Network File System Not Based on Microsoft Networking?

I'm looking for a simple way of sharing files between a few machines at a
remote office without turning on Microsoft File Sharing on any of the
machines. Is there some very secure way I could mount a remote file system
folder and map it onto the local computer as a folder on its own file
system? I'm aware of SSH as an option, but that won't let the client
mount a drive or folder that appears like a local drive or folder.

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Will