1 <?xml version="1.0" encoding="UTF-8"?>
2 <chapter id="configuration">
3 <title>Setting up Netatalk</title>
6 <title>File Services<indexterm>
7 <primary>File Services</primary>
9 <secondary>Netatalk's File Services</secondary>
12 <para>Netatalk supplies AFP<indexterm>
13 <primary>AFP</primary>
15 <secondary>Apple Filing Protocol</secondary>
16 </indexterm> services.</para>
19 <title>Setting up the AFP file server</title>
21 <para>AFP (the Apple Filing Protocol) is the protocol Apple Macintoshes
22 use for file services. The protocol has evolved over the years. The
23 latest changes to the protocol, called "AFP 3.3", were added with the
24 release of Snow Leopard<indexterm>
25 <primary>Snow Leopard</primary>
27 <secondary>Mac OS X 10.6</secondary>
28 </indexterm> (Mac OS X 10.6).</para>
30 <para>The afpd daemon offers the fileservices to Apple clients. The only
31 configuration file is <filename>afp.conf</filename>. It uses a ini style
32 configuration syntax.</para>
34 <para>Mac OS X 10.5 (Leopard) added support for Time Machine backups
35 over AFP. Two new functions ensure that backups are written to spinning
36 disk, not just in the server's cache. Different host operating systems
37 honour this cache flushing differently. To make a volume a Time Machine
38 target use the volume option "<option>time machine =
41 <para>Starting with Netatalk 2.1 UNIX symlinks<indexterm>
42 <primary>symlink</primary>
44 <secondary>UNIX symlink</secondary>
45 </indexterm> can be used on the server. Semantics are the same as for
46 eg NFS, ie they are not resolved on the server side but instead it's
47 completely up to the client to resolve them, resulting in links that
48 point somewhere inside the clients filesystem view.</para>
50 <para>Support for <link linkend="spotlight">Spotlight</link> has been
51 added in Netatalk 3.1. See this <link
52 linkend="spotlight_compile">section</link> for information on how to
53 compile Netatalk with Spotlight support.</para>
56 <title>afp.conf</title>
58 <para><filename>afp.conf</filename> is the configuration file used by
59 afpd to determine the behaviour and configuration of the AFP file
60 serverand the AFP volume that it provides.</para>
62 <para>The <filename>afp.conf</filename> is divided into several
63 sections:<variablelist>
68 <para>The global section defines general server options</para>
76 <para>The homes section defines user home volumes</para>
79 </variablelist>Any section not called <option>Global</option> or
80 <option>Homes</option> is interpreted as an AFP volume.</para>
82 <para>For sharing user homes by defining a <option>Homes</option>
83 section you must specify the option <option>basedir regex</option>
84 which can be a simple string with the path to the parent directory of
85 all user homes or a regular expression.</para>
89 <para><programlisting>[Homes]
91 </programlisting></para>
93 <para>Now any user logging into the AFP server will have a user volume
94 available whos path is <filename>/home/NAME</filename>.</para>
96 <para>A more complex setup would be a server with a large amount of
97 user homes which are split across eg two different
98 filesystems:<itemizedlist>
100 <para>/RAID1/homes</para>
104 <para>/RAID2/morehomes</para>
106 </itemizedlist>The following configuration is
107 required:<programlisting>[Homes]
108 basedir regex = /RAID./.*homes
109 </programlisting></para>
111 <para>If <option>basedir regex</option> contains symlink, set the
112 canonicalized absolute path. When <filename>/home</filename> links to
113 <filename>/usr/home</filename>: <programlisting>[Homes]
114 basedir regex = /usr/home</programlisting></para>
116 <para>For a more detailed explanation of the available options, please
117 refer to the <citerefentry>
118 <refentrytitle>afp.conf</refentrytitle>
120 <manvolnum>5</manvolnum>
121 </citerefentry> man page.</para>
126 <title id="spotlight">Spotlight<indexterm>
127 <primary>Spotlight</primary>
130 <para>Netatalk uses Tracker as the metadata backend. Recent Linux
131 distributions will provide the libtracker-sparql library which is
132 available since Tracker version 0.7. This version is referred to as
133 Tracker SPARQL.</para>
135 <para>Other system like FreeBSD, Solaris and systems derived from
136 Solaris will only ship Tracker version 0.6 which only offers a much more
137 restrcited feature set. We refer to this version as Tracker RDF. Solaris
138 users are advised to install Tracker from OpenCSW as this is at least
139 version 0.15 and thus supports SPARQL</para>
141 <para>You can enable Spotlight and indexing either globally or on a per
142 volume basis using the <option>spotlight</option>.</para>
144 <para>For Solaris with Tracker from OpenCSW also add:
145 <screen>dbus daemon = /opt/csw/bin/dbus-daemon</screen></para>
148 <para>Once Spotlight is enable for a single volume, all other volumes
149 won't be searchable at all.</para>
153 <title>Tracker RDF</title>
155 <para>Add all volume paths that should be searchable to
156 $sysconfdir/tracker/tracker.cfg:<screen>...
158 # List of directory roots to index and watch (separator=;)
159 WatchDirectoryRoots=/foo/bar;/another/volume
164 <title>Limitations and notes</title>
168 <para>Large filesystems</para>
170 <para>Tracker on Linux uses the inotify Kernel filesystem change
171 event API for tracking filesystem changes. On large filesystems
172 this may be problematic since the inotify API doesn't offer
173 recursive directory watches but instead requires that for every
174 subdirectoy watches must be added individually.</para>
176 <para>On Solaris the FEN file event notification system is used.
177 It is unkown which limitations and ressource consumption this
178 Solaris subsystem has,</para>
182 <para>Tracker RDF</para>
184 <para>The mapping of certain simple and of complex Spotlight to
185 Tracker RDF queries is imperfect. Also, Tracker RDF filename
186 searches are case sensitive! As a result there are two noticable
191 <para>On a Mac, a query entered in the Spotlight search menu
192 or in a Finder search toolbar is meant to express "search any
193 metadata field, file name or content for this string". With
194 Netatalk and Tracker RDF only filenames will be
199 <para>Searching files content must be done through explicitly
200 adding a "<emphasis>Contents</emphasis> contains ..."
206 <screeninfo>Case sensivity</screeninfo>
210 <imagedata fileref="http://netatalk.sourceforge.net/wiki/images/2/2a/Toolbar_search_is_name_search.png" />
216 <screeninfo>Searching metadata</screeninfo>
220 <imagedata fileref="http://netatalk.sourceforge.net/wiki/images/0/01/Searching_for_content.png" />
229 <title>Supported metadata attributes</title>
231 <para>The following list is the complete set of supported metadata
232 attributes in Tracker SPARQL search queries</para>
235 <title>Tracker SPARQL</title>
240 <entry align="center">Description</entry>
242 <entry align="center">Spotlight Key </entry>
250 <entry>kMDItemDisplayName, kMDItemFSName</entry>
254 <entry>Document content (full text search)</entry>
256 <entry>kMDItemTextContent</entry>
260 <entry>File type</entry>
262 <entry>_kMDItemGroupId, kMDItemContentTypeTree</entry>
266 <entry>File modification date</entry>
268 <entry>kMDItemFSContentChangeDate,
269 kMDItemContentModificationDate,
270 kMDItemAttributeChangeDate</entry>
274 <entry>Content Creation date</entry>
276 <entry>kMDItemContentCreationDate</entry>
280 <entry>The author, or authors, of the contents of the
283 <entry>kMDItemAuthors, kMDItemCreator</entry>
287 <entry>The name of the country where the item was
290 <entry>kMDItemCountry</entry>
294 <entry>Duration</entry>
296 <entry>kMDItemDurationSeconds</entry>
300 <entry>Number of pages</entry>
302 <entry>kMDItemNumberOfPages</entry>
306 <entry>Document title</entry>
308 <entry>kMDItemTitle</entry>
312 <entry>The width, in pixels, of the contents. For example, the
313 image width or the video frame width</entry>
315 <entry>kMDItemPixelWidth</entry>
319 <entry>The height, in pixels, of the contents. For example,
320 the image height or the video frame height</entry>
322 <entry>kMDItemPixelHeight</entry>
326 <entry>The color space model used by the document
329 <entry>kMDItemColorSpace</entry>
333 <entry>The number of bits per sample</entry>
335 <entry>kMDItemBitsPerSample</entry>
339 <entry>Focal length of the lens, in millimeters</entry>
341 <entry>kMDItemFocalLength</entry>
345 <entry>ISO speed</entry>
347 <entry>kMDItemISOSpeed</entry>
351 <entry>Orientation of the document. Possible values are 0
352 (landscape) and 1 (portrait)</entry>
354 <entry>kMDItemOrientation</entry>
358 <entry>Resolution width, in DPI</entry>
360 <entry>kMDItemResolutionWidthDPI</entry>
364 <entry>Resolution height, in DPI</entry>
366 <entry>kMDItemResolutionHeightDPI</entry>
370 <entry>Exposure time, in seconds</entry>
372 <entry>kMDItemExposureTimeSeconds</entry>
376 <entry>The composer of the music contained in the audio
379 <entry>kMDItemComposer</entry>
383 <entry>The musical genre of the song or composition</entry>
385 <entry>kMDItemMusicalGenre</entry>
391 <para>The following list is the complete set of supported metadata
392 attributes in Tracker RDF search queries:<table>
393 <title>Tracker RDF</title>
398 <entry align="center">Description</entry>
400 <entry align="center">Spotlight Key</entry>
408 <entry>kMDItemDisplayName, kMDItemFSName</entry>
412 <entry>Document content (full text search)</entry>
414 <entry>kMDItemTextContent</entry>
418 <entry>File type</entry>
420 <entry>_kMDItemGroupId, kMDItemContentTypeTree</entry>
424 <entry>File modification date</entry>
426 <entry>kMDItemFSContentChangeDate,
427 kMDItemContentModificationDate,
428 kMDItemAttributeChangeDate</entry>
432 <entry>Content Creation date</entry>
434 <entry>kMDItemContentCreationDate</entry>
438 <entry>The author, or authors, of the contents of the
441 <entry>kMDItemAuthors, kMDItemCreator</entry>
445 <entry>The name of the country where the item was
448 <entry>kMDItemCountry</entry>
452 <entry>Duration</entry>
454 <entry>kMDItemDurationSeconds</entry>
458 <entry>Number of pages</entry>
460 <entry>kMDItemNumberOfPages</entry>
464 <entry>Document title</entry>
466 <entry>kMDItemTitle</entry>
470 <entry>The width, in pixels, of the contents. For example,
471 the image width or the video frame width</entry>
473 <entry>kMDItemPixelWidth</entry>
477 <entry>The height, in pixels, of the contents. For example,
478 the image height or the video frame height</entry>
480 <entry>kMDItemPixelHeight</entry>
484 <entry>Focal length of the lens, in millimeters</entry>
486 <entry>kMDItemFocalLength</entry>
490 <entry>ISO speed</entry>
492 <entry>kMDItemISOSpeed</entry>
496 <entry>Orientation of the document. Possible values are 0
497 (landscape) and 1 (portrait)</entry>
499 <entry>kMDItemOrientation</entry>
503 <entry>Exposure time, in seconds</entry>
505 <entry>kMDItemExposureTimeSeconds</entry>
509 <entry>The musical genre of the song or composition</entry>
511 <entry>kMDItemMusicalGenre</entry>
519 <title>Using Tracker commandline tools on the server</title>
521 <para>Netatalk must be running. Then setup relevant environment
522 variables, adjust the prefix /usr/local/netatalk to match your
523 configured paths:<screen>$ su
526 export DBUS_SESSION_BUS_ADDRESS="unix:path=/tmp/spotlight.ipc"
527 export XDG_DATA_HOME=/usr/local/netatalk/var/netatalk
528 export XDG_CACHE_HOME=/usr/local/netatalk/var/netatalk
529 export XDG_CONFIG_HOME=/usr/local/netatalk/etc
533 <para>Tracker SPARQL:<screen># tracker-search QUERY
538 <para>Tracker RDF<screen># cat file.rdf
539 <rdfq:Condition>
541 <rdfq:contains>
542 <rdfq:Property name="File:Name" />
543 <rdf:String>SEARCHSTRING</rdf:String>
544 </rdfq:contains>
546 </rdfq:Condition>
547 # tracker-query -p file.rdf File:Name
549 # tracker-info -m File:Mime PATH
554 <title>References</title>
559 url="https://developer.apple.com/library/mac/#documentation/Carbon/Reference/MDItemRef/Reference/reference.html">MDItem</ulink></para>
564 url="https://live.gnome.org/Tracker/Documentation">Tracker</ulink></para>
570 <sect2 id="CNID-backends">
571 <title>CNID<indexterm>
572 <primary>CNID</primary>
574 <secondary>Catalog Node ID</secondary>
575 </indexterm> backends<indexterm>
576 <primary>Backend</primary>
578 <secondary>CNID backend</secondary>
581 <para>Unlike other protocols like SMB or NFS, the AFP protocol mostly
582 refers to files and directories by ID and not by a path (the IDs are
583 also called CNID, that means Catalog Node ID). A typical AFP request
584 uses a directory ID<indexterm>
585 <primary>DID</primary>
587 <secondary>Directory ID</secondary>
588 </indexterm> and a filename, something like <phrase>"server, please
589 open the file named 'Test' in the directory with id 167"</phrase>. For
590 example "Aliases" on the Mac basically work by ID (with a fallback to
591 the absolute path in more recent AFP clients. But this applies only to
592 Finder, not to applications).</para>
594 <para>Every file in an AFP volume has to have a unique file ID<indexterm>
595 <primary>FID</primary>
597 <secondary>File ID</secondary>
598 </indexterm>, IDs must, according to the specs, never be reused, and
599 IDs are 32 bit numbers (Directory IDs use the same ID pool). So, after
600 ~4 billion files/folders have been written to an AFP volume, the ID pool
601 is depleted and no new file can be written to the volume. No whining
604 <para>Netatalk needs to map IDs to files and folders in the host
605 filesystem. To achieve this, several different CNID backends<indexterm>
606 <primary>CNID backend</primary>
607 </indexterm> are available and can be choosed by the <option>cnid
608 scheme</option><indexterm>
609 <primary>cnidscheme</primary>
611 <secondary>specifying a CNID backend</secondary>
612 </indexterm> option in the <citerefentry>
613 <refentrytitle>afp.conf</refentrytitle>
615 <manvolnum>5</manvolnum>
616 </citerefentry> configuration file. A CNID backend is basically a
617 database storing ID <-> name mappings.</para>
619 <para>The CNID Databases are by default located in
620 <filename>/var/netatalk/CNID</filename>.</para>
622 <para>There is a command line utility called <command>dbd</command>
623 available which can be used to verify, repair and rebuild the CNID
627 <para>There are some CNID related things you should keep in mind when
628 working with netatalk:</para>
632 <para>Don't nest volumes<indexterm>
633 <primary>Nested volumes</primary>
638 <para>CNID backends are databases, so they turn afpd into a file
639 server/database mix.</para>
643 <para>If there's no more space on the filesystem left, the
644 database will get corrupted. You can work around this by either
645 using the <option>vol dbpath</option> option and put the database
646 files into another location or, if you use quotas, make sure the
647 CNID database folder is owned by a user/group without a
649 <primary>Quotas</primary>
651 <secondary>Disk usage quotas</secondary>
656 <para>Be careful with CNID databases for volumes that are mounted
657 via NFS. That is a pretty audacious decision to make anyway, but
658 putting a database there as well is really asking for trouble,
659 i.e. database corruption. Use the <option>vol dbpath</option>
660 directive to put the databases onto a local disk if you must use
662 <primary>NFS</primary>
664 <secondary>Network File System</secondary>
665 </indexterm> mounted volumes.</para>
671 <title>cdb<indexterm>
672 <primary>CDB</primary>
674 <secondary>"cdb" CNID backend</secondary>
677 <para>The "concurrent database" backend is based on Berkeley DB. With
678 this backend, several afpd daemons access the CNID database directly.
679 Berkeley DB locking is used to synchronize access, if more than one
680 afpd process is active for a volume. The drawback is, that the crash
681 of a single afpd process might corrupt the database. cdb should only
682 be used when sharing home directories for a larger number of users
683 <emphasis>and</emphasis> it has been determined that a large number of
684 <command>cnid_dbd</command> processes is problematic.</para>
688 <title>dbd<indexterm>
689 <primary>DBD</primary>
691 <secondary>"dbd" CNID backend</secondary>
694 <para>Access to the CNID database is restricted to the cnid_dbd daemon
695 process. afpd processes communicate with the daemon for database reads
696 and updates. The probability for database corruption is practically
699 <para>This is the default backend since Netatalk 2.1.</para>
703 <title>tdb<indexterm>
704 <primary>tdb</primary>
706 <secondary>"tdb" CNID backend</secondary>
709 <para><abbrev>tdb</abbrev> is another persistent CNID database, it's
710 Samba's <emphasis>Trivial Database</emphasis>. It could be used
711 instead of <abbrev>cdb</abbrev> for user volumes.<important>
712 <para>Only ever use it for volumes that are
713 <emphasis>not</emphasis> shared and accessed by multiple clients
715 </important>This backend is also used internally (as in-memory CNID
716 database) as a fallback in case opening the primary database can't be
717 opened, because <abbrev>tdb</abbrev> can work as in-memory database.
718 This of course means upon restart the CNIDs are gone.</para>
722 <title>last<indexterm>
723 <primary>Last</primary>
725 <secondary>"last" CNID backend</secondary>
728 <para>The last backend is a in-memory tdb database. It is not
729 persistent. Starting with netatalk 3.0, it becomes the <emphasis> read
730 only mode</emphasis> automatically. This is useful e.g. for
735 <sect2 id="charsets">
736 <title>Charsets<indexterm>
737 <primary>Charset</primary>
739 <secondary>character set</secondary>
740 </indexterm>/Unicode<indexterm>
741 <primary>Unicode</primary>
747 <title>Why Unicode?</title>
749 <para>Internally, computers don't know anything about characters and
750 texts, they only know numbers. Therefore, each letter is assigned a
751 number. A character set, often referred to as
752 <emphasis>charset</emphasis> or
753 <emphasis>codepage</emphasis><indexterm>
754 <primary>Codepage</primary>
755 </indexterm>, defines the mappings between numbers and
758 <para>If two or more computer systems need to communicate with each
759 other, the have to use the same character set. In the 1960s the
761 <primary>ASCII</primary>
763 <secondary>American Standard Code for Information
764 Interchange</secondary>
765 </indexterm> (American Standard Code for Information Interchange)
766 character set was defined by the American Standards Association. The
767 original form of ASCII represented 128 characters, more than enough to
768 cover the English alphabet and numerals. Up to date, ASCII has been
769 the normative character scheme used by computers.</para>
771 <para>Later versions defined 256 characters to produce a more
772 international fluency and to include some slightly esoteric graphical
773 characters. Using this mode of encoding each character takes exactly
774 one byte. Obviously, 256 characters still wasn't enough to map all the
775 characters used in the various languages into one character
778 <para>As a result localized character sets were defined later, e.g the
779 ISO-8859 character sets. Most operating system vendors introduced
780 their own characters sets to satisfy their needs, e.g. IBM defined the
781 <emphasis>codepage 437 (DOSLatinUS)</emphasis>, Apple introduced the
782 <emphasis>MacRoman</emphasis><indexterm>
783 <primary>MacRoman</primary>
785 <secondary>MacRoman charset</secondary>
786 </indexterm> codepage and so on. The characters that were assigned
787 number larger than 127 were referred to as
788 <emphasis>extended</emphasis> characters. These character sets
789 conflict with another, as they use the same number for different
790 characters, or vice versa.</para>
792 <para>Almost all of those characters sets defined 256 characters,
793 where the first 128 (0-127) character mappings are identical to ASCII.
794 As a result, communication between systems using different codepages
795 was effectively limited to the ASCII charset.</para>
797 <para>To solve this problem new, larger character sets were defined.
798 To make room for more character mappings, these character sets use at
799 least 2 bytes to store a character. They are therefore referred to as
800 <emphasis>multibyte</emphasis> character sets.</para>
802 <para>One standardized multibyte charset encoding scheme is known as
803 <ulink url="http://www.unicode.org/">unicode</ulink>. A big advantage
804 of using a multibyte charset is that you only need one. There is no
805 need to make sure two computers use the same charset when they are
806 communicating.</para>
810 <title>character sets used by Apple</title>
812 <para>In the past, Apple clients used single-byte charsets to
813 communicate over the network. Over the years Apple defined a number of
814 codepages, western users will most likely be using the
815 <emphasis>MacRoman</emphasis> codepage.</para>
817 <para>Codepages defined by Apple include:</para>
821 <para>MacArabic, MacFarsi</para>
825 <para>MacCentralEurope</para>
829 <para>MacChineseSimple</para>
833 <para>MacChineseTraditional</para>
837 <para>MacCroation</para>
841 <para>MacCyrillic</para>
845 <para>MacDevanagari</para>
849 <para>MacGreek</para>
853 <para>MacHebrew</para>
857 <para>MacIcelandic</para>
861 <para>MacJapanese</para>
865 <para>MacKorean</para>
869 <para>MacRoman</para>
873 <para>MacRomanian</para>
881 <para>MacTurkish</para>
885 <para>Starting with Mac OS X and AFP3, <ulink
886 url="http://www.utf-8.com/">UTF-8</ulink> is used. UTF-8 encodes
887 Unicode characters in an ASCII compatible way, each Unicode character
888 is encoded into 1-6 ASCII characters. UTF-8 is therefore not really a
889 charset itself, it's an encoding of the Unicode charset.</para>
891 <para>To complicate things, Unicode defines several <emphasis> <ulink
892 url="http://www.unicode.org/reports/tr15/index.html">normalization</ulink>
893 </emphasis> forms. While <ulink
894 url="http://www.samba.org">samba</ulink><indexterm>
895 <primary>Samba</primary>
896 </indexterm> uses <emphasis>precomposed</emphasis><indexterm>
897 <primary>Precomposed</primary>
899 <secondary>Precomposed Unicode normalization</secondary>
900 </indexterm> Unicode, which most Unix tools prefer as well, Apple
901 decided to use the <emphasis>decomposed</emphasis><indexterm>
902 <primary>Decomposed</primary>
904 <secondary>Decomposed Unicode normalization</secondary>
905 </indexterm> normalization.</para>
907 <para>For example lets take the German character
908 '<keycode>ä</keycode>'. Using the precomposed normalization, Unicode
909 maps this character to 0xE4. In decomposed normalization, 'ä' is
910 actually mapped to two characters, 0x61 and 0x308. 0x61 is the mapping
911 for an 'a', 0x308 is the mapping for a <emphasis>COMBINING
912 DIAERESIS</emphasis>.</para>
914 <para>Netatalk refers to precomposed UTF-8 as
915 <emphasis>UTF8</emphasis><indexterm>
916 <primary>UTF8</primary>
918 <secondary>Netatalk's precomposed UTF-8 encoding</secondary>
919 </indexterm> and to decomposed UTF-8 as
920 <emphasis>UTF8-MAC</emphasis><indexterm>
921 <primary>UTF8-MAC</primary>
923 <secondary>Netatalk's decomposed UTF-8 encoding</secondary>
928 <title>afpd and character sets</title>
930 <para>To support new AFP 3.x and older AFP 2.x clients at the same
931 time, afpd needs to be able to convert between the various charsets
932 used. AFP 3.x clients always use UTF8-MAC, AFP 2.x clients use one of
933 the Apple codepages.</para>
935 <para>At the time of this writing, netatalk supports the following
936 Apple codepages:</para>
940 <para>MAC_CENTRALEUROPE</para>
944 <para>MAC_CHINESE_SIMP</para>
948 <para>MAC_CHINESE_TRAD</para>
952 <para>MAC_CYRILLIC</para>
956 <para>MAC_GREEK</para>
960 <para>MAC_HEBREW</para>
964 <para>MAC_JAPANESE</para>
968 <para>MAC_KOREAN</para>
972 <para>MAC_ROMAN</para>
976 <para>MAC_TURKISH</para>
980 <para>afpd handles three different character set options:</para>
984 <term>unix charset<indexterm>
985 <primary>unix charset</primary>
987 <secondary>afpd's unix charset setting</secondary>
991 <para>This is the codepage used internally by your operating
992 system. If not specified, it defaults to <option>UTF8</option>.
993 If <option>LOCALE</option> is specified and your system support
994 Unix locales, afpd tries to detect the codepage. afpd uses this
995 codepage to read its configuration files, so you can use
996 extended characters for volume names, login messages, etc. see
998 <refentrytitle>afp.conf</refentrytitle>
1000 <manvolnum>5</manvolnum>
1001 </citerefentry>.</para>
1006 <term>mac charset<indexterm>
1007 <primary>mac charset</primary>
1009 <secondary>afpd's mac charset setting</secondary>
1013 <para>As already mentioned, older Mac OS clients (up to AFP 2.2)
1014 use codepages to communicate with afpd. However, there is no
1015 support for negotiating the codepage used by the client in the
1016 AFP protocol. If not specified otherwise, afpd assumes the
1017 <emphasis>MacRoman</emphasis> codepage is used. In case you're
1018 clients use another codepage, e.g.
1019 <emphasis>MacCyrillic</emphasis>, you'll <emphasis
1020 role="bold">have</emphasis> to explicitly configure this. see
1022 <refentrytitle>afp.conf</refentrytitle>
1024 <manvolnum>5</manvolnum>
1025 </citerefentry>.</para>
1030 <term>vol charset<indexterm>
1031 <primary>vol charset</primary>
1033 <secondary>afpd's vol charset setting</secondary>
1037 <para>This defines the charset afpd should use for filenames on
1038 disk. By default, it is the same as <option>unix
1039 charset</option>. If you have <ulink
1040 url="http://www.gnu.org/software/libiconv/">iconv</ulink><indexterm>
1041 <primary>Iconv</primary>
1043 <secondary>iconv encoding conversion engine</secondary>
1044 </indexterm> installed, you can use any iconv provided charset
1047 <para>afpd needs a way to preserve extended macintosh
1048 characters, or characters illegal in unix filenames, when saving
1049 files on a unix filesystem. Earlier versions used the the so
1050 called CAP encoding<indexterm>
1051 <primary>CAP encoding</primary>
1053 <secondary>CAP style character encoding</secondary>
1054 </indexterm>. An extended character (>0x7F) would be
1055 converted to a :xx hex sequence, e.g. the Apple Logo (MacRoman:
1056 0xF0) was saved as :f0. Some special characters will be
1057 converted as to :xx notation as well. '/' will be encoded to
1058 :2f, if <option>usedots</option> was not specified, a leading
1059 dot '.' will be encoded as :2e.</para>
1061 <para>Even though this version now uses <option>UTF8</option> as
1062 the default encoding for filenames, '/' will be converted to
1063 ':'. For western users another useful setting could be
1064 <option>vol charset = ISO-8859-15</option>.</para>
1066 <para>If a character cannot be converted from the <option>mac
1067 charset</option> to the selected <option>vol charset</option>,
1068 afpd will save it as a CAP encoded character. For AFP3 clients,
1069 afpd will convert the UTF8 character to <option>mac
1070 charset</option> first. If this conversion fails, you'll receive
1071 a -50 error on the mac. <emphasis>Note</emphasis>: Whenever you
1072 can, please stick with the default UTF8 volume format. see
1074 <refentrytitle>afp.conf</refentrytitle>
1076 <manvolnum>5</manvolnum>
1077 </citerefentry>.</para>
1084 <sect2 id="authentication">
1085 <title>Authentication<indexterm>
1086 <primary>Authentication</primary>
1088 <secondary>between AFP client and server</secondary>
1089 </indexterm></title>
1092 <title>AFP authentication basics</title>
1094 <para>Apple chose a flexible model called "User Authentication
1096 <primary>UAM</primary>
1098 <secondary>User Authentication Module</secondary>
1099 </indexterm> (UAMs) for authentication purposes between AFP client
1100 and server. An AFP client initially connecting to an AFP server will
1101 ask for the list of UAMs which the server provides, and will choose
1102 the one with strongest encryption that the client supports.</para>
1104 <para>Several UAMs have been developed by Apple over the time, some by
1105 3rd-party developers.</para>
1109 <title>UAMs supported by Netatalk</title>
1111 <para>Netatalk supports the following ones by default:</para>
1115 <para>"No User Authent"<indexterm>
1116 <primary>No User Authent</primary>
1118 <secondary>"No User Authent" UAM (guest access)</secondary>
1119 </indexterm> UAM (guest access without authentication)</para>
1123 <para>"Cleartxt Passwrd"<indexterm>
1124 <primary>Cleartxt Passwrd</primary>
1126 <secondary>"Cleartxt Passwrd" UAM</secondary>
1127 </indexterm> UAM (no password encryption)</para>
1131 <para>"Randnum exchange"<indexterm>
1132 <primary>Randnum exchange</primary>
1134 <secondary>"Randnum exchange" UAM</secondary>
1135 </indexterm>/"2-Way Randnum exchange"<indexterm>
1136 <primary>2-Way Randnum exchange</primary>
1138 <secondary>"2-Way Randnum exchange" UAM</secondary>
1139 </indexterm> UAMs (weak password encryption, separate password
1144 <para>"DHCAST128"<indexterm>
1145 <primary>DHCAST128</primary>
1147 <secondary>"DHCAST128" UAM</secondary>
1148 </indexterm> UAM (stronger password encryption)</para>
1152 <para>"DHX2"<indexterm>
1153 <primary>DHX2</primary>
1155 <secondary>"DHX2" UAM</secondary>
1156 </indexterm> UAM (successor of DHCAST128)</para>
1160 <para>There exist other optional UAMs as well:</para>
1164 <para>"PGPuam 1.0"<indexterm>
1165 <primary>PGPuam 1.0</primary>
1167 <secondary>"PGPuam 1.0" UAM</secondary>
1168 </indexterm><indexterm>
1169 <primary>uams_pgp.so</primary>
1171 <secondary>"PGPuam 1.0" UAM</secondary>
1172 </indexterm> UAM (PGP-based authentication for pre-Mac OS X
1173 clients. You'll also need the <ulink
1174 url="http://www.vmeng.com/vinnie/papers/pgpuam.html">PGPuam
1175 client</ulink> to let this work)</para>
1177 <para>You'll have to add <filename>"--enable-pgp-uam"</filename>
1178 to your configure switches to have this UAM available.</para>
1182 <para>"Kerberos IV"<indexterm>
1183 <primary>Kerberos IV</primary>
1185 <secondary>"Kerberos IV" UAM</secondary>
1186 </indexterm><indexterm>
1187 <primary>uams_krb4.so</primary>
1189 <secondary>"Kerberos IV" UAM</secondary>
1190 </indexterm>/"AFS Kerberos"<indexterm>
1191 <primary>AFS Kerberos</primary>
1193 <secondary>"AFS Kerberos" UAM (Kerberos IV)</secondary>
1194 </indexterm> UAMs (suitable to use <ulink
1195 url="http://web.mit.edu/macdev/KfM/Common/Documentation/faq.html">Kerberos
1196 v4 based authentication</ulink> and AFS file servers)</para>
1198 <para>Use <filename>"--enable-krb4-uam"</filename> at compile time
1199 to activate the build of this UAM.</para>
1203 <para>"Client Krb v2"<indexterm>
1204 <primary>Client Krb v2</primary>
1206 <secondary>"Client Krb v2" UAM (Kerberos V)</secondary>
1207 </indexterm> UAM (Kerberos V, suitable for "Single Sign On"
1208 Scenarios with OS X clients -- see below)</para>
1210 <para><filename>"--enable-krbV-uam"</filename> will provide you
1211 with the ability to use this UAM.</para>
1215 <para>You can configure which UAMs should be activated by defining
1216 "<option>uam list</option>" in <option>Global</option> section.
1217 <command>afpd</command> will log which UAMs it's using and if problems
1218 occur while activating them in either
1219 <filename>netatalk.log</filename> or syslog at startup time.
1221 <refentrytitle>asip-status.pl</refentrytitle>
1223 <manvolnum>1</manvolnum>
1224 </citerefentry> can be used to query the available UAMs of AFP
1225 servers as well.</para>
1227 <para>Having a specific UAM available at the server does not
1228 automatically mean that a client can use it. Client-side support is
1229 also necessary. For older Macintoshes running Mac OS < X DHCAST128
1230 support exists since AppleShare client 3.8.x.</para>
1232 <para>On OS X, there exist some client-side techniques to make the
1233 AFP-client more verbose, so one can have a look what's happening while
1234 negotiating the UAMs to use. Compare with this <ulink
1235 url="http://article.gmane.org/gmane.network.netatalk.devel/7383/">hint</ulink>.</para>
1239 <title>Which UAMs to activate?</title>
1241 <para>It depends primarily on your needs and on the kind of Mac OS
1242 versions you have to support. Basically one should try to use
1243 DHCAST128 and DHX2 where possible because of its strength of password
1248 <para>Unless you really have to supply guest access to your
1249 server's volumes ensure that you disable "No User Authent" since
1250 it might lead accidentally to unauthorized access. In case you
1251 must enable guest access take care that you enforce this on a per
1252 volume base using the access controls.</para>
1256 <para>The "ClearTxt Passwrd" UAM is as bad as it sounds since
1257 passwords go unencrypted over the wire. Try to avoid it at both
1258 the server's side as well as on the client's. Note: If you want to
1259 provide Mac OS 8/9 clients with NetBoot-services then you need
1260 uams_cleartext.so since the AFP-client integrated into the Mac's
1261 firmware can only deal with this basic form of
1262 authentication.</para>
1266 <para>Since "Randnum exchange"/"2-Way Randnum exchange" uses only
1267 56 bit DES for encryption it should be avoided as well. Another
1268 disadvantage is the fact that the passwords have to be stored in
1269 cleartext on the server and that it doesn't integrate into both
1270 PAM scenarios or classic /etc/shadow (you have to administrate
1271 passwords separately by using the <citerefentry>
1272 <refentrytitle>afppasswd</refentrytitle>
1274 <manvolnum>1</manvolnum>
1275 </citerefentry> utility, if clients should use these
1280 <para>"DHCAST128" or "DHX2" should be a good compromise for most
1281 people since it combines stronger encryption with PAM
1286 <para>Using the Kerberos V<indexterm>
1287 <primary>Kerberos V</primary>
1289 <secondary>"Client Krb v2" UAM</secondary>
1290 </indexterm> ("Client Krb v2") UAM, it's possible to implement
1291 real single sign on scenarios using Kerberos tickets. The password
1292 is not sent over the network. Instead, the user password is used
1293 to decrypt a service ticket for the appleshare server. The service
1294 ticket contains an encryption key for the client and some
1295 encrypted data (which only the appleshare server can decrypt). The
1296 encrypted portion of the service ticket is sent to the server and
1297 used to authenticate the user. Because of the way that the afpd
1298 service principal detection is implemented, this authentication
1299 method is vulnerable to man-in-the-middle attacks.</para>
1303 <para>For a more detailed overview over the technical implications of
1304 the different UAMs, please have a look at Apple's <ulink
1305 url="http://developer.apple.com/library/mac/#documentation/Networking/Conceptual/AFP/AFPSecurity/AFPSecurity.html#//apple_ref/doc/uid/TP40000854-CH232-SW1">File
1306 Server Security</ulink> pages.</para>
1310 <title>Using different authentication sources with specific
1313 <para>Some UAMs provide the ability to use different authentication
1314 "backends", namely <filename>uams_cleartext.so</filename>,
1315 <filename>uams_dhx.so</filename> and
1316 <filename>uams_dhx2.so</filename>. They can use either classic Unix
1317 passwords from <filename>/etc/passwd</filename>
1318 (<filename>/etc/shadow</filename>) or PAM if the system supports that.
1319 <filename>uams_cleartext.so</filename> can be symlinked to either
1320 <filename>uams_passwd.so</filename> or
1321 <filename>uams_pam.so</filename>, <filename>uams_dhx.so</filename> to
1322 <filename>uams_dhx_passwd.so</filename> or
1323 <filename>uams_dhx_pam.so</filename> and
1324 <filename>uams_dhx2.so</filename> to
1325 <filename>uams_dhx2_passwd.so</filename> or
1326 <filename>uams_dhx2_pam.so</filename>.</para>
1328 <para>So, if it looks like this in Netatalk's UAMs folder (per default
1329 <filename>/etc/netatalk/uams/</filename>):<programlisting>uams_clrtxt.so -> uams_pam.so
1330 uams_dhx.so -> uams_dhx_pam.so
1331 uams_dhx2.so -> uams_dhx2_pam.so</programlisting> then you're using PAM,
1332 otherwise classic Unix passwords. The main advantage of using PAM is
1333 that one can integrate Netatalk in centralized authentication
1334 scenarios, eg. via LDAP, NIS and the like. Please always keep in mind
1335 that the protection of your user's login credentials in such scenarios
1336 also depends on the strength of encryption that the UAM in question
1337 supplies. So think about eliminating weak UAMs like "ClearTxt Passwrd"
1338 and "Randnum exchange" completely from your network.</para>
1342 <title>Netatalk UAM overview table</title>
1344 <para>A small overview of the most common used UAMs.</para>
1346 <table orient="land">
1347 <title>Netatalk UAM overview</title>
1349 <tgroup align="center" cols="7">
1350 <colspec colname="col1" colnum="1" colwidth="0.5*" />
1352 <colspec colname="uam_guest" colnum="2" colwidth="1*" />
1354 <colspec colname="uam_clrtxt" colnum="3" colwidth="1*" />
1356 <colspec colname="uam_randnum" colnum="4" colwidth="1*" />
1358 <colspec colname="uam_dhx" colnum="5" colwidth="1*" />
1360 <colspec colname="uam_dhx2" colnum="6" colwidth="1*" />
1362 <colspec colname="uam_gss" colnum="7" colwidth="1*" />
1366 <entry align="center" rotate="0" valign="middle">UAM</entry>
1368 <entry>No User Authent<indexterm>
1369 <primary>uams_guest.so</primary>
1371 <secondary>"No User Authent" UAM (guest
1373 </indexterm></entry>
1375 <entry>Cleartxt Passwrd<indexterm>
1376 <primary>uams_cleartxt.so</primary>
1378 <secondary>"Cleartxt Passwrd" UAM</secondary>
1379 </indexterm></entry>
1381 <entry>(2-Way) Randnum exchange<indexterm>
1382 <primary>uams_randnum.so</primary>
1384 <secondary>"(2-Way) Randnum exchange" UAM</secondary>
1385 </indexterm></entry>
1387 <entry>DHCAST128<indexterm>
1388 <primary>uams_dhx.so</primary>
1390 <secondary>"DHCAST128" UAM</secondary>
1391 </indexterm></entry>
1393 <entry>DHX2<indexterm>
1394 <primary>uams_dhx2.so</primary>
1396 <secondary>"DHX2" UAM</secondary>
1397 </indexterm></entry>
1399 <entry>Client Krb v2<indexterm>
1400 <primary>uams_gss.so</primary>
1402 <secondary>"Client Krb v2" UAM (Kerberos V)</secondary>
1403 </indexterm></entry>
1407 <entry align="center" rotate="0" valign="middle">pssword
1410 <entry>guest access</entry>
1412 <entry>max. 8 characters</entry>
1414 <entry>max. 8 characters</entry>
1416 <entry>max. 64 characters</entry>
1418 <entry>max. 256 characters</entry>
1420 <entry>Kerberos tickets</entry>
1424 <entry align="center" rotate="0" valign="middle">Client
1427 <entry>built-in into all Mac OS versions</entry>
1429 <entry>built-in in all Mac OS versions except 10.0. Has to be
1430 activated explicitly in recent Mac OS X versions</entry>
1432 <entry>built-in into almost all Mac OS versions</entry>
1434 <entry>built-in since AppleShare client 3.8.4, available as a
1435 plug-in for 3.8.3, integrated in Mac OS X' AFP client</entry>
1437 <entry>built-in since Mac OS X 10.2</entry>
1439 <entry>built-in since Mac OS X 10.2</entry>
1443 <entry align="center" rotate="0"
1444 valign="middle">Encryption</entry>
1446 <entry>Enables guest access without authentication between
1447 client and server.</entry>
1449 <entry>Password will be sent in cleartext over the wire. Just
1450 as bad as it sounds, therefore avoid at all if possible (note:
1451 providing NetBoot services requires the ClearTxt UAM)</entry>
1453 <entry>8-byte random numbers are sent over the wire,
1454 comparable with DES, 56 bits. Vulnerable to offline dictionary
1455 attack. Requires passwords in clear on the server.</entry>
1457 <entry>Password will be encrypted with 128 bit SSL, user will
1458 be authenticated against the server but not vice versa.
1459 Therefor weak against man-in-the-middle attacks.</entry>
1461 <entry>Password will be encrypted using libgcrypt with CAST
1462 128 in CBC mode. User will be authenticated against the server
1463 but not vice versa. Therefor weak against man-in-the-middle
1466 <entry>Password is not sent over the network. Due to the
1467 service principal detection method, this authentication method
1468 is vulnerable to man-in-the-middle attacks.</entry>
1472 <entry align="center" rotate="0" valign="middle">Server
1475 <entry align="center" valign="middle">uams_guest.so</entry>
1477 <entry align="center" valign="middle">uams_cleartxt.so</entry>
1479 <entry align="center" valign="middle">uams_randnum.so</entry>
1481 <entry align="center" valign="middle">uams_dhx.so</entry>
1483 <entry align="center" valign="middle">uams_dhx2.so</entry>
1485 <entry align="center" valign="middle">uams_gss.so</entry>
1489 <entry align="center" rotate="0" valign="middle">Password
1490 storage method</entry>
1492 <entry align="center" valign="middle">None</entry>
1494 <entry align="center" valign="middle">Either /etc/passwd
1495 (/etc/shadow) or PAM</entry>
1497 <entry align="center" valign="middle">Passwords stored in
1498 clear text in a separate text file</entry>
1500 <entry align="center" valign="middle">Either /etc/passwd
1501 (/etc/shadow) or PAM</entry>
1503 <entry align="center" valign="middle">Either /etc/passwd
1504 (/etc/shadow) or PAM</entry>
1506 <entry align="center" valign="middle">At the Kerberos Key
1507 Distribution Center*</entry>
1513 <para>* Have a look at this <ulink
1514 url="http://cryptnet.net/fdp/admin/kerby-infra/en/kerby-infra.html">Kerberos
1515 overview</ulink></para>
1518 <sect3 id="sshtunnel">
1519 <title>SSH tunneling</title>
1521 <para>Tunneling and all sort of VPN stuff has nothing to do with AFP
1522 authentication and UAMs in general. But since Apple introduced an
1523 option called "Allow Secure Connections Using SSH" and many people
1524 tend to confuse both things, we'll speak about that here too.</para>
1526 <sect4 id="manualsshtunnel">
1527 <title>Manually tunneling an AFP session</title>
1529 <para>This works since the first AFP servers that spoke "AFP over
1530 TCP" appeared in networks. One simply tunnels the remote server's
1531 AFP port to a local port different than 548 and connects locally to
1532 this port afterwards. On OS X this can be done by</para>
1534 <programlisting>ssh -l $USER $SERVER -L 10548:127.0.0.1:548 sleep 3000</programlisting>
1536 <para>After establishing the tunnel one will use
1537 <filename>"afp://127.0.0.1:10548"</filename> in the "Connect to
1538 server" dialog. All AFP traffic including the initial connection
1539 attempts will be sent encrypted over the wire since the local AFP
1540 client will connect to the Mac's local port 10548 which will be
1541 forwarded to the remote server's AFP port (we used the default 548)
1544 <para>These sorts of tunnels are an ideal solution if you've to
1545 access an AFP server providing weak authentications mechanisms
1546 through the Internet without having the ability to use a "real" VPN.
1547 Note that you can let <command>ssh</command> compress the data by
1548 using its "-C" switch and that the tunnel endpoints can be different
1549 from both AFP client and server (compare with the SSH documentation
1550 for details).</para>
1553 <sect4 id="autosshtunnel">
1554 <title>Automatically establishing a tunneled AFP connection</title>
1556 <para>From Mac OS X 10.2 to 10.4, Apple added an "Allow Secure
1557 Connections Using SSH" checkbox to the "Connect to Server" dialog.
1558 The idea behind: When the server signals that it can be contacted by
1559 SSH then Mac OS X' AFP client tries to establish the tunnel and
1560 automagically sends all AFP traffic through it.</para>
1562 <para>But it took until the release of Mac OS X 10.3 that this
1563 feature worked the first time... partly. In case, the SSH tunnel
1564 can't be established the AFP client <emphasis
1565 role="strong">silently</emphasis> fell back to an unencrypted AFP
1566 connection attempt.</para>
1568 <para>Netatalk's afpd will report that it is capable of handling SSH
1569 tunneled AFP requests, when both "<option>advertise ssh</option>"
1570 and "<option>fqdn</option>" options are set in
1571 <option>Global</option> section (double check with <citerefentry>
1572 <refentrytitle>asip-status.pl</refentrytitle>
1574 <manvolnum>1</manvolnum>
1575 </citerefentry> after you restarted afpd when you made changes to
1576 the settings). But there are a couple of reasons why you don't want
1577 to use this option at all:</para>
1581 <para>Tunneling TCP over TCP (as SSH does) is not the best idea.
1582 There exist better solutions like VPNs based on the IP
1587 <para>Since this SSH kludge isn't a normal UAM that integrates
1588 directly into the AFP authentication mechanisms but instead uses
1589 a single flag signalling clients whether they can <emphasis
1590 role="strong">try</emphasis> to establish a tunnel or not, it
1591 makes life harder to see what's happening when things go
1596 <para>You cannot control which machines are logged on by
1597 Netatalk tools like a <command>macusers</command> since all
1598 connection attempts seem to be made from localhost.</para>
1602 <para>On the other side you've to limit access to afpd to
1603 localhost only (TCP wrappers) when you want to ensure that all
1604 AFP sessions are SSH encrypted or...</para>
1608 <para>...when you're using 10.2 - 10.3.3 then you get the
1609 opposite of what you'd expect: potentially unencrypted AFP
1610 communication (including logon credentials) on the network
1611 without a single notification that establishing the tunnel
1612 failed. Apple fixed that not until Mac OS X 10.3.4.</para>
1616 <para>Encrypting all AFP sessions via SSH can lead to a
1617 significantly higher load on the Netatalk server</para>
1625 <title>ACL Support<indexterm>
1626 <primary>ACLs</primary>
1627 </indexterm></title>
1629 <para>ACL support for AFP is implemented for ZFS ACLs on Solaris and
1630 derived platforms and for POSIX 1e ACLs on Linux.</para>
1633 <title>Configuration</title>
1635 <para>For a basic mode of operation there's nothing to configure.
1636 Netatalk reads ACLs on the fly and calculates effective permissions
1637 which are then send to the AFP client via the so called
1639 <primary>UARights</primary>
1640 </indexterm> permission bits. On a Mac, the Finder uses these bits
1641 to adjust permission in Finder windows. For example folder whos UNIX
1642 mode would only result in in read-only permissions for a user will not
1643 be displayed with a read-only icon and the user will be able to write
1644 to the folder given the folder has an ACL giving the user write
1647 <para>By default, the effective permission of the authenticated user
1648 are only mapped to the mentioned UARights<indexterm>
1649 <primary>UARights</primary>
1650 </indexterm>permission structure, not the UNIX mode. You can adjust
1651 this behaviour with the configuration option <link
1652 linkend="map_acls">map acls</link>.</para>
1654 <para>However, neither in Finder "Get Info" windows nor in Terminal
1655 will you be able to see the ACLs, that's a result of how ACLs in OS X
1656 are designed. If you want to be able to display ACLs on the client,
1657 things get more involved as you must then setup both client and server
1658 to be part on a authentication domain (directory service, eg LDAP,
1659 OpenDirectory). The reason is, that in OS X ACLs are bound to UUIDs,
1660 not just uid's or gid's. Therefor afpd must be able to map every
1661 filesystem uid and gid to a UUID so that it can return the server side
1662 ACLs which are bound to UNIX uid and gid mapped to OS X UUIDs.</para>
1664 <para>Netatalk can query a directory server using LDAP queries. Either
1665 the directory server already provides an UUID attribute for user and
1666 groups (Active Directory, Open Directory) or you reuse an unused
1667 attribute (or add a new one) to you directory server (eg
1670 <para>In detail:</para>
1674 <para>For Solaris/ZFS: ZFS Volumes</para>
1676 <para>You should configure a ZFS ACL know for any volume you want
1677 to use with Netatalk:</para>
1679 <screen>aclinherit = passthrough
1680 aclmode = passthrough</screen>
1682 <para>For an explanation of what this knob does and how to apply
1683 it, check your hosts ZFS documentation (eg man zfs).</para>
1687 <para>Authentication Domain</para>
1689 <para>Your server and the clients must be part of a security
1690 association where identity data is coming from a common source.
1691 ACLs in Darwin are based on UUIDs and so is the ACL specification
1692 in AFP 3.2. Therefor your source of identity data has to provide
1693 an attribute for every user and group where a UUID is stored as a
1694 ASCII string. In other words:</para>
1698 <para>you need an Open Directory Server or an LDAP server
1699 where you store UUIDs in some attribute</para>
1703 <para>your clients must be configured to use this
1708 <para>your server should be configured to use this server via
1709 nsswitch and PAM</para>
1713 <para>configure Netatalk via the special <link
1714 linkend="acl_options">LDAP options for ACLs</link> in <link
1715 linkend="afp.conf.5">afp.conf</link> so that Netatalk is able
1716 to retrieve the UUID for users and groups via LDAP search
1725 <title>OS X ACLs</title>
1727 <para>With Access Control Lists (ACLs) Mac OS X offers a powerful
1728 extension of the traditional UNIX permissions model. An ACL is an
1729 ordered list of Access Control Entries (ACEs) explicitly granting or
1730 denying a set of permissions to a given user or group.</para>
1732 <para>Unlike UNIX permissions, which are bound to user or group IDs,
1733 ACLs are tied to UUIDs. For this reason accessing an object's ACL
1734 requires server and client to use a common directory service which
1735 translates between UUIDs and user/group IDs.</para>
1737 <para>ACLs and UNIX permissions interact in a rather simple way. As
1738 ACLs are optional UNIX permissions act as a default mechanism for
1739 access control. Changing an objects's UNIX permissions will leave it's
1740 ACL intact and modifying an ACL will never change the object's UNIX
1741 permissions. While doing access checks, OS X first examines an
1742 object's ACL evaluating ACEs in order until all requested rights have
1743 been granted, a requested right has been explicitly denied by an ACE
1744 or the end of the list has been reached. In case there is no ACL or
1745 the permissions granted by the ACL are not sufficient to fulfill the
1746 request, OS X next evaluates the object's UNIX permissions. Therefore
1747 ACLs always have precedence over UNIX permissions.</para>
1751 <title>ZFS ACLs</title>
1753 <para>ZFS ACLs closely match OS X ACLs. Both offer mostly identical
1754 fine grained permissions and inheritance settings.</para>
1758 <title>POSIX ACLs</title>
1761 <title>Overview</title>
1763 <para>Compared to OS X or NFSv4 ACLs, Posix ACLs represent a
1764 different, less versatile approach to overcome the limitations of
1765 the traditional UNIX permissions. Implementations are based on the
1766 withdrawn Posix 1003.1e standard.</para>
1768 <para>The standard defines two types of ACLs. Files and directories
1769 can have access ACLs which are consulted for access checks.
1770 Directories can also have default ACLs irrelevant to access checks.
1771 When a new object is created inside a directory with a default ACL,
1772 the default ACL is applied to the new object as it's access ACL.
1773 Subdirectories inherit default ACLs from their parent. There are no
1774 further mechanisms of inheritance control.</para>
1776 <para>Architectural differences between Posix ACLs and OS X ACLs
1777 especially involve:</para>
1779 <para><itemizedlist>
1781 <para>No fine-granular permissions model. Like UNIX
1782 permissions Posix ACLs only differentiate between read, write
1783 and execute permissions.</para>
1787 <para>Entries within an ACL are unordered.</para>
1791 <para>Posix ACLs can only grant rights. There is no way to
1792 explicitly deny rights by an entry.</para>
1796 <para>UNIX permissions are integrated into an ACL as special
1799 </itemizedlist></para>
1801 <para>Posix 1003.1e defines 6 different types of ACL entries. The
1802 first three types are used to integrate standard UNIX permissions.
1803 They form a minimal ACL, their presence is mandatory and only one
1804 entry of each type is allowed within an ACL.</para>
1806 <para><itemizedlist>
1808 <para>ACL_USER_OBJ: the owner's access rights.</para>
1812 <para>ACL_GROUP_OBJ: the owning group's access rights.</para>
1816 <para>ACL_OTHER: everybody's access rights.</para>
1818 </itemizedlist></para>
1820 <para>The remaining entry types expand the traditional permissions
1823 <para><itemizedlist>
1825 <para>ACL_USER: grants access rights to a certain user.</para>
1829 <para>ACL_GROUP: grants access rights to a certain
1834 <para>ACL_MASK: limits the maximum access rights which can be
1835 granted by entries of type ACL_GROUP_OBJ, ACL_USER and
1836 ACL_GROUP. As the name suggests, this entry acts as a mask.
1837 Only one ACL_MASK entry is allowed per ACL. If an ACL contains
1838 ACL_USER or ACL_GROUP entries, an ACL_MASK entry must be
1839 present too, otherwise it is optional.</para>
1841 </itemizedlist></para>
1843 <para>In order to maintain compatibility with applications not aware
1844 of ACLs, Posix 1003.1e changes the semantics of system calls and
1845 utilities which retrieve or manipulate an objects UNIX permissions.
1846 In case an object only has a minimal ACL, the group permissions bits
1847 of the UNIX permissions correspond to the value of the ACL_GROUP_OBJ
1850 <para>However, if the ACL also contains an ACL_MASK entry, the
1851 behavior of those system calls and utilities is different. The group
1852 permissions bits of the UNIX permissions correspond to the value of
1853 the ACL_MASK entry, i. e. calling "chmod g-w" will not only revoke
1854 write access for the group, but for all entities which have been
1855 granted write access by ACL_USER or ACL_GROUP entries.</para>
1859 <title>Mapping POSIX ACLs to OS X ACLs</title>
1861 <para>When a client wants to read an object's ACL, afpd maps it's
1862 Posix ACL onto an equivalent OS X ACL. Writing an object's ACL
1863 requires afpd to map an OS X ACL onto a Posix ACL. Due to
1864 architectural restrictions of Posix ACLs, it is usually impossible
1865 to find an exact mapping so that the result of the mapping process
1866 will be an approximation of the original ACL's semantic.</para>
1868 <para><itemizedlist>
1870 <para>afpd silently discard entries which deny a set of
1871 permissions because they they can't be represented within the
1872 Posix architecture.</para>
1876 <para>As entries within Posix ACLs are unordered, it is
1877 impossible to preserve order.</para>
1881 <para>Inheritance control is subject to severe limitations as
1884 <para>Entries with the only_inherit flag set will only
1885 become part of the directory's default ACL.</para>
1889 <para>Entries with at least one of the flags
1890 file_inherit, directory_inherit or limit_inherit set,
1891 will become part of the directory's access and default
1892 ACL, but the restrictions they impose on inheritance
1893 will be ignored.</para>
1895 </itemizedlist></para>
1899 <para>The lack of a fine-granular permission model on the
1900 Posix side will normally result in an increase of granted
1903 </itemizedlist></para>
1905 <para>As OS X clients aren't aware of the Posix 1003.1e specific
1906 relationship between UNIX permissions and ACL_MASK, afpd does not
1907 expose this feature to the client to avoid compatibility issues and
1908 handles *unix permissions and ACLs the same way as Apple's reference
1909 implementation of AFP does. When an object's UNIX permissions are
1910 requested, afpd calculates proper group rights and returns the
1911 result together with the owner's and everybody's access rights to
1912 the caller via "permissions" and "ua_permissions" members of the
1913 FPUnixPrivs structure (see Apple Filing Protocol Reference, page
1914 181). Changing an object's permissions, afpd always updates
1915 ACL_USER_OBJ, ACL_GROUP_OBJ and ACL_OTHERS. If an ACL_MASK entry is
1916 present too, afpd recalculates it's value so that the new group
1917 rights become effective and existing entries of type ACL_USER or
1918 ACL_GROUP stay intact.</para>
1924 <title>Filesystem Change Events<indexterm>
1925 <primary>FCE</primary>
1926 </indexterm></title>
1928 <para>Netatalk includes a nifty filesystem change event mechanism where
1929 afpd processes notfiy interested listeners about certain filesystem
1930 event by UDP network datagrams.</para>
1932 <para>For the format of the UDP packets and for an example C application
1933 that demonstrates how to use these in a listener, take a look at the
1934 Netatalk sourcefile <filename>bin/misc/fce.c</filename>.</para>
1936 <para>The currently supported FCE events are<itemizedlist>
1938 <para>file modification (fmod)</para>
1942 <para>file deletion (fdel)</para>
1946 <para>directory deletion (ddel)</para>
1950 <para>file creation (fcre)</para>
1954 <para>directory deletion (ddel)</para>
1956 </itemizedlist></para>
1958 <para>For details on the available simple configuration options take a
1959 look at <filename><link
1960 linkend="fceconf">afp.conf</link></filename>.</para>
1965 <title>Starting and stopping Netatalk</title>
1967 <para>The Netatalk distribution comes with several operating system
1968 specific startup script templates that are tailored according to the
1969 options given to the "configure" script before compiling. Currently,
1970 templates are provided for RedHat (sysv style), RedHat (systemd style),
1971 SUSE (sysv style), SUSE (systemd style), Gentoo, NetBSD, Debian and
1972 Solaris. You can select to install the generated startup script(s)
1974 <primary>Startscript</primary>
1976 <secondary>startup script</secondary>
1977 </indexterm> by specifying a system type to "configure". To
1978 automatically install startup scripts give one of the available
1979 <option>--with-init-style</option> option to "configure".</para>
1981 <para>Since new releases of Linux distributions appear all the time and
1982 the startup procedure for the other systems mentioned above might change
1983 as well, it is probably a good idea to not blindly install a startup
1984 script but to look at it first to see if it will work on your system. If
1985 you use Netatalk as part of a fixed setup, like a Linux distribution, an
1986 RPM or a BSD package, things will probably have been arranged properly for
1987 you. The following therefore applies mostly for people who have compiled
1988 Netatalk themselves.</para>
1990 <para>The following daemon need to be started by whatever startup script
1991 mechanism is used:</para>
1995 <para>netatalk<indexterm>
1996 <primary>netatalk</primary>
2001 <para>Additionally, make sure that the configuration file
2002 <filename>afp.conf</filename> is in the right place.</para>