Do we know any technical reason for this? Or are we left to think this is somehow a political thing?

Perhaps a little tin foil hatty and definitely not the only reason but Microsoft owns Github and also makes a boatload of money off of Azure. Incumbent cloud providers like Azure have a major advantage in terms of having plenty of IPv4 addressing available whereas a new entrant to that market would have to buy or lease that space at a premium. Thus, these companies have an incentive to keep IPv4 a necessity.

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IshKebab 2 hours ago | parent [-]

IPv4 is going to be a necessity for many many decades no matter what Microsoft do. Even when IPv6 is at 99%, people aren't going to want 1 in every 100 people to not be able to access their site at all. It'll need to be like 99.9% before we start seeing serious IPv6-only services.

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michh 10 minutes ago | parent | next [-]

I don't know what the percentage would be, but we do have some historical precedent that could give us a clue.

Best one I can think of is when bigger websites started actually dropping SSLv3 and TLSv1.0 (and later TLSv1.1) support, cutting off older browsers and operating systems. Google and Amazon still support TLSv1.0, but plenty of others (including Microsoft) have dropped 1.0 and 1.1. HN itself doesn't accept 1.1 anymore either.

Then there's browser support. Lots of websites - big and small - cut off support for Internet Explorer 6 when it was somewhere below 5% marketshare because the juice was no longer worth the squeeze. Of course, few of those actually fully cut off the ability to browse the (now broken) website fully but it's a datapoint suggesting trade-offs can and will be made for this sort of thing. Or to put it in the present: a significant amount of webapps don't support Firefox (3% market share) to the extent their product is completely unusable in it.

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jiggawatts 2 hours ago | parent | prev [-]

Sure, but the implementation in the public clouds is totally backwards.

What they should have done is have their core network default to IPv6 with IPv4 an optional add-on for things like public IP addresses, CDN endpoints, edge routers, VPNs, etc...

Instead, their core networks are IPv4 only for the most part with IPv6 a distant afterthought.

	▲	fogllgldl an hour ago \| parent [-]
		IPv6 is the protocol of the future. And will be so.

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alex_duf 4 hours ago | parent | prev | next [-]

It's a possibly a managerial thing, which KPI are you improving when spending engineering time on adding IPv6 support?

That said, for their HTTP stack they use fastly (as far as I understand), which should make the shift moderately easier.

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mmbleh an hour ago | parent | prev | next [-]

IPv6 is very difficult to implement and enforce reliable rate limits on anonymous traffic. This is something we've struggled a lot with - there is no consistent implementation or standard when it comes to assigning of IPv6 addresses. sometimes a machine gets a full /64, other times a whole data center uses a full /64. So then we need to try and build knowledge of what level to block based on which IP range and for some it's just not worth the hassle.

	▲	Tuna-Fish 35 minutes ago \| parent [-]
		... But that's no different from IPv4. Sometimes you have one per user, sometimes there are ~1000 users per IP. Most of the ipv4 world is now behind CGNAT, one user per ip is simply a wrong assumption.

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denkmoon 5 hours ago | parent | prev | next [-]

Outdated beliefs probably. When I talk about v6 support in our b2b saas, PM laughs and says nobody uses that shit. Big tech are massive laggards on this funnily enough.

	▲	throw0101d 16 minutes ago \| parent \| next [-]
		> Outdated beliefs probably. When I talk about v6 support in our b2b saas, PM laughs and says nobody uses that shit. Nobody except the 140M subscribers on T-Mobile US's network: * https://www.youtube.com/watch?v=d6oBCYHzrTA But sure, be IPv4-only and add latency by forcing traffic through an extra translation box.
	▲	ViscountPenguin 4 hours ago \| parent \| prev \| next [-]
		It's because big tech is USA based mostly, where there's still a glut of ipv4 available.
	▲	10000truths 2 hours ago \| parent \| prev [-]
		Definitely not for the biggest ones. Google and Meta have so many machines in their data centers that IPv6 addressing becomes a technical necessity due to the risk of exhausting the RFC 1918 address space. Naturally, they were early adopters of IPv6.

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direwolf20 4 hours ago | parent | prev | next [-]

It could be that they don't want to implement IP bans in IPv6.

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merpkz an hour ago | parent | next [-]

How does IP bans work in IPv6 case? One just blocks whole /64 or /56 address range?

	▲	throw0101d 10 minutes ago \| parent [-]
		I have not had a deal with this, but if I was going to, I would start at the /64 and move up by nibble (4-bit) boundaries: /64, /60, /56, /52, /48. /56 is often recommended as the minimum as for a (residential) customer. /48 is considered a "site" address prefix, and is the smallest allocation that can be advertised in BGP: * https://blog.apnic.net/2020/06/01/why-is-a-48-the-recommende... * https://www.infoblox.com/blog/ipv6-coe/a-48-for-every-site-a... You get 65k subnets with it, which is what you get with 10/8.

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c0balt 3 hours ago | parent | prev [-]

Or the most likely more expensive rate limiting (computational wise)

	▲	michh 2 hours ago \| parent [-]
		I mean, given how the site performs on average I don't think they've optimized so much that the extra cpu cycles of ANDing with the fixed constant of 2^64-1 and then looking up or hashing a 16 byte integer - whatever they do - rather than a 4 byte one would increase the load significantly. Let's be pessimistic and say it's 20 extra cpu cycles, that's not gonna be much of a problem if their load balancers were made in the past 20 years.

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AtNightWeCode 3 hours ago | parent | prev [-]

You probably need a hefty security reimplementation if you want to add IPv6 to Github.