How to make an encrypted channel between 2 applications?

Question

Node.js

There are 2 applications (node.js in my case) between which I want to establish an encrypted channel and exchange messages.
This is almost completely solved by TLS and client authentication. For example something like this: https://gist.github.com/pcan/e384fcad2a83e3ce20f9a... .
However, there is a problem:
This approach involves creating a server certificate that is bound to a domain name:

Specify server Common Name, like 'localhost' or 'server.localhost'. The client will verify this, so make sure you have a vaild DNS name for this.

And I would like to avoid binding, since the conditional server in this case does not have and cannot have either a domain name or a static IP.
Thus, I want to get a scheme where there are 2 hosts that can change IP and have no domain name. And they should be able to connect to each other (anyone can act as the initiator-"client" of the connection) something like this, for example:
connectTo('123.123.123.123:8000');
At the same time, it is possible to exchange keys / certificates in advance.
Is this possible with TLS?
And how adequate and safe is it to use regular sockets and encrypt content? (like this https://stackoverflow.com/questions/22738754/node-...

Answer 1

Yes, it is certainly possible.
The server certificate will validate your client application. At the same time, you can set your own function to check the certificate through options.checkServerIdentity()
https://nodejs.org/api/tls.html#tls_tls_checkserve...
Usually, in such cases, it is not the name and not the chain of trust that is checked, but simply the hash of the certificate server (fingerprint or fingerprint256 ) and absolutely any self-signed certificate is suitable, and it is much safer and more reliable than trusting root CAs. This technique in applications is usually called Certificate pinning.