Server Build listens on IPv6 only on Linux machine

[Tchekda]

Describe the bug
When directly running the Linux Server Build on my computer, or in Docker (ubuntu:latest) or my debian server, the server starts correctly without errors, but listens only the IPv6 port (:::7777 in netstat)

Same thing happens when I run the Windows Server Build with wine on my Linux machine. But when running the Windows Server Build on a Windows machine, everything works fine....

When starting the server in a normal build through the UI, it listens on IPv4 and other players are joining the game perfectly

Logs :

Found path: /root/build/Linux.x86_64
Mono path[0] = '/root/build/Linux_Data/Managed'
Mono config path = '/root/build/Linux_Data/MonoBleedingEdge/etc'
PlayerPrefs - Creating folder: /root/.config/unity3d/Sépanou
PlayerPrefs - Creating folder: /root/.config/unity3d/Sépanou/Terres de l'Exil
Unable to load player prefs
Initialize engine version: 2019.4.21f1 (b76dac84db26)
[Subsystems] Discovering subsystems at path /root/build/Linux_Data/UnitySubsystems
Forcing GfxDevice: Null
GfxDevice: creating device client; threaded=0
NullGfxDevice:
   Version:  NULL 1.0 [1.0]
   Renderer: Null Device
   Vendor:   Unity Technologies
Begin MonoManager ReloadAssembly
- Completed reload, in  0.068 seconds
UnloadTime: 0.771187 ms
NetworkManager created singleton (DontDestroyOnLoad)
(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)
Mirror | mirror-networking.com | discord.gg/N9QVxbM
(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)
KcpTransport initialized!
(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)
Mirror: adding Network[Early/Late]Update to Unity...
(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)
Server started listening
(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)

How to reproduce the issue, step by step

I don't really know how to reproduce this bug. I'm using version 2019.4.21f1 of Unity. Here is the repo of the game : Unity Game.

Expected behavior

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Build target: Linux Standalone with Server Build ticked
• Unity version: 2019.4.21f1
• Mirror branch: Mirror 35.1.0

Additional context

If you need any more informations, I will try to answer your questions as best as I can

[SoftwareGuy]

:::7777 is actually valid. It's IPv4 in IPv6 notation, because it seems your distro is configured to favor IPv6 over IPv4. See here for more information, thanks to Stack Overflow. However, I would try to dig down into KCP and find where its server binding port logic is.

Also see if other transports are affected. If it's a KCP problem, then it needs to be reported on the kcp2k repository since that code is one of vis's babies.

[Tchekda]

:::7777 is actually valid. It's IPv4 in IPv6 notation, because it seems your distro is configured to favor IPv6 over IPv4. See here for more information, thanks to Stack Overflow. However, I would try to dig down into KCP and find where its server binding port logic is.

Also see if other transports are affected. If it's a KCP problem, then it needs to be reported on the kcp2k repository since that code is one of vis's babies.

Hi @SoftwareGuy thanks for your answer !

Oh, I didn't know that it was used like that.... So my connection problems aren't there, I will try to find why I can't connect on a Linux server....

root@980687c8746c:~# netstat -plnatu|grep 7777
udp6       0      0 :::7777                 :::*                                38/Linux.x86_64

Again, thank you so much for your explanation !

Edit : The problem was coming from my side, I misconfigured my firewall, now everything works. Thank you