Serverless data transfer protocol, what do you know about it?

Question

Computer networks

Write everything you know about serverless data transfer protocols.
The specifics are important, not the philosophy.
The ultimate goal is to transfer data from one program to another over the Internet without a server.
IP addresses are known in advance.

Answer 1

IP addresses are known in advance.

The problem of "serverless" data transfer is only in the absence of this item. If you can establish a direct connection between two points, you don't need a server.
The role of the server is to find users and link them. And then they can already connect with each other and privately exchange data. Some client can even become a server, or several clients (usually used on a local network).
In the context of a local network, there is no problem to take some port (or a range of ports) and broadcast a request like "I'm online dudes", as a result, someone who will act as a server will catch the request and send a response like "hello dude, here are all the other dudes."
Sending broadcast requests to the internet is clearly not a good idea, because there is usually a server with a known IP that does exactly the same thing.
If you already know everything, then there is no point in the server.

Answer 2

IP addresses are known in advance.

If you have a "gray" (local) IP (which is most often of interest ... static IP is too easy), then your idea with "serverless data transfer protocols" ;-) is hopeless .

Answer 3

1 open the admin panel of the router, look for DMZ
2 turn it on to the desired computer in LAN
3 do the same on the other side
4 establish a connection via IPs
5 rejoice
if something went wrong somewhere we are sad and go to the provider for a white IP

Answer 4

To bypass NAT, there is also UPnP, with the help of which software from the internal network can tell the router with NAT to forward certain ports for it.
Of course, the router must support UPnP.