mjhjmtu

so i am using MineOS, a turnkey with preinstalled node.js webUI for deploying Minecraftservers. Now i want the server to be reachable via IPv6, because thats all i get from my ISP. But my server instance only ever listens on IPv4. How can i get the java minecraft server to listen on IPv6?

Some netstat -ntlp output, which is always the same, regardless of my server.properties in minecraft:

root@MinecraftServer /etc/default# netstat -ntlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 493/sshd
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1194/master
tcp 0 0 0.0.0.0:25565 0.0.0.0:* LISTEN 1446/java
tcp 0 0 127.0.0.1:12319 0.0.0.0:* LISTEN 590/shellinaboxd
tcp 0 0 0.0.0.0:12320 0.0.0.0:* LISTEN 598/stunnel4
tcp 0 0 0.0.0.0:12321 0.0.0.0:* LISTEN 598/stunnel4
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN 978/mysqld
tcp6 0 0 :::22 :::* LISTEN 493/sshd
tcp6 0 0 :::8443 :::* LISTEN 1026/node

I also tried using the -Djava.net.preferIPv6Adresses=true and -Djava.net.preferIPv6Stack=true. Doesn't change a bit.
I changed the value for /proc/sys/net/ipv6/bindv6only to 1.

Here my ip6tables -L:

root@MinecraftServer /etc/default# ip6tables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT tcp anywhere anywhere tcp dpt:25565
ACCEPT tcp anywhere anywhere tcp dpt:25566
ACCEPT tcp anywhere anywhere tcp dpt:8443

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

I am able to reach a server on a windows maschine over the internet via IPv6! I am also able to reach the webUI over IPv6 on the turnkey maschine.

What else am i missing? All help appretiated!

SOLUTION:

The forge modification for minecraft set java.net.preferIPv4Stack=true up to the version 1.12.2-14.23.1.2555, which ruins every IPv6 attempt. For that reason i am using 6tunnel now, which creates a port forward from IPv6 to IPv4. I am still not reachable from the outside on the minecraftserver, but IPv6 is working.

I think you got the property names wrong. According to

• Networking IPv6 User Guide for JDK/JRE 5.0

The property names are:

• 
  java.net.preferIPv4Stack - note: IPv4 not IPv6
  


• 
  java.net.preferIPv6Addresses - note: two d characters not one.

You also need to check that you are not affected by this bug: https://bugs.mojang.com/browse/MC-3776

The culprit was the forge modification i used with minecraft. Up to version
1.12.2-14.23.1.2555 it sets java.net.preferIPv4Stack=true. 6tunnel is a workaround, which does a port forward from IPv6 to IPv4.