'll be living in a better place with more free IPs. So we can finally distribute static content from CDN through custom SSL without the $600/mo pricetag.
It's naive to think everyone would go to SNI-based hosts with IPs shared with strangers but at least within the same datacenter for the same company IPs can be more easily conserved.
[1]: https://blog.wireshark.org/2010/04/t-mobile-clever-or-insane...
I think if ARIN wanted to, they could give everyone a year to "substantiate their allocation" and set the policy something like "companies must return for reallocation any overallocations."
The risk of not returning an overallocation, well I'm not sure. ARIN certainly has teeth, and companies should simply be expected to correct these huge overallocations.
Just like the open source community comes together to solve serious problems, if we as a community enforced an ethical standard and some key people stood up raised this as an issue, I'm willing to bet ARIN could replenish a stockpile of IPv4 space.
So the question I'm asking is, since ARIN is empty, clearly they aren't interested in keeping a stockpile of addresses. Why not? I guess the more generous alternative is simply they have failed spectacularly at their stated goal.
ARIN can go over the pool of post 1997 addresses they have allocated, but I think you would find much smaller unallocated blocks.
When the three months are up you can go looking for four more companies, and hire some more lawyers too.
Watch this clip to understand why fractional solutions wont save us : https://www.youtube.com/watch?v=F-QA2rkpBSY
Warning, its "Perhaps the most boring video you'll ever see, and definitely the most important."
The only way they are going to give them up is if the is worth their while financially.
Put another way, what is the incremental value to provide access to your service to those IPv4 only users/devices? Whatever that value is, in theory you would be willing to pay a portion of that for access to IPv4 address space.
Luckily supply is not really constrained, so much as it is controlled. You can always get more IPs if you need them, but the cost associated I think will continue to increase... until enough people not only just support IPv6, but actually abandon their IPv4 addresses.
When the only devices that your software or service is designed to run on all support IPv6, then there's "no point" in having an IPv4 address. You almost have to get to the point where IPv4 is "not worth the trouble". And we are very, very far from that point I think. More to the point, more people are likely to think that it's IPv6 that is not worth the trouble.
Could of course just ignore that, but it's a good low pressure reminder to get around to sorting out IPv6...
Windows XP is a pain all right, the lack of SNI along with the limited v6 support means anyone using it really is stuck on v4.
Maybe the recent EOL for XP will cause a dramatic shift in the number of people continuing to use it? At least in the more well-off countries like the US, UK etc, opening the door for SNI :)
Anything that gets IPv6 adoption to mainstream is a Good Thing, but more likely we'll just start seeing the $1/mo/IP become $2/mo/IP, and upward... The squeeze will just continue as people make more money off of it, and we'll still need IPv4 addresses for compatibility with people running Windows XP in 2020.