Connect two servers with ethernet without SSH

I have two Ubuntu Servers.
I want to connect the two machines via ethernet.
I want to be able to view and transfer files between them.
I would prefer to do this without setting up SSH because these machines will not need to receive remote connections over the internet.

The machines will connect to the internet for updates... but it is not necessary for what I'm trying to do.

I've viewed https://askubuntu.com/questions/2283...thout-a-router and was able to setup the IPv4 setup and have my machines ping each other, but was not able to connect and transfer files.

I was able to setup a basic SSH server and use the Nautilus connect to server facility to successfully do what I want to do. But I'm not very savy with ssh setup and would rather not open myself up to unnecessary vulnerabilities associated with insecure ssh servers.

Any ideas of how to set this up securely without SSH?

Thanks