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+<chapter id="AccessControls">
+<chapterinfo>
+ &author.jht;
+ &author.jeremy;
+ <author>&person.jelmer;<contrib>drawing</contrib></author>
+ <pubdate>May 10, 2003</pubdate>
+</chapterinfo>
+<title>File, Directory and Share Access Controls</title>
+
+<para>
+<indexterm><primary>ACLs</primary></indexterm>
+Advanced MS Windows users are frequently perplexed when file, directory and share manipulation of
+resources shared via Samba do not behave in the manner they might expect. MS Windows network
+administrators are often confused regarding network access controls and how to
+provide users with the access they need while protecting resources from unauthorized access.
+</para>
+
+<para>
+Many UNIX administrators are unfamiliar with the MS Windows environment and in particular
+have difficulty in visualizing what the MS Windows user wishes to achieve in attempts to set file
+and directory access permissions.
+</para>
+
+<para>
+The problem lies in the differences in how file and directory permissions and controls work
+between the two environments. This difference is one that Samba cannot completely hide, even
+though it does try to bridge the chasm to a degree.
+</para>
+
+<para>
+<indexterm><primary>Extended Attributes</primary></indexterm>
+<indexterm><primary>ACLs</primary><secondary>POSIX</secondary></indexterm>
+
+POSIX Access Control List technology has been available (along with Extended Attributes)
+for UNIX for many years, yet there is little evidence today of any significant use. This
+explains to some extent the slow adoption of ACLs into commercial Linux products. MS Windows
+administrators are astounded at this, given that ACLs were a foundational capability of the now
+decade-old MS Windows NT operating system.
+</para>
+
+<para>
+The purpose of this chapter is to present each of the points of control that are possible with
+Samba-3 in the hope that this will help the network administrator to find the optimum method
+for delivering the best environment for MS Windows desktop users.
+</para>
+
+<para>
+This is an opportune point to mention that Samba was created to provide a means of interoperability
+and interchange of data between differing operating environments. Samba has no intent to change
+UNIX/Linux into a platform like MS Windows. Instead the purpose was and is to provide a sufficient
+level of exchange of data between the two environments. What is available today extends well
+beyond early plans and expectations, yet the gap continues to shrink.
+</para>
+
+<sect1>
+<title>Features and Benefits</title>
+
+ <para>
+ Samba offers a lot of flexibility in file system access management. These are the key access control
+ facilities present in Samba today:
+ </para>
+
+ <itemizedlist>
+ <title>Samba Access Control Facilities</title>
+ <listitem><para>
+ <indexterm><primary>permissions</primary><secondary>UNIX file and directory</secondary></indexterm>
+ <emphasis>UNIX File and Directory Permissions</emphasis>
+ </para>
+
+ <para>
+ Samba honors and implements UNIX file system access controls. Users
+ who access a Samba server will do so as a particular MS Windows user.
+ This information is passed to the Samba server as part of the logon or
+ connection setup process. Samba uses this user identity to validate
+ whether or not the user should be given access to file system resources
+ (files and directories). This chapter provides an overview for those
+ to whom the UNIX permissions and controls are a little strange or unknown.
+ </para>
+ </listitem>
+
+ <listitem><para>
+ <emphasis>Samba Share Definitions</emphasis>
+ </para>
+
+ <para>
+ In configuring share settings and controls in the &smb.conf; file,
+ the network administrator can exercise overrides to native file
+ system permissions and behaviors. This can be handy and convenient
+ to effect behavior that is more like what MS Windows NT users expect
+ but it is seldom the <emphasis>best</emphasis> way to achieve this.
+ The basic options and techniques are described herein.
+ </para>
+ </listitem>
+
+ <listitem><para>
+ <emphasis>Samba Share ACLs</emphasis>
+ <indexterm><primary>ACLs</primary><secondary>share</secondary></indexterm>
+ </para>
+
+ <para>
+ Just like it is possible in MS Windows NT to set ACLs on shares
+ themselves, so it is possible to do this in Samba.
+ Few people make use of this facility, yet it remains one of the
+ easiest ways to affect access controls (restrictions) and can often
+ do so with minimum invasiveness compared with other methods.
+ </para>
+ </listitem>
+
+ <listitem><para>
+ <indexterm><primary>ACLs</primary><secondary>POSIX</secondary></indexterm>
+ <indexterm><primary>ACLs</primary><secondary>Windows</secondary></indexterm>
+ <emphasis>MS Windows ACLs through UNIX POSIX ACLs</emphasis>
+ </para>
+
+ <para>
+ The use of POSIX ACLs on UNIX/Linux is possible only if the underlying
+ operating system supports them. If not, then this option will not be
+ available to you. Current UNIX technology platforms have native support
+ for POSIX ACLs. There are patches for the Linux kernel that also provide
+ this. Sadly, few Linux platforms ship today with native ACLs and
+ Extended Attributes enabled. This chapter has pertinent information
+ for users of platforms that support them.
+ </para>
+ </listitem>
+ </itemizedlist>
+
+</sect1>
+
+<sect1>
+<title>File System Access Controls</title>
+
+<para>
+Perhaps the most important recognition to be made is the simple fact that MS Windows NT4/200x/XP
+implement a totally divergent file system technology from what is provided in the UNIX operating system
+environment. First we consider what the most significant differences are, then we look
+at how Samba helps to bridge the differences.
+</para>
+
+ <sect2>
+ <title>MS Windows NTFS Comparison with UNIX File Systems</title>
+
+ <para>
+<indexterm><primary>NTFS</primary></indexterm>
+<indexterm><primary>File System</primary></indexterm>
+<indexterm><primary>File System</primary><secondary>UNIX</secondary></indexterm>
+<indexterm><primary>File System</primary><secondary>Windows</secondary></indexterm>
+
+ Samba operates on top of the UNIX file system. This means it is subject to UNIX file system conventions
+ and permissions. It also means that if the MS Windows networking environment requires file system
+ behavior that differs from UNIX file system behavior then somehow Samba is responsible for emulating
+ that in a transparent and consistent manner.
+ </para>
+
+ <para>
+ It is good news that Samba does this to a large extent and on top of that provides a high degree
+ of optional configuration to override the default behavior. We look at some of these over-rides,
+ but for the greater part we will stay within the bounds of default behavior. Those wishing to explore
+ the depths of control ability should review the &smb.conf; man page.
+ </para>
+
+ <para>The following compares file system features for UNIX with those of Microsoft Windows NT/200x:
+ <indexterm><primary>File System</primary><secondary>feature comparison</secondary></indexterm>
+
+ </para>
+
+ <variablelist>
+ <varlistentry>
+ <term>Name Space</term>
+ <listitem>
+ <para>
+ MS Windows NT4/200x/XP files names may be up to 254 characters long, and UNIX file names
+ may be 1023 characters long. In MS Windows, file extensions indicate particular file types,
+ in UNIX this is not so rigorously observed as all names are considered arbitrary.
+ </para>
+ <para>
+ What MS Windows calls a folder, UNIX calls a directory.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Case Sensitivity</term>
+ <listitem>
+ <para>
+ <indexterm><primary>8.3 file names</primary></indexterm>
+ <indexterm><primary>File System</primary><secondary>case sensitivity</secondary></indexterm>
+ MS Windows file names are generally upper case if made up of 8.3 (8 character file name
+ and 3 character extension. File names that are longer than 8.3 are case preserving and case
+ insensitive.
+ </para>
+
+ <para>
+ UNIX file and directory names are case sensitive and case preserving. Samba implements the
+ MS Windows file name behavior, but it does so as a user application. The UNIX file system
+ provides no mechanism to perform case insensitive file name lookups. MS Windows does this
+ by default. This means that Samba has to carry the processing overhead to provide features
+ that are not native to the UNIX operating system environment.
+ </para>
+ <para>
+ Consider the following. All are unique UNIX names but one single MS Windows file name:
+ <screen>
+ MYFILE.TXT
+ MyFile.txt
+ myfile.txt
+ </screen></para>
+
+ <para>
+ So clearly, in an MS Windows file name space these three files cannot co-exist, but in UNIX
+ they can.
+ </para>
+ <para>
+ So what should Samba do if all three are present? That which is lexically first will be
+ accessible to MS Windows users, the others are invisible and unaccessible &smbmdash; any
+ other solution would be suicidal.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Directory Separators</term>
+ <listitem>
+
+ <para>
+ <indexterm><primary>Directory Separators</primary></indexterm>
+ MS Windows and DOS uses the backslash <constant>\</constant> as a directory delimiter, and UNIX uses
+ the forward-slash <constant>/</constant> as its directory delimiter. This is handled transparently by Samba.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Drive Identification</term>
+ <listitem>
+ <para>
+ <indexterm><primary>Drive Identification</primary></indexterm>
+ MS Windows products support a notion of drive letters, like <command>C:</command> to represent
+ disk partitions. UNIX has no concept of separate identifiers for file partitions, each
+ such file system is mounted to become part of the overall directory tree.
+ The UNIX directory tree begins at <constant>/</constant> just like the root of a DOS drive is specified as
+ <constant>C:\</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>File Naming Conventions</term>
+ <listitem>
+ <para>
+ <indexterm><primary>File Naming Conventions</primary></indexterm>
+ MS Windows generally never experiences file names that begin with a dot (<constant>.</constant>) while in UNIX these
+ are commonly found in a user's home directory. Files that begin with a dot (<constant>.</constant>) are typically
+ either start-up files for various UNIX applications, or they may be files that contain
+ start-up configuration data.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Links and Short-Cuts</term>
+ <listitem>
+ <para>
+ <indexterm><primary>Links</primary><secondary>hard</secondary></indexterm>
+ <indexterm><primary>Links</primary><secondary>soft</secondary></indexterm>
+ <indexterm><primary>Short-Cuts</primary></indexterm>
+ MS Windows make use of <quote>links and short-cuts</quote> that are actually special types of files that will
+ redirect an attempt to execute the file to the real location of the file. UNIX knows of file and directory
+ links, but they are entirely different from what MS Windows users are used to.
+ </para>
+ <para>
+ Symbolic links are files in UNIX that contain the actual location of the data (file or directory). An
+ operation (like read or write) will operate directly on the file referenced. Symbolic links are also
+ referred to as <quote>soft links.</quote> A hard link is something that MS Windows is not familiar with. It allows
+ one physical file to be known simultaneously by more than one file name.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>
+ There are many other subtle differences that may cause the MS Windows administrator some temporary discomfort
+ in the process of becoming familiar with UNIX/Linux. These are best left for a text that is dedicated to the
+ purpose of UNIX/Linux training and education.
+ </para>
+
+ </sect2>
+
+ <sect2>
+ <title>Managing Directories</title>
+
+ <para>
+ There are three basic operations for managing directories: <command>create, delete, rename</command>.
+ <table frame="all">
+ <title>Managing Directories with UNIX and Windows</title>
+ <tgroup align="center" cols="3">
+ <thead>
+ <row><entry>Action</entry><entry>MS Windows Command</entry><entry>UNIX Command</entry></row>
+ </thead>
+
+ <tbody>
+ <row><entry>create</entry><entry>md folder</entry><entry>mkdir folder</entry></row>
+ <row><entry>delete</entry><entry>rd folder</entry><entry>rmdir folder</entry></row>
+ <row><entry>rename</entry><entry>rename oldname newname</entry><entry>mv oldname newname</entry></row>
+ </tbody>
+ </tgroup>
+ </table>
+ </para>
+
+ </sect2>
+
+ <sect2>
+ <title>File and Directory Access Control</title>
+
+
+ <para>
+ <indexterm><primary>ACLs</primary><secondary>File System</secondary></indexterm>
+ The network administrator is strongly advised to read foundational training manuals and reference materials
+ regarding file and directory permissions maintenance. Much can be achieved with the basic UNIX permissions
+ without having to resort to more complex facilities like POSIX Access Control Lists (ACLs) or Extended
+ Attributes (EAs).
+ </para>
+
+ <para>
+ UNIX/Linux file and directory access permissions involves setting three primary sets of data and one control set.
+ A UNIX file listing looks as follows:
+<screen>
+&prompt;<userinput>ls -la</userinput>
+total 632
+drwxr-xr-x 13 maryo gnomes 816 2003-05-12 22:56 .
+drwxrwxr-x 37 maryo gnomes 3800 2003-05-12 22:29 ..
+dr-xr-xr-x 2 maryo gnomes 48 2003-05-12 22:29 muchado02
+drwxrwxrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado03
+drw-rw-rw- 2 maryo gnomes 48 2003-05-12 22:29 muchado04
+d-w--w--w- 2 maryo gnomes 48 2003-05-12 22:29 muchado05
+dr--r--r-- 2 maryo gnomes 48 2003-05-12 22:29 muchado06
+drwsrwsrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado08
+---------- 1 maryo gnomes 1242 2003-05-12 22:31 mydata00.lst
+--w--w--w- 1 maryo gnomes 7754 2003-05-12 22:33 mydata02.lst
+-r--r--r-- 1 maryo gnomes 21017 2003-05-12 22:32 mydata04.lst
+-rw-rw-rw- 1 maryo gnomes 41105 2003-05-12 22:32 mydata06.lst
+&prompt;
+</screen>
+ </para>
+
+ <para>
+ The columns above represent (from left to right): permissions, number of hard links to file, owner, group, size (bytes), access date, access time, file name.
+ </para>
+
+ <para>
+ An overview of the permissions field can be found in <link linkend="access1">Overview of UNIX permissions field</link>.
+ </para>
+
+ <image id="access1" scale="40"><imagedescription>Overview of UNIX permissions field.</imagedescription><imagefile>access1</imagefile></image>
+
+ <para>
+ Any bit flag may be unset. An unset bit flag is the equivalent of <quote>cannot</quote> and is represented as a <quote>-</quote> character.
+
+ <example>
+ <title>Example File</title>
+ <programlisting>
+ -rwxr-x--- Means: The owner (user) can read, write, execute
+ the group can read and execute
+ everyone else cannot do anything with it.
+ </programlisting>
+ </example>
+
+ </para>
+
+ <para>
+ Additional possibilities in the [type] field are: c = character device, b = block device, p = pipe device, s = UNIX Domain Socket.
+ </para>
+
+ <para>
+ The letters <constant>rwxXst</constant> set permissions for the user, group and others as: read (r), write (w), execute (or access for directories) (x),
+ execute only if the file is a directory or already has execute permission for some user (X), set user or group ID on execution (s),
+ sticky (t).
+ </para>
+
+ <para>
+ When the sticky bit is set on a directory, files in that directory may be unlinked (deleted) or renamed only by root or their owner.
+ Without the sticky bit, anyone able to write to the directory can delete or rename files. The sticky bit is commonly found on
+ directories, such as <filename>/tmp</filename>, that are world-writable.
+ </para>
+
+ <para>
+ When the set user or group ID bit (s) is set on a directory, then all files created within it will be owned by the user and/or
+ group whose `set user or group' bit is set. This can be helpful in setting up directories for which it is desired that
+ all users who are in a group should be able to write to and read from a file, particularly when it is undesirable for that file
+ to be exclusively owned by a user whose primary group is not the group that all such users belong to.
+ </para>
+
+ <para>
+ When a directory is set <constant>d-wx--x---</constant> this means that the owner can read and create (write) files in it, but because
+ the (r) read flags are not set, files cannot be listed (seen) in the directory by anyone. The group can read files in the
+ directory but cannot create new files. If files in the directory are set to be readable and writable for the group, then
+ group members will be able to write to (or delete) them.
+ </para>
+
+ </sect2>
+
+</sect1>
+
+<sect1>
+<title>Share Definition Access Controls</title>
+
+
+<para>
+<indexterm><primary>permissions</primary><secondary>share</secondary></indexterm>
+The following parameters in the &smb.conf; file sections define a share control or effect access controls.
+Before using any of the following options, please refer to the man page for &smb.conf;.
+</para>
+
+ <sect2>
+ <title>User and Group-Based Controls</title>
+
+ <para>
+ User and group-based controls can prove quite useful. In some situations it is distinctly desirable to affect all
+ file system operations as if a single user were doing so. The use of the <smbconfoption><name>force user</name></smbconfoption> and
+ <smbconfoption><name>force group</name></smbconfoption> behavior will achieve this. In other situations it may be necessary to effect a
+ paranoia level of control to ensure that only particular authorized persons will be able to access a share or
+ its contents. Here the use of the <smbconfoption><name>valid users</name></smbconfoption> or the
+ <smbconfoption><name>invalid users</name></smbconfoption> may be most useful.
+ </para>
+
+ <para>
+ As always, it is highly advisable to use the least difficult to maintain and the least ambiguous method for
+ controlling access. Remember, when you leave the scene someone else will need to provide assistance and
+ if he finds too great a mess or does not understand what you have done, there is risk of
+ Samba being removed and an alternative solution being adopted.
+ </para>
+
+ <para>
+ <link linkend="ugbc">Following table</link> enumerates these controls.
+ </para>
+
+ <table frame='all' pgwide='0' id="ugbc"><title>User and Group Based Controls</title>
+ <tgroup cols='2'>
+ <colspec align="left"/>
+ <colspec align="justify" colwidth="1*"/>
+ <thead>
+ <row>
+ <entry align="center">Control Parameter</entry>
+ <entry align="center">Description - Action - Notes</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><smbconfoption><name>admin users</name></smbconfoption></entry>
+ <entry><para>
+ List of users who will be granted administrative privileges on the share.
+ They will do all file operations as the super-user (root).
+ Any user in this list will be able to do anything they like on the share,
+ irrespective of file permissions.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>force group</name></smbconfoption></entry>
+ <entry><para>
+ Specifies a UNIX group name that will be assigned as the default primary group
+ for all users connecting to this service.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>force user</name></smbconfoption></entry>
+ <entry><para>
+ Specifies a UNIX user name that will be assigned as the default user for all users connecting to this service.
+ This is useful for sharing files. Incorrect use can cause security problems.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>guest ok</name></smbconfoption></entry>
+ <entry><para>
+ If this parameter is set for a service, then no password is required to connect to the service. Privileges will be
+ those of the guest account.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>invalid users</name></smbconfoption></entry>
+ <entry><para>
+ List of users that should not be allowed to login to this service.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>only user</name></smbconfoption></entry>
+ <entry><para>
+ Controls whether connections with usernames not in the user list will be allowed.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>read list</name></smbconfoption></entry>
+ <entry><para>
+ List of users that are given read-only access to a service. Users in this list
+ will not be given write access, no matter what the read only option is set to.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>username</name></smbconfoption></entry>
+ <entry><para>
+ Refer to the &smb.conf; man page for more information -- this is a complex and potentially misused parameter.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>valid users</name></smbconfoption></entry>
+ <entry><para>
+ List of users that should be allowed to login to this service.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>write list</name></smbconfoption></entry>
+ <entry><para>
+ List of users that are given read-write access to a service.
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </sect2>
+
+ <sect2>
+ <title>File and Directory Permissions-Based Controls</title>
+
+ <para>
+ The following file and directory permission-based controls, if misused, can result in considerable difficulty to
+ diagnose causes of misconfiguration. Use them sparingly and carefully. By gradually introducing each one by one,
+ undesirable side effects may be detected. In the event of a problem, always comment all of them out and then gradually
+ reintroduce them in a controlled way.
+ </para>
+
+ <para>
+ Refer to <link linkend="fdpbc">the following table</link> for information regarding the parameters that may be used to affect file and
+ directory permission-based access controls.
+ </para>
+
+ <table frame='all' id="fdpbc"><title>File and Directory Permission Based Controls</title>
+ <tgroup cols='2'>
+ <colspec align="left"/>
+ <colspec align="justify" colwidth="1*"/>
+ <thead>
+ <row>
+ <entry align="center">Control Parameter</entry>
+ <entry align="center">Description - Action - Notes</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><smbconfoption><name>create mask</name></smbconfoption></entry>
+ <entry><para>
+ Refer to the &smb.conf; man page.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>directory mask</name></smbconfoption></entry>
+ <entry><para>
+ The octal modes used when converting DOS modes to UNIX modes when creating UNIX directories.
+ See also: directory security mask.
+ </para></entry></row>
+ <row>
+ <entry><smbconfoption><name>dos filemode</name></smbconfoption></entry>
+ <entry><para>
+ Enabling this parameter allows a user who has write access to the file to modify the permissions on it.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>force create mode</name></smbconfoption></entry>
+ <entry><para>
+ This parameter specifies a set of UNIX mode bit permissions that will always be set on a file created by Samba.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>force directory mode</name></smbconfoption></entry>
+ <entry><para>
+ This parameter specifies a set of UNIX mode bit permissions that will always be set on a directory created by Samba.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>force directory security mode</name></smbconfoption></entry>
+ <entry><para>
+ Controls UNIX permission bits modified when a Windows NT client is manipulating UNIX permissions on a directory.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>force security mode</name></smbconfoption></entry>
+ <entry><para>
+ Controls UNIX permission bits modified when a Windows NT client manipulates UNIX permissions.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>hide unreadable</name></smbconfoption></entry>
+ <entry><para>
+ Prevents clients from seeing the existence of files that cannot be read.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>hide unwriteable files</name></smbconfoption></entry>
+ <entry><para>
+ Prevents clients from seeing the existence of files that cannot be written to. Unwriteable directories are shown as usual.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>nt acl support</name></smbconfoption></entry>
+ <entry><para>
+ This parameter controls whether smbd will attempt to map UNIX permissions into Windows NT access control lists.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>security mask</name></smbconfoption></entry>
+ <entry><para>
+ Controls UNIX permission bits modified when a Windows NT client is manipulating the UNIX permissions on a file.
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </sect2>
+
+ <sect2>
+ <title>Miscellaneous Controls</title>
+
+ <para>
+ The following are documented because of the prevalence of administrators creating inadvertent barriers to file
+ access by not understanding the full implications of &smb.conf; file settings. See <link linkend="mcoc">following table</link>.
+ </para>
+
+ <table frame='all' id="mcoc"><title>Other Controls</title>
+ <tgroup cols='2'>
+ <colspec align="justify" colwidth="1*"/>
+ <colspec align="justify" colwidth="1*"/>
+ <thead>
+ <row>
+ <entry align="center">Control Parameter</entry>
+ <entry align="center">Description - Action - Notes</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><smbconfoption><name>case sensitive</name></smbconfoption>, <smbconfoption><name>default case</name></smbconfoption>, <smbconfoption><name>short preserve case</name></smbconfoption></entry>
+ <entry><para>
+ This means that all file name lookup will be done in a case sensitive manner.
+ Files will be created with the precise file name Samba received from the MS Windows client.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>csc policy</name></smbconfoption></entry>
+ <entry><para>
+ Client Side Caching Policy - parallels MS Windows client side file caching capabilities.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>dont descend</name></smbconfoption></entry>
+ <entry><para>
+ Allows specifying a comma-delimited list of directories that the server should always show as empty.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>dos filetime resolution</name></smbconfoption></entry>
+ <entry><para>
+ This option is mainly used as a compatibility option for Visual C++ when used against Samba shares.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>dos filetimes</name></smbconfoption></entry>
+ <entry><para>
+ DOS and Windows allow users to change file time stamps if they can write to the file. POSIX semantics prevent this.
+ This option allows DOS and Windows behavior.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>fake oplocks</name></smbconfoption></entry>
+ <entry><para>
+ Oplocks are the way that SMB clients get permission from a server to locally cache file operations. If a server grants an
+ oplock, the client is free to assume that it is the only one accessing the file and it will aggressively cache file data.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>hide dot files</name></smbconfoption>, <smbconfoption><name>hide files</name></smbconfoption>, <smbconfoption><name>veto files</name></smbconfoption></entry>
+ <entry><para>
+ Note: MS Windows Explorer allows over-ride of files marked as hidden so they will still be visible.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>read only</name></smbconfoption></entry>
+ <entry><para>
+ If this parameter is yes, then users of a service may not create or modify files in the service's directory.
+ </para></entry>
+ </row>
+ <row>
+ <entry><smbconfoption><name>veto files</name></smbconfoption></entry>
+ <entry><para>
+ List of files and directories that are neither visible nor accessible.
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </sect2>
+
+</sect1>
+
+<sect1>
+<title>Access Controls on Shares</title>
+
+
+ <para>
+<indexterm><primary>permissions</primary><secondary>share ACLs</secondary></indexterm>
+ This section deals with how to configure Samba per share access control restrictions.
+ By default, Samba sets no restrictions on the share itself. Restrictions on the share itself
+ can be set on MS Windows NT4/200x/XP shares. This can be an effective way to limit who can
+ connect to a share. In the absence of specific restrictions the default setting is to allow
+ the global user <constant>Everyone - Full Control</constant> (full control, change and read).
+ </para>
+
+ <para>
+ At this time Samba does not provide a tool for configuring access control setting on the share
+ itself. Samba does have the capacity to store and act on access control settings, but the only
+ way to create those settings is to use either the NT4 Server Manager or the Windows 200x MMC for
+ Computer Management.
+ </para>
+
+ <para>
+ Samba stores the per share access control settings in a file called <filename>share_info.tdb</filename>.
+ The location of this file on your system will depend on how Samba was compiled. The default location
+ for Samba's tdb files is under <filename>/usr/local/samba/var</filename>. If the <filename>tdbdump</filename>
+ utility has been compiled and installed on your system, then you can examine the contents of this file
+ by executing: <command>tdbdump share_info.tdb</command> in the directory containing the tdb files.
+ </para>
+
+ <sect2>
+ <title>Share Permissions Management</title>
+
+ <para>
+ The best tool for the task is platform dependant. Choose the best tool for your environment.
+ </para>
+
+ <sect3>
+ <title>Windows NT4 Workstation/Server</title>
+ <para>
+ The tool you need to use to manage share permissions on a Samba server is the NT Server Manager.
+ Server Manager is shipped with Windows NT4 Server products but not with Windows NT4 Workstation.
+ You can obtain the NT Server Manager for MS Windows NT4 Workstation from Microsoft &smbmdash; see details below.
+ </para>
+
+ <?latex \newpage ?>
+
+ <procedure>
+ <title>Instructions</title>
+ <step><para>
+ Launch the <application>NT4 Server Manager</application>, click on the Samba server you want to administer. From the menu
+ select <guimenu>Computer</guimenu>, then click on <guimenuitem>Shared Directories</guimenuitem>.
+ </para></step>
+
+ <step><para>
+ Click on the share that you wish to manage, then click the <guilabel>Properties</guilabel> tab. then click
+ the <guilabel>Permissions</guilabel> tab. Now you can add or change access control settings as you wish.
+ </para></step>
+ </procedure>
+
+ </sect3>
+
+ <sect3>
+ <title>Windows 200x/XP</title>
+
+ <para>
+ On <application>MS Windows NT4/200x/XP</application> system access control lists on the share itself are set using native
+ tools, usually from File Manager. For example, in Windows 200x, right click on the shared folder,
+ then select <guimenuitem>Sharing</guimenuitem>, then click on <guilabel>Permissions</guilabel>. The default
+ Windows NT4/200x permission allows <quote>Everyone</quote> full control on the share.
+ </para>
+
+ <para>
+ MS Windows 200x and later versions come with a tool called the <application>Computer Management</application> snap-in for the
+ Microsoft Management Console (MMC). This tool is located by clicking on <guimenu>Control Panel ->
+ Administrative Tools -> Computer Management</guimenu>.
+ </para>
+
+ <procedure>
+ <title>Instructions</title>
+ <step><para>
+ After launching the MMC with the Computer Management snap-in, click the menu item <guimenuitem>Action</guimenuitem>,
+ and select <guilabel>Connect to another computer</guilabel>. If you are not logged onto a domain you will be prompted
+ to enter a domain login user identifier and a password. This will authenticate you to the domain.
+ If you are already logged in with administrative privilege, this step is not offered.
+ </para></step>
+
+ <step><para>
+ If the Samba server is not shown in the <guilabel>Select Computer</guilabel> box, type in the name of the target
+ Samba server in the field <guilabel>Name:</guilabel>. Now click the on <guibutton>[+]</guibutton> next to
+ <guilabel>System Tools</guilabel>, then on the <guibutton>[+]</guibutton> next to <guilabel>Shared Folders</guilabel> in the
+ left panel.
+ </para></step>
+
+ <step><para>
+ In the right panel, double-click on the share on which you wish to set access control permissions.
+ Then click the tab <guilabel>Share Permissions</guilabel>. It is now possible to add access control entities
+ to the shared folder. Remember to set what type of access (full control, change, read) you
+ wish to assign for each entry.
+ </para></step>
+ </procedure>
+
+ <warning>
+ <para>
+ Be careful. If you take away all permissions from the <constant>Everyone</constant> user without removing this user,
+ effectively no user will be able to access the share. This is a result of what is known as
+ ACL precedence. Everyone with <emphasis>no access</emphasis> means that <constant>MaryK</constant> who is part of the group
+ <constant>Everyone</constant> will have no access even if she is given explicit full control access.
+ </para>
+ </warning>
+
+ </sect3>
+ </sect2>
+
+</sect1>
+
+<sect1>
+<title>MS Windows Access Control Lists and UNIX Interoperability</title>
+
+ <sect2>
+ <title>Managing UNIX Permissions Using NT Security Dialogs</title>
+
+
+ <para>
+<indexterm><primary>permissions</primary><secondary>file/directory ACLs</secondary></indexterm>
+ Windows NT clients can use their native security settings dialog box to view and modify the
+ underlying UNIX permissions.
+ </para>
+
+ <para>
+ This ability is careful not to compromise the security of the UNIX host on which Samba is running, and
+ still obeys all the file permission rules that a Samba administrator can set.
+ </para>
+
+ <para>
+ Samba does not attempt to go beyond POSIX ACLs, so the various finer-grained access control
+ options provided in Windows are actually ignored.
+ </para>
+
+ <note>
+ <para>
+ All access to UNIX/Linux system files via Samba is controlled by the operating system file access controls.
+ When trying to figure out file access problems, it is vitally important to find the identity of the Windows
+ user as it is presented by Samba at the point of file access. This can best be determined from the
+ Samba log files.
+ </para>
+ </note>
+ </sect2>
+
+ <sect2>
+ <title>Viewing File Security on a Samba Share</title>
+
+ <para>
+ From an NT4/2000/XP client, right click on any file or directory in a Samba-mounted drive letter
+ or UNC path. When the menu pops up, click on the <guilabel>Properties</guilabel> entry at the bottom
+ of the menu. This brings up the file <constant>Properties</constant> dialog box. Click on the
+ <guilabel>Security</guilabel> tab and you will see three buttons: <guibutton>Permissions</guibutton>,
+ <guibutton>Auditing</guibutton>, and <guibutton>Ownership</guibutton>. The <guibutton>Auditing</guibutton>
+ button will cause either an error message <errorname>`A requested privilege is not held by the client'</errorname>
+ to appear if the user is not the NT Administrator, or a dialog which is intended to allow an Administrator
+ to add auditing requirements to a file if the user is logged on as the NT Administrator. This dialog is
+ non-functional with a Samba share at this time, as the only useful button, the <guibutton>Add</guibutton>
+ button, will not currently allow a list of users to be seen.
+ </para>
+
+ </sect2>
+
+ <sect2>
+ <title>Viewing File Ownership</title>
+
+ <para>
+ Clicking on the <guibutton>Ownership</guibutton> button brings up a dialog box telling you who owns
+ the given file. The owner name will be displayed like this:
+ </para>
+
+ <para>
+ <command><quote>SERVER\user (Long name)</quote></command>
+ </para>
+
+ <para>
+ <replaceable>SERVER</replaceable> is the NetBIOS name of the Samba server, <replaceable>user</replaceable>
+ is the user name of the UNIX user who owns the file, and <replaceable>(Long name)</replaceable> is the
+ descriptive string identifying the user (normally found in the GECOS field of the UNIX password database).
+ Click on the <guibutton>Close </guibutton> button to remove this dialog.
+ </para>
+
+ <para>
+ If the parameter <smbconfoption><name>nt acl support</name></smbconfoption> is set to <constant>false</constant>,
+ the file owner will be shown as the NT user <emphasis>Everyone</emphasis>.
+ </para>
+
+ <para>
+ The <guibutton>Take Ownership</guibutton> button will not allow you to change the ownership of this file to
+ yourself (clicking it will display a dialog box complaining that the user you are currently logged onto
+ the NT client cannot be found). The reason for this is that changing the ownership of a file is a privileged
+ operation in UNIX, available only to the <emphasis>root</emphasis> user. As clicking on this button causes
+ NT to attempt to change the ownership of a file to the current user logged into the NT client, this will
+ not work with Samba at this time.</para>
+
+ <para>
+ There is an NT <command>chown</command> command that will work with Samba and allow a user with Administrator privilege connected
+ to a Samba server as root to change the ownership of files on both a local NTFS filesystem or remote mounted NTFS
+ or Samba drive. This is available as part of the <application>Seclib</application> NT security library written
+ by Jeremy Allison of the Samba Team, and is available from the main Samba FTP site.</para>
+
+ </sect2>
+
+ <sect2>
+ <title>Viewing File or Directory Permissions</title>
+
+ <para>
+ The third button is the <guibutton>Permissions</guibutton> button. Clicking on this brings up a dialog box
+ that shows both the permissions and the UNIX owner of the file or directory. The owner is displayed like this:
+ </para>
+
+ <para><command><replaceable>SERVER</replaceable>\
+ <replaceable>user</replaceable>
+ <replaceable>(Long name)</replaceable></command></para>
+
+ <para>Where <replaceable>SERVER</replaceable> is the NetBIOS name of the Samba server,
+ <replaceable>user</replaceable> is the user name of the UNIX user who owns the file, and
+ <replaceable>(Long name)</replaceable> is the descriptive string identifying the user (normally found in the
+ GECOS field of the UNIX password database).</para>
+
+ <para>
+ If the parameter <smbconfoption><name>nt acl support</name></smbconfoption> is set to <constant>false</constant>,
+ the file owner will be shown as the NT user <constant>Everyone</constant> and the permissions will be
+ shown as NT <quote>Full Control</quote>.
+ </para>
+
+
+ <para>
+ The permissions field is displayed differently for files and directories, so I'll describe the way file permissions
+ are displayed first.
+ </para>
+
+ <sect3>
+ <title>File Permissions</title>
+
+ <para>The standard UNIX user/group/world triplet and the corresponding <constant>read, write, execute</constant> permissions
+ triplets are mapped by Samba into a three element NT ACL with the <quote>r</quote>, <quote>w</quote> and <quote>x</quote> bits mapped into the corresponding
+ NT permissions. The UNIX world permissions are mapped into the global NT group <constant>Everyone</constant>, followed
+ by the list of permissions allowed for UNIX world. The UNIX owner and group permissions are displayed as an NT
+ <guiicon>user</guiicon> icon and an NT <guiicon>local group</guiicon> icon, respectively, followed by the list
+ of permissions allowed for the UNIX user and group.</para>
+
+ <para>Because many UNIX permission sets do not map into common NT names such as <constant>read</constant>,
+ <constant>change</constant> or <constant>full control</constant>, usually the permissions will be prefixed
+ by the words <constant>Special Access</constant> in the NT display list.</para>
+
+ <para>But what happens if the file has no permissions allowed for a particular UNIX user group or world component? In order
+ to allow <quote>no permissions</quote> to be seen and modified Samba then overloads the NT <constant>Take Ownership</constant> ACL attribute
+ (which has no meaning in UNIX) and reports a component with no permissions as having the NT <command>O</command> bit set.
+ This was chosen, of course, to make it look like a zero, meaning zero permissions. More details on the decision behind this is
+ given below.</para>
+ </sect3>
+
+ <sect3>
+ <title>Directory Permissions</title>
+
+ <para>Directories on an NT NTFS file system have two different sets of permissions. The first set is the ACL set on the
+ directory itself, which is usually displayed in the first set of parentheses in the normal <constant>RW</constant>
+ NT style. This first set of permissions is created by Samba in exactly the same way as normal file permissions are, described
+ above, and is displayed in the same way.</para>
+
+ <para>The second set of directory permissions has no real meaning in the UNIX permissions world and represents the <constant>
+ inherited</constant> permissions that any file created within this directory would inherit.</para>
+
+ <para>Samba synthesizes these inherited permissions for NT by returning as an NT ACL the UNIX permission mode that a new file
+ created by Samba on this share would receive.</para>
+ </sect3>
+ </sect2>
+
+ <sect2>
+ <title>Modifying File or Directory Permissions</title>
+
+ <para>Modifying file and directory permissions is as simple
+ as changing the displayed permissions in the dialog box, and
+ clicking on <guibutton>OK</guibutton>. However, there are
+ limitations that a user needs to be aware of, and also interactions
+ with the standard Samba permission masks and mapping of DOS
+ attributes that need to also be taken into account.</para>
+
+ <para>If the parameter <smbconfoption><name>nt acl support</name></smbconfoption>
+ is set to <constant>false</constant>, any attempt to set
+ security permissions will fail with an <errorname>`Access Denied'
+ </errorname> message.</para>
+
+ <para>The first thing to note is that the <guibutton>Add</guibutton>
+ button will not return a list of users in Samba (it will give
+ an error message saying <errorname>`The remote procedure call failed
+ and did not execute'</errorname>). This means that you can only
+ manipulate the current user/group/world permissions listed in
+ the dialog box. This actually works quite well as these are the
+ only permissions that UNIX actually has.</para>
+
+ <para>If a permission triplet (either user, group, or world)
+ is removed from the list of permissions in the NT dialog box,
+ then when the <guibutton>OK</guibutton> button is pressed it will
+ be applied as <quote>no permissions</quote> on the UNIX side. If you then
+ view the permissions again, the <quote>no permissions</quote> entry will appear
+ as the NT <command>O</command> flag, as described above. This
+ allows you to add permissions back to a file or directory once
+ you have removed them from a triplet component.</para>
+
+ <para>As UNIX supports only the <quote>r</quote>, <quote>w</quote> and <quote>x</quote> bits of
+ an NT ACL, if other NT security attributes such as <constant>Delete Access</constant> are
+ selected they will be ignored when applied on the Samba server.</para>
+
+ <para>When setting permissions on a directory, the second
+ set of permissions (in the second set of parentheses) is
+ by default applied to all files within that directory. If this
+ is not what you want, you must un-check the <guilabel>Replace
+ permissions on existing files</guilabel> check-box in the NT
+ dialog before clicking on <guibutton>OK</guibutton>.</para>
+
+ <para>If you wish to remove all permissions from a
+ user/group/world component, you may either highlight the
+ component and click on the <guibutton>Remove</guibutton> button,
+ or set the component to only have the special <constant>Take
+ Ownership</constant> permission (displayed as <command>O
+ </command>) highlighted.</para>
+ </sect2>
+
+ <sect2>
+ <title>Interaction with the Standard Samba <quote>create mask</quote> Parameters</title>
+
+ <para>There are four parameters that control interaction with the standard Samba <parameter>create mask</parameter> parameters.
+ These are:
+
+ <itemizedlist>
+ <listitem><smbconfoption><name>security mask</name></smbconfoption></listitem>
+ <listitem><smbconfoption><name>force security mode</name></smbconfoption></listitem>
+ <listitem><smbconfoption><name>directory security mask</name></smbconfoption></listitem>
+ <listitem><smbconfoption><name>force directory security mode</name></smbconfoption></listitem>
+ </itemizedlist>
+
+ </para>
+
+ <para>Once a user clicks on <guibutton>OK</guibutton> to apply the
+ permissions, Samba maps the given permissions into a user/group/world
+ r/w/x triplet set, and then checks the changed permissions for a
+ file against the bits set in the
+ <smbconfoption><name>security mask</name></smbconfoption> parameter. Any bits that
+ were changed that are not set to <quote>1</quote> in this parameter are left alone
+ in the file permissions.</para>
+
+ <para>Essentially, zero bits in the <smbconfoption><name>security mask</name></smbconfoption>
+ may be treated as a set of bits the user is <emphasis>not</emphasis>
+ allowed to change, and one bits are those the user is allowed to change.
+ </para>
+
+ <para>If not explicitly set, this parameter defaults to the same value as
+ the <smbconfoption><name>create mask</name></smbconfoption> parameter. To allow a user to modify all the
+ user/group/world permissions on a file, set this parameter to 0777.
+ </para>
+
+ <para>Next Samba checks the changed permissions for a file against the bits set in the
+ <smbconfoption><name>force security mode</name></smbconfoption> parameter. Any bits
+ that were changed that correspond to bits set to <quote>1</quote> in this parameter
+ are forced to be set.</para>
+
+ <para>Essentially, bits set in the <parameter>force security mode</parameter> parameter
+ may be treated as a set of bits that, when modifying security on a file, the user has always set to be <quote>on</quote>.</para>
+
+ <para>If not explicitly set, this parameter defaults to the same value
+ as the <smbconfoption><name>force create mode</name></smbconfoption> parameter.
+ To allow a user to modify all the user/group/world permissions on a file
+ with no restrictions set this parameter to 000. The
+ <smbconfoption><name>security mask</name></smbconfoption> and <parameter>force
+ security mode</parameter> parameters are applied to the change
+ request in that order.</para>
+
+ <para>For a directory, Samba will perform the same operations as
+ described above for a file except it uses the parameter <parameter>
+ directory security mask</parameter> instead of <parameter>security
+ mask</parameter>, and <parameter>force directory security mode
+ </parameter> parameter instead of <parameter>force security mode
+ </parameter>.</para>
+
+ <para>The <smbconfoption><name>directory security mask</name></smbconfoption> parameter
+ by default is set to the same value as the <parameter>directory mask
+ </parameter> parameter and the <parameter>force directory security
+ mode</parameter> parameter by default is set to the same value as
+ the <smbconfoption><name>force directory mode</name></smbconfoption> parameter.
+ In this way Samba enforces the permission restrictions that
+ an administrator can set on a Samba share, while still allowing users
+ to modify the permission bits within that restriction.</para>
+
+ <para>If you want to set up a share that allows users full control
+ in modifying the permission bits on their files and directories and
+ does not force any particular bits to be set <quote>on</quote>, then set the following
+ parameters in the &smb.conf; file in that share-specific section:
+ </para>
+
+ <smbconfblock>
+ <smbconfoption><name>security mask</name><value>0777</value></smbconfoption>
+ <smbconfoption><name>force security mode</name><value>0</value></smbconfoption>
+ <smbconfoption><name>directory security mask</name><value>0777</value></smbconfoption>
+ <smbconfoption><name>force directory security mode</name><value>0</value></smbconfoption>
+ </smbconfblock>
+ </sect2>
+
+ <sect2>
+ <title>Interaction with the Standard Samba File Attribute Mapping</title>
+
+ <note>
+ <para>Samba maps some of the DOS attribute bits (such as <quote>read
+ only</quote>) into the UNIX permissions of a file. This means there can
+ be a conflict between the permission bits set via the security
+ dialog and the permission bits set by the file attribute mapping.
+ </para>
+ </note>
+
+ <para>If a file has no UNIX read access for the owner, it will show up
+ as <quote>read only</quote> in the standard file attributes tabbed dialog.
+ Unfortunately, this dialog is the same one that contains the security information
+ in another tab.</para>
+
+ <para>What this can mean is that if the owner changes the permissions
+ to allow himself read access using the security dialog, clicks on
+ <guibutton>OK</guibutton> to get back to the standard attributes tab
+ dialog, and clicks on <guibutton>OK</guibutton> on that dialog, then
+ NT will set the file permissions back to read-only (as that is what
+ the attributes still say in the dialog). This means that after setting
+ permissions and clicking on <guibutton>OK</guibutton> to get back to the
+ attributes dialog, you should always press <guibutton>Cancel</guibutton>
+ rather than <guibutton>OK</guibutton> to ensure that your changes
+ are not overridden.</para>
+ </sect2>
+</sect1>
+
+<sect1>
+<title>Common Errors</title>
+
+<para>
+File, directory and share access problems are common on the mailing list. The following
+are examples taken from the mailing list in recent times.
+</para>
+
+
+ <sect2>
+ <title>Users Cannot Write to a Public Share</title>
+
+ <para>
+ <quote>
+ We are facing some troubles with file/directory permissions. I can log on the domain as admin user(root),
+ and there's a public share on which everyone needs to have permission to create/modify files, but only
+ root can change the file, no one else can. We need to constantly go to the server to
+ <userinput>chgrp -R users *</userinput> and <userinput>chown -R nobody *</userinput> to allow others users to change the file.
+ </quote>
+ </para>
+
+ <para>
+ There are many ways to solve this problem and here are a few hints:
+ </para>
+
+ <procedure>
+ <step>
+ <para>
+ Go to the top of the directory that is shared.
+ </para>
+ </step>
+
+ <step>
+ <para>
+ Set the ownership to what ever public owner and group you want
+<screen>
+&prompt;find 'directory_name' -type d -exec chown user.group {}\;
+&prompt;find 'directory_name' -type d -exec chmod 1775 'directory_name'
+&prompt;find 'directory_name' -type f -exec chmod 0775 {} \;
+&prompt;find 'directory_name' -type f -exec chown user.group {}\;
+</screen>
+ </para>
+
+ <note><para>
+ The above will set the <constant>sticky bit</constant> on all directories. Read your
+ UNIX/Linux man page on what that does. It causes the OS to assign
+ to all files created in the directories the ownership of the
+ directory.
+ </para></note>
+ </step>
+ <step>
+ <para>
+
+ Directory is: <replaceable>/foodbar</replaceable>
+<screen>
+&prompt;<userinput>chown jack.engr /foodbar</userinput>
+</screen>
+ </para>
+
+ <note><para>
+ <para>This is the same as doing:</para>
+<screen>
+&prompt;<userinput>chown jack /foodbar</userinput>
+&prompt;<userinput>chgrp engr /foodbar</userinput>
+</screen>
+ </para></note>
+ </step>
+ <step>
+ <para>Now type:
+
+<screen>
+&prompt;<userinput>chmod 6775 /foodbar</userinput>
+&prompt;<userinput>ls -al /foodbar/..</userinput>
+</screen>
+
+ </para>
+
+ <para>You should see:
+<screen>
+drwsrwsr-x 2 jack engr 48 2003-02-04 09:55 foodbar
+</screen>
+ </para>
+ </step>
+ <step>
+
+ <para>Now type:
+<screen>
+&prompt;<userinput>su - jill</userinput>
+&prompt;<userinput>cd /foodbar</userinput>
+&prompt;<userinput>touch Afile</userinput>
+&prompt;<userinput>ls -al</userinput>
+</screen>
+ </para>
+
+ <para>
+ You should see that the file <filename>Afile</filename> created by Jill will have ownership
+ and permissions of Jack, as follows:
+<screen>
+-rw-r--r-- 1 jack engr 0 2003-02-04 09:57 Afile
+</screen>
+ </para>
+ </step>
+
+ <step>
+ <para>
+ Now in your &smb.conf; for the share add:
+ <smbconfblock>
+<smbconfoption><name>force create mode</name><value>0775</value></smbconfoption>
+<smbconfoption><name>force directory mode</name><value>6775</value></smbconfoption>
+ </smbconfblock>
+ </para>
+
+ <note><para>
+ These procedures are needed only if your users are not members of the group
+ you have used. That is if within the OS do not have write permission on the directory.
+ </para>
+ </note>
+
+ <para>
+ An alternative is to set in the &smb.conf; entry for the share:
+ <smbconfblock>
+<smbconfoption><name>force user</name><value>jack</value></smbconfoption>
+<smbconfoption><name>force group</name><value>engr</value></smbconfoption>
+ </smbconfblock>
+ </para>
+ </step>
+ </procedure>
+ </sect2>
+
+
+ <sect2>
+ <title>File Operations Done as <emphasis>root</emphasis> with <emphasis>force user</emphasis> Set</title>
+
+ <para>
+ When you have a user in <smbconfoption><name>admin users</name></smbconfoption>, Samba will always do file operations for
+ this user as <emphasis>root</emphasis>, even if <smbconfoption><name>force user</name></smbconfoption> has been set.
+ </para>
+ </sect2>
+
+ <sect2>
+ <title>MS Word with Samba Changes Owner of File</title>
+
+ <para>
+ <emphasis>Question:</emphasis> <quote>When user B saves a word document that is owned by user A the updated file is now owned by user B.
+ Why is Samba doing this? How do I fix this?</quote>
+ </para>
+
+ <para>
+ <emphasis>Answer:</emphasis> Word does the following when you modify/change a Word document: MS Word creates a NEW document with
+ a temporary name, Word then closes the old document and deletes it, Word then renames the new document to the original document name.
+ There is no mechanism by which Samba can in any way know that the new document really should be owned by the owners
+ of the original file. Samba has no way of knowing that the file will be renamed by MS Word. As far as Samba is able
+ to tell, the file that gets created is a NEW file, not one that the application (Word) is updating.
+ </para>
+
+ <para>
+ There is a work-around to solve the permissions problem. That work-around involves understanding how you can manage file
+ system behavior from within the &smb.conf; file, as well as understanding how UNIX file systems work. Set on the directory
+ in which you are changing Word documents: <command>chmod g+s `directory_name'</command> This ensures that all files will
+ be created with the group that owns the directory. In &smb.conf; share declaration section set:
+ </para>
+
+ <para>
+ <smbconfblock>
+ <smbconfoption><name>force create mode</name><value>0660</value></smbconfoption>
+ <smbconfoption><name>force directory mode</name><value>0770</value></smbconfoption>
+ </smbconfblock>
+ </para>
+
+ <para>
+ These two settings will ensure that all directories and files that get created in the share will be read/writable by the
+ owner and group set on the directory itself.
+ </para>
+
+ </sect2>
+
+</sect1>
+
+</chapter>