How is the Openvpn data channel encrypted?

Question

openvpn

I'm trying to figure out how openvpn works. The data channel is usually encrypted, eg. The question is what key: if DH is clear, but if DH is disabled, then where else do the client and server get the symmetric key from? Googled - everywhere they write that symmetric encryption. It is not clear just what.
Or here's another: in the server settings and clients there is a "cipher" parameter - a cipher for the data channel. I understand that this is clearly not for the dh session key. And for what then? Or is the data channel still encrypted with certificates and its encryption is asymmetric?

Answer 1

Without Diffie-Hellman, OpenVPN does not work in principle, when specified dh none, ECDH will be used forcibly (which is written in the manual).