I see this sentiment from time to time, but it doesn't make sense to me. Any way you do it you need to deploy new hardware, new firewall rules, new end user applications, etc... What parts of IPv6 are harder now than they would be with just a fat IPv4? Is it really so complicated now that you can't fragment packets on path? Is Neighbor Discovery Protocol really so much more difficult to understand than Address Resolution Protocol? Do you yearn for DHCP and NAT?
Administrators memorized IPs a lot. This is hard to under estimate and is frequently the disconnect I see when a SWE doesn’t understand why people could possibly complain about ipv6.
This is likely the #1 issue I hear from people in the field.
#2, for better or worse, NAT became peoples’ comfort blanket. It’s a boneheaded stateful firewall regardless of how long people can scream “NAT isn’t security”. By forcing people to take both changes at the same time, adoption was setup for failure. So many places in the US turned it off “because nothing I use is v6 only” and they weren’t quite sure if they were exposing their end hosts accidentally.
#3, link local addresses, guids, etc all assigned at the same time is a steep learning curve. Which will be used for which flows in the network? If my ISP changes my prefixes, do I know have to reconfigure all of my local network firewalls?
#4, prefix delegation, should each client behind my router get its own /64? My ISP only gives me 128 of them to hand out which is a problem for IOT. Guidance here is weak.
Burning all of the early adopters with the slaac vs dhcpv6 vs privacy extensions didn’t help either.
Nobody gives a shit about fragmentation. The upgrade UX was a disaster.
#1 seems pretty unavoidable. Yes, bigger numbers are harder to remember, but we're in this mess in the first place because we made the numbers too small. It's kind of like complaining that phone numbers are too hard to memorize after we switched to 10 digit dialing. That may be true, but since we all have address books built into the phones now it's really not an issue.
#2 is people being nervous, but seriously the "DENY incoming on $WANIF if not in state table" rule is all you need. This always struck me as "I refuse to learn anything new, no matter how little I need to learn".
#3 Again, people worried about the firewalls when they really don't need to be.
#4 A /64 is a subnet. Normally all of your devices would be on the same subnet, although with IPv6 you get a whole bunch which is nice. You can put the IoT devices on a different subnet that is partitioned from the rest of your network because they are IoT devices which means they are adorable little security vulnerabilities.
I think your last point is a good one. DHCP6 was poorly named. People thought it would work like DHCP did in IPv4 but it's really not intended for that. It's really only meant for routers, not for end hosts.
You missed a couple of points where I think IPv6 did have some flaws. SLAAC originally lacked a lot of the extensions that DHCP offered, like DNS server advertisement. In theory you could anycast your DNS queries, but DNS is a dodgy enough protocol already and this was really not a great idea. It's one of those things that works great in the lab, but is kind of a nightmare in the real world. It also offers no way to communicate back to a DNS server what IP address you have chosen, so if two hosts want to communicate with each other, especially if they are not in the same subnet, it becomes difficult to determine what their partner's address is. All in all the IPv6 committee considered DNS to be an application protocol and outside of their scope, but application developers consider it part of the network and so it got left out in the cold.
Using the MAC address to create the IPv6 address was also a bad idea from a big data standpoint. Luckily that was one of many options so it was easy to switch without breaking anything.
> #2 is people being nervous, but seriously the "DENY incoming on $WANIF if not in state table" rule is all you need.
This didn’t exist. Many of the early implementations of “support” for ipv6 was a checkbox that said “enable”. These cheap routers (which is what the majority of people without deep pockets are on) rarely even gave you an explicit stateful firewall UI.
If you got a “firewall” option at all, it was to block stuff from getting out of your network, not in. Know why? Because “NAT already did that”. If you wanted inbound unsolicited traffic you used port forwards or the “DMZ”.
It’s not people being nervous, it’s the vast majority of network vendors not making the UX any good. I pushed people to try v6 hard, it was not the rosy transition it was supposed to be. v6 for a while ended up being a great accidental exfil path for malware for administrators that screwed this up. Don’t try to downplay it, it just makes you sound like an armchair quarterback, not smart.
> #4 A /64 is a subnet. Normally all of your devices would be on the same subnet, although with IPv6 you get a whole bunch which is nice.
A /60 is also a subnet, so is a /127. Subnetting is just breaking up larger IP spaces.
Anyway, you missed the point of the comment. What I was getting at is that doing prefix delegation for home users for anything more than a /64 is immensely wasteful. Yet a bunch of very large ISPs do just that.
Want to guess why? Once again, bone-headed implementations in off the shelf routers that do give a /64 per WiFi client. Untold waste in the v6 space because addressing guidance was (and still is) so poor.
If your firewall can do NAT (and spoiler alert: it can) then it has stateful logic built in. Maybe some of the really early home stuff didn't support it on IPv6, but that's long in the past. If you're worried about IPv6 using to exfil data then you're well beyond a great many administrators in locking down the network. Usually malware just exfils on IPv4 HTTPS because that's already allowed, and it's only avoided in places where the deep packet inspection services only run on IPv4.
This is where you see a lot of corporate pushback on IPv6. The Deep Packet Inspection vendors have been very slow to adopt so corporate policy is often just to block all IPv6 period.
I won't argue against a lot of home routers having egregiously bad firewall configuration UIs though.
In IPv6 a /64 is special. It's the smallest network you are supposed to allocate. Some people think it is the equivalent of an IPv4 single address, but this isn't quite right. It is still a full subnet. It is better thought of as the IPv4 /24 behind a single NAT address. Home administrators are expected to put all of their hosts on it. Assigning a /64 to each client is not supposed to be a typical use case, and would be mostly to avoid having the clients inter-communicate. The problem however isn't wasted space, it's just that you'll exhaust your typical home /56 too quickly.
I can see you're concerned about running out of IPv6 addresses due to excessive waste, but we've not even scratched the surface on them. The address space is mindbogglingly huge. A lot of the optimizations we have to do to save space with IPv4 are simply not relevant in IPv6.
Just about every thread on HN has a debate between the optimal and why can't people just get it and the practical and why they can't get it to be optimal.
If you can't implement it easy enough for it to be optimal once in place, it's not optimal. Whatever the advantages of ipv6 are, it wasn't enough to suck everyone in. You have to consider your environment. And re-training sysadmins is part of it and just telling them "lol it's easy" isn't going to do much to get them there.
By the time we get fully switched over, I wonder if we won't be pining for whatever comes next.
A lot of the trade-offs that people like to complain about IPv6 were specifically made to "rip the (backwards compatibility hack) band-aid off" and help make sure that we won't be pining for "whatever comes next" anytime soon.
IPv6 could have been a lot more pragmatically backwards compatible, absolutely. It would have been much more doomed as a temporary solution in that case. The IPv6 we got was designed to be a more permanent solution, which makes it feel much less pragmatic. That's somewhat how trade-offs work.
Right - I’m not a network admin, but back a few decades when I was hanging around the CS lab and setting up home networks, I sure had to type in IP addresses by hand a lot. If they were more than four bytes long that would have been painful!
