Mildly cursed factoid about UNC paths:
- UNC Paths can contain IP addresses such as \\192.168.1.1\share
- IPv6 addresses are supported as well
- IPv6 addresses contain colons
- can't have colons in Windows paths since colons are reserved for drive letters
So Microsoft came up with the the ipv6-literal.net domain that's special-cased by Windows so you can to write IPv6 addresses in UNC paths as 2a0e-3c0--21.ipv6-literal.net without it hitting any resolvers.
Turns out, it's worse than this: The ipv6-literal.net shenanigans aren't limited to UNC paths.
It works in all places:
> ping 2a0e-3c0--21.ipv6-literal.net
Pinging 2a0e:3c0::21 with 32 bytes of data:
Also works in browsers: http://2a0e-3c0--21.ipv6-literal.net/
Thanks to @casandro for asking.
@xtaran @karotte @casandro @GossiTheDog
That's an old one! We came up with it for IPv6 when I was working at Microsoft. I think it was introduced in Windows XP SP1. We were worried that typing addresses like 2001:2:3::abcd was not going to work well in a variety of user interfaces, hence the "2001-2-3--abcd.ipv6-literal.net" hack. One of the team members (maybe me, not sure now) registered it on a personal account, and then transferred ownership to Microsoft before shipping.
@karotte @casandro Not on Linux it seems:
```
stuartl@vk4msl-tp:~$ ping 2a0e-3c0--21.ipv6-literal.net
ping: 2a0e-3c0--21.ipv6-literal.net: Name or service not known
stuartl@vk4msl-tp:~$ uname -a
Linux vk4msl-tp 6.12.12+bpo-rt-amd64 #1 SMP PREEMPT_RT Debian 6.12.12-1~bpo12+1 (2025-02-23) x86_64 GNU/Linux
```
As I recall…
Windows 2000 had IPv6 as a "technology preview" that had to be separately downloaded and installed.
Windows XP whad it disabled by default, but did otherwise ship with it.
Windows Vista and later turned it on by default.
Anything currently supported by Microsoft right now will have it turned on unless the user/administrator turns it off manually.
So "only few" actually covers a lot of users.
Whether that domain exists or what its DNS servers say is only relevant for users of other, non-Microsoft OSs.
@tauon I mean, what else could they have done? I agree that the solution is a bit bonkers, but I don't immediately see any other viable solutions that don't conflict with anything else.
They could at least held on to the ipv6-literal.net domain.
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Ge0rG ➡️ Easter-H-Egg\\[2a0e-3c0--21]\share?)2a0e-3c0--21._ip6?)> They could at least held on to the ipv6-literal.net domain.
They could have used ipv6-literal.arpa and probably even gotten it through IANA, though I don't remember if Microsoft literally ever engaged with the IETF.
(also @tauon you don't need to have DNS records for these domains if you just specify that there are none)
This document describes how the zone identifier of an IPv6 scoped address, defined in the IPv6 Scoped Address Architecture (RFC 4007), should be entered into a user interface. It obsoletes RFC 6874 and updates RFC 4007, RFC 7622 and RFC 8089. Discussion Venue This note is to be removed before publishing as an RFC. Discussion of this document takes place on the 6MAN mailing list ([email protected]), which is archived at https://mailarchive.ietf.org/arch/browse/ipv6/ (https://mailarchive.ietf.org/arch/browse/ipv6/).
@kitten @tauon @karotte both of them should be interpreted as an integer, that's all that they are. The dots/colons are just there to make it easier on people.
This works in most browsers FYI, at least for v4 - take your router's IP and slap it in your address bar as an integer instead and it'll navigate to your router.
@jernej__s @pmmeurcatpics @karotte
It's even worse than that, a few years (oh or was it almost 10 by now?) where the spooler service was able to write raw filenames to disk that bypassed all of the usual validations and you could end up with such files on disk. And you probably can imagine what trying to access such a file could have caused. I think there wasn't a way to get rid of these names except for reformatting C or Hexeditor edits of the filesystem...
@casandro Turns out, yes:
> ping 2a0e-3c0--21.ipv6-literal.net
Pinging 2a0e:3c0::21 with 32 bytes of data:
Also works in browsers: http://2a0e-3c0--21.ipv6-literal.net/
cat::<kleinesFilmröllchen>
chrysn
SnowFox
pathetic piss kitten
draeath
mwguy
Arcaik
Tony “Abolish ICE” Arcieri🌹🦀
shironeko
radentscheiderin :ferris:
Klaus Frank
aburka 🫣
CyberFrogipv6-literal.net domain. If some subdomains of ipv6-literal.net hit the DNS instead of being resolved internally (no idea whether they do) and if something important were happening on ipv6-literal.net (currently it doesn’t – the domain is parked), there could be some issues because anybody can effectively have their own ipv6-literal.net subdomain without consent of the domain owner (who isn’t Microsoft it seems).Well imagine a bad actor getting control over that domain and generating AAAA-RRs for all of the subdomains pointing to something else on public servers.
I don't even want to know how many firewalls and other devices you could confuse with this.
Like what happens when you send an E-Mail from an IP that has a PTR-RR pointing towards one of these?
Questions over questions...