Bug MC-3776 (IPv6 Does Not Work) is marked as fixed, so I went to test out Minecraft between two IPv6-only hosts. While it is possible to connect to another multiplayer session over IPv6 by entering the IPv6 address manually in the "server address" box of the "direct connect" UI screen (you have to remember to enclose the IPv6 address in square brackets so the port number can be distinguished from the IP address segments delimited by colons (what are these called? IPv4 called the octets, since they were 8bits. So hexidectets for IPv6? Ed: sources suggest "hextet", "hexadectet", "hexadecatet", "quibble", "quartet", or "piece")).
But IPv4 multiplayer servers on your LAN show up automatically under your list of multiplayer servers, so the kids can connect without manually entering IP addresses. This functionality should also work with IPv6.
Note that while it is possible to play multiplayer over IPv6, you still have to be dual stack, because IPv4 is required to download the jar files (MCL-2627 Launcher will not download game over IPv6) and to authenticate to Mojang
This may be a manifestation or consequence of MC-98598 "LAN List does not populate reliably"
Steps to reproduce
On server machine, turn off IPv4 (eg on MacOS, go to System Preferences -> Network -> Advanced -> TCP/IP -> Configure IPv4 = Off), but ensure that IPv6 is enabled and addressable.
On client machine, turn off IPv4 as well, and IPv6 is enabled. Both hosts are now IPv6-only single stack hosts.
On server machine, launch Minecraft session, enter a Minecraft world, hit escape to pause, and choose "Open to LAN" -> "Start LAN World"
On client machine, choose "Multiplayer" from the title screen
Expected results
Server machine session is seen at the bottom "local network" section of the "Play Multiplayer" server list
→ Note that if the session does show up, you might be able to connect at a low level, but you wouldn't be able to authenticate on an IPv6-only host, so you would not successfully join the session until WEB-197 is fixed. This report is only about populating LAN list, not connecting/authenticating.
Actual results
Server session is not seen
Related issues
is blocked by
is duplicated by
Attachments
Comments
migrated
ziggurism
How do you add a label to a bugreport? I want this to be in the IPv6 label https://bugs.mojang.com/browse/MC-2507?jql=labels%20%3D%20ipv6
ziggurism
This bugreport appears to be a duplicate of MC-56782 (Open to lan only listens on IPv4). I didn't find it because I was searching in the IPv6 label. Apologies for the duplication.
But that bugreport was itself marked as a duplicate of MC-3776 (IPv6 Does Not Work). Since MC-3776 was recently resolved as fixed, but the game is still not listening for IPv6 multiplayer sessions, either MC-3776 or MC-56782 needs to be reopened. Or this one needs to be left open.
migrated
Fixed the link on MC-56782 🙂
ziggurism
Confirm issue in 1.11
SunCat
@unknown, you, as the reporter of the ticket, can update the affected versions yourself.
ziggurism
Oh right, thanks.
Uriel Salischiker
Is this still a issue in the latest version of the game(currently 1.13.1)?
If so, please add it to the affected versions, thanks!
ziggurism
On my macs, I can no longer reliably populate LAN multiplayer sessions, even if the host is not IPv6 only. I think that's MC-98598. The list also doesn't populate for IPv6-only hosts, but the discrepancy between "expected behavior" and "actual behavior" does not occur, so I cannot test this bug. Is MC-98598 a mac-only issue? Maybe this could be tested on windows boxes.
wobst.michael
Can this still be reproduced in 1.16.1 or later?
pulpetti
I don't think that the original creator of this bug report is active anymore. (Doesn't seem to be updating this surtain post anymore.)
Moesh
Is this still a concern in 1.17 or later?
ziggurism
Mojang have stated that they're not interested in supporting IPv6 for the foreseeable future, so there is no point in me updating this bug for newer versions. Just close it as "won't fix" like the rest of them
migrated
This is still a problem in 1.20.4, 8 years after being reported.
I made a mod that lets dedicated servers send these pings out, and while I found out that 224.0.2.60 is being used for IPv4 I also found some GitHub commits using ff75:230::60 for the same thing, but there is no code I can see in vanilla Minecraft that uses this address.
I just checked and there isn't even code for listening/multicasting on IPv6 in the client or server.
Please add it 😇
Edit: I decided to see if I could fix it in MCP-Reborn, the answer is yes.
To listen for IPv6 multicast, add a joinGroup call for the IPv6 group address to the already existing socket, since Java was already listening on IPv6.
The address is not wrapped in '[' and ']' as required, so the other change is to add that in the addServer function if the address is instanceof Inet6Address.
Took me all of 10 minutes total....... ᵃⁿᵈ ⁱ'ᵐ ⁿᵒᵗ ᵉᵛᵉⁿ ᵃ ʲᵃᵛᵃ ᵖʳᵒᵍʳᵃᵐᵐᵉʳ ʲᵘˢᵗ ᵃ ⁿᵉʳᵈ
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