Installation guide

Chapter 10. Network File System (NFS)
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Important
In order for NFS to work with a default installation of Red Hat Enterprise Linux with a firewall
enabled, configure IPTables with the default TCP port 2049. Without proper IPTables
configuration, NFS will not function properly.
The NFS initialization script and rpc.nfsd process now allow binding to any specified port
during system start up. However, this can be error-prone if the port is unavailable, or if it conflicts
with another daemon.
10.1.1. Required Services
Red Hat Enterprise Linux uses a combination of kernel-level support and daemon processes to
provide NFS file sharing. All NFS versions rely on Remote Procedure Calls (RPC) between clients and
servers. RPC services under Red Hat Enterprise Linux 6 are controlled by the rpcbind service. To
share or mount NFS file systems, the following services work together, depending on which version of
NFS is implemented:
Note
The portmap service was used to map RPC program numbers to IP address port number
combinations in earlier versions of Red Hat Enterprise Linux. This service is now replaced by
rpcbind in Red Hat Enterprise Linux 6 to enable IPv6 support. For more information about this
change, refer to the following links:
• TI-RPC / rpcbind support: http://nfsv4.bullopensource.org/doc/tirpc_rpcbind.php
• IPv6 support in NFS: http://nfsv4.bullopensource.org/doc/nfs_ipv6.php
nfs
service nfs start starts the NFS server and the appropriate RPC processes to service
requests for shared NFS file systems.
nfslock
service nfslock start activates a mandatory service that starts the appropriate RPC
processes which allow NFS clients to lock files on the server.
rpcbind
rpcbind accepts port reservations from local RPC services. These ports are then made available
(or advertised) so the corresponding remote RPC services can access them. rpcbind responds
to requests for RPC services and sets up connections to the requested RPC service. This is not
used with NFSv4.
The following RPC processes facilitate NFS services:
rpc.mountd
This process receives mount requests from NFS clients and verifies that the requested file system
is currently exported. This process is started automatically by the nfs service and does not
require user configuration.