1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML
><HEAD
><TITLE
>Integrating MS Windows networks with Samba</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REL="HOME"
TITLE="SAMBA Project Documentation"
HREF="samba-howto-collection.html"><LINK
REL="UP"
TITLE="Optional configuration"
HREF="optional.html"><LINK
REL="PREVIOUS"
TITLE="Optional configuration"
HREF="optional.html"><LINK
REL="NEXT"
TITLE="UNIX Permission Bits and Windows NT Access Control Lists"
HREF="unix-permissions.html"></HEAD
><BODY
CLASS="CHAPTER"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>SAMBA Project Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="optional.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="unix-permissions.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="CHAPTER"
><H1
><A
NAME="INTEGRATE-MS-NETWORKS"
></A
>Chapter 9. Integrating MS Windows networks with Samba</H1
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1416"
>9.1. Agenda</A
></H1
><P
>To identify the key functional mechanisms of MS Windows networking
to enable the deployment of Samba as a means of extending and/or
replacing MS Windows NT/2000 technology.</P
><P
>We will examine:</P
><P
></P
><OL
TYPE="1"
><LI
><P
>Name resolution in a pure Unix/Linux TCP/IP
environment
</P
></LI
><LI
><P
>Name resolution as used within MS Windows
networking
</P
></LI
><LI
><P
>How browsing functions and how to deploy stable
and dependable browsing using Samba
</P
></LI
><LI
><P
>MS Windows security options and how to
configure Samba for seemless integration
</P
></LI
><LI
><P
>Configuration of Samba as:</P
><P
></P
><OL
TYPE="a"
><LI
><P
>A stand-alone server</P
></LI
><LI
><P
>An MS Windows NT 3.x/4.0 security domain member
</P
></LI
><LI
><P
>An alternative to an MS Windows NT 3.x/4.0 Domain Controller
</P
></LI
></OL
></LI
></OL
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1438"
>9.2. Name Resolution in a pure Unix/Linux world</A
></H1
><P
>The key configuration files covered in this section are:</P
><P
></P
><UL
><LI
><P
><TT
CLASS="FILENAME"
>/etc/hosts</TT
></P
></LI
><LI
><P
><TT
CLASS="FILENAME"
>/etc/resolv.conf</TT
></P
></LI
><LI
><P
><TT
CLASS="FILENAME"
>/etc/host.conf</TT
></P
></LI
><LI
><P
><TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
></P
></LI
></UL
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1454"
>9.2.1. <TT
CLASS="FILENAME"
>/etc/hosts</TT
></A
></H2
><P
>Contains a static list of IP Addresses and names.
eg:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> 127.0.0.1 localhost localhost.localdomain
192.168.1.1 bigbox.caldera.com bigbox alias4box</PRE
></P
><P
>The purpose of <TT
CLASS="FILENAME"
>/etc/hosts</TT
> is to provide a
name resolution mechanism so that uses do not need to remember
IP addresses.</P
><P
>Network packets that are sent over the physical network transport
layer communicate not via IP addresses but rather using the Media
Access Control address, or MAC address. IP Addresses are currently
32 bits in length and are typically presented as four (4) decimal
numbers that are separated by a dot (or period). eg: 168.192.1.1</P
><P
>MAC Addresses use 48 bits (or 6 bytes) and are typically represented
as two digit hexadecimal numbers separated by colons. eg:
40:8e:0a:12:34:56</P
><P
>Every network interfrace must have an MAC address. Associated with
a MAC address there may be one or more IP addresses. There is NO
relationship between an IP address and a MAC address, all such assignments
are arbitary or discretionary in nature. At the most basic level all
network communications takes place using MAC addressing. Since MAC
addresses must be globally unique, and generally remains fixed for
any particular interface, the assignment of an IP address makes sense
from a network management perspective. More than one IP address can
be assigned per MAC address. One address must be the primary IP address,
this is the address that will be returned in the ARP reply.</P
><P
>When a user or a process wants to communicate with another machine
the protocol implementation ensures that the "machine name" or "host
name" is resolved to an IP address in a manner that is controlled
by the TCP/IP configuration control files. The file
<TT
CLASS="FILENAME"
>/etc/hosts</TT
> is one such file.</P
><P
>When the IP address of the destination interface has been
determined a protocol called ARP/RARP is used to identify
the MAC address of the target interface. ARP stands for Address
Resolution Protocol, and is a broadcast oriented method that
uses UDP (User Datagram Protocol) to send a request to all
interfaces on the local network segment using the all 1's MAC
address. Network interfaces are programmed to respond to two
MAC addresses only; their own unique address and the address
ff:ff:ff:ff:ff:ff. The reply packet from an ARP request will
contain the MAC address and the primary IP address for each
interface.</P
><P
>The <TT
CLASS="FILENAME"
>/etc/hosts</TT
> file is foundational to all
Unix/Linux TCP/IP installations and as a minumum will contain
the localhost and local network interface IP addresses and the
primary names by which they are known within the local machine.
This file helps to prime the pump so that a basic level of name
resolution can exist before any other method of name resolution
becomes available.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1470"
>9.2.2. <TT
CLASS="FILENAME"
>/etc/resolv.conf</TT
></A
></H2
><P
>This file tells the name resolution libraries:</P
><P
></P
><UL
><LI
><P
>The name of the domain to which the machine
belongs
</P
></LI
><LI
><P
>The name(s) of any domains that should be
automatically searched when trying to resolve unqualified
host names to their IP address
</P
></LI
><LI
><P
>The name or IP address of available Domain
Name Servers that may be asked to perform name to address
translation lookups
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1481"
>9.2.3. <TT
CLASS="FILENAME"
>/etc/host.conf</TT
></A
></H2
><P
><TT
CLASS="FILENAME"
>/etc/host.conf</TT
> is the primary means by
which the setting in /etc/resolv.conf may be affected. It is a
critical configuration file. This file controls the order by
which name resolution may procede. The typical structure is:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> order hosts,bind
multi on</PRE
></P
><P
>then both addresses should be returned. Please refer to the
man page for host.conf for further details.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1489"
>9.2.4. <TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
></A
></H2
><P
>This file controls the actual name resolution targets. The
file typically has resolver object specifications as follows:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> # /etc/nsswitch.conf
#
# Name Service Switch configuration file.
#
passwd: compat
# Alternative entries for password authentication are:
# passwd: compat files nis ldap winbind
shadow: compat
group: compat
hosts: files nis dns
# Alternative entries for host name resolution are:
# hosts: files dns nis nis+ hesoid db compat ldap wins
networks: nis files dns
ethers: nis files
protocols: nis files
rpc: nis files
services: nis files</PRE
></P
><P
>Of course, each of these mechanisms requires that the appropriate
facilities and/or services are correctly configured.</P
><P
>It should be noted that unless a network request/message must be
sent, TCP/IP networks are silent. All TCP/IP communications assumes a
principal of speaking only when necessary.</P
><P
>Starting with version 2.2.0 samba has Linux support for extensions to
the name service switch infrastructure so that linux clients will
be able to obtain resolution of MS Windows NetBIOS names to IP
Addresses. To gain this functionality Samba needs to be compiled
with appropriate arguments to the make command (ie: <B
CLASS="COMMAND"
>make
nsswitch/libnss_wins.so</B
>). The resulting library should
then be installed in the <TT
CLASS="FILENAME"
>/lib</TT
> directory and
the "wins" parameter needs to be added to the "hosts:" line in
the <TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
> file. At this point it
will be possible to ping any MS Windows machine by it's NetBIOS
machine name, so long as that machine is within the workgroup to
which both the samba machine and the MS Windows machine belong.</P
></DIV
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1501"
>9.3. Name resolution as used within MS Windows networking</A
></H1
><P
>MS Windows networking is predicated about the name each machine
is given. This name is known variously (and inconsistently) as
the "computer name", "machine name", "networking name", "netbios name",
"SMB name". All terms mean the same thing with the exception of
"netbios name" which can apply also to the name of the workgroup or the
domain name. The terms "workgroup" and "domain" are really just a
simply name with which the machine is associated. All NetBIOS names
are exactly 16 characters in length. The 16th character is reserved.
It is used to store a one byte value that indicates service level
information for the NetBIOS name that is registered. A NetBIOS machine
name is therefore registered for each service type that is provided by
the client/server.</P
><P
>The following are typical NetBIOS name/service type registrations:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> Unique NetBIOS Names:
MACHINENAME<00> = Server Service is running on MACHINENAME
MACHINENAME<03> = Generic Machine Name (NetBIOS name)
MACHINENAME<20> = LanMan Server service is running on MACHINENAME
WORKGROUP<1b> = Domain Master Browser
Group Names:
WORKGROUP<03> = Generic Name registered by all members of WORKGROUP
WORKGROUP<1c> = Domain Controllers / Netlogon Servers
WORKGROUP<1d> = Local Master Browsers
WORKGROUP<1e> = Internet Name Resolvers</PRE
></P
><P
>It should be noted that all NetBIOS machines register their own
names as per the above. This is in vast contrast to TCP/IP
installations where traditionally the system administrator will
determine in the /etc/hosts or in the DNS database what names
are associated with each IP address.</P
><P
>One further point of clarification should be noted, the <TT
CLASS="FILENAME"
>/etc/hosts</TT
>
file and the DNS records do not provide the NetBIOS name type information
that MS Windows clients depend on to locate the type of service that may
be needed. An example of this is what happens when an MS Windows client
wants to locate a domain logon server. It find this service and the IP
address of a server that provides it by performing a lookup (via a
NetBIOS broadcast) for enumeration of all machines that have
registered the name type *<1c>. A logon request is then sent to each
IP address that is returned in the enumerated list of IP addresses. Which
ever machine first replies then ends up providing the logon services.</P
><P
>The name "workgroup" or "domain" really can be confusing since these
have the added significance of indicating what is the security
architecture of the MS Windows network. The term "workgroup" indicates
that the primary nature of the network environment is that of a
peer-to-peer design. In a WORKGROUP all machines are responsible for
their own security, and generally such security is limited to use of
just a password (known as SHARE MODE security). In most situations
with peer-to-peer networking the users who control their own machines
will simply opt to have no security at all. It is possible to have
USER MODE security in a WORKGROUP environment, thus requiring use
of a user name and a matching password.</P
><P
>MS Windows networking is thus predetermined to use machine names
for all local and remote machine message passing. The protocol used is
called Server Message Block (SMB) and this is implemented using
the NetBIOS protocol (Network Basic Input Output System). NetBIOS can
be encapsulated using LLC (Logical Link Control) protocol - in which case
the resulting protocol is called NetBEUI (Network Basic Extended User
Interface). NetBIOS can also be run over IPX (Internetworking Packet
Exchange) protocol as used by Novell NetWare, and it can be run
over TCP/IP protocols - in which case the resulting protocol is called
NBT or NetBT, the NetBIOS over TCP/IP.</P
><P
>MS Windows machines use a complex array of name resolution mechanisms.
Since we are primarily concerned with TCP/IP this demonstration is
limited to this area.</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1513"
>9.3.1. The NetBIOS Name Cache</A
></H2
><P
>All MS Windows machines employ an in memory buffer in which is
stored the NetBIOS names and IP addresses for all external
machines that that machine has communicated with over the
past 10-15 minutes. It is more efficient to obtain an IP address
for a machine from the local cache than it is to go through all the
configured name resolution mechanisms.</P
><P
>If a machine whose name is in the local name cache has been shut
down before the name had been expired and flushed from the cache, then
an attempt to exchange a message with that machine will be subject
to time-out delays. i.e.: Its name is in the cache, so a name resolution
lookup will succeed, but the machine can not respond. This can be
frustrating for users - but it is a characteristic of the protocol.</P
><P
>The MS Windows utility that allows examination of the NetBIOS
name cache is called "nbtstat". The Samba equivalent of this
is called "nmblookup".</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1518"
>9.3.2. The LMHOSTS file</A
></H2
><P
>This file is usually located in MS Windows NT 4.0 or
2000 in <TT
CLASS="FILENAME"
>C:\WINNT\SYSTEM32\DRIVERS\ETC</TT
> and contains
the IP Address and the machine name in matched pairs. The
<TT
CLASS="FILENAME"
>LMHOSTS</TT
> file performs NetBIOS name
to IP address mapping oriented.</P
><P
>It typically looks like:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> # Copyright (c) 1998 Microsoft Corp.
#
# This is a sample LMHOSTS file used by the Microsoft Wins Client (NetBIOS
# over TCP/IP) stack for Windows98
#
# This file contains the mappings of IP addresses to NT computernames
# (NetBIOS) names. Each entry should be kept on an individual line.
# The IP address should be placed in the first column followed by the
# corresponding computername. The address and the comptername
# should be separated by at least one space or tab. The "#" character
# is generally used to denote the start of a comment (see the exceptions
# below).
#
# This file is compatible with Microsoft LAN Manager 2.x TCP/IP lmhosts
# files and offers the following extensions:
#
# #PRE
# #DOM:<domain>
# #INCLUDE <filename>
# #BEGIN_ALTERNATE
# #END_ALTERNATE
# \0xnn (non-printing character support)
#
# Following any entry in the file with the characters "#PRE" will cause
# the entry to be preloaded into the name cache. By default, entries are
# not preloaded, but are parsed only after dynamic name resolution fails.
#
# Following an entry with the "#DOM:<domain>" tag will associate the
# entry with the domain specified by <domain>. This affects how the
# browser and logon services behave in TCP/IP environments. To preload
# the host name associated with #DOM entry, it is necessary to also add a
# #PRE to the line. The <domain> is always preloaded although it will not
# be shown when the name cache is viewed.
#
# Specifying "#INCLUDE <filename>" will force the RFC NetBIOS (NBT)
# software to seek the specified <filename> and parse it as if it were
# local. <filename> is generally a UNC-based name, allowing a
# centralized lmhosts file to be maintained on a server.
# It is ALWAYS necessary to provide a mapping for the IP address of the
# server prior to the #INCLUDE. This mapping must use the #PRE directive.
# In addtion the share "public" in the example below must be in the
# LanManServer list of "NullSessionShares" in order for client machines to
# be able to read the lmhosts file successfully. This key is under
# \machine\system\currentcontrolset\services\lanmanserver\parameters\nullsessionshares
# in the registry. Simply add "public" to the list found there.
#
# The #BEGIN_ and #END_ALTERNATE keywords allow multiple #INCLUDE
# statements to be grouped together. Any single successful include
# will cause the group to succeed.
#
# Finally, non-printing characters can be embedded in mappings by
# first surrounding the NetBIOS name in quotations, then using the
# \0xnn notation to specify a hex value for a non-printing character.
#
# The following example illustrates all of these extensions:
#
# 102.54.94.97 rhino #PRE #DOM:networking #net group's DC
# 102.54.94.102 "appname \0x14" #special app server
# 102.54.94.123 popular #PRE #source server
# 102.54.94.117 localsrv #PRE #needed for the include
#
# #BEGIN_ALTERNATE
# #INCLUDE \\localsrv\public\lmhosts
# #INCLUDE \\rhino\public\lmhosts
# #END_ALTERNATE
#
# In the above example, the "appname" server contains a special
# character in its name, the "popular" and "localsrv" server names are
# preloaded, and the "rhino" server name is specified so it can be used
# to later #INCLUDE a centrally maintained lmhosts file if the "localsrv"
# system is unavailable.
#
# Note that the whole file is parsed including comments on each lookup,
# so keeping the number of comments to a minimum will improve performance.
# Therefore it is not advisable to simply add lmhosts file entries onto the
# end of this file.</PRE
></P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1526"
>9.3.3. HOSTS file</A
></H2
><P
>This file is usually located in MS Windows NT 4.0 or 2000 in
<TT
CLASS="FILENAME"
>C:\WINNT\SYSTEM32\DRIVERS\ETC</TT
> and contains
the IP Address and the IP hostname in matched pairs. It can be
used by the name resolution infrastructure in MS Windows, depending
on how the TCP/IP environment is configured. This file is in
every way the equivalent of the Unix/Linux <TT
CLASS="FILENAME"
>/etc/hosts</TT
> file.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1531"
>9.3.4. DNS Lookup</A
></H2
><P
>This capability is configured in the TCP/IP setup area in the network
configuration facility. If enabled an elaborate name resolution sequence
is followed the precise nature of which isdependant on what the NetBIOS
Node Type parameter is configured to. A Node Type of 0 means use
NetBIOS broadcast (over UDP broadcast) is first used if the name
that is the subject of a name lookup is not found in the NetBIOS name
cache. If that fails then DNS, HOSTS and LMHOSTS are checked. If set to
Node Type 8, then a NetBIOS Unicast (over UDP Unicast) is sent to the
WINS Server to obtain a lookup before DNS, HOSTS, LMHOSTS, or broadcast
lookup is used.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1534"
>9.3.5. WINS Lookup</A
></H2
><P
>A WINS (Windows Internet Name Server) service is the equivaent of the
rfc1001/1002 specified NBNS (NetBIOS Name Server). A WINS server stores
the names and IP addresses that are registered by a Windows client
if the TCP/IP setup has been given at least one WINS Server IP Address.</P
><P
>To configure Samba to be a WINS server the following parameter needs
to be added to the <TT
CLASS="FILENAME"
>smb.conf</TT
> file:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> wins support = Yes</PRE
></P
><P
>To configure Samba to use a WINS server the following parameters are
needed in the smb.conf file:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> wins support = No
wins server = xxx.xxx.xxx.xxx</PRE
></P
><P
>where <VAR
CLASS="REPLACEABLE"
>xxx.xxx.xxx.xxx</VAR
> is the IP address
of the WINS server.</P
></DIV
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1546"
>9.4. How browsing functions and how to deploy stable and
dependable browsing using Samba</A
></H1
><P
>As stated above, MS Windows machines register their NetBIOS names
(i.e.: the machine name for each service type in operation) on start
up. Also, as stated above, the exact method by which this name registration
takes place is determined by whether or not the MS Windows client/server
has been given a WINS server address, whether or not LMHOSTS lookup
is enabled, or if DNS for NetBIOS name resolution is enabled, etc.</P
><P
>In the case where there is no WINS server all name registrations as
well as name lookups are done by UDP broadcast. This isolates name
resolution to the local subnet, unless LMHOSTS is used to list all
names and IP addresses. In such situations Samba provides a means by
which the samba server name may be forcibly injected into the browse
list of a remote MS Windows network (using the "remote announce" parameter).</P
><P
>Where a WINS server is used, the MS Windows client will use UDP
unicast to register with the WINS server. Such packets can be routed
and thus WINS allows name resolution to function across routed networks.</P
><P
>During the startup process an election will take place to create a
local master browser if one does not already exist. On each NetBIOS network
one machine will be elected to function as the domain master browser. This
domain browsing has nothing to do with MS security domain control.
Instead, the domain master browser serves the role of contacting each local
master browser (found by asking WINS or from LMHOSTS) and exchanging browse
list contents. This way every master browser will eventually obtain a complete
list of all machines that are on the network. Every 11-15 minutes an election
is held to determine which machine will be the master browser. By the nature of
the election criteria used, the machine with the highest uptime, or the
most senior protocol version, or other criteria, will win the election
as domain master browser.</P
><P
>Clients wishing to browse the network make use of this list, but also depend
on the availability of correct name resolution to the respective IP
address/addresses. </P
><P
>Any configuration that breaks name resolution and/or browsing intrinsics
will annoy users because they will have to put up with protracted
inability to use the network services.</P
><P
>Samba supports a feature that allows forced synchonisation
of browse lists across routed networks using the "remote
browse sync" parameter in the smb.conf file. This causes Samba
to contact the local master browser on a remote network and
to request browse list synchronisation. This effectively bridges
two networks that are separated by routers. The two remote
networks may use either broadcast based name resolution or WINS
based name resolution, but it should be noted that the "remote
browse sync" parameter provides browse list synchronisation - and
that is distinct from name to address resolution, in other
words, for cross subnet browsing to function correctly it is
essential that a name to address resolution mechanism be provided.
This mechanism could be via DNS, <TT
CLASS="FILENAME"
>/etc/hosts</TT
>,
and so on.</P
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1556"
>9.5. MS Windows security options and how to configure
Samba for seemless integration</A
></H1
><P
>MS Windows clients may use encrypted passwords as part of a
challenege/response authentication model (a.k.a. NTLMv1) or
alone, or clear text strings for simple password based
authentication. It should be realized that with the SMB
protocol the password is passed over the network either
in plain text or encrypted, but not both in the same
authentication requets.</P
><P
>When encrypted passwords are used a password that has been
entered by the user is encrypted in two ways:</P
><P
></P
><UL
><LI
><P
>An MD4 hash of the UNICODE of the password
string. This is known as the NT hash.
</P
></LI
><LI
><P
>The password is converted to upper case,
and then padded or trucated to 14 bytes. This string is
then appended with 5 bytes of NULL characters and split to
form two 56 bit DES keys to encrypt a "magic" 8 byte value.
The resulting 16 bytes for the LanMan hash.
</P
></LI
></UL
><P
>You should refer to the <A
HREF="ENCRYPTION.html"
TARGET="_top"
>Password Encryption</A
> chapter in this HOWTO collection
for more details on the inner workings</P
><P
>MS Windows 95 pre-service pack 1, MS Windows NT versions 3.x
and version 4.0 pre-service pack 3 will use either mode of
password authentication. All versions of MS Windows that follow
these versions no longer support plain text passwords by default.</P
><P
>MS Windows clients have a habit of dropping network mappings that
have been idle for 10 minutes or longer. When the user attempts to
use the mapped drive connection that has been dropped, the client
re-establishes the connection using
a cached copy of the password.</P
><P
>When Microsoft changed the default password mode, they dropped support for
caching of the plain text password. This means that when the registry
parameter is changed to re-enable use of plain text passwords it appears to
work, but when a dropped mapping attempts to revalidate it will fail if
the remote authentication server does not support encrypted passwords.
This means that it is definitely not a good idea to re-enable plain text
password support in such clients.</P
><P
>The following parameters can be used to work around the
issue of Windows 9x client upper casing usernames and
password before transmitting them to the SMB server
when using clear text authentication.</P
><P
><PRE
CLASS="PROGRAMLISTING"
> <A
HREF="smb.conf.5.html#PASSWORDLEVEL"
TARGET="_top"
>passsword level</A
> = <VAR
CLASS="REPLACEABLE"
>integer</VAR
>
<A
HREF="smb.conf.5.html#USERNAMELEVEL"
TARGET="_top"
>username level</A
> = <VAR
CLASS="REPLACEABLE"
>integer</VAR
></PRE
></P
><P
>By default Samba will lower case the username before attempting
to lookup the user in the database of local system accounts.
Because UNIX usernames conventionally only contain lower case
character, the <VAR
CLASS="PARAMETER"
>username level</VAR
> parameter
is rarely even needed.</P
><P
>However, password on UNIX systems often make use of mixed case
characters. This means that in order for a user on a Windows 9x
client to connect to a Samba server using clear text authentication,
the <VAR
CLASS="PARAMETER"
>password level</VAR
> must be set to the maximum
number of upper case letter which <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>could</I
></SPAN
> appear
is a password. Note that is the server OS uses the traditional
DES version of crypt(), then a <VAR
CLASS="PARAMETER"
>password level</VAR
>
of 8 will result in case insensitive passwords as seen from Windows
users. This will also result in longer login times as Samba
hash to compute the permutations of the password string and
try them one by one until a match is located (or all combinations fail).</P
><P
>The best option to adopt is to enable support for encrypted passwords
where ever Samba is used. There are three configuration possibilities
for support of encrypted passwords:</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1584"
>9.5.1. Use MS Windows NT as an authentication server</A
></H2
><P
>This method involves the additions of the following parameters
in the smb.conf file:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> encrypt passwords = Yes
security = server
password server = "NetBIOS_name_of_PDC"</PRE
></P
><P
>There are two ways of identifying whether or not a username and
password pair was valid or not. One uses the reply information provided
as part of the authentication messaging process, the other uses
just and error code.</P
><P
>The down-side of this mode of configuration is the fact that
for security reasons Samba will send the password server a bogus
username and a bogus password and if the remote server fails to
reject the username and password pair then an alternative mode
of identification of validation is used. Where a site uses password
lock out after a certain number of failed authentication attempts
this will result in user lockouts.</P
><P
>Use of this mode of authentication does require there to be
a standard Unix account for the user, this account can be blocked
to prevent logons by other than MS Windows clients.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1592"
>9.5.2. Make Samba a member of an MS Windows NT security domain</A
></H2
><P
>This method involves additon of the following paramters in the smb.conf file:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> encrypt passwords = Yes
security = domain
workgroup = "name of NT domain"
password server = *</PRE
></P
><P
>The use of the "*" argument to "password server" will cause samba
to locate the domain controller in a way analogous to the way
this is done within MS Windows NT.</P
><P
>In order for this method to work the Samba server needs to join the
MS Windows NT security domain. This is done as follows:</P
><P
></P
><UL
><LI
><P
>On the MS Windows NT domain controller using
the Server Manager add a machine account for the Samba server.
</P
></LI
><LI
><P
>Next, on the Linux system execute:
<B
CLASS="COMMAND"
>smbpasswd -r PDC_NAME -j DOMAIN_NAME</B
>
</P
></LI
></UL
><P
>Use of this mode of authentication does require there to be
a standard Unix account for the user in order to assign
a uid once the account has been authenticated by the remote
Windows DC. This account can be blocked to prevent logons by
other than MS Windows clients by things such as setting an invalid
shell in the <TT
CLASS="FILENAME"
>/etc/passwd</TT
> entry.</P
><P
>An alternative to assigning UIDs to Windows users on a
Samba member server is presented in the <A
HREF="winbind.html"
TARGET="_top"
>Winbind Overview</A
> chapter in
this HOWTO collection.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1609"
>9.5.3. Configure Samba as an authentication server</A
></H2
><P
>This mode of authentication demands that there be on the
Unix/Linux system both a Unix style account as well as an
smbpasswd entry for the user. The Unix system account can be
locked if required as only the encrypted password will be
used for SMB client authentication.</P
><P
>This method involves addition of the following parameters to
the smb.conf file:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>## please refer to the Samba PDC HOWTO chapter later in
## this collection for more details
[global]
encrypt passwords = Yes
security = user
domain logons = Yes
; an OS level of 33 or more is recommended
os level = 33
[NETLOGON]
path = /somewhare/in/file/system
read only = yes</PRE
></P
><P
>in order for this method to work a Unix system account needs
to be created for each user, as well as for each MS Windows NT/2000
machine. The following structure is required.</P
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN1616"
>9.5.3.1. Users</A
></H3
><P
>A user account that may provide a home directory should be
created. The following Linux system commands are typical of
the procedure for creating an account.</P
><P
><PRE
CLASS="PROGRAMLISTING"
> # useradd -s /bin/bash -d /home/"userid" -m "userid"
# passwd "userid"
Enter Password: <pw>
# smbpasswd -a "userid"
Enter Password: <pw></PRE
></P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN1621"
>9.5.3.2. MS Windows NT Machine Accounts</A
></H3
><P
>These are required only when Samba is used as a domain
controller. Refer to the Samba-PDC-HOWTO for more details.</P
><P
><PRE
CLASS="PROGRAMLISTING"
> # useradd -s /bin/false -d /dev/null "machine_name"\$
# passwd -l "machine_name"\$
# smbpasswd -a -m "machine_name"</PRE
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1626"
>9.6. Conclusions</A
></H1
><P
>Samba provides a flexible means to operate as...</P
><P
></P
><UL
><LI
><P
>A Stand-alone server - No special action is needed
other than to create user accounts. Stand-alone servers do NOT
provide network logon services, meaning that machines that use this
server do NOT perform a domain logon but instead make use only of
the MS Windows logon which is local to the MS Windows
workstation/server.
</P
></LI
><LI
><P
>An MS Windows NT 3.x/4.0 security domain member.
</P
></LI
><LI
><P
>An alternative to an MS Windows NT 3.x/4.0
Domain Controller.
</P
></LI
></UL
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="optional.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="samba-howto-collection.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="unix-permissions.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Optional configuration</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="optional.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>UNIX Permission Bits and Windows NT Access Control Lists</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
|
