Although FTP and SSH permits authenticated file access, they are not intended to implement a remote file system. A remote (network) file system is one that is completely transparent. In other words, a file that is on a remote host should appear as a file on a local machine in a remote file system.
The main difference between a remote file system and authenticated file access is that the former is intended for an entire system (multiple users), whereas the latter is intended for individual users. There are file systems that are based on SSH, such as sshfs and lufs. However, these file systems are not as efficient or flexible as file systems designed for remote file access.
The two most commonly used remote file systems are NFS (network file system) and SMB/Samba (server message block). NFS traces its root back to Sun Microsystems, whereas SMB traces its root back to IBM (and not Microsoft!). The two file systems have about the same age (circa 1984 and 1985, respectively). NFS has always been popular amongst servers, while SMB gained popularity due to its application known as “Windows share”.
Regardless of the file system, file serving is much more common among intranet hosts compared to Internet hosts. This is not a matter of possibility, as both NFS and SMB can function on top of TCP/IP. This is a matter of practicality.
The relatively slow and unreliability of the Internet makes remote file system serving rather impractical. This is, however, slowly being changed as broadband Internet access become more efficient. Note that both NFS and SMB are considered somewhat insecure. This is another reason why NFS and SMB should not be implemented on the Internet.