MOUNT.CIFS(8)MOUNT.CIFS(8)NAMEmount.cifs - mount using the Common Internet File System (CIFS)
SYNOPSISmount.cifs {service} {mount-point} [-o options]
DESCRIPTION
This tool is part of the samba(7) suite.
mount.cifs mounts a Linux CIFS filesystem. It is usually invoked indi‐
rectly by the mount(8) command when using the "-t cifs" option. This
command only works in Linux, and the kernel must support the cifs
filesystem. The CIFS protocol is the successor to the SMB protocol and
is supported by most Windows servers and many other commercial servers
and Network Attached Storage appliances as well as by the popular Open
Source server Samba.
The mount.cifs utility attaches the UNC name (exported network re‐
source) to the local directory mount-point. It is possible to set the
mode for mount.cifs to setuid root to allow non-root users to mount
shares to directories for which they have write permission.
Options to mount.cifs are specified as a comma-separated list of
key=value pairs. It is possible to send options other than those listed
here, assuming that the cifs filesystem kernel module (cifs.ko) sup‐
ports them. Unrecognized cifs mount options passed to the cifs vfs ker‐
nel code will be logged to the kernel log.
mount.cifs causes the cifs vfs to launch a thread named cifsd. After
mounting it keeps running until the mounted resource is unmounted (usu‐
ally via the umount utility).
OPTIONS
user=arg
specifies the username to connect as. If this is not given, then
the environment variable USER is used. This option can also take
the form "user%password" or "workgroup/user" or "workgroup/us‐
er%password" to allow the password and workgroup to be specified
as part of the username.
Note
The cifs vfs accepts the parameter user=, or for users familiar
with smbfs it accepts the longer form of the parameter user‐
name=. Similarly the longer smbfs style parameter names may be
accepted as synonyms for the shorter cifs parameters pass=,dom=
and cred=.
password=arg
specifies the CIFS password. If this option is not given then
the environment variable PASSWD is used. If the password is not
specified directly or indirectly via an argument to mount
mount.cifs will prompt for a password, unless the guest option
is specified.
Note that a password which contains the delimiter character
(i.e. a comma ',') will fail to be parsed correctly on the com‐
mand line. However, the same password defined in the PASSWD en‐
vironment variable or via a credentials file (see below) or en‐
tered at the password prompt will be read correctly.
credentials=filename
specifies a file that contains a username and/or password. The
format of the file is:
username=value
password=value
This is preferred over having passwords in plaintext in a shared
file, such as /etc/fstab. Be sure to protect any credentials
file properly.
uid=arg
sets the uid that will own all files on the mounted filesystem.
It may be specified as either a username or a numeric uid. This
parameter is ignored when the target server supports the CIFS
Unix extensions.
gid=arg
sets the gid that will own all files on the mounted filesystem.
It may be specified as either a groupname or a numeric gid. This
parameter is ignored when the target server supports the CIFS
Unix extensions.
port=arg
sets the port number on the server to attempt to contact to ne‐
gotiate CIFS support. If the CIFS server is not listening on
this port or if it is not specified, the default ports will be
tried i.e. port 445 is tried and if no response then port 139 is
tried.
netbiosname=arg
When mounting to servers via port 139, specifies the RFC1001
source name to use to represent the client netbios machine name
when doing the RFC1001 netbios session initialize.
file_mode=arg
If the server does not support the CIFS Unix extensions this
overrides the default file mode.
dir_mode=arg
If the server does not support the CIFS Unix extensions this
overrides the default mode for directories.
ip=arg sets the destination host or IP address.
domain=arg
sets the domain (workgroup) of the user
guest don't prompt for a password
iocharset
Charset used to convert local path names to and from Unicode.
Unicode is used by default for network path names if the server
supports it. If iocharset is not specified then the nls_default
specified during the local client kernel build will be used. If
server does not support Unicode, this parameter is unused.
ro mount read-only
rw mount read-write
setuids
If the CIFS Unix extensions are negotiated with the server the
client will attempt to set the effective uid and gid of the lo‐
cal process on newly created files, directories, and devices
(create, mkdir, mknod).
nosetuids
The client will not attempt to set the uid and gid on on newly
created files, directories, and devices (create, mkdir, mknod)
which will result in the server setting the uid and gid to the
default (usually the server uid of the user who mounted the
share). Letting the server (rather than the client) set the uid
and gid is the default. This parameter has no effect if the CIFS
Unix Extensions are not negotiated.
perm Client does permission checks (vfs_permission check of uid and
gid of the file against the mode and desired operation), Note
that this is in addition to the normal ACL check on the target
machine done by the server software. Client permission checking
is enabled by default.
noperm Client does not do permission checks. This can expose files on
this mount to access by other users on the local client system.
It is typically only needed when the server supports the CIFS
Unix Extensions but the UIDs/GIDs on the client and server sys‐
tem do not match closely enough to allow access by the user do‐
ing the mount. Note that this does not affect the normal ACL
check on the target machine done by the server software (of the
server ACL against the user name provided at mount time).
directio
Do not do inode data caching on files opened on this mount. This
precludes mmaping files on this mount. In some cases with fast
networks and little or no caching benefits on the client (e.g.
when the application is doing large sequential reads bigger than
page size without rereading the same data) this can provide bet‐
ter performance than the default behavior which caches reads
(readahead) and writes (writebehind) through the local Linux
client pagecache if oplock (caching token) is granted and held.
Note that direct allows write operations larger than page size
to be sent to the server. On some kernels this requires the
cifs.ko module to be built with the CIFS_EXPERIMENTAL configure
option.
mapchars
Translate six of the seven reserved characters (not backslash,
but including the colon, question mark, pipe, asterik, greater
than and less than characters) to the remap range (above
0xF000), which also allows the CIFS client to recognize files
created with such characters by Windows's POSIX emulation. This
can also be useful when mounting to most versions of Samba
(which also forbids creating and opening files whose names con‐
tain any of these seven characters). This has no effect if the
server does not support Unicode on the wire.
nomapchars
Do not translate any of these seven characters (default)
intr currently unimplemented
nointr (default) currently unimplemented
hard The program accessing a file on the cifs mounted file system
will hang when the server crashes.
soft (default) The program accessing a file on the cifs mounted file
system will not hang when the server crashes and will return er‐
rors to the user application.
--verbose
Print additional debugging information for the mount. Note that
this parameter must be specified before the -o. For example:
mount -t cifs //server/share /mnt --verbose -o user=username
noacl Do not allow POSIX ACL operations even if server would support
them.
The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to
Samba servers version 3.10 and later. Setting POSIX ACLs re‐
quires enabling both XATTR and then POSIX support in the CIFS
configuration options when building the cifs module. POSIX ACL
support can be disabled on a per mount basic by specifying "noa‐
cl" on mount.
serverino
Use inode numbers (unique persistent file identifiers) returned
by the server instead of automatically generating temporary in‐
ode numbers on the client. Although server inode numbers make it
easier to spot hardlinked files (as they will have the same in‐
ode numbers) and inode numbers may be persistent (which is user‐
ful for some sofware), the server does not guarantee that the
inode numbers are unique if multiple server side mounts are ex‐
ported under a single share (since inode numbers on the servers
might not be unique if multiple filesystems are mounted under
the same shared higher level directory). Note that not all
servers support returning server inode numbers, although those
that support the CIFS Unix Extensions, and Windows 2000 and lat‐
er servers typically do support this (although not necessarily
on every local server filesystem). Parameter has no effect if
the server lacks support for returning inode numbers or equiva‐
lent.
noserverino
client generates inode numbers (rather than using the actual one
from the server) by default.
nouser_xattr
(default) Do not allow getfattr/setfattr to get/set xattrs, even
if server would support it otherwise.
rsize=arg
default network read size
wsize=arg
default network write size
ENVIRONMENT VARIABLES
The variable USER may contain the username of the person to be used to
authenticate to the server. The variable can be used to set both user‐
name and password by using the format username%password.
The variable PASSWD may contain the password of the person using the
client.
The variable PASSWD_FILE may contain the pathname of a file to read the
password from. A single line of input is read and used as the password.
NOTES
This command may be used only by root, unless installed setuid, in
which case the noeexec and nosuid mount flags are enabled.
CONFIGURATION
The primary mechanism for making configuration changes and for reading
debug information for the cifs vfs is via the Linux /proc filesystem.
In the directory /proc/fs/cifs are various configuration files and
pseudo files which can display debug information. For more information
see the kernel file fs/cifs/README.
BUGS
Mounting using the CIFS URL specification is currently not supported.
The credentials file does not handle usernames or passwords with lead‐
ing space.
Note that the typical response to a bug report is a suggestion to try
the latest version first. So please try doing that first, and always
include which versions you use of relevant software when reporting bugs
(minimum: mount.cifs (try mount.cifs -V), kernel (see /proc/version)
and server type you are trying to contact.
VERSION
This man page is correct for version 1.34 of the cifs vfs filesystem
(roughly Linux kernel 2.6.12).
SEE ALSO
Documentation/filesystems/cifs.txt and fs/cifs/README in the linux ker‐
nel source tree may contain additional options and information.
umount.cifs(8)AUTHOR
Steve French
The syntax and manpage were loosely based on that of smbmount. It was
converted to Docbook/XML by Jelmer Vernooij.
The maintainer of the Linux cifs vfs and the userspace tool mount.cifs
is Steve French. The Linux CIFS Mailing list is the preferred place to
ask questions regarding these programs.
MOUNT.CIFS(8)
