IPv6 / UPnP / CGNAT / DDNS host game lobby

[Zoukambada]

Make it possible to host a game behind a Firewall or CGNAT through UPnP or IPv6.
Maybe creating a settings inside the .INI that link the user login name to an specific IP / Hostname address like for example using a Dynamic DNS service such as tplinkdns.com, DuckDNS, dynv6 or noip.

This would help people create their lobby without the need of faking a LAN with radmin or other tools. And people would be able to find easier the lobby of those people without the need of other tools as well.

[emoose]

It does use UPnP already, but I guess maybe support for it isn't that great.

IIRC the main issue with NAT is that game only uses a single port for hosting games, and doesn't allow connecting/hosting to any other port numbers, even if master server reported a lobby at some other port number, the game code would ignore that and only try connecting to the normal port number.

If the game did allow other port numbers, we could have used STUN to allow game to tunnel through NAT, but since STUN results in the forwarded/tunnelled port number being random, we'd have the issue above.
(In fact the game already has code for STUN built into it as part of the Demonware library, but it goes completely unused :/)

I'd thought of somehow patching/hooking the game to allow other port numbers, but the netcode part is pretty far removed from the demonware/master server part, couldn't see a good way for it to pass port number over from demonware -> netcode. (and since the Sumo netcode is still almost completely unmapped, that makes it even harder...)

Do wonder if there's any kind of radmin-like library we could use to make some kind of private network built into the game (rather than needing something installed seperate).
Since we can patch all the games network calls to the OS, we could probably forward those to some private-network library instead, but don't really know if there is such a thing still available though (or if it would even be free to use - if it needs a host we can always put something on the master server though)
Pretty sure I did see something like this on github years ago...

[Zoukambada]

I forgot the name, as I am not on pc I cant access my web browser history. Yesterday I was searching about how to host over CGNAT. As unfortunately I had to change my ISP I got dammed by this CGNAT curse.

Ohh I just found this project here:
https://github.com/siryazgan/RoomConnect

It uses ngrok.com to integrate and it makes possible create lobbies for games over CGNAT. It seems to be seamless.

But the thing is, ngrok in the free plan doesn't use UDP, just TCP ports.
Maybe there's another service that could be used. I heard about Pingyy.

If you need testers for such a feature, there's a bunch of people on discord that uses radmin and has blocked ports or CGNAT. @Tenome is one of them.

[Zoukambada]

It does use UPnP already, but I guess maybe support for it isn't that great.

IIRC the main issue with NAT is that game only uses a single port for hosting games, and doesn't allow connecting/hosting to any other port numbers, even if master server reported a lobby at some other port number, the game code would ignore that and only try connecting to the normal port number.

If the game did allow other port numbers, we could have used STUN to allow game to tunnel through NAT, but since STUN results in the forwarded/tunnelled port number being random, we'd have the issue above. (In fact the game already has code for STUN built into it as part of the Demonware library, but it goes completely unused :/)

I'd thought of somehow patching/hooking the game to allow other port numbers, but the netcode part is pretty far removed from the demonware/master server part, couldn't see a good way for it to pass port number over from demonware -> netcode. (and since the Sumo netcode is still almost completely unmapped, that makes it even harder...)

Do wonder if there's any kind of radmin-like library we could use to make some kind of private network built into the game (rather than needing something installed seperate). Since we can patch all the games network calls to the OS, we could probably forward those to some private-network library instead, but don't really know if there is such a thing still available though (or if it would even be free to use - if it needs a host we can always put something on the master server though) Pretty sure I did see something like this on github years ago...

Hello emoose,

Thank you for your detailed explanation regarding the single-port limitation and the challenges of implementing STUN/NAT Traversal in the current netcode. I completely understand that the netcode's rigidity is the main obstacle.

I researched a solution based on your closing idea: "Do wonder if there's any kind of radmin-like library we could use to make some kind of private network built into the game."

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Proposal: Embedding a P2P Mesh VPN for NAT Traversal

The solution you are looking for is a modern P2P (Peer-to-Peer) Networking Library with integrated NAT Traversal. This technology creates a Virtual Mesh Network that is specifically designed to bypass CGNAT and firewalls without requiring the user to open ports or modify router settings.

If the game could be "hooked" to communicate over this virtual network interface, it would solve the problem entirely, as the game would see all players as being on the same local network (LAN).

Recommended Libraries (Zero-Cost & Community Friendly)

I recommend two solutions that are ideal for this kind of integration. They are either Open-Source or offer a robust Free Tier, meaning there is no cost to you or the players.

1. ZeroTier (Highly Recommended)

• Type: P2P Mesh VPN / Software-Defined Networking.
• Why it works: It acts as a full-stack network virtualization tool. You can integrate its SDK into the Tweaks, and players only need to join a single OutRun network ID. It handles all the complex firewall/CGNAT piercing automatically.
• Cost: Free for up to 50 members per network (more than enough for the community).

2. ENet or RakNet (Lower-Level P2P Libraries)

• Type: Dedicated P2P Game Networking Libraries.
• Why it works: They provide the foundational tools for building UDP communication and, in some versions, include basic STUN/NAT Traversal logic. This would require more custom coding on your part to ensure the NAT Traversal is robust enough for CGNAT.

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Conclusion on the STUN Barrier

Since the game's code is hardcoded to a single port, the most efficient solution is to bypass traditional NAT Traversal methods (like STUN/TURN/ICE) entirely and use a pre-existing VPN library that creates a guaranteed private network. ZeroTier is a strong candidate for this integration.

Thank you again for your amazing work on the Tweaks.

(P.S. This research was performed using the Gemini AI model to quickly aggregate and analyze technical solutions for NAT Traversal.)