Provided by: cifs-utils_5.1-1ubuntu1_i386 bug


       mount.cifs - mount using the Common Internet File System (CIFS)


       mount.cifs {service} {mount-point} [-o options]


       This tool is part of the cifs-utils suite.

       mount.cifs mounts a Linux CIFS filesystem. It is usually invoked
       indirectly 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
       resource) specified as service (using //server/share syntax, where
       "server" is the server name or IP address and "share" is the name of
       the share) to the local directory mount-point.

       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)
       supports them. Unrecognized cifs mount options passed to the cifs vfs
       kernel 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
       (usually via the umount utility).

       mount.cifs -V command displays the version of cifs mount helper.

       modinfo cifs command displays the version of cifs module.


           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/user%password" to allow the password and workgroup to be
           specified as part of the username.

               The cifs vfs accepts the parameter user=, or for users familiar
               with smbfs it accepts the longer form of the parameter
               username=. Similarly the longer smbfs style parameter names may
               be accepted as synonyms for the shorter cifs parameters
               pass=,dom= and cred=.

           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

           Note that a password which contains the delimiter character (i.e. a
           comma ´,´) will fail to be parsed correctly on the command line.
           However, the same password defined in the PASSWD environment
           variable or via a credentials file (see below) or entered at the
           password prompt will be read correctly.

           specifies a file that contains a username and/or password and
           optionally the name of the workgroup. The format of the file is:


           This is preferred over having passwords in plaintext in a shared
           file, such as /etc/fstab. Be sure to protect any credentials file

           sets the uid that will own all files or directories on the mounted
           filesystem when the server does not provide ownership information.
           It may be specified as either a username or a numeric uid. When not
           specified, the default is uid 0. The mount.cifs helper must be at
           version 1.10 or higher to support specifying the uid in non-numeric
           form. See the section on FILE AND DIRECTORY OWNERSHIP AND
           PERMISSIONS below for more information.

           instructs the client to ignore any uid provided by the server for
           files and directories and to always assign the owner to be the
           value of the uid= option. See the section on FILE AND DIRECTORY
           OWNERSHIP AND PERMISSIONS below for more information.

           sets the uid of the owner of the credentials cache. This is
           primarily useful with sec=krb5. The default is the real uid of the
           process performing the mount. Setting this parameter directs the
           upcall to look for a credentials cache owned by that user.

           sets the gid that will own all files or directories on the mounted
           filesystem when the server does not provide ownership information.
           It may be specified as either a groupname or a numeric gid. When
           not specified, the default is gid 0. The mount.cifs helper must be
           at version 1.10 or higher to support specifying the gid in
           non-numeric form. See the section on FILE AND DIRECTORY OWNERSHIP
           AND PERMISSIONS below for more information.

           instructs the client to ignore any gid provided by the server for
           files and directories and to always assign the owner to be the
           value of the gid= option. See the section on FILE AND DIRECTORY
           OWNERSHIP AND PERMISSIONS below for more information.

           sets the port number on which the client will attempt to contact
           the CIFS server. If this value is specified, look for an existing
           connection with this port, and use that if one exists. If one
           doesn't exist, try to create a new connection on that port. If that
           connection fails, return an error. If this value isn't specified,
           look for an existing connection on port 445 or 139. If no such
           connection exists, try to connect on port 445 first and then port
           139 if that fails. Return an error if both fail.

           Specify the server netbios name (RFC1001 name) to use when
           attempting to setup a session to the server. Although rarely needed
           for mounting to newer servers, this option is needed for mounting
           to some older servers (such as OS/2 or Windows 98 and Windows ME)
           since when connecting over port 139 they, unlike most newer
           servers, do not support a default server name. A server name can be
           up to 15 characters long and is usually uppercased.

           Synonym for servernetbiosname.

           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.

           If the server does not support the CIFS Unix extensions this
           overrides the default file mode.

           If the server does not support the CIFS Unix extensions this
           overrides the default mode for directories.

           sets the destination IP address. This option is set automatically
           if the server name portion of the requested UNC name can be
           resolved so rarely needs to be specified by the user.

           sets the domain (workgroup) of the user

           don´t prompt for a password

           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.

           mount read-only

           mount read-write

           If the CIFS Unix extensions are negotiated with the server the
           client will attempt to set the effective uid and gid of the local
           process on newly created files, directories, and devices (create,
           mkdir, mknod). If the CIFS Unix Extensions are not negotiated, for
           newly created files and directories instead of using the default
           uid and gid specified on the the mount, cache the new file´s uid
           and gid locally which means that the uid for the file can change
           when the inode is reloaded (or the user remounts the share).

           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.If the CIFS Unix Extensions are not negotiated then the
           uid and gid for new files will appear to be the uid (gid) of the
           mounter or the uid (gid) parameter specified on the mount.

           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

           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 system do not
           match closely enough to allow access by the user doing 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).

           Instructs the server to maintain ownership and permissions in
           memory that can´t be stored on the server. This information can
           disappear at any time (whenever the inode is flushed from the
           cache), so while this may help make some applications work, it´s
           behavior is somewhat unreliable. See the section below on FILE AND
           DIRECTORY OWNERSHIP AND PERMISSIONS for more information.

           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 better
           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.

           Use for switching on strict cache mode. In this mode the client
           reads from the cache all the time it has Oplock Level II, otherwise
           - read from the server. As for write - the client stores a data in
           the cache in Exclusive Oplock case, otherwise - write directly to
           the server.

           Forward pid of a process who opened a file to any read or write
           operation on that file. This prevent applications like WINE from
           failing on read and write if we use mandatory brlock style.

           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 contain any of these seven
           characters). This has no effect if the server does not support
           Unicode on the wire. Please note that the files created with
           mapchars mount option may not be accessible if the share is mounted
           without that option.

           Do not translate any of these seven characters (default)

           currently unimplemented

           (default) currently unimplemented

           The program accessing a file on the cifs mounted file system will
           hang when the server crashes.

           (default) The program accessing a file on the cifs mounted file
           system will not hang when the server crashes and will return errors
           to the user application.

           Do not allow POSIX ACL operations even if server would support

           The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to
           Samba servers version 3.0.10 and later. Setting POSIX ACLs requires
           enabling both CIFS_XATTR and then CIFS_POSIX support in the CIFS
           configuration options when building the cifs module. POSIX ACL
           support can be disabled on a per mount basis by specifying "noacl"
           on mount.

           This option is used to map CIFS/NTFS ACLs to/from Linux permission
           bits, map SIDs to/from UIDs and GIDs, and get and set Security

           DESCRIPTORS for more information.

           Request case insensitive path name matching (case sensitive is the
           default if the server suports it).

           Synonym for nocase.

           Security mode. Allowed values are:

           ·   none attempt to connection as a null user (no name)

           ·   krb5 Use Kerberos version 5 authentication

           ·   krb5i Use Kerberos authentication and forcibly enable packet

           ·   ntlm Use NTLM password hashing (default)

           ·   ntlmi Use NTLM password hashing and force packet signing

           ·   ntlmv2 Use NTLMv2 password hashing

           ·   ntlmv2i Use NTLMv2 password hashing and force packet signing

           ·   ntlmssp Use NTLMv2 password hashing encapsulated in Raw NTLMSSP

           ·   ntlmsspi Use NTLMv2 password hashing encapsulated in Raw
               NTLMSSP message, and force packet signing

           If the server requires signing during protocol negotiation, then it
           may be enabled automatically. Packet signing may also be enabled
           automatically if it's enabled in /proc/fs/cifs/SecurityFlags.

           Do not send byte range lock requests to the server. This is
           necessary for certain applications that break with cifs style
           mandatory byte range locks (and most cifs servers do not yet
           support requesting advisory byte range locks).

           When the CIFS Unix Extensions are not negotiated, attempt to create
           device files and fifos in a format compatible with Services for
           Unix (SFU). In addition retrieve bits 10-12 of the mode via the
           SETFILEBITS extended attribute (as SFU does). In the future the
           bottom 9 bits of the mode mode also will be emulated using queries
           of the security descriptor (ACL). [NB: requires version 1.39 or
           later of the CIFS VFS. To recognize symlinks and be able to create
           symlinks in an SFU interoperable form requires version 1.40 or
           later of the CIFS VFS kernel module.

           Use inode numbers (unique persistent file identifiers) returned by
           the server instead of automatically generating temporary inode
           numbers on the client. Although server inode numbers make it easier
           to spot hardlinked files (as they will have the same inode numbers)
           and inode numbers may be persistent (which is userful for some
           sofware), the server does not guarantee that the inode numbers are
           unique if multiple server side mounts are exported 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 later 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 equivalent. This behavior is enabled by default.

           Client generates inode numbers itself rather than using the actual
           ones from the server.

           See section INODE NUMBERS for more information.

           Disable the CIFS Unix Extensions for this mount. This can be useful
           in order to turn off multiple settings at once. This includes POSIX
           acls, POSIX locks, POSIX paths, symlink support and retrieving
           uids/gids/mode from the server. This can also be useful to work
           around a bug in a server that supports Unix Extensions.

           See section INODE NUMBERS for more information.

           (default) Do not allow getfattr/setfattr to get/set xattrs, even if
           server would support it otherwise.

           default network read size (usually 16K). The client currently can
           not use rsize larger than CIFSMaxBufSize. CIFSMaxBufSize defaults
           to 16K and may be changed (from 8K to the maximum kmalloc size
           allowed by your kernel) at module install time for cifs.ko. Setting
           CIFSMaxBufSize to a very large value will cause cifs to use more
           memory and may reduce performance in some cases. To use rsize
           greater than 127K (the original cifs protocol maximum) also
           requires that the server support a new Unix Capability flag (for
           very large read) which some newer servers (e.g. Samba 3.0.26 or
           later) do. rsize can be set from a minimum of 2048 to a maximum of
           130048 (127K or CIFSMaxBufSize, whichever is smaller)

           Maximum amount of data that the kernel will send in a write request
           in bytes. Prior to kernel 3.0.0, the default and maximum was 57344
           (14 * 4096 pages). As of 3.0.0, the default is 1M, and the maximum
           allowed is 16M. Note that this value is just a starting point for
           negotiation in 3.0.0 and up. The client and server may negotiate
           this size downward according to the server's capabilities. In
           kernels prior to 3.0.0, no negotiation is performed. It can end up
           with an existing superblock if this value isn't specified or it's
           greater or equal than the existing one.

           Enable local disk caching using FS-Cache for CIFS. This option
           could be useful to improve performance on a slow link, heavily
           loaded server and/or network where reading from the disk is faster
           than reading from the server (over the network). This could also
           impact the scalability positively as the number of calls to the
           server are reduced. But, be warned that local caching is not
           suitable for all workloads, for e.g., read-once type workloads. So,
           you need to consider carefully the situation/workload before using
           this option. Currently, local disk caching is enabled for CIFS
           files opened as read-only.

           NOTE: This feature is available only in the recent kernels that
           have been built with the kernel config option CONFIG_CIFS_FSCACHE.
           You also need to have cachefilesd daemon installed and running to
           make the cache operational.

           Map user accesses to individual credentials when accessing the
           server. By default, CIFS mounts only use a single set of user
           credentials (the mount credentials) when accessing a share. With
           this option, the client instead creates a new session with the
           server using the user's credentials whenever a new user accesses
           the mount. Further accesses by that user will also use those
           credentials. Because the kernel cannot prompt for passwords,
           multiuser mounts are limited to mounts using sec= options that
           don't require passwords.

           With this change, it's feasible for the server to handle
           permissions enforcement, so this option also implies "noperm".
           Furthermore, when unix extensions aren't in use and the
           administrator has not overriden ownership using the uid= or gid=
           options, ownership of files is presented as the current user
           accessing the share.

           The time (in seconds) that the CIFS client caches attributes of a
           file or directory before it requests attribute information from a
           server. During this period the changes that occur on the server
           remain undetected until the client checks the server again.

           By default, the attribute cache timeout is set to 1 second. This
           means more frequent on-the-wire calls to the server to check
           whether attributes have changed which could impact performance.
           With this option users can make a tradeoff between performance and
           cache metadata correctness, depending on workload needs. Shorter
           timeouts mean better cache coherency, but frequent increased number
           of calls to the server. Longer timeouts mean a reduced number of
           calls to the server but looser cache coherency. The actimeo value
           is a positive integer that can hold values between 0 and a maximum
           value of 2^30 * HZ (frequency of timer interrupt) setting.

           If unix extensions are enabled on a share, then the client will
           typically allow filenames to include any character besides '/' in a
           pathname component, and will use forward slashes as a pathname
           delimiter. This option prevents the client from attempting to
           negotiate the use of posix-style pathnames to the server.

           Inverse of noposixpaths.

           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


       It´s generally preferred to use forward slashes (/) as a delimiter in
       service names. They are considered to be the "universal delimiter"
       since they are generally not allowed to be embedded within path
       components on Windows machines and the client can convert them to
       blackslashes (\) unconditionally. Conversely, backslash characters are
       allowed by POSIX to be part of a path component, and can´t be
       automatically converted in the same way.

       mount.cifs will attempt to convert backslashes to forward slashes where
       it´s able to do so, but it cannot do so in any path component following
       the sharename.


       When Unix Extensions are enabled, we use the actual inode number
       provided by the server in response to the POSIX calls as an inode

       When Unix Extensions are disabled and "serverino" mount option is
       enabled there is no way to get the server inode number. The client
       typically maps the server-assigned "UniqueID" onto an inode number.

       Note that the UniqueID is a different value from the server inode
       number. The UniqueID value is unique over the scope of the entire
       server and is often greater than 2 power 32. This value often makes
       programs that are not compiled with LFS (Large File Support), to
       trigger a glibc EOVERFLOW error as this won´t fit in the target
       structure field. It is strongly recommended to compile your programs
       with LFS support (i.e. with -D_FILE_OFFSET_BITS=64) to prevent this
       problem. You can also use "noserverino" mount option to generate inode
       numbers smaller than 2 power 32 on the client. But you may not be able
       to detect hardlinks properly.


       This option is used to work with file objects which posses Security
       Descriptors and CIFS/NTFS ACL instead of UID, GID, file permission
       bits, and POSIX ACL as user authentication model. This is the most
       common authentication model for CIFS servers and is the one used by

       Support for this requires both CIFS_XATTR and CIFS_ACL support in the
       CIFS configuration options when building the cifs module.

       A CIFS/NTFS ACL is mapped to file permission bits using an algorithm
       specified in the following Microsoft TechNet document:


       In order to map SIDs to/from UIDs and GIDs, the following is required:

       ·   a kernel upcall to the cifs.idmap utility set up via request-

       ·   winbind support configured via nsswitch.conf(5) and smb.conf(5)

       Please refer to the respective manpages of cifs.idmap(8) and
       winbindd(8) for more information.

       Security descriptors for a file object can be retrieved and set
       directly using extended attribute named system.cifs_acl. The security
       descriptors presented via this interface are "raw" blobs of data and
       need a userspace utility to either parse and format or to assemble it
       such as getcifsacl(8) and setcifsacl(8) respectively.

       Some of the things to consider while using this mount option:

       ·   There may be an increased latency when handling metadata due to
           additional requests to get and set security descriptors.

       ·   The mapping between a CIFS/NTFS ACL and POSIX file permission bits
           is imperfect and some ACL information may be lost in the

       ·   If either upcall to cifs.idmap is not setup correctly or winbind is
           not configured and running, ID mapping will fail. In that case uid
           and gid will default to either to those values of the share or to
           the values of uid and/or gid mount options if specified.


       The core CIFS protocol does not provide unix ownership information or
       mode for files and directories. Because of this, files and directories
       will generally appear to be owned by whatever values the uid= or gid=
       options are set, and will have permissions set to the default file_mode
       and dir_mode for the mount. Attempting to change these values via
       chmod/chown will return success but have no effect.

       When the client and server negotiate unix extensions, files and
       directories will be assigned the uid, gid, and mode provided by the
       server. Because CIFS mounts are generally single-user, and the same
       credentials are used no matter what user accesses the mount, newly
       created files and directories will generally be given ownership
       corresponding to whatever credentials were used to mount the share.

       If the uid´s and gid´s being used do not match on the client and
       server, the forceuid and forcegid options may be helpful. Note however,
       that there is no corresponding option to override the mode. Permissions
       assigned to a file when forceuid or forcegid are in effect may not
       reflect the the real permissions.

       When unix extensions are not negotiated, it´s also possible to emulate
       them locally on the server using the "dynperm" mount option. When this
       mount option is in effect, newly created files and directories will
       receive what appear to be proper permissions. These permissions are not
       stored on the server however and can disappear at any time in the
       future (subject to the whims of the kernel flushing out the inode
       cache). In general, this mount option is discouraged.

       It´s also possible to override permission checking on the client
       altogether via the noperm option. Server-side permission checks cannot
       be overriden. The permission checks done by the server will always
       correspond to the credentials used to mount the share, and not
       necessarily to the user who is accessing the share.


       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
       username and password by using the format username%password.

       The variable PASSWD may contain the password of the person using the

       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.


       This command may be used only by root, unless installed setuid, in
       which case the noeexec and nosuid mount flags are enabled. When
       installed as a setuid program, the program follows the conventions set
       forth by the mount program for user mounts.

       Some samba client tools like smbclient(8) honour client-side
       configuration parameters present in smb.conf. Unlike those client
       tools, mount.cifs ignores smb.conf completely.


       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. There are additional
       startup options such as maximum buffer size and number of buffers which
       only may be set when the kernel cifs vfs (cifs.ko module) is loaded.
       These can be seen by running the modinfo utility against the file
       cifs.ko which will list the options that may be passed to cifs during
       module installation (device driver load). For more information see the
       kernel file fs/cifs/README.


       Mounting using the CIFS URL specification is currently not supported.

       The credentials file does not handle usernames or passwords with
       leading 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.


       This man page is correct for version 1.74 of the cifs vfs filesystem
       (roughly Linux kernel 3.0).


       Documentation/filesystems/cifs.txt and fs/cifs/README in the linux
       kernel source tree may contain additional options and information.



       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.