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>To enable Spotlight put this in your afp.conf:</para>
148 <para>This will enable Spotlight functionality. For Solaris with Tracker
149 from OpenCSW also add:<screen>dbus daemon = /opt/csw/bin/dbus-daemon</screen></para>
152 <title>Tracker SPARQL</title>
154 <para>Next you must enbale Spotlight indexing on a per volume
162 <para>Only volumes with a setting of spotlight = yes will be
163 searchable with Spotlight.</para>
166 <para>All other volumes won't be searchable at all</para>
171 <title>Tracker RDF</title>
173 <para>Add all volume paths that should be searchable to
174 $sysconfdir/tracker/tracker.cfg:<screen>...
176 # List of directory roots to index and watch (separator=;)
177 WatchDirectoryRoots=/foo/bar;/another/volume
182 <title>Limitations and notes</title>
186 <para>Large filesystems</para>
188 <para>Tracker on Linux uses the inotify Kernel filesystem change
189 event API for tracking filesystem changes. On large filesystems
190 this may be problematic since the inotify API doesn't offer
191 recursive directory watches but instead requires that for every
192 subdirectoy watches must be added individually.</para>
194 <para>On Solaris the FEN file event notification system is used.
195 It is unkown which limitations and ressource consumption this
196 Solaris subsystem has,</para>
200 <para>Tracker RDF</para>
202 <para>The mapping of certain simple and of complex Spotlight to
203 Tracker RDF queries is imperfect. Also, Tracker RDF filename
204 searches are case sensitive! As a result there are two noticable
209 <para>On a Mac, a query entered in the Spotlight search menu
210 or in a Finder search toolbar is meant to express "search any
211 metadata field, file name or content for this string". With
212 Netatalk and Tracker RDF only filenames will be
217 <para>Searching files content must be done through explicitly
218 adding a "<emphasis>Contents</emphasis> contains ..."
224 <screeninfo>Case sensivity</screeninfo>
228 <imagedata fileref="http://netatalk.sourceforge.net/wiki/images/2/2a/Toolbar_search_is_name_search.png" />
234 <screeninfo>Searching metadata</screeninfo>
238 <imagedata fileref="http://netatalk.sourceforge.net/wiki/images/0/01/Searching_for_content.png" />
247 <title>Supported metadata attributes</title>
249 <para>The following list is the complete set of supported metadata
250 attributes in Tracker SPARQL search queries</para>
253 <title>Tracker SPARQL</title>
258 <entry align="center">Description</entry>
260 <entry align="center">Spotlight Key </entry>
268 <entry>kMDItemDisplayName, kMDItemFSName</entry>
272 <entry>Document content (full text search)</entry>
274 <entry>kMDItemTextContent</entry>
278 <entry>File type</entry>
280 <entry>_kMDItemGroupId, kMDItemContentTypeTree</entry>
284 <entry>File modification date</entry>
286 <entry>kMDItemFSContentChangeDate,
287 kMDItemContentModificationDate,
288 kMDItemAttributeChangeDate</entry>
292 <entry>Content Creation date</entry>
294 <entry>kMDItemContentCreationDate</entry>
298 <entry>The author, or authors, of the contents of the
301 <entry>kMDItemAuthors, kMDItemCreator</entry>
305 <entry>The name of the country where the item was
308 <entry>kMDItemCountry</entry>
312 <entry>Duration</entry>
314 <entry>kMDItemDurationSeconds</entry>
318 <entry>Number of pages</entry>
320 <entry>kMDItemNumberOfPages</entry>
324 <entry>Document title</entry>
326 <entry>kMDItemTitle</entry>
330 <entry>The width, in pixels, of the contents. For example, the
331 image width or the video frame width</entry>
333 <entry>kMDItemPixelWidth</entry>
337 <entry>The height, in pixels, of the contents. For example,
338 the image height or the video frame height</entry>
340 <entry>kMDItemPixelHeight</entry>
344 <entry>The color space model used by the document
347 <entry>kMDItemColorSpace</entry>
351 <entry>The number of bits per sample</entry>
353 <entry>kMDItemBitsPerSample</entry>
357 <entry>Focal length of the lens, in millimeters</entry>
359 <entry>kMDItemFocalLength</entry>
363 <entry>ISO speed</entry>
365 <entry>kMDItemISOSpeed</entry>
369 <entry>Orientation of the document. Possible values are 0
370 (landscape) and 1 (portrait)</entry>
372 <entry>kMDItemOrientation</entry>
376 <entry>Resolution width, in DPI</entry>
378 <entry>kMDItemResolutionWidthDPI</entry>
382 <entry>Resolution height, in DPI</entry>
384 <entry>kMDItemResolutionHeightDPI</entry>
388 <entry>Exposure time, in seconds</entry>
390 <entry>kMDItemExposureTimeSeconds</entry>
394 <entry>The composer of the music contained in the audio
397 <entry>kMDItemComposer</entry>
401 <entry>The musical genre of the song or composition</entry>
403 <entry>kMDItemMusicalGenre</entry>
409 <para>The following list is the complete set of supported metadata
410 attributes in Tracker RDF search queries:<table>
411 <title>Tracker RDF</title>
416 <entry align="center">Description</entry>
418 <entry align="center">Spotlight Key</entry>
426 <entry>kMDItemDisplayName, kMDItemFSName</entry>
430 <entry>Document content (full text search)</entry>
432 <entry>kMDItemTextContent</entry>
436 <entry>File type</entry>
438 <entry>_kMDItemGroupId, kMDItemContentTypeTree</entry>
442 <entry>File modification date</entry>
444 <entry>kMDItemFSContentChangeDate,
445 kMDItemContentModificationDate,
446 kMDItemAttributeChangeDate</entry>
450 <entry>Content Creation date</entry>
452 <entry>kMDItemContentCreationDate</entry>
456 <entry>The author, or authors, of the contents of the
459 <entry>kMDItemAuthors, kMDItemCreator</entry>
463 <entry>The name of the country where the item was
466 <entry>kMDItemCountry</entry>
470 <entry>Duration</entry>
472 <entry>kMDItemDurationSeconds</entry>
476 <entry>Number of pages</entry>
478 <entry>kMDItemNumberOfPages</entry>
482 <entry>Document title</entry>
484 <entry>kMDItemTitle</entry>
488 <entry>The width, in pixels, of the contents. For example,
489 the image width or the video frame width</entry>
491 <entry>kMDItemPixelWidth</entry>
495 <entry>The height, in pixels, of the contents. For example,
496 the image height or the video frame height</entry>
498 <entry>kMDItemPixelHeight</entry>
502 <entry>Focal length of the lens, in millimeters</entry>
504 <entry>kMDItemFocalLength</entry>
508 <entry>ISO speed</entry>
510 <entry>kMDItemISOSpeed</entry>
514 <entry>Orientation of the document. Possible values are 0
515 (landscape) and 1 (portrait)</entry>
517 <entry>kMDItemOrientation</entry>
521 <entry>Exposure time, in seconds</entry>
523 <entry>kMDItemExposureTimeSeconds</entry>
527 <entry>The musical genre of the song or composition</entry>
529 <entry>kMDItemMusicalGenre</entry>
537 <title>Using Tracker commandline tools on the server</title>
539 <para>Netatalk must be running. Then setup relevant environment
540 variables, adjust the prefix /usr/local/netatalk to match your
541 configured paths:<screen>$ su
544 export DBUS_SESSION_BUS_ADDRESS="unix:path=/tmp/spotlight.ipc"
545 export XDG_DATA_HOME=/usr/local/netatalk/var/netatalk
546 export XDG_CACHE_HOME=/usr/local/netatalk/var/netatalk
547 export XDG_CONFIG_HOME=/usr/local/netatalk/etc
551 <para>Tracker SPARQL:<screen># tracker-search QUERY
556 <para>Tracker RDF<screen># cat file.rdf
557 <rdfq:Condition>
559 <rdfq:contains>
560 <rdfq:Property name="File:Name" />
561 <rdf:String>SEARCHSTRING</rdf:String>
562 </rdfq:contains>
564 </rdfq:Condition>
565 # tracker-query -p file.rdf File:Name
567 # tracker-info -m File:Mime PATH
572 <title>References</title>
577 url="https://developer.apple.com/library/mac/#documentation/Carbon/Reference/MDItemRef/Reference/reference.html">MDItem</ulink></para>
582 url="https://live.gnome.org/Tracker/Documentation">Tracker</ulink></para>
588 <sect2 id="CNID-backends">
589 <title>CNID<indexterm>
590 <primary>CNID</primary>
592 <secondary>Catalog Node ID</secondary>
593 </indexterm> backends<indexterm>
594 <primary>Backend</primary>
596 <secondary>CNID backend</secondary>
599 <para>Unlike other protocols like SMB or NFS, the AFP protocol mostly
600 refers to files and directories by ID and not by a path (the IDs are
601 also called CNID, that means Catalog Node ID). A typical AFP request
602 uses a directory ID<indexterm>
603 <primary>DID</primary>
605 <secondary>Directory ID</secondary>
606 </indexterm> and a filename, something like <phrase>"server, please
607 open the file named 'Test' in the directory with id 167"</phrase>. For
608 example "Aliases" on the Mac basically work by ID (with a fallback to
609 the absolute path in more recent AFP clients. But this applies only to
610 Finder, not to applications).</para>
612 <para>Every file in an AFP volume has to have a unique file ID<indexterm>
613 <primary>FID</primary>
615 <secondary>File ID</secondary>
616 </indexterm>, IDs must, according to the specs, never be reused, and
617 IDs are 32 bit numbers (Directory IDs use the same ID pool). So, after
618 ~4 billion files/folders have been written to an AFP volume, the ID pool
619 is depleted and no new file can be written to the volume. No whining
622 <para>Netatalk needs to map IDs to files and folders in the host
623 filesystem. To achieve this, several different CNID backends<indexterm>
624 <primary>CNID backend</primary>
625 </indexterm> are available and can be choosed by the <option>cnid
626 scheme</option><indexterm>
627 <primary>cnidscheme</primary>
629 <secondary>specifying a CNID backend</secondary>
630 </indexterm> option in the <citerefentry>
631 <refentrytitle>afp.conf</refentrytitle>
633 <manvolnum>5</manvolnum>
634 </citerefentry> configuration file. A CNID backend is basically a
635 database storing ID <-> name mappings.</para>
637 <para>The CNID Databases are by default located in
638 <filename>/var/netatalk/CNID</filename>.</para>
640 <para>There is a command line utility called <command>dbd</command>
641 available which can be used to verify, repair and rebuild the CNID
645 <para>There are some CNID related things you should keep in mind when
646 working with netatalk:</para>
650 <para>Don't nest volumes<indexterm>
651 <primary>Nested volumes</primary>
656 <para>CNID backends are databases, so they turn afpd into a file
657 server/database mix.</para>
661 <para>If there's no more space on the filesystem left, the
662 database will get corrupted. You can work around this by either
663 using the <option>vol dbpath</option> option and put the database
664 files into another location or, if you use quotas, make sure the
665 CNID database folder is owned by a user/group without a
667 <primary>Quotas</primary>
669 <secondary>Disk usage quotas</secondary>
674 <para>Be careful with CNID databases for volumes that are mounted
675 via NFS. That is a pretty audacious decision to make anyway, but
676 putting a database there as well is really asking for trouble,
677 i.e. database corruption. Use the <option>vol dbpath</option>
678 directive to put the databases onto a local disk if you must use
680 <primary>NFS</primary>
682 <secondary>Network File System</secondary>
683 </indexterm> mounted volumes.</para>
689 <title>cdb<indexterm>
690 <primary>CDB</primary>
692 <secondary>"cdb" CNID backend</secondary>
695 <para>The "concurrent database" backend is based on Berkeley DB. With
696 this backend, several afpd daemons access the CNID database directly.
697 Berkeley DB locking is used to synchronize access, if more than one
698 afpd process is active for a volume. The drawback is, that the crash
699 of a single afpd process might corrupt the database. cdb should only
700 be used when sharing home directories for a larger number of users
701 <emphasis>and</emphasis> it has been determined that a large number of
702 <command>cnid_dbd</command> processes is problematic.</para>
706 <title>dbd<indexterm>
707 <primary>DBD</primary>
709 <secondary>"dbd" CNID backend</secondary>
712 <para>Access to the CNID database is restricted to the cnid_dbd daemon
713 process. afpd processes communicate with the daemon for database reads
714 and updates. The probability for database corruption is practically
717 <para>This is the default backend since Netatalk 2.1.</para>
721 <title>tdb<indexterm>
722 <primary>tdb</primary>
724 <secondary>"tdb" CNID backend</secondary>
727 <para><abbrev>tdb</abbrev> is another persistent CNID database, it's
728 Samba's <emphasis>Trivial Database</emphasis>. It could be used
729 instead of <abbrev>cdb</abbrev> for user volumes.<important>
730 <para>Only ever use it for volumes that are
731 <emphasis>not</emphasis> shared and accessed by multiple clients
733 </important>This backend is also used internally (as in-memory CNID
734 database) as a fallback in case opening the primary database can't be
735 opened, because <abbrev>tdb</abbrev> can work as in-memory database.
736 This of course means upon restart the CNIDs are gone.</para>
740 <title>last<indexterm>
741 <primary>Last</primary>
743 <secondary>"last" CNID backend</secondary>
746 <para>The last backend is a in-memory tdb database. It is not
747 persistent. Starting with netatalk 3.0, it becomes the <emphasis> read
748 only mode</emphasis> automatically. This is useful e.g. for
753 <sect2 id="charsets">
754 <title>Charsets<indexterm>
755 <primary>Charset</primary>
757 <secondary>character set</secondary>
758 </indexterm>/Unicode<indexterm>
759 <primary>Unicode</primary>
765 <title>Why Unicode?</title>
767 <para>Internally, computers don't know anything about characters and
768 texts, they only know numbers. Therefore, each letter is assigned a
769 number. A character set, often referred to as
770 <emphasis>charset</emphasis> or
771 <emphasis>codepage</emphasis><indexterm>
772 <primary>Codepage</primary>
773 </indexterm>, defines the mappings between numbers and
776 <para>If two or more computer systems need to communicate with each
777 other, the have to use the same character set. In the 1960s the
779 <primary>ASCII</primary>
781 <secondary>American Standard Code for Information
782 Interchange</secondary>
783 </indexterm> (American Standard Code for Information Interchange)
784 character set was defined by the American Standards Association. The
785 original form of ASCII represented 128 characters, more than enough to
786 cover the English alphabet and numerals. Up to date, ASCII has been
787 the normative character scheme used by computers.</para>
789 <para>Later versions defined 256 characters to produce a more
790 international fluency and to include some slightly esoteric graphical
791 characters. Using this mode of encoding each character takes exactly
792 one byte. Obviously, 256 characters still wasn't enough to map all the
793 characters used in the various languages into one character
796 <para>As a result localized character sets were defined later, e.g the
797 ISO-8859 character sets. Most operating system vendors introduced
798 their own characters sets to satisfy their needs, e.g. IBM defined the
799 <emphasis>codepage 437 (DOSLatinUS)</emphasis>, Apple introduced the
800 <emphasis>MacRoman</emphasis><indexterm>
801 <primary>MacRoman</primary>
803 <secondary>MacRoman charset</secondary>
804 </indexterm> codepage and so on. The characters that were assigned
805 number larger than 127 were referred to as
806 <emphasis>extended</emphasis> characters. These character sets
807 conflict with another, as they use the same number for different
808 characters, or vice versa.</para>
810 <para>Almost all of those characters sets defined 256 characters,
811 where the first 128 (0-127) character mappings are identical to ASCII.
812 As a result, communication between systems using different codepages
813 was effectively limited to the ASCII charset.</para>
815 <para>To solve this problem new, larger character sets were defined.
816 To make room for more character mappings, these character sets use at
817 least 2 bytes to store a character. They are therefore referred to as
818 <emphasis>multibyte</emphasis> character sets.</para>
820 <para>One standardized multibyte charset encoding scheme is known as
821 <ulink url="http://www.unicode.org/">unicode</ulink>. A big advantage
822 of using a multibyte charset is that you only need one. There is no
823 need to make sure two computers use the same charset when they are
824 communicating.</para>
828 <title>character sets used by Apple</title>
830 <para>In the past, Apple clients used single-byte charsets to
831 communicate over the network. Over the years Apple defined a number of
832 codepages, western users will most likely be using the
833 <emphasis>MacRoman</emphasis> codepage.</para>
835 <para>Codepages defined by Apple include:</para>
839 <para>MacArabic, MacFarsi</para>
843 <para>MacCentralEurope</para>
847 <para>MacChineseSimple</para>
851 <para>MacChineseTraditional</para>
855 <para>MacCroation</para>
859 <para>MacCyrillic</para>
863 <para>MacDevanagari</para>
867 <para>MacGreek</para>
871 <para>MacHebrew</para>
875 <para>MacIcelandic</para>
879 <para>MacJapanese</para>
883 <para>MacKorean</para>
887 <para>MacRoman</para>
891 <para>MacRomanian</para>
899 <para>MacTurkish</para>
903 <para>Starting with Mac OS X and AFP3, <ulink
904 url="http://www.utf-8.com/">UTF-8</ulink> is used. UTF-8 encodes
905 Unicode characters in an ASCII compatible way, each Unicode character
906 is encoded into 1-6 ASCII characters. UTF-8 is therefore not really a
907 charset itself, it's an encoding of the Unicode charset.</para>
909 <para>To complicate things, Unicode defines several <emphasis> <ulink
910 url="http://www.unicode.org/reports/tr15/index.html">normalization</ulink>
911 </emphasis> forms. While <ulink
912 url="http://www.samba.org">samba</ulink><indexterm>
913 <primary>Samba</primary>
914 </indexterm> uses <emphasis>precomposed</emphasis><indexterm>
915 <primary>Precomposed</primary>
917 <secondary>Precomposed Unicode normalization</secondary>
918 </indexterm> Unicode, which most Unix tools prefer as well, Apple
919 decided to use the <emphasis>decomposed</emphasis><indexterm>
920 <primary>Decomposed</primary>
922 <secondary>Decomposed Unicode normalization</secondary>
923 </indexterm> normalization.</para>
925 <para>For example lets take the German character
926 '<keycode>ä</keycode>'. Using the precomposed normalization, Unicode
927 maps this character to 0xE4. In decomposed normalization, 'ä' is
928 actually mapped to two characters, 0x61 and 0x308. 0x61 is the mapping
929 for an 'a', 0x308 is the mapping for a <emphasis>COMBINING
930 DIAERESIS</emphasis>.</para>
932 <para>Netatalk refers to precomposed UTF-8 as
933 <emphasis>UTF8</emphasis><indexterm>
934 <primary>UTF8</primary>
936 <secondary>Netatalk's precomposed UTF-8 encoding</secondary>
937 </indexterm> and to decomposed UTF-8 as
938 <emphasis>UTF8-MAC</emphasis><indexterm>
939 <primary>UTF8-MAC</primary>
941 <secondary>Netatalk's decomposed UTF-8 encoding</secondary>
946 <title>afpd and character sets</title>
948 <para>To support new AFP 3.x and older AFP 2.x clients at the same
949 time, afpd needs to be able to convert between the various charsets
950 used. AFP 3.x clients always use UTF8-MAC, AFP 2.x clients use one of
951 the Apple codepages.</para>
953 <para>At the time of this writing, netatalk supports the following
954 Apple codepages:</para>
958 <para>MAC_CENTRALEUROPE</para>
962 <para>MAC_CHINESE_SIMP</para>
966 <para>MAC_CHINESE_TRAD</para>
970 <para>MAC_CYRILLIC</para>
974 <para>MAC_GREEK</para>
978 <para>MAC_HEBREW</para>
982 <para>MAC_JAPANESE</para>
986 <para>MAC_KOREAN</para>
990 <para>MAC_ROMAN</para>
994 <para>MAC_TURKISH</para>
998 <para>afpd handles three different character set options:</para>
1002 <term>unix charset<indexterm>
1003 <primary>unix charset</primary>
1005 <secondary>afpd's unix charset setting</secondary>
1009 <para>This is the codepage used internally by your operating
1010 system. If not specified, it defaults to <option>UTF8</option>.
1011 If <option>LOCALE</option> is specified and your system support
1012 Unix locales, afpd tries to detect the codepage. afpd uses this
1013 codepage to read its configuration files, so you can use
1014 extended characters for volume names, login messages, etc. see
1016 <refentrytitle>afp.conf</refentrytitle>
1018 <manvolnum>5</manvolnum>
1019 </citerefentry>.</para>
1024 <term>mac charset<indexterm>
1025 <primary>mac charset</primary>
1027 <secondary>afpd's mac charset setting</secondary>
1031 <para>As already mentioned, older Mac OS clients (up to AFP 2.2)
1032 use codepages to communicate with afpd. However, there is no
1033 support for negotiating the codepage used by the client in the
1034 AFP protocol. If not specified otherwise, afpd assumes the
1035 <emphasis>MacRoman</emphasis> codepage is used. In case you're
1036 clients use another codepage, e.g.
1037 <emphasis>MacCyrillic</emphasis>, you'll <emphasis
1038 role="bold">have</emphasis> to explicitly configure this. see
1040 <refentrytitle>afp.conf</refentrytitle>
1042 <manvolnum>5</manvolnum>
1043 </citerefentry>.</para>
1048 <term>vol charset<indexterm>
1049 <primary>vol charset</primary>
1051 <secondary>afpd's vol charset setting</secondary>
1055 <para>This defines the charset afpd should use for filenames on
1056 disk. By default, it is the same as <option>unix
1057 charset</option>. If you have <ulink
1058 url="http://www.gnu.org/software/libiconv/">iconv</ulink><indexterm>
1059 <primary>Iconv</primary>
1061 <secondary>iconv encoding conversion engine</secondary>
1062 </indexterm> installed, you can use any iconv provided charset
1065 <para>afpd needs a way to preserve extended macintosh
1066 characters, or characters illegal in unix filenames, when saving
1067 files on a unix filesystem. Earlier versions used the the so
1068 called CAP encoding<indexterm>
1069 <primary>CAP encoding</primary>
1071 <secondary>CAP style character encoding</secondary>
1072 </indexterm>. An extended character (>0x7F) would be
1073 converted to a :xx hex sequence, e.g. the Apple Logo (MacRoman:
1074 0xF0) was saved as :f0. Some special characters will be
1075 converted as to :xx notation as well. '/' will be encoded to
1076 :2f, if <option>usedots</option> was not specified, a leading
1077 dot '.' will be encoded as :2e.</para>
1079 <para>Even though this version now uses <option>UTF8</option> as
1080 the default encoding for filenames, '/' will be converted to
1081 ':'. For western users another useful setting could be
1082 <option>vol charset = ISO-8859-15</option>.</para>
1084 <para>If a character cannot be converted from the <option>mac
1085 charset</option> to the selected <option>vol charset</option>,
1086 afpd will save it as a CAP encoded character. For AFP3 clients,
1087 afpd will convert the UTF8 character to <option>mac
1088 charset</option> first. If this conversion fails, you'll receive
1089 a -50 error on the mac. <emphasis>Note</emphasis>: Whenever you
1090 can, please stick with the default UTF8 volume format. see
1092 <refentrytitle>afp.conf</refentrytitle>
1094 <manvolnum>5</manvolnum>
1095 </citerefentry>.</para>
1102 <sect2 id="authentication">
1103 <title>Authentication<indexterm>
1104 <primary>Authentication</primary>
1106 <secondary>between AFP client and server</secondary>
1107 </indexterm></title>
1110 <title>AFP authentication basics</title>
1112 <para>Apple chose a flexible model called "User Authentication
1114 <primary>UAM</primary>
1116 <secondary>User Authentication Module</secondary>
1117 </indexterm> (UAMs) for authentication purposes between AFP client
1118 and server. An AFP client initially connecting to an AFP server will
1119 ask for the list of UAMs which the server provides, and will choose
1120 the one with strongest encryption that the client supports.</para>
1122 <para>Several UAMs have been developed by Apple over the time, some by
1123 3rd-party developers.</para>
1127 <title>UAMs supported by Netatalk</title>
1129 <para>Netatalk supports the following ones by default:</para>
1133 <para>"No User Authent"<indexterm>
1134 <primary>No User Authent</primary>
1136 <secondary>"No User Authent" UAM (guest access)</secondary>
1137 </indexterm> UAM (guest access without authentication)</para>
1141 <para>"Cleartxt Passwrd"<indexterm>
1142 <primary>Cleartxt Passwrd</primary>
1144 <secondary>"Cleartxt Passwrd" UAM</secondary>
1145 </indexterm> UAM (no password encryption)</para>
1149 <para>"Randnum exchange"<indexterm>
1150 <primary>Randnum exchange</primary>
1152 <secondary>"Randnum exchange" UAM</secondary>
1153 </indexterm>/"2-Way Randnum exchange"<indexterm>
1154 <primary>2-Way Randnum exchange</primary>
1156 <secondary>"2-Way Randnum exchange" UAM</secondary>
1157 </indexterm> UAMs (weak password encryption, separate password
1162 <para>"DHCAST128"<indexterm>
1163 <primary>DHCAST128</primary>
1165 <secondary>"DHCAST128" UAM</secondary>
1166 </indexterm> UAM (stronger password encryption)</para>
1170 <para>"DHX2"<indexterm>
1171 <primary>DHX2</primary>
1173 <secondary>"DHX2" UAM</secondary>
1174 </indexterm> UAM (successor of DHCAST128)</para>
1178 <para>There exist other optional UAMs as well:</para>
1182 <para>"PGPuam 1.0"<indexterm>
1183 <primary>PGPuam 1.0</primary>
1185 <secondary>"PGPuam 1.0" UAM</secondary>
1186 </indexterm><indexterm>
1187 <primary>uams_pgp.so</primary>
1189 <secondary>"PGPuam 1.0" UAM</secondary>
1190 </indexterm> UAM (PGP-based authentication for pre-Mac OS X
1191 clients. You'll also need the <ulink
1192 url="http://www.vmeng.com/vinnie/papers/pgpuam.html">PGPuam
1193 client</ulink> to let this work)</para>
1195 <para>You'll have to add <filename>"--enable-pgp-uam"</filename>
1196 to your configure switches to have this UAM available.</para>
1200 <para>"Kerberos IV"<indexterm>
1201 <primary>Kerberos IV</primary>
1203 <secondary>"Kerberos IV" UAM</secondary>
1204 </indexterm><indexterm>
1205 <primary>uams_krb4.so</primary>
1207 <secondary>"Kerberos IV" UAM</secondary>
1208 </indexterm>/"AFS Kerberos"<indexterm>
1209 <primary>AFS Kerberos</primary>
1211 <secondary>"AFS Kerberos" UAM (Kerberos IV)</secondary>
1212 </indexterm> UAMs (suitable to use <ulink
1213 url="http://web.mit.edu/macdev/KfM/Common/Documentation/faq.html">Kerberos
1214 v4 based authentication</ulink> and AFS file servers)</para>
1216 <para>Use <filename>"--enable-krb4-uam"</filename> at compile time
1217 to activate the build of this UAM.</para>
1221 <para>"Client Krb v2"<indexterm>
1222 <primary>Client Krb v2</primary>
1224 <secondary>"Client Krb v2" UAM (Kerberos V)</secondary>
1225 </indexterm> UAM (Kerberos V, suitable for "Single Sign On"
1226 Scenarios with OS X clients -- see below)</para>
1228 <para><filename>"--enable-krbV-uam"</filename> will provide you
1229 with the ability to use this UAM.</para>
1233 <para>You can configure which UAMs should be activated by defining
1234 "<option>uam list</option>" in <option>Global</option> section.
1235 <command>afpd</command> will log which UAMs it's using and if problems
1236 occur while activating them in either
1237 <filename>netatalk.log</filename> or syslog at startup time.
1239 <refentrytitle>asip-status.pl</refentrytitle>
1241 <manvolnum>1</manvolnum>
1242 </citerefentry> can be used to query the available UAMs of AFP
1243 servers as well.</para>
1245 <para>Having a specific UAM available at the server does not
1246 automatically mean that a client can use it. Client-side support is
1247 also necessary. For older Macintoshes running Mac OS < X DHCAST128
1248 support exists since AppleShare client 3.8.x.</para>
1250 <para>On OS X, there exist some client-side techniques to make the
1251 AFP-client more verbose, so one can have a look what's happening while
1252 negotiating the UAMs to use. Compare with this <ulink
1253 url="http://article.gmane.org/gmane.network.netatalk.devel/7383/">hint</ulink>.</para>
1257 <title>Which UAMs to activate?</title>
1259 <para>It depends primarily on your needs and on the kind of Mac OS
1260 versions you have to support. Basically one should try to use
1261 DHCAST128 and DHX2 where possible because of its strength of password
1266 <para>Unless you really have to supply guest access to your
1267 server's volumes ensure that you disable "No User Authent" since
1268 it might lead accidentally to unauthorized access. In case you
1269 must enable guest access take care that you enforce this on a per
1270 volume base using the access controls.</para>
1274 <para>The "ClearTxt Passwrd" UAM is as bad as it sounds since
1275 passwords go unencrypted over the wire. Try to avoid it at both
1276 the server's side as well as on the client's. Note: If you want to
1277 provide Mac OS 8/9 clients with NetBoot-services then you need
1278 uams_cleartext.so since the AFP-client integrated into the Mac's
1279 firmware can only deal with this basic form of
1280 authentication.</para>
1284 <para>Since "Randnum exchange"/"2-Way Randnum exchange" uses only
1285 56 bit DES for encryption it should be avoided as well. Another
1286 disadvantage is the fact that the passwords have to be stored in
1287 cleartext on the server and that it doesn't integrate into both
1288 PAM scenarios or classic /etc/shadow (you have to administrate
1289 passwords separately by using the <citerefentry>
1290 <refentrytitle>afppasswd</refentrytitle>
1292 <manvolnum>1</manvolnum>
1293 </citerefentry> utility, if clients should use these
1298 <para>"DHCAST128" or "DHX2" should be a good compromise for most
1299 people since it combines stronger encryption with PAM
1304 <para>Using the Kerberos V<indexterm>
1305 <primary>Kerberos V</primary>
1307 <secondary>"Client Krb v2" UAM</secondary>
1308 </indexterm> ("Client Krb v2") UAM, it's possible to implement
1309 real single sign on scenarios using Kerberos tickets. The password
1310 is not sent over the network. Instead, the user password is used
1311 to decrypt a service ticket for the appleshare server. The service
1312 ticket contains an encryption key for the client and some
1313 encrypted data (which only the appleshare server can decrypt). The
1314 encrypted portion of the service ticket is sent to the server and
1315 used to authenticate the user. Because of the way that the afpd
1316 service principal detection is implemented, this authentication
1317 method is vulnerable to man-in-the-middle attacks.</para>
1321 <para>For a more detailed overview over the technical implications of
1322 the different UAMs, please have a look at Apple's <ulink
1323 url="http://developer.apple.com/library/mac/#documentation/Networking/Conceptual/AFP/AFPSecurity/AFPSecurity.html#//apple_ref/doc/uid/TP40000854-CH232-SW1">File
1324 Server Security</ulink> pages.</para>
1328 <title>Using different authentication sources with specific
1331 <para>Some UAMs provide the ability to use different authentication
1332 "backends", namely <filename>uams_cleartext.so</filename>,
1333 <filename>uams_dhx.so</filename> and
1334 <filename>uams_dhx2.so</filename>. They can use either classic Unix
1335 passwords from <filename>/etc/passwd</filename>
1336 (<filename>/etc/shadow</filename>) or PAM if the system supports that.
1337 <filename>uams_cleartext.so</filename> can be symlinked to either
1338 <filename>uams_passwd.so</filename> or
1339 <filename>uams_pam.so</filename>, <filename>uams_dhx.so</filename> to
1340 <filename>uams_dhx_passwd.so</filename> or
1341 <filename>uams_dhx_pam.so</filename> and
1342 <filename>uams_dhx2.so</filename> to
1343 <filename>uams_dhx2_passwd.so</filename> or
1344 <filename>uams_dhx2_pam.so</filename>.</para>
1346 <para>So, if it looks like this in Netatalk's UAMs folder (per default
1347 <filename>/etc/netatalk/uams/</filename>):<programlisting>uams_clrtxt.so -> uams_pam.so
1348 uams_dhx.so -> uams_dhx_pam.so
1349 uams_dhx2.so -> uams_dhx2_pam.so</programlisting> then you're using PAM,
1350 otherwise classic Unix passwords. The main advantage of using PAM is
1351 that one can integrate Netatalk in centralized authentication
1352 scenarios, eg. via LDAP, NIS and the like. Please always keep in mind
1353 that the protection of your user's login credentials in such scenarios
1354 also depends on the strength of encryption that the UAM in question
1355 supplies. So think about eliminating weak UAMs like "ClearTxt Passwrd"
1356 and "Randnum exchange" completely from your network.</para>
1360 <title>Netatalk UAM overview table</title>
1362 <para>A small overview of the most common used UAMs.</para>
1364 <table orient="land">
1365 <title>Netatalk UAM overview</title>
1367 <tgroup align="center" cols="7">
1368 <colspec colname="col1" colnum="1" colwidth="0.5*" />
1370 <colspec colname="uam_guest" colnum="2" colwidth="1*" />
1372 <colspec colname="uam_clrtxt" colnum="3" colwidth="1*" />
1374 <colspec colname="uam_randnum" colnum="4" colwidth="1*" />
1376 <colspec colname="uam_dhx" colnum="5" colwidth="1*" />
1378 <colspec colname="uam_dhx2" colnum="6" colwidth="1*" />
1380 <colspec colname="uam_gss" colnum="7" colwidth="1*" />
1384 <entry align="center" rotate="0" valign="middle">UAM</entry>
1386 <entry>No User Authent<indexterm>
1387 <primary>uams_guest.so</primary>
1389 <secondary>"No User Authent" UAM (guest
1391 </indexterm></entry>
1393 <entry>Cleartxt Passwrd<indexterm>
1394 <primary>uams_cleartxt.so</primary>
1396 <secondary>"Cleartxt Passwrd" UAM</secondary>
1397 </indexterm></entry>
1399 <entry>(2-Way) Randnum exchange<indexterm>
1400 <primary>uams_randnum.so</primary>
1402 <secondary>"(2-Way) Randnum exchange" UAM</secondary>
1403 </indexterm></entry>
1405 <entry>DHCAST128<indexterm>
1406 <primary>uams_dhx.so</primary>
1408 <secondary>"DHCAST128" UAM</secondary>
1409 </indexterm></entry>
1411 <entry>DHX2<indexterm>
1412 <primary>uams_dhx2.so</primary>
1414 <secondary>"DHX2" UAM</secondary>
1415 </indexterm></entry>
1417 <entry>Client Krb v2<indexterm>
1418 <primary>uams_gss.so</primary>
1420 <secondary>"Client Krb v2" UAM (Kerberos V)</secondary>
1421 </indexterm></entry>
1425 <entry align="center" rotate="0" valign="middle">pssword
1428 <entry>guest access</entry>
1430 <entry>max. 8 characters</entry>
1432 <entry>max. 8 characters</entry>
1434 <entry>max. 64 characters</entry>
1436 <entry>max. 256 characters</entry>
1438 <entry>Kerberos tickets</entry>
1442 <entry align="center" rotate="0" valign="middle">Client
1445 <entry>built-in into all Mac OS versions</entry>
1447 <entry>built-in in all Mac OS versions except 10.0. Has to be
1448 activated explicitly in recent Mac OS X versions</entry>
1450 <entry>built-in into almost all Mac OS versions</entry>
1452 <entry>built-in since AppleShare client 3.8.4, available as a
1453 plug-in for 3.8.3, integrated in Mac OS X' AFP client</entry>
1455 <entry>built-in since Mac OS X 10.2</entry>
1457 <entry>built-in since Mac OS X 10.2</entry>
1461 <entry align="center" rotate="0"
1462 valign="middle">Encryption</entry>
1464 <entry>Enables guest access without authentication between
1465 client and server.</entry>
1467 <entry>Password will be sent in cleartext over the wire. Just
1468 as bad as it sounds, therefore avoid at all if possible (note:
1469 providing NetBoot services requires the ClearTxt UAM)</entry>
1471 <entry>8-byte random numbers are sent over the wire,
1472 comparable with DES, 56 bits. Vulnerable to offline dictionary
1473 attack. Requires passwords in clear on the server.</entry>
1475 <entry>Password will be encrypted with 128 bit SSL, user will
1476 be authenticated against the server but not vice versa.
1477 Therefor weak against man-in-the-middle attacks.</entry>
1479 <entry>Password will be encrypted using libgcrypt with CAST
1480 128 in CBC mode. User will be authenticated against the server
1481 but not vice versa. Therefor weak against man-in-the-middle
1484 <entry>Password is not sent over the network. Due to the
1485 service principal detection method, this authentication method
1486 is vulnerable to man-in-the-middle attacks.</entry>
1490 <entry align="center" rotate="0" valign="middle">Server
1493 <entry align="center" valign="middle">uams_guest.so</entry>
1495 <entry align="center" valign="middle">uams_cleartxt.so</entry>
1497 <entry align="center" valign="middle">uams_randnum.so</entry>
1499 <entry align="center" valign="middle">uams_dhx.so</entry>
1501 <entry align="center" valign="middle">uams_dhx2.so</entry>
1503 <entry align="center" valign="middle">uams_gss.so</entry>
1507 <entry align="center" rotate="0" valign="middle">Password
1508 storage method</entry>
1510 <entry align="center" valign="middle">None</entry>
1512 <entry align="center" valign="middle">Either /etc/passwd
1513 (/etc/shadow) or PAM</entry>
1515 <entry align="center" valign="middle">Passwords stored in
1516 clear text in a separate text file</entry>
1518 <entry align="center" valign="middle">Either /etc/passwd
1519 (/etc/shadow) or PAM</entry>
1521 <entry align="center" valign="middle">Either /etc/passwd
1522 (/etc/shadow) or PAM</entry>
1524 <entry align="center" valign="middle">At the Kerberos Key
1525 Distribution Center*</entry>
1531 <para>* Have a look at this <ulink
1532 url="http://cryptnet.net/fdp/admin/kerby-infra/en/kerby-infra.html">Kerberos
1533 overview</ulink></para>
1536 <sect3 id="sshtunnel">
1537 <title>SSH tunneling</title>
1539 <para>Tunneling and all sort of VPN stuff has nothing to do with AFP
1540 authentication and UAMs in general. But since Apple introduced an
1541 option called "Allow Secure Connections Using SSH" and many people
1542 tend to confuse both things, we'll speak about that here too.</para>
1544 <sect4 id="manualsshtunnel">
1545 <title>Manually tunneling an AFP session</title>
1547 <para>This works since the first AFP servers that spoke "AFP over
1548 TCP" appeared in networks. One simply tunnels the remote server's
1549 AFP port to a local port different than 548 and connects locally to
1550 this port afterwards. On OS X this can be done by</para>
1552 <programlisting>ssh -l $USER $SERVER -L 10548:127.0.0.1:548 sleep 3000</programlisting>
1554 <para>After establishing the tunnel one will use
1555 <filename>"afp://127.0.0.1:10548"</filename> in the "Connect to
1556 server" dialog. All AFP traffic including the initial connection
1557 attempts will be sent encrypted over the wire since the local AFP
1558 client will connect to the Mac's local port 10548 which will be
1559 forwarded to the remote server's AFP port (we used the default 548)
1562 <para>These sorts of tunnels are an ideal solution if you've to
1563 access an AFP server providing weak authentications mechanisms
1564 through the Internet without having the ability to use a "real" VPN.
1565 Note that you can let <command>ssh</command> compress the data by
1566 using its "-C" switch and that the tunnel endpoints can be different
1567 from both AFP client and server (compare with the SSH documentation
1568 for details).</para>
1571 <sect4 id="autosshtunnel">
1572 <title>Automatically establishing a tunneled AFP connection</title>
1574 <para>From Mac OS X 10.2 to 10.4, Apple added an "Allow Secure
1575 Connections Using SSH" checkbox to the "Connect to Server" dialog.
1576 The idea behind: When the server signals that it can be contacted by
1577 SSH then Mac OS X' AFP client tries to establish the tunnel and
1578 automagically sends all AFP traffic through it.</para>
1580 <para>But it took until the release of Mac OS X 10.3 that this
1581 feature worked the first time... partly. In case, the SSH tunnel
1582 can't be established the AFP client <emphasis
1583 role="strong">silently</emphasis> fell back to an unencrypted AFP
1584 connection attempt.</para>
1586 <para>Netatalk's afpd will report that it is capable of handling SSH
1587 tunneled AFP requests, when both "<option>advertise ssh</option>"
1588 and "<option>fqdn</option>" options are set in
1589 <option>Global</option> section (double check with <citerefentry>
1590 <refentrytitle>asip-status.pl</refentrytitle>
1592 <manvolnum>1</manvolnum>
1593 </citerefentry> after you restarted afpd when you made changes to
1594 the settings). But there are a couple of reasons why you don't want
1595 to use this option at all:</para>
1599 <para>Tunneling TCP over TCP (as SSH does) is not the best idea.
1600 There exist better solutions like VPNs based on the IP
1605 <para>Since this SSH kludge isn't a normal UAM that integrates
1606 directly into the AFP authentication mechanisms but instead uses
1607 a single flag signalling clients whether they can <emphasis
1608 role="strong">try</emphasis> to establish a tunnel or not, it
1609 makes life harder to see what's happening when things go
1614 <para>You cannot control which machines are logged on by
1615 Netatalk tools like a <command>macusers</command> since all
1616 connection attempts seem to be made from localhost.</para>
1620 <para>On the other side you've to limit access to afpd to
1621 localhost only (TCP wrappers) when you want to ensure that all
1622 AFP sessions are SSH encrypted or...</para>
1626 <para>...when you're using 10.2 - 10.3.3 then you get the
1627 opposite of what you'd expect: potentially unencrypted AFP
1628 communication (including logon credentials) on the network
1629 without a single notification that establishing the tunnel
1630 failed. Apple fixed that not until Mac OS X 10.3.4.</para>
1634 <para>Encrypting all AFP sessions via SSH can lead to a
1635 significantly higher load on the Netatalk server</para>
1643 <title>ACL Support<indexterm>
1644 <primary>ACLs</primary>
1645 </indexterm></title>
1647 <para>ACL support for AFP is implemented for ZFS ACLs on Solaris and
1648 derived platforms and for POSIX 1e ACLs on Linux.</para>
1651 <title>Configuration</title>
1653 <para>For a basic mode of operation there's nothing to configure.
1654 Netatalk reads ACLs on the fly and calculates effective permissions
1655 which are then send to the AFP client via the so called
1657 <primary>UARights</primary>
1658 </indexterm> permission bits. On a Mac, the Finder uses these bits
1659 to adjust permission in Finder windows. For example folder whos UNIX
1660 mode would only result in in read-only permissions for a user will not
1661 be displayed with a read-only icon and the user will be able to write
1662 to the folder given the folder has an ACL giving the user write
1665 <para>By default, the effective permission of the authenticated user
1666 are only mapped to the mentioned UARights<indexterm>
1667 <primary>UARights</primary>
1668 </indexterm>permission structure, not the UNIX mode. You can adjust
1669 this behaviour with the configuration option <link
1670 linkend="map_acls">map acls</link>.</para>
1672 <para>However, neither in Finder "Get Info" windows nor in Terminal
1673 will you be able to see the ACLs, that's a result of how ACLs in OS X
1674 are designed. If you want to be able to display ACLs on the client,
1675 things get more involved as you must then setup both client and server
1676 to be part on a authentication domain (directory service, eg LDAP,
1677 OpenDirectory). The reason is, that in OS X ACLs are bound to UUIDs,
1678 not just uid's or gid's. Therefor afpd must be able to map every
1679 filesystem uid and gid to a UUID so that it can return the server side
1680 ACLs which are bound to UNIX uid and gid mapped to OS X UUIDs.</para>
1682 <para>Netatalk can query a directory server using LDAP queries. Either
1683 the directory server already provides an UUID attribute for user and
1684 groups (Active Directory, Open Directory) or you reuse an unused
1685 attribute (or add a new one) to you directory server (eg
1688 <para>In detail:</para>
1692 <para>For Solaris/ZFS: ZFS Volumes</para>
1694 <para>You should configure a ZFS ACL know for any volume you want
1695 to use with Netatalk:</para>
1697 <screen>aclinherit = passthrough
1698 aclmode = passthrough</screen>
1700 <para>For an explanation of what this knob does and how to apply
1701 it, check your hosts ZFS documentation (eg man zfs).</para>
1705 <para>Authentication Domain</para>
1707 <para>Your server and the clients must be part of a security
1708 association where identity data is coming from a common source.
1709 ACLs in Darwin are based on UUIDs and so is the ACL specification
1710 in AFP 3.2. Therefor your source of identity data has to provide
1711 an attribute for every user and group where a UUID is stored as a
1712 ASCII string. In other words:</para>
1716 <para>you need an Open Directory Server or an LDAP server
1717 where you store UUIDs in some attribute</para>
1721 <para>your clients must be configured to use this
1726 <para>your server should be configured to use this server via
1727 nsswitch and PAM</para>
1731 <para>configure Netatalk via the special <link
1732 linkend="acl_options">LDAP options for ACLs</link> in <link
1733 linkend="afp.conf.5">afp.conf</link> so that Netatalk is able
1734 to retrieve the UUID for users and groups via LDAP search
1743 <title>OS X ACLs</title>
1745 <para>With Access Control Lists (ACLs) Mac OS X offers a powerful
1746 extension of the traditional UNIX permissions model. An ACL is an
1747 ordered list of Access Control Entries (ACEs) explicitly granting or
1748 denying a set of permissions to a given user or group.</para>
1750 <para>Unlike UNIX permissions, which are bound to user or group IDs,
1751 ACLs are tied to UUIDs. For this reason accessing an object's ACL
1752 requires server and client to use a common directory service which
1753 translates between UUIDs and user/group IDs.</para>
1755 <para>ACLs and UNIX permissions interact in a rather simple way. As
1756 ACLs are optional UNIX permissions act as a default mechanism for
1757 access control. Changing an objects's UNIX permissions will leave it's
1758 ACL intact and modifying an ACL will never change the object's UNIX
1759 permissions. While doing access checks, OS X first examines an
1760 object's ACL evaluating ACEs in order until all requested rights have
1761 been granted, a requested right has been explicitly denied by an ACE
1762 or the end of the list has been reached. In case there is no ACL or
1763 the permissions granted by the ACL are not sufficient to fulfill the
1764 request, OS X next evaluates the object's UNIX permissions. Therefore
1765 ACLs always have precedence over UNIX permissions.</para>
1769 <title>ZFS ACLs</title>
1771 <para>ZFS ACLs closely match OS X ACLs. Both offer mostly identical
1772 fine grained permissions and inheritance settings.</para>
1776 <title>POSIX ACLs</title>
1779 <title>Overview</title>
1781 <para>Compared to OS X or NFSv4 ACLs, Posix ACLs represent a
1782 different, less versatile approach to overcome the limitations of
1783 the traditional UNIX permissions. Implementations are based on the
1784 withdrawn Posix 1003.1e standard.</para>
1786 <para>The standard defines two types of ACLs. Files and directories
1787 can have access ACLs which are consulted for access checks.
1788 Directories can also have default ACLs irrelevant to access checks.
1789 When a new object is created inside a directory with a default ACL,
1790 the default ACL is applied to the new object as it's access ACL.
1791 Subdirectories inherit default ACLs from their parent. There are no
1792 further mechanisms of inheritance control.</para>
1794 <para>Architectural differences between Posix ACLs and OS X ACLs
1795 especially involve:</para>
1797 <para><itemizedlist>
1799 <para>No fine-granular permissions model. Like UNIX
1800 permissions Posix ACLs only differentiate between read, write
1801 and execute permissions.</para>
1805 <para>Entries within an ACL are unordered.</para>
1809 <para>Posix ACLs can only grant rights. There is no way to
1810 explicitly deny rights by an entry.</para>
1814 <para>UNIX permissions are integrated into an ACL as special
1817 </itemizedlist></para>
1819 <para>Posix 1003.1e defines 6 different types of ACL entries. The
1820 first three types are used to integrate standard UNIX permissions.
1821 They form a minimal ACL, their presence is mandatory and only one
1822 entry of each type is allowed within an ACL.</para>
1824 <para><itemizedlist>
1826 <para>ACL_USER_OBJ: the owner's access rights.</para>
1830 <para>ACL_GROUP_OBJ: the owning group's access rights.</para>
1834 <para>ACL_OTHER: everybody's access rights.</para>
1836 </itemizedlist></para>
1838 <para>The remaining entry types expand the traditional permissions
1841 <para><itemizedlist>
1843 <para>ACL_USER: grants access rights to a certain user.</para>
1847 <para>ACL_GROUP: grants access rights to a certain
1852 <para>ACL_MASK: limits the maximum access rights which can be
1853 granted by entries of type ACL_GROUP_OBJ, ACL_USER and
1854 ACL_GROUP. As the name suggests, this entry acts as a mask.
1855 Only one ACL_MASK entry is allowed per ACL. If an ACL contains
1856 ACL_USER or ACL_GROUP entries, an ACL_MASK entry must be
1857 present too, otherwise it is optional.</para>
1859 </itemizedlist></para>
1861 <para>In order to maintain compatibility with applications not aware
1862 of ACLs, Posix 1003.1e changes the semantics of system calls and
1863 utilities which retrieve or manipulate an objects UNIX permissions.
1864 In case an object only has a minimal ACL, the group permissions bits
1865 of the UNIX permissions correspond to the value of the ACL_GROUP_OBJ
1868 <para>However, if the ACL also contains an ACL_MASK entry, the
1869 behavior of those system calls and utilities is different. The group
1870 permissions bits of the UNIX permissions correspond to the value of
1871 the ACL_MASK entry, i. e. calling "chmod g-w" will not only revoke
1872 write access for the group, but for all entities which have been
1873 granted write access by ACL_USER or ACL_GROUP entries.</para>
1877 <title>Mapping POSIX ACLs to OS X ACLs</title>
1879 <para>When a client wants to read an object's ACL, afpd maps it's
1880 Posix ACL onto an equivalent OS X ACL. Writing an object's ACL
1881 requires afpd to map an OS X ACL onto a Posix ACL. Due to
1882 architectural restrictions of Posix ACLs, it is usually impossible
1883 to find an exact mapping so that the result of the mapping process
1884 will be an approximation of the original ACL's semantic.</para>
1886 <para><itemizedlist>
1888 <para>afpd silently discard entries which deny a set of
1889 permissions because they they can't be represented within the
1890 Posix architecture.</para>
1894 <para>As entries within Posix ACLs are unordered, it is
1895 impossible to preserve order.</para>
1899 <para>Inheritance control is subject to severe limitations as
1902 <para>Entries with the only_inherit flag set will only
1903 become part of the directory's default ACL.</para>
1907 <para>Entries with at least one of the flags
1908 file_inherit, directory_inherit or limit_inherit set,
1909 will become part of the directory's access and default
1910 ACL, but the restrictions they impose on inheritance
1911 will be ignored.</para>
1913 </itemizedlist></para>
1917 <para>The lack of a fine-granular permission model on the
1918 Posix side will normally result in an increase of granted
1921 </itemizedlist></para>
1923 <para>As OS X clients aren't aware of the Posix 1003.1e specific
1924 relationship between UNIX permissions and ACL_MASK, afpd does not
1925 expose this feature to the client to avoid compatibility issues and
1926 handles *unix permissions and ACLs the same way as Apple's reference
1927 implementation of AFP does. When an object's UNIX permissions are
1928 requested, afpd calculates proper group rights and returns the
1929 result together with the owner's and everybody's access rights to
1930 the caller via "permissions" and "ua_permissions" members of the
1931 FPUnixPrivs structure (see Apple Filing Protocol Reference, page
1932 181). Changing an object's permissions, afpd always updates
1933 ACL_USER_OBJ, ACL_GROUP_OBJ and ACL_OTHERS. If an ACL_MASK entry is
1934 present too, afpd recalculates it's value so that the new group
1935 rights become effective and existing entries of type ACL_USER or
1936 ACL_GROUP stay intact.</para>
1942 <title>Filesystem Change Events<indexterm>
1943 <primary>FCE</primary>
1944 </indexterm></title>
1946 <para>Netatalk includes a nifty filesystem change event mechanism where
1947 afpd processes notfiy interested listeners about certain filesystem
1948 event by UDP network datagrams.</para>
1950 <para>For the format of the UDP packets and for an example C application
1951 that demonstrates how to use these in a listener, take a look at the
1952 Netatalk sourcefile <filename>bin/misc/fce.c</filename>.</para>
1954 <para>The currently supported FCE events are<itemizedlist>
1956 <para>file modification (fmod)</para>
1960 <para>file deletion (fdel)</para>
1964 <para>directory deletion (ddel)</para>
1968 <para>file creation (fcre)</para>
1972 <para>directory deletion (ddel)</para>
1974 </itemizedlist></para>
1976 <para>For details on the available simple configuration options take a
1977 look at <filename><link
1978 linkend="fceconf">afp.conf</link></filename>.</para>
1983 <title>Starting and stopping Netatalk</title>
1985 <para>The Netatalk distribution comes with several operating system
1986 specific startup script templates that are tailored according to the
1987 options given to the "configure" script before compiling. Currently,
1988 templates are provided for RedHat (sysv style), RedHat (systemd style),
1989 SUSE (sysv style), SUSE (systemd style), Gentoo, NetBSD, Debian and
1990 Solaris. You can select to install the generated startup script(s)
1992 <primary>Startscript</primary>
1994 <secondary>startup script</secondary>
1995 </indexterm> by specifying a system type to "configure". To
1996 automatically install startup scripts give one of the available
1997 <option>--with-init-style</option> option to "configure".</para>
1999 <para>Since new releases of Linux distributions appear all the time and
2000 the startup procedure for the other systems mentioned above might change
2001 as well, it is probably a good idea to not blindly install a startup
2002 script but to look at it first to see if it will work on your system. If
2003 you use Netatalk as part of a fixed setup, like a Linux distribution, an
2004 RPM or a BSD package, things will probably have been arranged properly for
2005 you. The following therefore applies mostly for people who have compiled
2006 Netatalk themselves.</para>
2008 <para>The following daemon need to be started by whatever startup script
2009 mechanism is used:</para>
2013 <para>netatalk<indexterm>
2014 <primary>netatalk</primary>
2019 <para>Additionally, make sure that the configuration file
2020 <filename>afp.conf</filename> is in the right place.</para>