Can you send a packet without connecting first? (NAT Punchthrough)

Hi everyone,

I've been using the com.unity.transport layer for a good week now and I've enjoyed working with it so far. For me it's the perfect balance between a "low level" & "high level" networking framework.

However for the past couple of days I've been wrapping my head around NAT Punchtrough in order for players to allow to connect to eachother without port forwarding.

After reading up on many great articles such as:
https://keithjohnston.wordpress.com/2014/02/17/nat-punch-through-for-multiplayer-games/
https://bford.info/pub/net/p2pnat/

And reading though source repositories of implementations such as:
https://github.com/MidLevel/MLAPI.Puncher

I've come to the conclusion that the game server needs to be able to send packets from the same public port as it is listening to.

But the only packet you can send without establishing a connection first is... a connect packet.
So my question is: Can you send a packet without connecting?

Because when you send a connection packet from a new NetworkDriver, it uses a different external port than the one listening (logical, I think). And when I want to bind the same port as the NetworkDriver that is listening it doesn't work.

Sending a connect message from the NetworkDriver that is listening is also not really working. (and feels very awkward anyway)

So is there a way to do this? Or any other way to implement NAT Punchthrough with this transport layer? (I would prefer not to mix multiple networking layers)

Thank you guys so much in advance!

EDIT: Mayor edit as I've done more research.

 

Thanks for your reply!

Do you have any idea if this will ever be supported or does it go against the architecture of the transport package? (as it's build upon the connectionless protocol UDP)

EDIT: Fixed my post as I found out that UTP stands for Unity Transport Package

 

Alright thanks, that clears everything up!

NAT Punchthrough is listed as "in consideration" on the roadmap: https://unity.com/roadmap/unity-platform/multiplayer-networking so that gives me hope ^^

I'm excited to see where this package goes after 1.0.0, thank you once again!

 

NAT Punchthrough is a must have feature for UTP and I can't believe it's just under consideration after 1.0
I can't even connect to other computers on the same office network because of the firewall.

I know a small % of players can't do NAT Punchthrough so I understand the need for Unity Relay, but as things are now almost all players need to use Unity Relay.

Just like LiteNetLib, RakNet, SteamNetworkingSockets etc... I would like this to be a core feature in UTP.