well I guess that would depend on your definition of “easiest”. One option that works out of the box is transferring file via SSH. Depending on your preference you could use a utility such as rsync or scp to transfer files. There is also sshfs which allows you to mount a remote file system via SSH. Some Linux distros support this out of the box through their file browsers. If you are using Windows you may want to take a look at WinSCP [1].