fs/cifs/README

   1 The CIFS VFS support for Linux supports many advanced network filesystem
   2 features such as heirarchical dfs like namespace, hardlinks, locking and more.
   3 It was designed to comply with the SNIA CIFS Technical Reference (which
   4 supersedes the 1992 X/Open SMB Standard) as well as to perform best practice
   5 practical interoperability with Windows 2000, Windows XP, Samba and equivalent
   6 servers.
   7
   8 For questions or bug reports please contact:
   9     sfrench@samba.org (sfrench@us.ibm.com)
  10
  11 Build instructions:
  12 ==================
  13 For Linux 2.4:
  14 1) Get the kernel source (e.g.from http://www.kernel.org)
  15 and download the cifs vfs source (see the project page
  16 at http://us1.samba.org/samba/Linux_CIFS_client.html)
  17 and change directory into the top of the kernel directory
  18 then patch the kernel (e.g. "patch -p1 < cifs_24.patch")
  19 to add the cifs vfs to your kernel configure options if
  20 it has not already been added (e.g. current SuSE and UL
  21 users do not need to apply the cifs_24.patch since the cifs vfs is
  22 already in the kernel configure menu) and then
  23 mkdir linux/fs/cifs and then copy the current cifs vfs files from
  24 the cifs download to your kernel build directory e.g.
  25
  26         cp <cifs_download_dir>/fs/cifs/* to <kernel_download_dir>/fs/cifs
  27
  28 2) make menuconfig (or make xconfig)
  29 3) select cifs from within the network filesystem choices
  30 4) save and exit
  31 5) make dep
  32 6) make modules (or "make" if CIFS VFS not to be built as a module)
  33
  34 For Linux 2.6:
  35 1) Download the kernel (e.g. from http://www.kernel.org)
  36 and change directory into the top of the kernel directory tree
  37 (e.g. /usr/src/linux-2.5.73)
  38 2) make menuconfig (or make xconfig)
  39 3) select cifs from within the network filesystem choices
  40 4) save and exit
  41 5) make
  42
  43
  44 Installation instructions:
  45 =========================
  46 If you have built the CIFS vfs as module (successfully) simply
  47 type "make modules_install" (or if you prefer, manually copy the file to
  48 the modules directory e.g. /lib/modules/2.4.10-4GB/kernel/fs/cifs/cifs.o).
  49
  50 If you have built the CIFS vfs into the kernel itself, follow the instructions
  51 for your distribution on how to install a new kernel (usually you
  52 would simply type "make install").
  53
  54 If you do not have the utility mount.cifs (in the Samba 3.0 source tree and on
  55 the CIFS VFS web site) copy it to the same directory in which mount.smbfs and
  56 similar files reside (usually /sbin).  Although the helper software is not
  57 required, mount.cifs is recommended.  Eventually the Samba 3.0 utility program
  58 "net" may also be helpful since it may someday provide easier mount syntax for
  59 users who are used to Windows e.g.  net use <mount point> <UNC name or cifs URL>
  60 Note that running the Winbind pam/nss module (logon service) on all of your
  61 Linux clients is useful in mapping Uids and Gids consistently across the
  62 domain to the proper network user.  The mount.cifs mount helper can be
  63 trivially built from Samba 3.0 or later source e.g. by executing:
  64
  65         gcc samba/source/client/mount.cifs.c -o mount.cifs
  66
  67 If cifs is built as a module, then the size and number of network buffers
  68 and maximum number of simultaneous requests to one server can be configured.
  69 Changing these from their defaults is not recommended. By executing modinfo
  70         modinfo kernel/fs/cifs/cifs.ko
  71 on kernel/fs/cifs/cifs.ko the list of configuration changes that can be made
  72 at module initialization time (by running insmod cifs.ko) can be seen.
  73
  74 Allowing User Mounts
  75 ====================
  76 To permit users to mount and unmount over directories they own is possible
  77 with the cifs vfs.  A way to enable such mounting is to mark the mount.cifs
  78 utility as suid (e.g. "chmod +s /sbin/mount.cifs). To enable users to
  79 umount shares they mount requires
  80 1) mount.cifs version 1.4 or later
  81 2) an entry for the share in /etc/fstab indicating that a user may
  82 unmount it e.g.
  83 //server/usersharename  /mnt/username cifs user 0 0
  84
  85 Note that when the mount.cifs utility is run suid (allowing user mounts),
  86 in order to reduce risks, the "nosuid" mount flag is passed in on mount to
  87 disallow execution of an suid program mounted on the remote target.
  88 When mount is executed as root, nosuid is not passed in by default,
  89 and execution of suid programs on the remote target would be enabled
  90 by default. This can be changed, as with nfs and other filesystems,
  91 by simply specifying "nosuid" among the mount options. For user mounts
  92 though to be able to pass the suid flag to mount requires rebuilding
  93 mount.cifs with the following flag:
  94
  95         gcc samba/source/client/mount.cifs.c -DCIFS_ALLOW_USR_SUID -o mount.cifs
  96
  97 There is a corresponding manual page for cifs mounting in the Samba 3.0 and
  98 later source tree in docs/manpages/mount.cifs.8
  99
 100 Allowing User Unmounts
 101 ======================
 102 To permit users to ummount directories that they have user mounted (see above),
 103 the utility umount.cifs may be used.  It may be invoked directly, or if
 104 umount.cifs is placed in /sbin, umount can invoke the cifs umount helper
 105 (at least for most versions of the umount utility) for umount of cifs
 106 mounts, unless umount is invoked with -i (which will avoid invoking a umount
 107 helper). As with mount.cifs, to enable user unmounts umount.cifs must be marked
 108 as suid (e.g. "chmod +s /sbin/umount.cifs") or equivalent (some distributions
 109 allow adding entries to a file to the /etc/permissions file to achieve the
 110 equivalent suid effect).  For this utility to succeed the target path
 111 must be a cifs mount, and the uid of the current user must match the uid
 112 of the user who mounted the resource.
 113
 114 Also note that the customary way of allowing user mounts and unmounts is
 115 (instead of using mount.cifs and unmount.cifs as suid) to add a line
 116 to the file /etc/fstab for each //server/share you wish to mount, but
 117 this can become unwieldy when potential mount targets include many
 118 or  unpredictable UNC names.
 119
 120 Samba Considerations
 121 ====================
 122 To get the maximum benefit from the CIFS VFS, we recommend using a server that
 123 supports the SNIA CIFS Unix Extensions standard (e.g.  Samba 2.2.5 or later or
 124 Samba 3.0) but the CIFS vfs works fine with a wide variety of CIFS servers.
 125 Note that uid, gid and file permissions will display default values if you do
 126 not have a server that supports the Unix extensions for CIFS (such as Samba
 127 2.2.5 or later).  To enable the Unix CIFS Extensions in the Samba server, add
 128 the line:
 129
 130         unix extensions = yes
 131
 132 to your smb.conf file on the server.  Note that the following smb.conf settings
 133 are also useful (on the Samba server) when the majority of clients are Unix or
 134 Linux:
 135
 136         case sensitive = yes
 137         delete readonly = yes
 138         ea support = yes
 139
 140 Note that server ea support is required for supporting xattrs from the Linux
 141 cifs client, and that EA support is present in later versions of Samba (e.g.
 142 3.0.6 and later (also EA support works in all versions of Windows, at least to
 143 shares on NTFS filesystems).  Extended Attribute (xattr) support is an optional
 144 feature of most Linux filesystems which may require enabling via
 145 make menuconfig. Client support for extended attributes (user xattr) can be
 146 disabled on a per-mount basis by specifying "nouser_xattr" on mount.
 147
 148 The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to Samba servers
 149 version 3.10 and later.  Setting POSIX ACLs requires enabling both XATTR and
 150 then POSIX support in the CIFS configuration options when building the cifs
 151 module.  POSIX ACL support can be disabled on a per mount basic by specifying
 152 "noacl" on mount.
 153
 154 Some administrators may want to change Samba's smb.conf "map archive" and
 155 "create mask" parameters from the default.  Unless the create mask is changed
 156 newly created files can end up with an unnecessarily restrictive default mode,
 157 which may not be what you want, although if the CIFS Unix extensions are
 158 enabled on the server and client, subsequent setattr calls (e.g. chmod) can
 159 fix the mode.  Note that creating special devices (mknod) remotely
 160 may require specifying a mkdev function to Samba if you are not using
 161 Samba 3.0.6 or later.  For more information on these see the manual pages
 162 ("man smb.conf") on the Samba server system.  Note that the cifs vfs,
 163 unlike the smbfs vfs, does not read the smb.conf on the client system
 164 (the few optional settings are passed in on mount via -o parameters instead).
 165 Note that Samba 2.2.7 or later includes a fix that allows the CIFS VFS to delete
 166 open files (required for strict POSIX compliance).  Windows Servers already
 167 supported this feature. Samba server does not allow symlinks that refer to files
 168 outside of the share, so in Samba versions prior to 3.0.6, most symlinks to
 169 files with absolute paths (ie beginning with slash) such as:
 170          ln -s /mnt/foo bar
 171 would be forbidden. Samba 3.0.6 server or later includes the ability to create
 172 such symlinks safely by converting unsafe symlinks (ie symlinks to server
 173 files that are outside of the share) to a samba specific format on the server
 174 that is ignored by local server applications and non-cifs clients and that will
 175 not be traversed by the Samba server).  This is opaque to the Linux client
 176 application using the cifs vfs. Absolute symlinks will work to Samba 3.0.5 or
 177 later, but only for remote clients using the CIFS Unix extensions, and will
 178 be invisbile to Windows clients and typically will not affect local
 179 applications running on the same server as Samba.
 180
 181 Use instructions:
 182 ================
 183 Once the CIFS VFS support is built into the kernel or installed as a module
 184 (cifs.o), you can use mount syntax like the following to access Samba or Windows
 185 servers:
 186
 187   mount -t cifs //9.53.216.11/e$ /mnt -o user=myname,pass=mypassword
 188
 189 Before -o the option -v may be specified to make the mount.cifs
 190 mount helper display the mount steps more verbosely.
 191 After -o the following commonly used cifs vfs specific options
 192 are supported:
 193
 194   user=<username>
 195   pass=<password>
 196   domain=<domain name>
 197
 198 Other cifs mount options are described below.  Use of TCP names (in addition to
 199 ip addresses) is available if the mount helper (mount.cifs) is installed. If
 200 you do not trust the server to which are mounted, or if you do not have
 201 cifs signing enabled (and the physical network is insecure), consider use
 202 of the standard mount options "noexec" and "nosuid" to reduce the risk of
 203 running an altered binary on your local system (downloaded from a hostile server
 204 or altered by a hostile router).
 205
 206 Although mounting using format corresponding to the CIFS URL specification is
 207 not possible in mount.cifs yet, it is possible to use an alternate format
 208 for the server and sharename (which is somewhat similar to NFS style mount
 209 syntax) instead of the more widely used UNC format (i.e. \\server\share):
 210   mount -t cifs tcp_name_of_server:share_name /mnt -o user=myname,pass=mypasswd
 211
 212 When using the mount helper mount.cifs, passwords may be specified via alternate
 213 mechanisms, instead of specifying it after -o using the normal "pass=" syntax
 214 on the command line:
 215 1) By including it in a credential file. Specify credentials=filename as one
 216 of the mount options. Credential files contain two lines
 217         username=someuser
 218         password=your_password
 219 2) By specifying the password in the PASSWD environment variable (similarly
 220 the user name can be taken from the USER environment variable).
 221 3) By specifying the password in a file by name via PASSWD_FILE
 222 4) By specifying the password in a file by file descriptor via PASSWD_FD
 223
 224 If no password is provided, mount.cifs will prompt for password entry
 225
 226 Restrictions
 227 ============
 228 Servers must support the NTLM SMB dialect (which is the most recent, supported
 229 by Samba and Windows NT version 4, 2000 and XP and many other SMB/CIFS servers)
 230 Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC
 231 1001/1002 support for "Netbios-Over-TCP/IP." Neither of these is likely to be a
 232 problem as most servers support this.  IPv6 support is planned for the future,
 233 and is almost complete.
 234
 235 Valid filenames differ between Windows and Linux.  Windows typically restricts
 236 filenames which contain certain reserved characters (e.g.the character :
 237 which is used to delimit the beginning of a stream name by Windows), while
 238 Linux allows a slightly wider set of valid characters in filenames. Windows
 239 servers can remap such characters when an explicit mapping is specified in
 240 the Server's registry.  Samba starting with version 3.10 will allow such
 241 filenames (ie those which contain valid Linux characters, which normally
 242 would be forbidden for Windows/CIFS semantics) as long as the server is
 243 configured for Unix Extensions (and the client has not disabled
 244 /proc/fs/cifs/LinuxExtensionsEnabled).
 245
 246
 247 CIFS VFS Mount Options
 248 ======================
 249 A partial list of the supported mount options follows:
 250   user          The user name to use when trying to establish
 251                 the CIFS session.
 252   password      The user password.  If the mount helper is
 253                 installed, the user will be prompted for password
 254                 if it is not supplied.
 255   ip            The ip address of the target server
 256   unc           The target server Universal Network Name (export) to
 257                 mount.
 258   domain        Set the SMB/CIFS workgroup name prepended to the
 259                 username during CIFS session establishment
 260   uid           If CIFS Unix extensions are not supported by the server
 261                 this overrides the default uid for inodes. For mounts to
 262                 servers which do support the CIFS Unix extensions, such
 263                 as a properly configured Samba server, the server provides
 264                 the uid, gid and mode.  For servers which do not support
 265                 the Unix extensions, the default uid (and gid) returned on
 266                 lookup of existing files is the uid (gid) of the person
 267                 who executed the mount (root, except when mount.cifs
 268                 is configured setuid for user mounts) unless the "uid="
 269                 (gid) mount option is specified.  For the uid (gid) of newly
 270                 created files and directories, ie files created since
 271                 the last mount of the server share, the expected uid
 272                 (gid) is cached as as long as the inode remains in
 273                 memory on the client.   Also note that permission
 274                 checks (authorization checks) on accesses to a file occur
 275                 at the server, but there are cases in which an administrator
 276                 may want to restrict at the client as well.  For those
 277                 servers which do not report a uid/gid owner
 278                 (such as Windows), permissions can also be checked at the
 279                 client, and a crude form of client side permission checking
 280                 can be enabled by specifying file_mode and dir_mode on
 281                 the client
 282   gid           If CIFS Unix extensions are not supported by the server
 283                 this overrides the default gid for inodes.
 284   file_mode     If CIFS Unix extensions are not supported by the server
 285                 this overrides the default mode for file inodes.
 286   dir_mode      If CIFS Unix extensions are not supported by the server
 287                 this overrides the default mode for directory inodes.
 288   port          attempt to contact the server on this tcp port, before
 289                 trying the usual ports (port 445, then 139).
 290   iocharset     Codepage used to convert local path names to and from
 291                 Unicode. Unicode is used by default for network path
 292                 names if the server supports it.  If iocharset is
 293                 not specified then the nls_default specified
 294                 during the local client kernel build will be used.
 295                 If server does not support Unicode, this parameter is
 296                 unused.
 297   rsize         default read size
 298   wsize         default write size
 299   rw            mount the network share read-write (note that the
 300                 server may still consider the share read-only)
 301   ro            mount network share read-only
 302   version       used to distinguish different versions of the
 303                 mount helper utility (not typically needed)
 304   sep           if first mount option (after the -o), overrides
 305                 the comma as the separator between the mount
 306                 parms. e.g.
 307                         -o user=myname,password=mypassword,domain=mydom
 308                 could be passed instead with period as the separator by
 309                         -o sep=.user=myname.password=mypassword.domain=mydom
 310                 this might be useful when comma is contained within username
 311                 or password or domain. This option is less important
 312                 when the cifs mount helper cifs.mount (version 1.1 or later)
 313                 is used.
 314   nosuid        Do not allow remote executables with the suid bit
 315                 program to be executed.  This is only meaningful for mounts
 316                 to servers such as Samba which support the CIFS Unix Extensions.
 317                 If you do not trust the servers in your network (your mount
 318                 targets) it is recommended that you specify this option for
 319                 greater security.
 320   exec          Permit execution of binaries on the mount.
 321   noexec        Do not permit execution of binaries on the mount.
 322   dev           Recognize block devices on the remote mount.
 323   nodev         Do not recognize devices on the remote mount.
 324   suid          Allow remote files on this mountpoint with suid enabled to
 325                 be executed (default for mounts when executed as root,
 326                 nosuid is default for user mounts).
 327   credentials   Although ignored by the cifs kernel component, it is used by
 328                 the mount helper, mount.cifs. When mount.cifs is installed it
 329                 opens and reads the credential file specified in order
 330                 to obtain the userid and password arguments which are passed to
 331                 the cifs vfs.
 332   guest         Although ignored by the kernel component, the mount.cifs
 333                 mount helper will not prompt the user for a password
 334                 if guest is specified on the mount options.  If no
 335                 password is specified a null password will be used.
 336   perm          Client does permission checks (vfs_permission check of uid
 337                 and gid of the file against the mode and desired operation),
 338                 Note that this is in addition to the normal ACL check on the
 339                 target machine done by the server software.
 340                 Client permission checking is enabled by default.
 341   noperm        Client does not do permission checks.  This can expose
 342                 files on this mount to access by other users on the local
 343                 client system. It is typically only needed when the server
 344                 supports the CIFS Unix Extensions but the UIDs/GIDs on the
 345                 client and server system do not match closely enough to allow
 346                 access by the user doing the mount.
 347                 Note that this does not affect the normal ACL check on the
 348                 target machine done by the server software (of the server
 349                 ACL against the user name provided at mount time).
 350   serverino     Use servers inode numbers instead of generating automatically
 351                 incrementing inode numbers on the client.  Although this will
 352                 make it easier to spot hardlinked files (as they will have
 353                 the same inode numbers) and inode numbers may be persistent,
 354                 note that the server does not guarantee that the inode numbers
 355                 are unique if multiple server side mounts are exported under a
 356                 single share (since inode numbers on the servers might not
 357                 be unique if multiple filesystems are mounted under the same
 358                 shared higher level directory).  Note that this requires that
 359                 the server support the CIFS Unix Extensions as other servers
 360                 do not return a unique IndexNumber on SMB FindFirst (most
 361                 servers return zero as the IndexNumber).  Parameter has no
 362                 effect to Windows servers and others which do not support the
 363                 CIFS Unix Extensions.
 364   noserverino   Client generates inode numbers (rather than using the actual one
 365                 from the server) by default.
 366   setuids       If the CIFS Unix extensions are negotiated with the server
 367                 the client will attempt to set the effective uid and gid of
 368                 the local process on newly created files, directories, and
 369                 devices (create, mkdir, mknod).
 370   nosetuids     The client will not attempt to set the uid and gid on
 371                 on newly created files, directories, and devices (create,
 372                 mkdir, mknod) which will result in the server setting the
 373                 uid and gid to the default (usually the server uid of the
 374                 user who mounted the share).  Letting the server (rather than
 375                 the client) set the uid and gid is the default. This
 376                 parameter has no effect if the CIFS Unix Extensions are not
 377                 negotiated.
 378   netbiosname   When mounting to servers via port 139, specifies the RFC1001
 379                 source name to use to represent the client netbios machine
 380                 name when doing the RFC1001 netbios session initialize.
 381   direct        Do not do inode data caching on files opened on this mount.
 382                 This precludes mmaping files on this mount. In some cases
 383                 with fast networks and little or no caching benefits on the
 384                 client (e.g. when the application is doing large sequential
 385                 reads bigger than page size without rereading the same data)
 386                 this can provide better performance than the default
 387                 behavior which caches reads (readahead) and writes
 388                 (writebehind) through the local Linux client pagecache
 389                 if oplock (caching token) is granted and held. Note that
 390                 direct allows write operations larger than page size
 391                 to be sent to the server.
 392   acl           Allow setfacl and getfacl to manage posix ACLs if server
 393                 supports them.  (default)
 394   noacl         Do not allow setfacl and getfacl calls on this mount
 395   user_xattr    Allow getting and setting user xattrs as OS/2 EAs (extended
 396                 attributes) to the server (default) e.g. via setfattr
 397                 and getfattr utilities.
 398   nouser_xattr  Do not allow getfattr/setfattr to get/set xattrs
 399   mapchars      Translate six of the seven reserved characters (not backslash)
 400                         *?<>|:
 401                 to the remap range (above 0xF000), which also
 402                 allows the CIFS client to recognize files created with
 403                 such characters by Windows's POSIX emulation. This can
 404                 also be useful when mounting to most versions of Samba
 405                 (which also forbids creating and opening files
 406                 whose names contain any of these seven characters).
 407                 This has no effect if the server does not support
 408                 Unicode on the wire.
 409  nomapchars     Do not translate any of these seven characters (default).
 410  remount        remount the share (often used to change from ro to rw mounts
 411                 or vice versa)
 412
 413 The mount.cifs mount helper also accepts a few mount options before -o
 414 including:
 415
 416         -S      take password from stdin (equivalent to setting the environment
 417                 variable "PASSWD_FD=0"
 418         -V      print mount.cifs version
 419         -?      display simple usage information
 420
 421 With recent 2.6 kernel versions of modutils, the version of the cifs kernel
 422 module can be displayed via modinfo.
 423
 424 Misc /proc/fs/cifs Flags and Debug Info
 425 =======================================
 426 Informational pseudo-files:
 427 DebugData               Displays information about active CIFS sessions
 428                         and shares, as well as the cifs.ko version.
 429 Stats                   Lists summary resource usage information as well as per
 430                         share statistics, if CONFIG_CIFS_STATS in enabled
 431                         in the kernel configuration.
 432
 433 Configuration pseudo-files:
 434 MultiuserMount          If set to one, more than one CIFS session to
 435                         the same server ip address can be established
 436                         if more than one uid accesses the same mount
 437                         point and if the uids user/password mapping
 438                         information is available. (default is 0)
 439 PacketSigningEnabled    If set to one, cifs packet signing is enabled
 440                         and will be used if the server requires
 441                         it.  If set to two, cifs packet signing is
 442                         required even if the server considers packet
 443                         signing optional. (default 1)
 444 cifsFYI                 If set to one, additional debug information is
 445                         logged to the system error log. (default 0)
 446 ExtendedSecurity        If set to one, SPNEGO session establishment
 447                         is allowed which enables more advanced
 448                         secure CIFS session establishment (default 0)
 449 NTLMV2Enabled           If set to one, more secure password hashes
 450                         are used when the server supports them and
 451                         when kerberos is not negotiated (default 0)
 452 traceSMB                If set to one, debug information is logged to the
 453                         system error log with the start of smb requests
 454                         and responses (default 0)
 455 LookupCacheEnable       If set to one, inode information is kept cached
 456                         for one second improving performance of lookups
 457                         (default 1)
 458 OplockEnabled           If set to one, safe distributed caching enabled.
 459                         (default 1)
 460 LinuxExtensionsEnabled  If set to one then the client will attempt to
 461                         use the CIFS "UNIX" extensions which are optional
 462                         protocol enhancements that allow CIFS servers
 463                         to return accurate UID/GID information as well
 464                         as support symbolic links. If you use servers
 465                         such as Samba that support the CIFS Unix
 466                         extensions but do not want to use symbolic link
 467                         support and want to map the uid and gid fields
 468                         to values supplied at mount (rather than the
 469                         actual values, then set this to zero. (default 1)
 470
 471 These experimental features and tracing can be enabled by changing flags in
 472 /proc/fs/cifs (after the cifs module has been installed or built into the
 473 kernel, e.g.  insmod cifs).  To enable a feature set it to 1 e.g.  to enable
 474 tracing to the kernel message log type:
 475
 476         echo 1 > /proc/fs/cifs/cifsFYI
 477
 478 and for more extensive tracing including the start of smb requests and responses
 479
 480         echo 1 > /proc/fs/cifs/traceSMB
 481
 482 Two other experimental features are under development and to test
 483 require enabling CONFIG_CIFS_EXPERIMENTAL
 484
 485         More efficient write operations
 486
 487         DNOTIFY fcntl: needed for support of directory change
 488                             notification and perhaps later for file leases)
 489
 490 Per share (per client mount) statistics are available in /proc/fs/cifs/Stats
 491 if the kernel was configured with cifs statistics enabled.  The statistics
 492 represent the number of successful (ie non-zero return code from the server)
 493 SMB responses to some of the more common commands (open, delete, mkdir etc.).
 494 Also recorded is the total bytes read and bytes written to the server for
 495 that share.  Note that due to client caching effects this can be less than the
 496 number of bytes read and written by the application running on the client.
 497 The statistics for the number of total SMBs and oplock breaks are different in
 498 that they represent all for that share, not just those for which the server
 499 returned success.
 500
 501 Also note that "cat /proc/fs/cifs/DebugData" will display information about
 502 the active sessions and the shares that are mounted.  Note: NTLMv2 enablement
 503 will not work since its implementation is not quite complete yet. Do not alter
 504 the ExtendedSecurity configuration value unless you are doing specific testing.
 505 Enabling extended security works to Windows 2000 Workstations and XP but not to
 506 Windows 2000 server or Samba since it does not usually send "raw NTLMSSP"
 507 (instead it sends NTLMSSP encapsulated in SPNEGO/GSSAPI, which support is not
 508 complete in the CIFS VFS yet).