NFS is Sun's Network File System. NFS is The NetworkFileSystem 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. One of the nicest things about NFS is that it's stateless, each client doesn't use up extra resources on the server, and, if the server goes away (and the comes back) the clients will not be effected. At least thats the theory.

NFS doesn't have many of the more advanted NetworkFileSystem's features such as disconnected operation.

NFS can be problematic to control using a firewall due to the fact that it does not use pre-defined ports. The tutorial entitled "Configuring NFS for firewall control" takes you through the steps involved in sorting this issue out.