.\"@(#)nfs.5"
-.TH NFS 5 "2 November 2007"
+.TH NFS 5 "9 October 2012"
.SH NAME
nfs \- fstab format and options for the
.B nfs
.BR automount (8)
for details).
.TP 1.5i
+.BR rdirplus " / " nordirplus
+Selects whether to use NFS v3 or v4 READDIRPLUS requests.
+If this option is not specified, the NFS client uses READDIRPLUS requests
+on NFS v3 or v4 mounts to read small directories.
+Some applications perform better if the client uses only READDIR requests
+for all directories.
+.TP 1.5i
.BI retry= n
The number of minutes that the
.BR mount (8)
.BR mount (8)
command exits immediately after the first failure.
.TP 1.5i
-.BI sec= mode
-The RPCGSS security flavor to use for accessing files on this mount point.
-If the
-.B sec
-option is not specified, or if
-.B sec=sys
-is specified, the NFS client uses the AUTH_SYS security flavor
-for all NFS requests on this mount point.
-Valid security flavors are
+.BI sec= flavor
+The security flavor to use for accessing files on this mount point.
+If the server does not support this flavor, the mount operation fails.
+If
+.B sec=
+is not specified, the client attempts to find
+a security flavor that both the client and the server supports.
+Valid
+.I flavors
+are
.BR none ,
.BR sys ,
.BR krb5 ,
.BR krb5i ,
and
-.BR krb5p ,
+.BR krb5p .
Refer to the SECURITY CONSIDERATIONS section for details.
.TP 1.5i
.BR sharecache " / " nosharecache
.IP
The DATA AND METADATA COHERENCE section contains a
detailed discussion of these trade-offs.
+.TP 1.5i
+.BR fsc " / " nofsc
+Enable/Disables the cache of (read-only) data pages to the local disk
+using the FS-Cache facility. See cachefilesd(8)
+and <kernel_soruce>/Documentation/filesystems/caching
+for detail on how to configure the FS-Cache facility.
+Default value is nofsc.
.SS "Options for NFS versions 2 and 3 only"
Use these options, along with the options in the above subsection,
for NFS versions 2 and 3 only.
.TP 1.5i
.BI proto= netid
-The transport protocol name and protocol family the NFS client uses
-to transmit requests to the NFS server for this mount point.
-If an NFS server has both an IPv4 and an IPv6 address, using a specific
-netid will force the use of IPv4 or IPv6 networking to communicate
-with that server.
-.IP
-If support for TI-RPC is built into the
-.B mount.nfs
-command,
-.I netid
-is a valid netid listed in
-.IR /etc/netconfig .
-The value "rdma" may also be specified.
-If the
-.B mount.nfs
-command does not have TI-RPC support, then
+The
.I netid
-is one of "tcp," "udp," or "rdma," and only IPv4 may be used.
+determines the transport that is used to communicate with the NFS
+server. Available options are
+.BR udp ", " udp6 ", "tcp ", " tcp6 ", and " rdma .
+Those which end in
+.B 6
+use IPv6 addresses and are only available if support for TI-RPC is
+built in. Others use IPv4 addresses.
.IP
Each transport protocol uses different default
.B retrans
through a firewall that blocks the rpcbind protocol.
.TP 1.5i
.BI mountproto= netid
-The transport protocol name and protocol family the NFS client uses
+The transport the NFS client uses
to transmit requests to the NFS server's mountd service when performing
this mount request, and when later unmounting this mount point.
.IP
-If support for TI-RPC is built into the
+.I netid
+may be one of
+.BR udp ", and " tcp
+which use IPv4 address or, if TI-RPC is built into the
.B mount.nfs
command,
-.I netid
-is a valid netid listed in
-.IR /etc/netconfig .
-Otherwise,
-.I netid
-is one of "tcp" or "udp," and only IPv4 may be used.
+.BR udp6 ", and " tcp6
+which use IPv6 addresses.
.IP
This option can be used when mounting an NFS server
through a firewall that blocks a particular transport.
if the negotiation causes problems on the client or server.
Refer to the SECURITY CONSIDERATIONS section for more details.
.TP 1.5i
-.BR rdirplus " / " nordirplus
-Selects whether to use NFS version 3 READDIRPLUS requests.
-If this option is not specified, the NFS client uses READDIRPLUS requests
-on NFS version 3 mounts to read small directories.
-Some applications perform better if the client uses only READDIR requests
-for all directories.
-.TP 1.5i
.BR local_lock= mechanism
Specifies whether to use local locking for any or both of the flock and the
POSIX locking mechanisms.
for NFS version 4 and newer.
.TP 1.5i
.BI proto= netid
-The transport protocol name and protocol family the NFS client uses
-to transmit requests to the NFS server for this mount point.
-If an NFS server has both an IPv4 and an IPv6 address, using a specific
-netid will force the use of IPv4 or IPv6 networking to communicate
-with that server.
-.IP
-If support for TI-RPC is built into the
-.B mount.nfs
-command,
-.I netid
-is a valid netid listed in
-.IR /etc/netconfig .
-Otherwise,
+The
.I netid
-is one of "tcp" or "udp," and only IPv4 may be used.
+determines the transport that is used to communicate with the NFS
+server. Supported options are
+.BR tcp ", " tcp6 ", and " rdma .
+.B tcp6
+use IPv6 addresses and is only available if support for TI-RPC is
+built in. Both others use IPv4 addresses.
.IP
All NFS version 4 servers are required to support TCP,
so if this mount option is not specified, the NFS version 4 client
the behavior of this option in more detail.
.TP 1.5i
.BI clientaddr= n.n.n.n
+.TP 1.5i
+.BI clientaddr= n:n: ... :n
Specifies a single IPv4 address (in dotted-quad form),
or a non-link-local IPv6 address,
that the NFS client advertises to allow servers
In addition to combining these sideband protocols with the main NFS protocol,
NFS version 4 introduces more advanced forms of access control,
authentication, and in-transit data protection.
-The NFS version 4 specification mandates NFSv4 ACLs,
-RPCGSS authentication, and RPCGSS security flavors
+The NFS version 4 specification mandates support for
+strong authentication and security flavors
that provide per-RPC integrity checking and encryption.
Because NFS version 4 combines the
function of the sideband protocols into the main NFS protocol,
the new security features apply to all NFS version 4 operations
including mounting, file locking, and so on.
RPCGSS authentication can also be used with NFS versions 2 and 3,
-but does not protect their sideband protocols.
+but it does not protect their sideband protocols.
.P
The
.B sec
-mount option specifies the RPCGSS security mode
+mount option specifies the security flavor
that is in effect on a given NFS mount point.
Specifying
.B sec=krb5
is also available.
.P
The NFS version 4 protocol allows
-clients and servers to negotiate among multiple security flavors
-during mount processing.
-However, Linux does not yet implement such negotiation.
-The Linux client specifies a single security flavor at mount time
-which remains in effect for the lifetime of the mount.
-If the server does not support this flavor,
-the initial mount request is rejected by the server.
+a client to renegotiate the security flavor
+when the client crosses into a new filesystem on the server.
+The newly negotiated flavor effects only accesses of the new filesystem.
+.P
+Such negotiation typically occurs when a client crosses
+from a server's pseudo-fs
+into one of the server's exported physical filesystems,
+which often have more restrictive security settings than the pseudo-fs.
.SS "Using non-privileged source ports"
NFS clients usually communicate with NFS servers via network sockets.
Each end of a socket is assigned a port value, which is simply a number
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