Why is port forwarding required for vpn?

Question

VPN

I wanted to ask this question. Why do many client/server applications not require port forwarding on the router? For example games. Or the same team viewer . Why are they running waiting for a connection and do not require port forwarding on the router. And if you raise a vpn server on a PC using standard windows tools, then port forwarding is required. And I also wanted to ask a similar question. Does OpenVPN require port forwarding?

Answer 1

For example games. Or the same team viewer .

They work as clients. Those. initiate the connection themselves. NAT mechanisms work here, and everything works.
When a server is configured behind NAT, the router cannot know which machine to forward incoming packets to. Therefore, you must specify explicitly or use UPnP.

Answer 2

There is no magic ingredient.
Teamweaver, Skype and other similar programs have an official server that they connect to when online.
If you go to a computer via teamweaver, then initially you make a request not to it, but to the teamweaver server, which looks for whether the client is online, and gives the client a command to open a connection, which transfers to you.

Answer 3

Does open VPN require port forwarding?

Answer 4

Port forwarding is required by servers, not by clients. It's the same with OpenVPN.