Basic IPV6 Support by oliver408i · Pull Request #2566 · SubnauticaNitrox/Nitrox

oliver408i · 2025-11-02T06:18:44Z

IPv6 connectivity is increasingly common (especially on modern home networks). This PR aims to add basic ipv6 support to Nitrox.
These changes let Nitrox host/join over IPv6 while preserving existing IPv4 behavior.

All changes were pretty much just in general networking, so I don't expect anything in game to have changed.
Some hardcoded IPv4 strings were changed to allow ipv6 to show up, but by default everything still shows IPv4. However, this allows IPv6-only networks (if somehow someone was using one of those) to function with nitrox.

A note:
LiteNetLib was still IPv4-only, helper utilities filtered to IPv4, and address handling broke when IPv6 literals or mapped addresses appeared (e.g., discovery showing ::ffff:). This was fixed with changes to NetHelper.cs. These changes also added support for ipv6 to a few helper functions too.

Test: Open a server, try connecting to it with ::1 (IPv6 loopback). Confirm it works (it should also give you admin perms).

A note on authorship: Codex was used to review the code to see where code needed to be changed to use IPv6 and it also directly wrote a few of the helper functions in NetHelper.cs (mostly the IPv6 local ip detection). As this is pretty common code (not specific to Nitrox or Subnautica), I believe this is ok. I have reviewed and tested all changes.

A note on why add IPv6:

Allows IPv6-only networks to use Nitrox
Future proof (IPv6 connectivity continues to grow worldwide)
Removes some hardcoded IPv4 logic
No NAT on IPv6 (but firewalls still exist. In some situations, this can help a bit)
It's nice to have I guess... There aren't any tradeoffs I can see.

IPv6 LAN discovery is NOT added in this PR, that could be future work.

Coding-Hen

Would be nice to have some ipv6 support but I have some comments on the code below

Nitrox.Model/Helper/NetHelper.cs

Coding-Hen · 2025-11-02T09:18:32Z

Nitrox.Model/Helper/NetHelper.cs

                }
+
+                if (ipv6Candidate == null
+                    && address.AddressFamily == AddressFamily.InterNetworkV6


You could also combine this if with the one above to reduce your code paths but it might be better to have them apart for readability

Coding-Hen · 2025-11-02T09:21:49Z

Nitrox.Model/Helper/NetHelper.cs

+                if (address.AddressFamily is AddressFamily.InterNetwork or AddressFamily.InterNetworkV6)
                {
-                    yield return (ip.Address, ni.Name.Replace("VPN", "").Trim());
+                    if (address.IsIPv4MappedToIPv6)


I believe if you restructure this as an if else and then have it drop out to the return below the ifs then you can move the normalise there and allow the inner works of that to mean you don't have to call it here

Coding-Hen · 2025-11-02T09:25:23Z

Nitrox.Model/Helper/NetHelper.cs

    /// </summary>
    public static bool IsPrivate(this IPAddress address)
    {
+        address = NormalizeAddress(address);


I'm not sure what the benefit of doing this at a high scope is, can we not move this with the range method below as the other range method calls it itself anyway

Coding-Hen · 2025-11-02T09:38:12Z

Nitrox.Model/Serialization/ServerList.cs

            string name = parts[0].Trim();
            return new Entry(name, address, port);
+
+            static string ParseAddressWithOptionalPort(string value, out int parsedPort)


I'm not saying there is but I feel like there must be a better c# way of splitting an ipv6 and port off each other than having to do searches for indexes of : in the strings as well. I do know that ipv6 is not an easy thing to parse out with all the :: etc that can go on.

I assume we are then expecting people to put their ipv6 addresses in the server box in a particular format with the [ ] around it do we need to highlight this to them?

You only use the [] in urls and ssh (for example) when you need to specify the username or need to add :port after the ip. See RFC3986 for more info.

I'll look into splitting the ipv6, but since the user is supposed to put the port in a different box in the ui anyway I don't think this is a big concern.

Nitrox.Model/Serialization/ServerList.cs

Coding-Hen · 2025-11-02T09:46:46Z

Nitrox.Model/Helper/NetHelper.cs

            {
-                if (ip.Address.AddressFamily == AddressFamily.InterNetwork)
+                IPAddress address = ip.Address;
+                if (address.IsIPv4MappedToIPv6)


I think you either don't need this check here or you don't have it in the method you call to avoid doubling up the IsIPv4MappedToIPv6 call

Coding-Hen · 2025-11-02T09:49:44Z

Nitrox.Model/Helper/NetHelper.cs

+                    && !address.IsIPv6LinkLocal
+                    && !address.IsIPv6Multicast)
+                {
+                    ipv6Candidate = address;


Unless I have missed something why would you want to continue looping after assigning here rather than just returning early after assigning the cache

Kiaos · 2025-11-04T06:16:39Z

Did a play test and it works. Did the test on the test server. Then we tested on my own server.

Kiaos · 2025-11-04T21:28:21Z

After this is merged i have a update for server logs and what not here: Kiaos/Nitrox@master...Kiaos:Nitrox:pr-2566

you can check it out. this needs to be merged first.

Coding-Hen

Just a few comments. Overall looks good though. Will be nice to add ipv6 support

Nitrox.Model/Extensions/IpAddressExtensions.cs

Nitrox.Server.Subnautica/Server.cs

NitroxClient/MonoBehaviours/Gui/MainMenu/ServersList/MainMenuCreateServerPanel.cs

Coding-Hen

LGTM

github-actions · 2025-11-25T11:45:59Z

Test Results

244 tests +1 243 ✅ +1 6s ⏱️ ±0s
1 suites ±0 1 💤 ±0
1 files ±0 0 ❌ ±0

Results for commit 7c35917. ± Comparison against base commit f9ef1f4.

This pull request removes 2 and adds 3 tests. Note that renamed tests count towards both.

Nitrox.Model.Helper.NetHelperTest ‑ ShouldMatchLocalhostIps
Nitrox.Model.Helper.NetHelperTest ‑ ShouldMatchPrivateIps

Nitrox.Model.Extensions.IpAddressExtensionsTest ‑ ShouldMatchLocalhostIps
Nitrox.Model.Extensions.IpAddressExtensionsTest ‑ ShouldMatchPrivateIps
Nitrox.Test.Patcher.Patches.PatchesTranspilerTest ‑ AllPatchesTranspilerSanity (NitroxPatcher.Patches.Dynamic.ErrorMessage_OnLateUpdate_Patch,0)

…anyway

ipv6 support

692c9ba

Coding-Hen requested changes Nov 2, 2025

View reviewed changes

ipv6 support fixes

5227656

oliver408i requested a review from Coding-Hen November 2, 2025 21:17

dartasen requested a review from Measurity November 23, 2025 21:01

Measurity added 2 commits November 24, 2025 00:38

Merge remote-tracking branch 'upstream/master' into HEAD

3412a96

Simplified IPv6 code

b14a0d2

Measurity approved these changes Nov 24, 2025

View reviewed changes

Coding-Hen requested changes Nov 24, 2025

View reviewed changes

Fixed IsPrivate check for IPv6 ranges

a9fbc25

Measurity requested a review from Coding-Hen November 24, 2025 21:01

Improved variable naming in IpAddressExtensions

7c35917

Coding-Hen approved these changes Nov 24, 2025

View reviewed changes

dartasen approved these changes Dec 3, 2025

View reviewed changes

Moved mapped ipv4 check to below loopback check as it'll always fail …

0f38ed6

…anyway

Measurity merged commit 064b974 into SubnauticaNitrox:master Dec 3, 2025

Measurity added this to the 1.8.0.2 milestone Dec 3, 2025

oliver408i mentioned this pull request Dec 29, 2025

Show ipv6 in server console #2612

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github-actions bot commented Nov 25, 2025

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Kiaos commented Nov 4, 2025 •

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