Created by SunMicrosystems, NFS is the Network FileSystem for Unix. NFS works on a RemoteProcedureCall system, translating all the calls you make on the local machine to open(2), read(2), write(2), close(2) etc to calls on the remote machine.

A nice thing about NFS is that it's stateless. Therefore, resource use on the server does not scale with the number of clients, and clients won't be affected as servers disappear and reappear. At least in theory.

On the other hand, it lacks many advanced and even not so advanced features or newer networked FileSystems, such as disconnected operation. Its security model is simpleminded at best -- it maps UIDs between machines, not even attempting to authenticate users. Locking on NFS is notoriously unreliable. Performance is a mixed bag; many combinations of NFS server and client implementations lead to abysmal throughput. These and an assortment of other problems have led many a SysAdmin to expand the NFS acronym as Nightmare FileSystem.

Because it is built on RPC, it does not use any single port and is therefor difficult for FireWalls to handle. Configuring NFS for firewall control steps you through the configuration process.