Section: File Formats and Conventions (5)
smb.conf - The configuration file for the Samba suite
Thesmb.conffile is a configuration file for the Samba suite.smb.confcontains runtime configuration information for the Samba programs. The complete description of the file format and possible parameters held within are here for reference purposes.
HOW CONFIGURATION CHANGES ARE APPLIED
The Samba suite includes a number of different programs. Some of them operate in a client mode, others are server daemons that provide various services to its clients. Thesmb.conffile is processed in the following way:
- *The Samba suite's client applications read their configuration only once. Any changes made after start aren't reflected in the context of already running client code.
- *The Samba suite's server daemons reload their configuration when requested. However, already active connections do not change their configuration. More detailed information can be found insmbd(8)andwinbindd(8)manual pages.
To request Samba server daemons to refresh their configuration, please usesmbcontrol(1)utility.
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 parameter.
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 discarded. Leading, trailing and internal whitespace in section and parameter names is irrelevant. Leading and trailing whitespace in a parameter value is discarded. Internal whitespace within a parameter value is retained verbatim.
Any line beginning with a semicolon (lq;rq) or a hash (lq#rq) character is ignored, as are lines containing only whitespace.
Any line ending in alq\rqis 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, 1/0 or true/false. Case is not significant in boolean values, but is preserved in string values. Some items such as create masks are numeric.
Each section in the configuration file (except for the [global] section) describes a shared resource (known as alqsharerq). The section name is the name of the shared resource and the parameters within the section define the shares attributes.
There are three special sections, [global], [homes] and [printers], which are described underspecial 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 designatedguestservices, in which case no password is required to access them. A specified UNIXguest accountis 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 theuser =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 namefoo:
[foo] m[blue]path = /home/barm m[blue]read only = nom
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. Theguest okparameter means access will be permitted as the default guest user (specified elsewhere):
[aprinter] m[blue]path = /usr/spool/publicm m[blue]read only = yesm m[blue]printable = yesm m[blue]guest ok = yesm
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 username.
- *If no path was given, the path is set to the user's home directory.
If you decide to use apath =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 islqhomesrq, except that the share name is not 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]m[blue]read only = nom
An important point is that if guest access is specified in the [homes] section, all home directories will be visible to all clientswithout a password. In the very unlikely event that this is actually desirable, it is wise to also specifyread only access.
Thebrowseableflag for auto home directories will be inherited from the global browseable flag, not the [homes] browseable flag. This is useful as it means settingbrowseable = noin 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
- *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]m[blue]path = /usr/spool/publicmm[blue]guest ok = yesmm[blue]printable = yesm
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:
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 (|).
On SYSV systems which use lpstat to determine what printers are defined on the system you may be able to useprintcap name = lpstatto automatically obtain a list of printers. See theprintcap nameoption for more details.
Starting with Samba version 3.0.23 the capability for non-root users to add, modify, and delete their own share definitions has been added. This capability is calledusersharesand is controlled by a set of parameters in the [global] 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.
- 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 absolute 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 absolute 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 creating new usershares. All other share parameters not specified in the user defined share definition are copied from this named share.
To allow members of the UNIX groupfooto create user defined shares, create the directory to contain the share definitions as follows:
mkdir /usr/local/samba/lib/usershareschgrp foo /usr/local/samba/lib/usershareschmod 1770 /usr/local/samba/lib/usershares
Then add the parameters
m[blue]usershare path = /usr/local/samba/lib/usersharesm m[blue]usershare max shares = 10m # (or the desired number of shares)
to the global section of yoursmb.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 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 sections. For the purposes of the following descriptions the [homes] and [printers] sections will be considered normal. The letterGin parentheses indicates that a parameter is specific to the [global] section. The letterSindicates that a parameter can be specified in a service specific section. AllSparameters 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.
Many of the strings that are settable in the config file can take substitutions. For example the optionlqpath = /tmp/%urqis interpreted aslqpath = /tmp/johnrqif 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:
- session username (the username that the client wanted, not necessarily the same as the one they got).
- primary group name of %U.
- the Internet hostname that Samba is running on.
- 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] sectionsmb ports = 139. This will cause Samba to not listen on port 445 and will permit include functionality to function as it did with Samba 2.x.
- the NetBIOS name of the server. This allows you to change your config based on what the client calls you. Your server can have alqdual personalityrq.
- the Internet name of the client machine.
- the selected protocol level after protocol negotiation. It can be one of CORE, COREPLUS, LANMAN1, LANMAN2, NT1, SMB2_02, SMB2_10, SMB2_22, SMB2_24, SMB3_00, SMB3_02, SMB3_10, SMB3_11 or SMB2_FF.
- the process id of the current server process.
- The architecture of the remote machine. It currently recognizes Samba (Samba), the Linux CIFS file system (CIFSFS), OS/2, (OS2), Mac OS X (OSX), Windows for Workgroups (WfWg), Windows 9x/ME (Win95), Windows NT (WinNT), Windows 2000 (Win2K), Windows XP (WinXP), Windows XP 64-bit(WinXP64), Windows 2003 including 2003R2 (Win2K3), and Windows Vista (Vista). Anything else will be known asUNKNOWN.
- the IP address of the client machine.
Before 4.0.0 it could contain IPv4 mapped IPv6 addresses, now it only contains IPv4 or IPv6 addresses.
- the IP address of the client machine, colons/dots replaced by underscores.
- the local IP address to which a client connected.
Before 4.0.0 it could contain IPv4 mapped IPv6 addresses, now it only contains IPv4 or IPv6 addresses.
- the local IP address to which a client connected, colons/dots replaced by underscores.
- the current date and time.
- the current date and time in a minimal format without colons (YYYYYmmdd_HHMMSS).
- name of the domain or workgroup of the current user.
- the winbind separator.
- the value of the environment variableenvar.
The following substitutes apply only to some configuration options (only those that are used when a connection has been established):
- the name of the current service, if any.
- the root directory of the current service, if any.
- username of the current service, if any.
- primary group name of %u.
- the home directory of the user given by %u.
- 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-automountoption, this value will be the same as %L.
- 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 othersmb.confoptions.
Samba supportsname manglingso 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 testparm program.
These options can be set separately for each service.
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 supports case-sensitive filename so setting this option to auto is that same as setting it to no for them. Defaultauto.
default case = upper/lower
- controls what the default case is for new filenames (ie. files that don't currently exist in the filesystem). Defaultlower. IMPORTANT NOTE: As part of the optimizations for directories containing large numbers of files, the following special case applies. If the optionsm[blue]case sensitive = yesm,m[blue]preserve case = Nom, andm[blue]short preserve case = Nomare set, then the case ofallincoming client filenames, not just new filenames, will be modified. See additional notes below.
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 thedefaultcase. Defaultyes.
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 thedefaultcase. This option can be used withpreserve case = yesto permit long filenames to retain their case, while short names are lowercased. Defaultyes.
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 sensitive = 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.
Starting with Samba version 3.2.0, the capability to store Samba configuration in the registry is available. The configuration is stored in the registry keyHKLM\Software\Samba\smbconf. There are two levels of registry configuration:
- 1.Share definitions stored in registry are used. This is triggered by setting the global parameterregistry sharestolqyesrqinsmb.conf.
The registry shares are loaded not at startup but on demand at runtime bysmbd. Shares defined insmb.conftake priority over shares of the same name defined in registry.
- 2.Globalsmb.confoptions stored in registry are used. This can be activated in two different ways:
Firstly, a registry only configuration is triggered by settingm[blue]config backend = registrymin the [global] section ofsmb.conf. This resets everything that has been read from config files to this point and reads the content of the global configuration section from the registry. This is the recommended method of using registry based configuration.
Secondly, a mixed configuration can be activated by a special new meaning of the parameterm[blue]include = registrymin the [global] section ofsmb.conf. This reads the global options from registry with the same priorities as for an include of a text file. This may be especially useful in cases where an initial configuration is needed to access the registry.
Activation of global registry options automatically activates registry shares. So in the registry only case, shares are loaded on demand only.
Note: To make registry-based configurations foolproof at least to a certain extent, the use oflock directoryandconfig backendinside the registry configuration has been disabled: Especially by changing thelock directoryinside the registry configuration, one would create a broken setup where the daemons do not see the configuration they loaded once it is active.
The registry configuration can be accessed with tools likeregeditornet (rpc) registryin the keyHKLM\Software\Samba\smbconf. More conveniently, theconfsubcommand of thenet(8)utility offers a dedicated interface to read and write the registry based configuration locally, i.e. directly accessing the database file, circumventing the server.
IDENTITY MAPPING CONSIDERATIONS
In the SMB protocol, users, groups, and machines are represented by their security identifiers (SIDs). On POSIX system Samba processes need to run under corresponding POSIX user identities and with supplemental POSIX groups to allow access to the files owned by those users and groups. The process of mapping SIDs to POSIX users and groups is calledIDENTITY MAPPINGor, in short,ID MAPPING.
Samba supports multiple ways to map SIDs to POSIX users and groups. The configuration is driven by them[blue]idmap config DOMAIN : OPTIONmoption which allows one to specify identity mapping (idmap) options for each domain separately.
Identity mapping modules implement different strategies for mapping of SIDs to POSIX user and group identities. They are applicable to different use cases and scenarios. It is advised to read the documentation of the individual identity mapping modules before choosing a specific scenario to use. Each identity management module is documented in a separate manual page. The standard idmap backends are tdb (idmap_tdb(8)), tdb2 (idmap_tdb2(8)), ldap (idmap_ldap(8)), rid (idmap_rid(8)), hash (idmap_hash(8)), autorid (idmap_autorid(8)), ad (idmap_ad(8)), nss (idmap_nss(8)), and rfc2307 (idmap_rfc2307(8)).
Overall, ID mapping configuration should be decided carefully. Changes to the already deployed ID mapping configuration may create the risk of losing access to the data or disclosing the data to the wrong parties.
This example shows how to configure two domains withidmap_rid(8), the principal domain and a trusted domain, leaving the default id mapping scheme at tdb.
[global] security = domain workgroup = MAIN idmap config * : backend = tdb idmap config * : range = 1000000-1999999 idmap config MAIN : backend = rid idmap config MAIN : range = 5000000-5999999 idmap config TRUSTED : backend = rid idmap config TRUSTED : range = 6000000-6999999
EXPLANATION OF EACH PARAMETER
abort shutdown script (G)
- This a full path name to a script called bysmbd(8)that should stop a shutdown procedure issued by them[blue]shutdown scriptm.
If the connected user possesses theSeRemoteShutdownPrivilege, right, this command will be run as root.
Default:abort shutdown script = ""
Example:abort shutdown script = /sbin/shutdown -c
access based share enum (S)
- If this parameter isyesfor a service, then the share hosted by the service will only be visible to users who have read or write access to the share during share enumeration (for example net view \\sambaserver). The share ACLs which allow or deny the access to the share can be modified using for example theshareseccommand or using the appropriate Windows tools. This has parallels to access based enumeration, the main difference being that only share permissions are evaluated, and security descriptors on files contained on the share are not used in computing enumeration access rights.
Default:access based share enum = no
acl allow execute always (S)
- This boolean parameter controls the behaviour ofsmbd(8)when receiving a protocol request of "open for execution" from a Windows client. With Samba 3.6 and older, the execution right in the ACL was not checked, so a client could execute a file even if it did not have execute rights on the file. In Samba 4.0, this has been fixed, so that by default, i.e. when this parameter is set to "False", "open for execution" is now denied when execution permissions are not present.
If this parameter is set to "True", Samba does not check execute permissions on "open for execution", thus re-establishing the behaviour of Samba 3.6. This can be useful to smoothen upgrades from older Samba versions to 4.0 and newer. This setting is not meant to be used as a permanent setting, but as a temporary relief: It is recommended to fix the permissions in the ACLs and reset this parameter to the default after a certain transition period.
Default:acl allow execute always = no
acl check permissions (S)
- Please note this parameter is now deprecated in Samba 3.6.2 and will be removed in a future version of Samba.
This boolean parameter controls whatsmbd(8)does on receiving a protocol request of "open for delete" from a Windows client. If a Windows client doesn't have permissions to delete a file then they expect this to be denied at open time. POSIX systems normally only detect restrictions on delete by actually attempting to delete the file or directory. As Windows clients can (and do) "back out" a delete request by unsetting the "delete on close" bit Samba cannot delete the file immediately on "open for delete" request as we cannot restore such a deleted file. With this parameter set to true (the default) then smbd checks the file system permissions directly on "open for delete" and denies the request without actually deleting the file if the file system permissions would seem to deny it. This is not perfect, as it's possible a user could have deleted a file without Samba being able to check the permissions correctly, but it is close enough to Windows semantics for mostly correct behaviour. Samba will correctly check POSIX ACL semantics in this case.
If this parameter is set to "false" Samba doesn't check permissions on "open for delete" and allows the open. If the user doesn't have permission to delete the file this will only be discovered at close time, which is too late for the Windows user tools to display an error message to the user. The symptom of this is files that appear to have been deleted "magically" re-appearing on a Windows explorer refresh. This is an extremely advanced protocol option which should not need to be changed. This parameter was introduced in its final form in 3.0.21, an earlier version with slightly different semantics was introduced in 3.0.20. That older version is not documented here.
Default:acl check permissions = yes
acl group control (S)
- In a POSIX filesystem, only the owner of a file or directory and the superuser can modify the permissions and ACLs on a file. If this parameter is set, then Samba overrides this restriction, and also allows theprimary group ownerof a file or directory to modify the permissions and ACLs on that file.
On a Windows server, groups may be the owner of a file or directory - thus allowing anyone in that group to modify the permissions on it. This allows the delegation of security controls on a point in the filesystem to the group owner of a directory and anything below it also owned by that group. This means there are multiple people with permissions to modify ACLs on a file or directory, easing manageability.
This parameter allows Samba to also permit delegation of the control over a point in the exported directory hierarchy in much the same way as Windows. This allows all members of a UNIX group to control the permissions on a file or directory they have group ownership on.
This parameter is best used with them[blue]inherit ownermoption and also on a share containing directories with the UNIXsetgid bitset on them, which causes new files and directories created within it to inherit the group ownership from the containing directory.
This parameter was deprecated in Samba 3.0.23, but re-activated in Samba 3.0.31 and above, as it now only controls permission changes if the user is in the owning primary group. It is now no longer equivalent to thedos filemodeoption.
Default:acl group control = no
acl map full control (S)
- This boolean parameter controls whethersmbd(8)maps a POSIX ACE entry of "rwx" (read/write/execute), the maximum allowed POSIX permission set, into a Windows ACL of "FULL CONTROL". If this parameter is set to true any POSIX ACE entry of "rwx" will be returned in a Windows ACL as "FULL CONTROL", is this parameter is set to false any POSIX ACE entry of "rwx" will be returned as the specific Windows ACL bits representing read, write and execute.
Default:acl map full control = yes
add group script (G)
- This is the full pathname to a script that will be runAS ROOTbysmbd(8)when a new group is requested. It will expand any%gto the group name passed. This script is only useful for installations using the Windows NT domain administration tools. The script is free to create a group with an arbitrary name to circumvent unix group name restrictions. In that case the script must print the numeric gid of the created group on stdout.
Default:add group script =
Example:add group script = /usr/sbin/groupadd %g
additional dns hostnames (G)
- A list of additional DNS names by which this host can be identified
Default:additional dns hostnames = # empty string (no additional dns names)
Example:additional dns hostnames = host2.example.com host3.other.com
add machine script (G)
- This is the full pathname to a script that will be run bysmbd(8)when a machine is added to Samba's domain and a Unix account matching the machine's name appended with a "$" does not already exist.
This option is very similar to them[blue]add user scriptm, and likewise uses the %u substitution for the account name. Do not use the %m substitution.
Default:add machine script =
Example:add machine script = /usr/sbin/adduser -n -g machines -c Machine -d /var/lib/nobody -s /bin/false %u
addport command (G)
- Samba 3.0.23 introduced support for adding printer ports remotely using the Windows "Add Standard TCP/IP Port Wizard". This option defines an external program to be executed when smbd receives a request to add a new Port to the system. The script is passed two parameters:
The deviceURI is in the format of socket://<hostname>[:<portnumber>] or lpd://<hostname>/<queuename>.
- *port name
- *device URI
Default:addport command =
Example:addport command = /etc/samba/scripts/addport.sh
addprinter command (G)
- With the introduction of MS-RPC based printing support for Windows NT/2000 clients in Samba 2.2, The MS Add Printer Wizard (APW) icon is now also available in the "Printers..." folder displayed a share listing. The APW allows for printers to be add remotely to a Samba or Windows NT/2000 print server.
For a Samba host this means that the printer must be physically added to the underlying printing system. Theaddprinter commanddefines a script to be run which will perform the necessary operations for adding the printer to the print system and to add the appropriate service definition to thesmb.conffile in order that it can be shared bysmbd(8).
Theaddprinter commandis automatically invoked with the following parameter (in order):
All parameters are filled in from the PRINTER_INFO_2 structure sent by the Windows NT/2000 client with one exception. The "Windows 9x driver location" parameter is included for backwards compatibility only. The remaining fields in the structure are generated from answers to the APW questions.
- *printer name
- *share name
- *port name
- *driver name
- *Windows 9x driver location
Once theaddprinter commandhas been executed,smbdwill reparse thesmb.confto determine if the share defined by the APW exists. If the sharename is still invalid, thensmbdwill return an ACCESS_DENIED error to the client.
Theaddprinter commandprogram can output a single line of text, which Samba will set as the port the new printer is connected to. If this line isn't output, Samba won't reload its printer shares.
Default:addprinter command =
Example:addprinter command = /usr/bin/addprinter
add share command (G)
- Samba 2.2.0 introduced the ability to dynamically add and delete shares via the Windows NT 4.0 Server Manager. Theadd share commandis used to define an external program or script which will add a new service definition tosmb.conf.
In order to successfully execute theadd share command,smbdrequires that the administrator connects using a root account (i.e. uid == 0) or has theSeDiskOperatorPrivilege. Scripts defined in theadd share commandparameter are executed as root.
When executed,smbdwill automatically invoke theadd share commandwith five parameters.
This parameter is only used to add file shares. To add printer shares, see them[blue]addprinter commandm.
- *configFile- the location of the globalsmb.conffile.
- *shareName- the name of the new share.
- *pathName- path to an **existing** directory on disk.
- *comment- comment string to associate with the new share.
- *max connectionsNumber of maximum simultaneous connections to this share.
Default:add share command =
Example:add share command = /usr/local/bin/addshare
add user script (G)
- This is the full pathname to a script that will be runAS ROOTbysmbd(8)under special circumstances described below.
Normally, a Samba server requires that UNIX users are created for all users accessing files on this server. For sites that use Windows NT account databases as their primary user database creating these users and keeping the user list in sync with the Windows NT PDC is an onerous task. This option allows smbd to create the required UNIX usersON DEMANDwhen a user accesses the Samba server.
When the Windows user attempts to access the Samba server, at login (session setup in the SMB protocol) time,smbd(8)contacts them[blue]password servermand attempts to authenticate the given user with the given password. If the authentication succeeds thensmbdattempts to find a UNIX user in the UNIX password database to map the Windows user into. If this lookup fails, andm[blue]add user scriptmis set thensmbdwill call the specified scriptAS ROOT, expanding any%uargument to be the user name to create.
If this script successfully creates the user thensmbdwill continue on as though the UNIX user already existed. In this way, UNIX users are dynamically created to match existing Windows NT accounts.
See alsom[blue]securitym,m[blue]password serverm,m[blue]delete user scriptm.
Default:add user script =
Example:add user script = /usr/local/samba/bin/add_user %u
add user to group script (G)
- Full path to the script that will be called when a user is added to a group using the Windows NT domain administration tools. It will be run bysmbd(8)AS ROOT. Any%gwill be replaced with the group name and any%uwill be replaced with the user name.
Note that theaddusercommand used in the example below does not support the used syntax on all systems.
Default:add user to group script =
Example:add user to group script = /usr/sbin/adduser %u %g
administrative share (S)
- If this parameter is set toyesfor a share, then the share will be an administrative share. The Administrative Shares are the default network shares created by all Windows NT-based operating systems. These are shares like C$, D$ or ADMIN$. The type of these shares is STYPE_DISKTREE_HIDDEN.
See the section below onm[blue]securitymfor more information about this option.
Default:administrative share = no
admin users (S)
- This is a list of users who will be granted administrative privileges on the share. This means that they will do all file operations as the super-user (root).
You should use this option very carefully, as any user in this list will be able to do anything they like on the share, irrespective of file permissions.
Default:admin users =
Example:admin users = jason
afs share (S)
- This parameter controls whether special AFS features are enabled for this share. If enabled, it assumes that the directory exported via thepathparameter is a local AFS import. The special AFS features include the attempt to hand-craft an AFS token if you enabled --with-fake-kaserver in configure.
Default:afs share = no
afs token lifetime (G)
- This parameter controls the lifetime of tokens that the AFS fake-kaserver claims. In reality these never expire but this lifetime controls when the afs client will forget the token.
Set this parameter to 0 to getNEVERDATE.
Default:afs token lifetime = 604800
afs username map (G)
- If you are using the fake kaserver AFS feature, you might want to hand-craft the usernames you are creating tokens for. For example this is necessary if you have users from several domain in your AFS Protection Database. One possible scheme to code users as DOMAIN+User as it is done by winbind with the + as a separator.
The mapped user name must contain the cell name to log into, so without setting this parameter there will be no token.
Default:afs username map =
Example:afs username map = %uAATTafs.samba.org
aio max threads (G)
- The integer parameter specifies the maximum number of threads each smbd process will create when doing parallel asynchronous IO calls. If the number of outstanding calls is greater than this number the requests will not be refused but go onto a queue and will be scheduled in turn as outstanding requests complete.
Related command:m[blue]aio read sizem
Related command:m[blue]aio write sizem
Default:aio max threads = 100
aio read size (S)
- If this integer parameter is set to a non-zero value, Samba will read from files asynchronously when the request size is bigger than this value. Note that it happens only for non-chained and non-chaining reads and when not using write cache.
The only reasonable values for this parameter are 0 (no async I/O) and 1 (always do async I/O).
Related command:m[blue]write cache sizem
Related command:m[blue]aio write sizem
Default:aio read size = 1
Example:aio read size = 0 # Always do reads synchronously
aio write behind (S)
- If Samba has been built with asynchronous I/O support, Samba will not wait until write requests are finished before returning the result to the client for files listed in this parameter. Instead, Samba will immediately return that the write request has been finished successfully, no matter if the operation will succeed or not. This might speed up clients without aio support, but is really dangerous, because data could be lost and files could be damaged.
The syntax is identical to them[blue]veto filesmparameter.
Default:aio write behind =
Example:aio write behind = /*.tmp/
aio write size (S)
- If this integer parameter is set to a non-zero value, Samba will write to files asynchronously when the request size is bigger than this value. Note that it happens only for non-chained and non-chaining reads and when not using write cache.
The only reasonable values for this parameter are 0 (no async I/O) and 1 (always do async I/O).
Compared tom[blue]aio read sizemthis parameter has a smaller effect, most writes should end up in the file system cache. Writes that require space allocation might benefit most from going asynchronous.
Related command:m[blue]write cache sizem
Related command:m[blue]aio read sizem
Default:aio write size = 1
Example:aio write size = 0 # Always do writes synchronously
algorithmic rid base (G)
- This determines how Samba will use its algorithmic mapping from uids/gid to the RIDs needed to construct NT Security Identifiers.
Setting this option to a larger value could be useful to sites transitioning from WinNT and Win2k, as existing user and group rids would otherwise clash with system users etc.
All UIDs and GIDs must be able to be resolved into SIDs for the correct operation of ACLs on the server. As such the algorithmic mapping can't be 'turned off', but pushing it 'out of the way' should resolve the issues. Users and groups can then be assigned 'low' RIDs in arbitrary-rid supporting backends.
Default:algorithmic rid base = 1000
Example:algorithmic rid base = 100000
allocation roundup size (S)
- This parameter allows an administrator to tune the allocation size reported to Windows clients. This is only useful for old SMB1 clients because modern SMB dialects eliminated that bottleneck and have better performance by default. Using this parameter may cause difficulties for some applications, e.g. MS Visual Studio. If the MS Visual Studio compiler starts to crash with an internal error, set this parameter to zero for this share. Settings this parameter to a large value can also cause small files to allocate more space on the disk than needed.
This parameter is deprecated and will be removed in one of the next Samba releases.
The integer parameter specifies the roundup size in bytes.
Default:allocation roundup size = 0
Example:allocation roundup size = 1048576 # (to set it to the former default of 1 MiB)
allow dcerpc auth level connect (G)
- This option controls whether DCERPC services are allowed to be used with DCERPC_AUTH_LEVEL_CONNECT, which provides authentication, but no per message integrity nor privacy protection.
Some interfaces like samr, lsarpc and netlogon have a hard-coded default ofnoand epmapper, mgmt and rpcecho have a hard-coded default ofyes.
The behavior can be overwritten per interface name (e.g. lsarpc, netlogon, samr, srvsvc, winreg, wkssvc ...) by using 'allow dcerpc auth level connect:interface = yes' as option.
This option yields precedence to the implementation specific restrictions. E.g. the drsuapi and backupkey protocols require DCERPC_AUTH_LEVEL_PRIVACY. The dnsserver protocol requires DCERPC_AUTH_LEVEL_INTEGRITY.
Default:allow dcerpc auth level connect = no
Example:allow dcerpc auth level connect = yes
allow dns updates (G)
- This option determines what kind of updates to the DNS are allowed.
DNS updates can either be disallowed completely by setting it todisabled, enabled over secure connections only by setting it tosecure onlyor allowed in all cases by setting it tononsecure.
Default:allow dns updates = secure only
Example:allow dns updates = disabled
allow insecure wide links (G)
- In normal operation the optionm[blue]wide linksmwhich allows the server to follow symlinks outside of a share path is automatically disabled whenm[blue]unix extensionsmare enabled on a Samba server. This is done for security purposes to prevent UNIX clients creating symlinks to areas of the server file system that the administrator does not wish to export.
Settingm[blue]allow insecure wide linksmto true disables the link between these two parameters, removing this protection and allowing a site to configure the server to follow symlinks (by settingm[blue]wide linksmto "true") even whenm[blue]unix extensionsmis turned on.
It is not recommended to enable this option unless you fully understand the implications of allowing the server to follow symbolic links created by UNIX clients. For most normal Samba configurations this would be considered a security hole and setting this parameter is not recommended.
This option was added at the request of sites who had deliberately set Samba up in this way and needed to continue supporting this functionality without having to patch the Samba code.
Default:allow insecure wide links = no
allow nt4 crypto (G)
- This option controls whether the netlogon server (currently only in 'active directory domain controller' mode), will reject clients which does not support NETLOGON_NEG_STRONG_KEYS nor NETLOGON_NEG_SUPPORTS_AES.
This option was added with Samba 4.2.0. It may lock out clients which worked fine with Samba versions up to 4.1.x. as the effective default was "yes" there, while it is "no" now.
If you have clients without RequireStrongKey = 1 in the registry, you may need to set "allow nt4 crypto = yes", until you have fixed all clients.
"allow nt4 crypto = yes" allows weak crypto to be negotiated, maybe via downgrade attacks.
This option yields precedence to the 'reject md5 clients' option.
Default:allow nt4 crypto = no
allow trusted domains (G)
- This option only takes effect when them[blue]securitymoption is set toserver,domainorads. If it is set to no, then attempts to connect to a resource from a domain or workgroup other than the one which smbd is running in will fail, even if that domain is trusted by the remote server doing the authentication.
This is useful if you only want your Samba server to serve resources to users in the domain it is a member of. As an example, suppose that there are two domains DOMA and DOMB. DOMB is trusted by DOMA, which contains the Samba server. Under normal circumstances, a user with an account in DOMB can then access the resources of a UNIX account with the same account name on the Samba server even if they do not have an account in DOMA. This can make implementing a security boundary difficult.
Default:allow trusted domains = yes
allow unsafe cluster upgrade (G)
- If set to no (the default), smbd checks at startup if other smbd versions are running in the cluster and refuses to start if so. This is done to protect data corruption in internal data structures due to incompatible Samba versions running concurrently in the same cluster. Setting this parameter toyesdisables this safety check.
Default:allow unsafe cluster upgrade = no
apply group policies (G)
- This option controls whether winbind will execute the gpupdate command defined inm[blue]gpo update commandmon the Group Policy update interval. The Group Policy update interval is defined as every 90 minutes, plus a random offset between 0 and 30 minutes. This applies Group Policy Machine polices to the client or KDC and machine policies to a server.
Default:apply group policies = no
Example:apply group policies = yes
async smb echo handler (G)
- This parameter specifies whether Samba should fork the async smb echo handler. It can be beneficial if your file system can block syscalls for a very long time. In some circumstances, it prolongs the timeout that Windows uses to determine whether a connection is dead. This parameter is only for SMB1. For SMB2 and above TCP keepalives can be used instead.
Default:async smb echo handler = no
auth event notification (G)
- When enabled, this option causes Samba (acting as an Active Directory Domain Controller) to stream authentication events across the internal message bus. Scripts built using Samba's python bindings can listen to these events by registering as the serviceauth_event.
This should be considered a developer option (it assists in the Samba testsuite) rather than a facility for external auditing, as message delivery is not guaranteed (a feature that the testsuite works around). Additionally Samba must be compiled with the jansson support for this option to be effective.
The authentication events are also logged via the normal logging methods when them[blue]log levelmis set appropriately.
Default:auth event notification = no
- This parameter is a synonym forauto services.
auto services (G)
- This is a list of services that you want to be automatically added to the browse lists. This is most useful for homes and printers services that would otherwise not be visible.
Note that if you just want all printers in your printcap file loaded then them[blue]load printersmoption is easier.
Default:auto services =
Example:auto services = fred lp colorlp
- This parameter lets you "turn off" a service. Ifavailable = no, thenALLattempts to connect to the service will fail. Such failures are logged.
Default:available = yes
bind dns directory
- This parameter is a synonym forbinddns dir.
binddns dir (G)
- This parameters defines the directory samba will use to store the configuration files for bind, such as named.conf. NOTE: The bind dns directory needs to be on the same mount point as the private directory!
Default:binddns dir = /var/lib/samba/bind-dns
bind interfaces only (G)
- This global parameter allows the Samba admin to limit what interfaces on a machine will serve SMB requests. It affects file servicesmbd(8)and name servicenmbd(8)in a slightly different ways.
For name service it causesnmbdto bind to ports 137 and 138 on the interfaces listed in them[blue]interfacesmparameter.nmbdalso binds to the "all addresses" interface (0.0.0.0) on ports 137 and 138 for the purposes of reading broadcast messages. If this option is not set thennmbdwill service name requests on all of these sockets. Ifm[blue]bind interfaces onlymis set thennmbdwill check the source address of any packets coming in on the broadcast sockets and discard any that don't match the broadcast addresses of the interfaces in them[blue]interfacesmparameter list. As unicast packets are received on the other sockets it allowsnmbdto refuse to serve names to machines that send packets that arrive through any interfaces not listed in them[blue]interfacesmlist. IP Source address spoofing does defeat this simple check, however, so it must not be used seriously as a security feature fornmbd.
For file service it causessmbd(8)to bind only to the interface list given in them[blue]interfacesmparameter. This restricts the networks thatsmbdwill serve, to packets coming in on those interfaces. Note that you should not use this parameter for machines that are serving PPP or other intermittent or non-broadcast network interfaces as it will not cope with non-permanent interfaces.
Ifm[blue]bind interfaces onlymis set and the network address127.0.0.1is not added to them[blue]interfacesmparameter listsmbpasswd(8)may not work as expected due to the reasons covered below.
To change a users SMB password, thesmbpasswdby default connects to thelocalhost - 127.0.0.1address as an SMB client to issue the password change request. Ifm[blue]bind interfaces onlymis set then unless the network address127.0.0.1is added to them[blue]interfacesmparameter list thensmbpasswdwill fail to connect in it's default mode.smbpasswdcan be forced to use the primary IP interface of the local host by using itssmbpasswd(8)-r remote machineparameter, withremote machineset to the IP name of the primary interface of the local host.
Default:bind interfaces only = no
blocking locks (S)
- This parameter controls the behavior ofsmbd(8)when given a request by a client to obtain a byte range lock on a region of an open file, and the request has a time limit associated with it.
If this parameter is set and the lock range requested cannot be immediately satisfied, samba will internally queue the lock request, and periodically attempt to obtain the lock until the timeout period expires.
If this parameter is set tono, then samba will behave as previous versions of Samba would and will fail the lock request immediately if the lock range cannot be obtained.
Default:blocking locks = yes
block size (S)
- This parameter controls the behavior ofsmbd(8)when reporting disk free sizes. By default, this reports a disk block size of 1024 bytes.
Changing this parameter may have some effect on the efficiency of client writes, this is not yet confirmed. This parameter was added to allow advanced administrators to change it (usually to a higher value) and test the effect it has on client write performance without re-compiling the code. As this is an experimental option it may be removed in a future release.
Changing this option does not change the disk free reporting size, just the block size unit reported to the client.
Default:block size = 1024
Example:block size = 4096
- This parameter is a synonym forbrowseable.
- This controls whether this share is seen in the list of available shares in a net view and in the browse list.
Default:browseable = yes
browse list (G)
- This controls whethersmbd(8)will serve a browse list to a client doing aNetServerEnumcall. Normally set toyes. You should never need to change this.
Default:browse list = yes
cache directory (G)
- Usually, most of the TDB files are stored in thelock directory. Since Samba 3.4.0, it is possible to differentiate between TDB files with persistent data and TDB files with non-persistent data using thestate directoryand thecache directoryoptions.
This option specifies the directory for storing TDB files containing non-persistent data that will be kept across service restarts. The directory should be placed on persistent storage, but the data can be safely deleted by an administrator.
Default:cache directory = /var/lib/samba
Example:cache directory = /var/run/samba/locks/cache
- This parameter is a synonym forcase sensitive.
case sensitive (S)
- See the discussion in the sectionm[blue]name manglingm.
Default:case sensitive = auto
change notify (G)
- This parameter specifies whether Samba should reply to a client's file change notify requests.
You should never need to change this parameter
Default:change notify = yes
change share command (G)
- Samba 2.2.0 introduced the ability to dynamically add and delete shares via the Windows NT 4.0 Server Manager. Thechange share commandis used to define an external program or script which will modify an existing service definition insmb.conf.
In order to successfully execute thechange share command,smbdrequires that the administrator connects using a root account (i.e. uid == 0) or has theSeDiskOperatorPrivilege. Scripts defined in thechange share commandparameter are executed as root.
When executed,smbdwill automatically invoke thechange share commandwith six parameters.
- *configFile- the location of the globalsmb.conffile.
- *shareName- the name of the new share.
- *pathName- path to an **existing** directory on disk.