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config CIFS
tristate "SMB3 and CIFS support (advanced network filesystem)"
depends on INET
select NLS
select CRYPTO
select CRYPTO_MD4
select CRYPTO_MD5
select CRYPTO_SHA256
select CRYPTO_ARC4
This is the client VFS module for the SMB3 family of NAS protocols,
as well as for earlier dialects such as SMB2.1, SMB2 and the
Common Internet File System (CIFS) protocol. CIFS was the successor
to the original dialect, the Server Message Block (SMB) protocol, the
native file sharing mechanism for most early PC operating systems.
The SMB3 protocol is supported by most modern operating systems and
NAS appliances (e.g. Samba, Windows 8, Windows 2012, MacOS).
The older CIFS protocol was included in Windows NT4, 2000 and XP (and
later) as well by Samba (which provides excellent CIFS and SMB3
server support for Linux and many other operating systems). Limited
support for OS/2 and Windows ME and similar very old servers is
provided as well.
The cifs module provides an advanced network file system client
for mounting to SMB3 (and CIFS) compliant servers. It includes
support for DFS (hierarchical name space), secure per-user
session establishment via Kerberos or NTLM or NTLMv2,
safe distributed caching (oplock), optional packet
signing, Unicode and other internationalization improvements.
In general, the default dialects, SMB3 and later, enable better
performance, security and features, than would be possible with CIFS.
Note that when mounting to Samba, due to the CIFS POSIX extensions,
CIFS mounts can provide slightly better POSIX compatibility
than SMB3 mounts. SMB2/SMB3 mount options are also
slightly simpler (compared to CIFS) due to protocol improvements.
If you need to mount to Samba, Macs or Windows from this machine, say Y.
bool "CIFS statistics"
depends on CIFS
Enabling this option will cause statistics for each server share
mounted by the cifs client to be displayed in /proc/fs/cifs/Stats
config CIFS_STATS2
bool "Extended statistics"
depends on CIFS_STATS
Enabling this option will allow more detailed statistics on SMB
request timing to be displayed in /proc/fs/cifs/DebugData and also
allow optional logging of slow responses to dmesg (depending on the
value of /proc/fs/cifs/cifsFYI, see fs/cifs/README for more details).
These additional statistics may have a minor effect on performance
and memory utilization.
Unless you are a developer or are doing network performance analysis
or tuning, say N.
bool "Support legacy servers which use weaker LANMAN security"
depends on CIFS
Modern CIFS servers including Samba and most Windows versions
(since 1997) support stronger NTLM (and even NTLMv2 and Kerberos)
security mechanisms. These hash the password more securely
than the mechanisms used in the older LANMAN version of the
SMB protocol but LANMAN based authentication is needed to
establish sessions with some old SMB servers.
Enabling this option allows the cifs module to mount to older
LANMAN based servers such as OS/2 and Windows 95, but such
mounts may be less secure than mounts using NTLM or more recent
security mechanisms if you are on a public network. Unless you
have a need to access old SMB servers (and are on a private
network) you probably want to say N. Even if this support
is enabled in the kernel build, LANMAN authentication will not be
used automatically. At runtime LANMAN mounts are disabled but
can be set to required (or optional) either in
/proc/fs/cifs (see fs/cifs/README for more detail) or via an
option on the mount command. This support is disabled by
default in order to reduce the possibility of a downgrade
If unsure, say N.
bool "Kerberos/SPNEGO advanced session setup"
depends on CIFS && KEYS
Enables an upcall mechanism for CIFS which accesses userspace helper
utilities to provide SPNEGO packaged (RFC 4178) Kerberos tickets
which are needed to mount to certain secure servers (for which more
secure Kerberos authentication is required). If unsure, say Y.
bool "CIFS extended attributes"
depends on CIFS
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page, or visit
<> for details). CIFS maps the name of
extended attributes beginning with the user namespace prefix
to SMB/CIFS EAs. EAs are stored on Windows servers without the
user namespace prefix, but their names are seen by Linux cifs clients
prefaced by the user namespace prefix. The system namespace
(used by some filesystems to store ACLs) is not supported at
this time.
If unsure, say Y.
bool "CIFS POSIX Extensions"
depends on CIFS_XATTR
Enabling this option will cause the cifs client to attempt to
negotiate a newer dialect with servers, such as Samba 3.0.5
or later, that optionally can handle more POSIX like (rather
than Windows like) file behavior. It also enables
support for POSIX ACLs (getfacl and setfacl) to servers
(such as Samba 3.10 and later) which can negotiate
CIFS POSIX ACL support. If unsure, say N.
config CIFS_ACL
bool "Provide CIFS ACL support"
depends on CIFS_XATTR && KEYS
Allows fetching CIFS/NTFS ACL from the server. The DACL blob
is handed over to the application/caller. See the man
page for getcifsacl for more information. If unsure, say Y.
bool "Enable CIFS debugging routines"
default y
depends on CIFS
Enabling this option adds helpful debugging messages to
the cifs code which increases the size of the cifs module.
If unsure, say Y.
config CIFS_DEBUG2
bool "Enable additional CIFS debugging routines"
depends on CIFS_DEBUG
Enabling this option adds a few more debugging routines
to the cifs code which slightly increases the size of
the cifs module and can cause additional logging of debug
messages in some error paths, slowing performance. This
option can be turned off unless you are debugging
cifs problems. If unsure, say N.
bool "Dump encryption keys for offline decryption (Unsafe)"
depends on CIFS_DEBUG
Enabling this will dump the encryption and decryption keys
used to communicate on an encrypted share connection on the
console. This allows Wireshark to decrypt and dissect
encrypted network captures. Enable this carefully.
If unsure, say N.
bool "DFS feature support"
depends on CIFS && KEYS
Distributed File System (DFS) support is used to access shares
transparently in an enterprise name space, even if the share
moves to a different server. This feature also enables
an upcall mechanism for CIFS which contacts userspace helper
utilities to provide server name resolution (host names to
IP addresses) which is needed for implicit mounts of DFS junction
points. If unsure, say Y.
bool "Allow nfsd to export CIFS file system"
depends on CIFS && BROKEN
Allows NFS server to export a CIFS mounted share (nfsd over cifs)
config CIFS_SMB311
bool "SMB3.1.1 network file system support (Experimental)"
depends on CIFS
This enables experimental support for the newest, SMB3.1.1, dialect.
This dialect includes improved security negotiation features.
If unsure, say N
bool "Provide CIFS client caching support"
depends on CIFS=m && FSCACHE || CIFS=y && FSCACHE=y
Makes CIFS FS-Cache capable. Say Y here if you want your CIFS data
to be cached locally on disk through the general filesystem cache
manager. If unsure, say N.