Required Services - Red Hat ENTERPRISE LINUX 4.5.0 Reference Manual

Chapter 9. Network File Syste...
The only time NFS performs authentication is when a client system attempts to mount the
shared NFS resource. To limit access to the NFS service, TCP wrappers are used. TCP
wrappers read the
/etc/hosts.allow
client or network is permitted or denied access to the NFS service. For more information on
configuring access controls with TCP wrappers, refer to
.
xinetd
After the client is granted access by TCP wrappers, the NFS server refers to its configuration
file, , to determine whether the client is allowed to access any of the exported file
/etc/exports
systems. Once access is granted, all file and directory operations are available to the user.
Important
In order for NFS to work with a default installation of Red Hat Enterprise Linux
with a firewall enabled, IPTables with the default TCP port 2049 must be
configured. Without an IPTables configuration, NFS does not function properly.
The NFS initialization script and
specified port during system start up. However, this can be error prone if the port
is unavailable or conflicts with another daemon.

1.1. Required Services

Red Hat Enterprise Linux uses a combination of kernel-level support and daemon processes to
provide NFS file sharing. NFSv2 and NFSv3 rely on Remote Procedure Calls (RPC) to encode
and decode requests between clients and servers. RPC services under Linux are controlled by
the service. To share or mount NFS file systems, the following services work together,
portmap
depending on which version of NFS is implemented:
• — Starts the appropriate RPC processes to service requests for shared NFS file
nfs
systems.
• — An optional service that starts the appropriate RPC processes to allow NFS
nfslock
clients to lock files on the server.
• — The RPC service for Linux; it responds to requests for RPC services and sets up
portmap
connections to the requested RPC service. This is not used with NFSv4.
The following RPC processes facilitate NFS services:
• — This process receives mount requests from NFS clients and verifies the
rpc.mountd
requested file system is currently exported. This process is started automatically by the
service and does not require user configuration. This is not used with NFSv4.
132
and
/etc/hosts.deny
Chapter 17, TCP Wrappers and
process now allow binding to any
rpc.nfsd
files to determine if a particular
nfs