smb.conf(5)
SMB.CONF(5) FILE FORMATS SMB.CONF(5)
NAME
smb.conf - The configuration file for the Samba suite
SYNOPSIS
The smb.conf file is a configuration file for the Samba
suite. smb.conf contains runtime configuration information
for the Samba programs. The smb.conf file is designed to be
configured and administered by the swat(8) program. The com-
plete description of the file format and possible parameters
held within are here for reference purposes.
FILE FORMAT
The file consists of sections and parameters. A section
begins with the name of the section in square brackets and
continues until the next section begins. Sections contain
parameters of the form:
name = value
The file is line-based - that is, each newline-terminated
line represents either a comment, a section name or a param-
eter.
Section and parameter names are not case sensitive.
Only the first equals sign in a parameter is significant.
Whitespace before or after the first equals sign is dis-
carded. Leading, trailing and internal whitespace in section
and parameter names is irrelevant. Leading and trailing whi-
tespace in a parameter value is discarded. Internal whi-
tespace within a parameter value is retained verbatim.
Any line beginning with a semicolon (“;”) or a
hash (“#”) character is ignored, as are lines
containing only whitespace.
Any line ending in a “#8221; is continued on the next
line in the customary UNIX fashion.
The values following the equals sign in parameters are all
either a string (no quotes needed) or a boolean, which may
be given as yes/no, 0/1 or true/false. Case is not signifi-
cant in boolean values, but is preserved in string values.
Some items such as create masks are numeric.
SECTION DESCRIPTIONS
Each section in the configuration file (except for the [glo-
bal] section) describes a shared resource (known as a
“share”). The section name is the name of the
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shared resource and the parameters within the section define
the shares attributes.
There are three special sections, [global], [homes] and
[printers], which are described under special sections. The
following notes apply to ordinary section descriptions.
A share consists of a directory to which access is being
given plus a description of the access rights which are
granted to the user of the service. Some housekeeping
options are also specifiable.
Sections are either file share services (used by the client
as an extension of their native file systems) or printable
services (used by the client to access print services on the
host running the server).
Sections may be designated guest services, in which case no
password is required to access them. A specified UNIX guest
account is used to define access privileges in this case.
Sections other than guest services will require a password
to access them. The client provides the username. As older
clients only provide passwords and not usernames, you may
specify a list of usernames to check against the password
using the user = option in the share definition. For modern
clients such as Windows 95/98/ME/NT/2000, this should not be
necessary.
The access rights granted by the server are masked by the
access rights granted to the specified or guest UNIX user by
the host system. The server does not grant more access than
the host system grants.
The following sample section defines a file space share. The
user has write access to the path /home/bar. The share is
accessed via the share name foo:
[foo]
path = /home/bar
read only = no
The following sample section defines a printable share. The
share is read-only, but printable. That is, the only write
access permitted is via calls to open, write to and close a
spool file. The guest ok parameter means access will be per-
mitted as the default guest user (specified elsewhere):
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[aprinter]
path = /usr/spool/public
read only = yes
printable = yes
guest ok = yes
SPECIAL SECTIONS
The [global] section
Parameters in this section apply to the server as a whole,
or are defaults for sections that do not specifically define
certain items. See the notes under PARAMETERS for more
information.
The [homes] section
If a section called [homes] is included in the configuration
file, services connecting clients to their home directories
can be created on the fly by the server.
When the connection request is made, the existing sections
are scanned. If a match is found, it is used. If no match is
found, the requested section name is treated as a username
and looked up in the local password file. If the name exists
and the correct password has been given, a share is created
by cloning the [homes] section.
Some modifications are then made to the newly created share:
•
The share name is changed from homes to the located user-
name.
•
If no path was given, the path is set to the user's home
directory.
If you decide to use a path = line in your [homes] section,
it may be useful to use the %S macro. For example:
path = /data/pchome/%S
is useful if you have different home directories for your
PCs than for UNIX access.
This is a fast and simple way to give a large number of
clients access to their home directories with a minimum of
fuss.
A similar process occurs if the requested section name is
“homes”, except that the share name is not
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changed to that of the requesting user. This method of using
the [homes] section works well if different users share a
client PC.
The [homes] section can specify all the parameters a normal
service section can specify, though some make more sense
than others. The following is a typical and suitable [homes]
section:
[homes]
read only = no
An important point is that if guest access is specified in
the [homes] section, all home directories will be visible to
all clients without a password. In the very unlikely event
that this is actually desirable, it is wise to also specify
read only access.
The browseable flag for auto home directories will be inher-
ited from the global browseable flag, not the [homes]
browseable flag. This is useful as it means setting browse-
able = no in the [homes] section will hide the [homes] share
but make any auto home directories visible.
The [printers] section
This section works like [homes], but for printers.
If a [printers] section occurs in the configuration file,
users are able to connect to any printer specified in the
local host's printcap file.
When a connection request is made, the existing sections are
scanned. If a match is found, it is used. If no match is
found, but a [homes] section exists, it is used as described
above. Otherwise, the requested section name is treated as a
printer name and the appropriate printcap file is scanned to
see if the requested section name is a valid printer share
name. If a match is found, a new printer share is created by
cloning the [printers] section.
A few modifications are then made to the newly created
share:
•
The share name is set to the located printer name
•
If no printer name was given, the printer name is set to
the located printer name
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•
If the share does not permit guest access and no username
was given, the username is set to the located printer
name.
The [printers] service MUST be printable - if you specify
otherwise, the server will refuse to load the configuration
file.
Typically the path specified is that of a world-writeable
spool directory with the sticky bit set on it. A typical
[printers] entry looks like this:
[printers]
path = /usr/spool/public
guest ok = yes
printable = yes
All aliases given for a printer in the printcap file are
legitimate printer names as far as the server is concerned.
If your printing subsystem doesn't work like that, you will
have to set up a pseudo-printcap. This is a file consisting
of one or more lines like this:
alias|alias|alias|alias...
Each alias should be an acceptable printer name for your
printing subsystem. In the [global] section, specify the new
file as your printcap. The server will only recognize names
found in your pseudo-printcap, which of course can contain
whatever aliases you like. The same technique could be used
simply to limit access to a subset of your local printers.
An alias, by the way, is defined as any component of the
first entry of a printcap record. Records are separated by
newlines, components (if there are more than one) are
separated by vertical bar symbols (|).
Note
On SYSV systems which use lpstat to determine what printers
are defined on the system you may be able to use printcap
name = lpstat to automatically obtain a list of printers.
See the printcap name option for more details.
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USERSHARES
Starting with Samba version 3.0.23 the capability for non-
root users to add, modify, and delete their own share defin-
itions has been added. This capability is called usershares
and is controlled by a set of parameters in the
section of the smb.conf. The relevant parameters are :
usershare allow guests
Controls if usershares can permit guest access.
usershare max shares
Maximum number of user defined shares allowed.
usershare owner only
If set only directories owned by the sharing user can be
shared.
usershare path
Points to the directory containing the user defined share
definitions. The filesystem permissions on this directory
control who can create user defined shares.
usershare prefix allow list
Comma-separated list of abolute pathnames restricting
what directories can be shared. Only directories below
the pathnames in this list are permitted.
usershare prefix deny list
Comma-separated list of abolute pathnames restricting
what directories can be shared. Directories below the
pathnames in this list are prohibited.
usershare template share
Names a pre-existing share used as a template for creat-
ing new usershares. All other share parameters not speci-
fied in the user defined share definition are copied from
this named share.
To allow members of the UNIX group foo to create user
defined shares, create the directory to contain the share
definitions as follows:
Become root:
mkdir /usr/local/samba/lib/usershares
chgrp foo /usr/local/samba/lib/usershares
chmod 1770 /usr/local/samba/lib/usershares
Then add the parameters
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usershare path = /usr/local/samba/lib/usershares
usershare max shares = 10 # (or the desired number of shares)
to the global section of your smb.conf. Members of the group
foo may then manipulate the user defined shares using the
following commands.
net usershare add sharename path [comment] [acl] [guest_ok=[y|n]]
To create or modify (overwrite) a user defined share.
net usershare delete sharename
To delete a user defined share.
net usershare list wildcard-sharename
To list user defined shares.
net usershare info wildcard-sharename
To print information about user defined shares.
PARAMETERS
Parameters define the specific attributes of sections.
Some parameters are specific to the [global] section (e.g.,
security). Some parameters are usable in all sections (e.g.,
create mask). All others are permissible only in normal sec-
tions. For the purposes of the following descriptions the
[homes] and [printers] sections will be considered normal.
The letter G in parentheses indicates that a parameter is
specific to the [global] section. The letter S indicates
that a parameter can be specified in a service specific sec-
tion. All S parameters can also be specified in the [global]
section - in which case they will define the default
behavior for all services.
Parameters are arranged here in alphabetical order - this
may not create best bedfellows, but at least you can find
them! Where there are synonyms, the preferred synonym is
described, others refer to the preferred synonym.
VARIABLE SUBSTITUTIONS
Many of the strings that are settable in the config file can
take substitutions. For example the option “path =
/tmp/%u” is interpreted as “path =
/tmp/john” if the user connected with the username
john.
These substitutions are mostly noted in the descriptions
below, but there are some general substitutions which apply
whenever they might be relevant. These are:
%U session username (the username that the client wanted,
not necessarily the same as the one they got).
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%G primary group name of %U.
%h the Internet hostname that Samba is running on.
%m the NetBIOS name of the client machine (very useful).
This parameter is not available when Samba listens on
port 445, as clients no longer send this information. If
you use this macro in an include statement on a domain
that has a Samba domain controller be sure to set in the
[global] section smb ports = 139. This will cause Samba
to not listen on port 445 and will permit include func-
tionality to function as it did with Samba 2.x.
%L the NetBIOS name of the server. This allows you to change
your config based on what the client calls you. Your
server can have a “dual personality”.
%M the Internet name of the client machine.
%R the selected protocol level after protocol negotiation.
It can be one of CORE, COREPLUS, LANMAN1, LANMAN2 or NT1.
%d the process id of the current server process.
%a the architecture of the remote machine. It currently
recognizes Samba (Samba), the Linux CIFS file system
(CIFSFS), OS/2, (OS2), Windows for Workgroups (WfWg),
Windows 9x/ME (Win95), Windows NT (WinNT), Windows 2000
(Win2K), Windows XP (WinXP), and Windows 2003 (Win2K3).
Anything else will be known as UNKNOWN.
%I the IP address of the client machine.
%i the local IP address to which a client connected.
%T the current date and time.
%D name of the domain or workgroup of the current user.
%w the winbind separator.
%$(envvar)
the value of the environment variable envar.
The following substitutes apply only to some configuration
options (only those that are used when a connection has been
established):
%S the name of the current service, if any.
%P the root directory of the current service, if any.
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%u username of the current service, if any.
%g primary group name of %u.
%H the home directory of the user given by %u.
%N the name of your NIS home directory server. This is
obtained from your NIS auto.map entry. If you have not
compiled Samba with the --with-automount option, this
value will be the same as %L.
%p the path of the service's home directory, obtained from
your NIS auto.map entry. The NIS auto.map entry is split
up as %N:%p.
There are some quite creative things that can be done with
these substitutions and other smb.conf options.
NAME MANGLING
Samba supports name mangling so that DOS and Windows clients
can use files that don't conform to the 8.3 format. It can
also be set to adjust the case of 8.3 format filenames.
There are several options that control the way mangling is
performed, and they are grouped here rather than listed
separately. For the defaults look at the output of the test-
parm program.
All of these options can be set separately for each service
(or globally, of course).
The options are:
case sensitive = yes/no/auto
controls whether filenames are case sensitive. If they
aren't, Samba must do a filename search and match on
passed names. The default setting of auto allows clients
that support case sensitive filenames (Linux CIFSVFS and
smbclient 3.0.5 and above currently) to tell the Samba
server on a per-packet basis that they wish to access the
file system in a case-sensitive manner (to support UNIX
case sensitive semantics). No Windows or DOS system sup-
ports case-sensitive filename so setting this option to
auto is that same as setting it to no for them. Default
auto.
default case = upper/lower
controls what the default case is for new filenames (ie.
files that don't currently exist in the filesystem).
Default lower. IMPORTANT NOTE: This option will be used
to modify the case of all incoming client filenames, not
just new filenames if the options case sensitive = yes,
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preserve case = No, short preserve case = No are set.
This change is needed as part of the optimisations for
directories containing large numbers of files.
preserve case = yes/no
controls whether new files (ie. files that don't
currently exist in the filesystem) are created with the
case that the client passes, or if they are forced to be
the default case. Default yes.
short preserve case = yes/no
controls if new files (ie. files that don't currently
exist in the filesystem) which conform to 8.3 syntax,
that is all in upper case and of suitable length, are
created upper case, or if they are forced to be the
default case. This option can be used with preserve case
= yes to permit long filenames to retain their case,
while short names are lowercased. Default yes.
By default, Samba 3.0 has the same semantics as a Windows NT
server, in that it is case insensitive but case preserving.
As a special case for directories with large numbers of
files, if the case options are set as follows, "case sensi-
tive = yes", "case preserve = no", "short preserve case =
no" then the "default case" option will be applied and will
modify all filenames sent from the client when accessing
this share.
NOTE ABOUT USERNAME/PASSWORD VALIDATION
There are a number of ways in which a user can connect to a
service. The server uses the following steps in determining
if it will allow a connection to a specified service. If all
the steps fail, the connection request is rejected. However,
if one of the steps succeeds, the following steps are not
checked.
If the service is marked “guest only = yes” and
the server is running with share-level security
(“security = share”, steps 1 to 5 are skipped.
1. If the client has passed a username/password pair and
that username/password pair is validated by the UNIX
system's password programs, the connection is made as
that username. This includes the \serverrvice%username
method of passing a username.
2. If the client has previously registered a username with
the system and now supplies a correct password for that
username, the connection is allowed.
3. The client's NetBIOS name and any previously used user-
names are checked against the supplied password. If they
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match, the connection is allowed as the corresponding
user.
4. If the client has previously validated a
username/password pair with the server and the client has
passed the validation token, that username is used.
5. If a user = field is given in the smb.conf file for the
service and the client has supplied a password, and that
password matches (according to the UNIX system's password
checking) with one of the usernames from the user =
field, the connection is made as the username in the user
= line. If one of the usernames in the user = list begins
with a @, that name expands to a list of names in the
group of the same name.
6. If the service is a guest service, a connection is made
as the username given in the guest account = for the ser-
vice, irrespective of the supplied password.
EXPLANATION OF EACH PARAMETER
abort shutdown script (G)
This a full path name to a script called by smbd(8) that
should stop a shutdown procedure issued by the shutdown
script.
If the connected user posseses the SeRemoteShutdown-
Privilege, right, this command will be run as user.
Default: abort shutdown script =
Example: abort shutdown script = /sbin/shutdown -c
acl check permissions (S)
This boolean parameter controls what
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