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
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
|
---
title: Chapter 31. Network Servers
part: IV. Network Communication
prev: books/handbook/mail
next: books/handbook/firewalls
description: This chapter covers some of the more frequently used network services on UNIX systems
tags: ["network", "servers", "inetd", "NFS", "NIS", "LDAP", "DHCP", "DNS", "Apache HTTP", "FTP", "Samba", "NTP", "iSCSI"]
showBookMenu: true
weight: 36
path: "/books/handbook/"
---
[[network-servers]]
= Network Servers
:doctype: book
:toc: macro
:toclevels: 1
:icons: font
:sectnums:
:sectnumlevels: 6
:sectnumoffset: 31
:partnums:
:source-highlighter: rouge
:experimental:
:images-path: books/handbook/network-servers/
ifdef::env-beastie[]
ifdef::backend-html5[]
:imagesdir: ../../../../images/{images-path}
endif::[]
ifndef::book[]
include::shared/authors.adoc[]
include::shared/mirrors.adoc[]
include::shared/releases.adoc[]
include::shared/attributes/attributes-{{% lang %}}.adoc[]
include::shared/{{% lang %}}/teams.adoc[]
include::shared/{{% lang %}}/mailing-lists.adoc[]
include::shared/{{% lang %}}/urls.adoc[]
toc::[]
endif::[]
ifdef::backend-pdf,backend-epub3[]
include::../../../../../shared/asciidoctor.adoc[]
endif::[]
endif::[]
ifndef::env-beastie[]
toc::[]
include::../../../../../shared/asciidoctor.adoc[]
endif::[]
[[network-servers-synopsis]]
== Synopsis
This chapter covers some of the more frequently used network services on UNIX(R) systems.
This includes installing, configuring, testing, and maintaining many different types of network services.
Example configuration files are included throughout this chapter for reference.
By the end of this chapter, readers will know:
* How to manage the inetd daemon.
* How to set up the Network File System (NFS).
* How to set up the Network Information Server (NIS) for centralizing and sharing user accounts.
* How to set FreeBSD up to act as an LDAP server or client
* How to set up automatic network settings using DHCP.
* How to set up a Domain Name Server (DNS).
* How to set up the Apache HTTP Server.
* How to set up a File Transfer Protocol (FTP) server.
* How to set up a file and print server for Windows(R) clients using Samba.
* How to synchronize the time and date, and set up a time server using the Network Time Protocol (NTP).
* How to set up iSCSI.
This chapter assumes a basic knowledge of:
* [.filename]#/etc/rc# scripts.
* Network terminology.
* Installation of additional third-party software (crossref:ports[ports,Installing Applications: Packages and Ports]).
[[network-inetd]]
== The inetd Super-Server
The man:inetd[8] daemon is sometimes referred to as a Super-Server because it manages connections for many services.
Instead of starting multiple applications, only the inetd service needs to be started.
When a connection is received for a service that is managed by inetd, it determines which program the connection is destined for, spawns a process for that program, and delegates the program a socket.
Using inetd for services that are not heavily used can reduce system load, when compared to running each daemon individually in stand-alone mode.
Primarily, inetd is used to spawn other daemons, but several trivial protocols are handled internally, such as chargen, auth, time, echo, discard, and daytime.
This section covers the basics of configuring inetd.
[[network-inetd-conf]]
=== Configuration File
Configuration of inetd is done by editing [.filename]#/etc/inetd.conf#.
Each line of this configuration file represents an application which can be started by inetd.
By default, every line starts with a comment (`+#+`), meaning that inetd is not listening for any applications.
To configure inetd to listen for an application's connections, remove the `+#+` at the beginning of the line for that application.
After saving your edits, configure inetd to start at system boot by editing [.filename]#/etc/rc.conf#:
[.programlisting]
....
inetd_enable="YES"
....
To start inetd now, so that it listens for the service you configured, type:
[source,shell]
....
# service inetd start
....
Once inetd is started, it needs to be notified whenever a modification is made to [.filename]#/etc/inetd.conf#:
[[network-inetd-reread]]
.Reloading the inetd Configuration File
[example]
====
[source,shell]
....
# service inetd reload
....
====
Typically, the default entry for an application does not need to be edited beyond removing the `+#+`.
In some situations, it may be appropriate to edit the default entry.
As an example, this is the default entry for man:ftpd[8] over IPv4:
[.programlisting]
....
ftp stream tcp nowait root /usr/libexec/ftpd ftpd -l
....
The seven columns in an entry are as follows:
[.programlisting]
....
service-name
socket-type
protocol
{wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]
user[:group][/login-class]
server-program
server-program-arguments
....
where:
service-name::
The service name of the daemon to start.
It must correspond to a service listed in [.filename]#/etc/services#.
This determines which port inetd listens on for incoming connections to that service.
When using a custom service, it must first be added to [.filename]#/etc/services#.
socket-type::
Either `stream`, `dgram`, `raw`, or `seqpacket`.
Use `stream` for TCP connections and `dgram` for UDP services.
protocol::
Use one of the following protocol names:
+
[.informaltable]
[cols="1,1", frame="none", options="header"]
|===
| Protocol Name
| Explanation
|tcp or tcp4
|TCP IPv4
|udp or udp4
|UDP IPv4
|tcp6
|TCP IPv6
|udp6
|UDP IPv6
|tcp46
|Both TCP IPv4 and IPv6
|udp46
|Both UDP IPv4 and IPv6
|===
{wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]::
In this field, `wait` or `nowait` must be specified.
`max-child`, `max-connections-per-ip-per-minute` and `max-child-per-ip` are optional.
+
`wait|nowait` indicates whether or not the service is able to handle its own socket.
`dgram` socket types must use `wait` while `stream` daemons, which are usually multi-threaded, should use `nowait`.
`wait` usually hands off multiple sockets to a single daemon, while `nowait` spawns a child daemon for each new socket.
+
The maximum number of child daemons inetd may spawn is set by `max-child`.
For example, to limit ten instances of the daemon, place a `/10` after `nowait`.
Specifying `/0` allows an unlimited number of children.
+
`max-connections-per-ip-per-minute` limits the number of connections from any particular IP address per minute.
Once the limit is reached, further connections from this IP address will be dropped until the end of the minute.
For example, a value of `/10` would limit any particular IP address to ten connection attempts per minute.
`max-child-per-ip` limits the number of child processes that can be started on behalf on any single IP address at any moment.
These options can limit excessive resource consumption and help to prevent Denial of Service attacks.
+
An example can be seen in the default settings for man:fingerd[8]:
+
[.programlisting]
....
finger stream tcp nowait/3/10 nobody /usr/libexec/fingerd fingerd -k -s
....
user::
The username the daemon will run as.
Daemons typically run as `root`, `daemon`, or `nobody`.
server-program::
The full path to the daemon.
If the daemon is a service provided by inetd internally, use `internal`.
server-program-arguments::
Used to specify any command arguments to be passed to the daemon on invocation.
If the daemon is an internal service, use `internal`.
[[network-inetd-cmdline]]
=== Command-Line Options
Like most server daemons, inetd has a number of options that can be used to modify its behavior.
By default, inetd is started with `-wW -C 60`.
These options enable TCP wrappers for all services, including internal services, and prevent any IP address from requesting any service more than 60 times per minute.
To change the default options which are passed to inetd, add an entry for `inetd_flags` in [.filename]#/etc/rc.conf#.
If inetd is already running, restart it with `service inetd restart`.
The available rate limiting options are:
-c maximum::
Specify the default maximum number of simultaneous invocations of each service, where the default is unlimited.
May be overridden on a per-service basis by using `max-child` in [.filename]#/etc/inetd.conf#.
-C rate::
Specify the default maximum number of times a service can be invoked from a single IP address per minute.
May be overridden on a per-service basis by using `max-connections-per-ip-per-minute` in [.filename]#/etc/inetd.conf#.
-R rate::
Specify the maximum number of times a service can be invoked in one minute, where the default is `256`.
A rate of `0` allows an unlimited number.
-s maximum::
Specify the maximum number of times a service can be invoked from a single IP address at any one time, where the default is unlimited.
May be overridden on a per-service basis by using `max-child-per-ip` in [.filename]#/etc/inetd.conf#.
Additional options are available. Refer to man:inetd[8] for the full list of options.
[[network-inetd-security]]
=== Security Considerations
Many of the daemons which can be managed by inetd are not security-conscious.
Some daemons, such as fingerd, can provide information that may be useful to an attacker.
Only enable the services which are needed and monitor the system for excessive connection attempts.
`max-connections-per-ip-per-minute`, `max-child` and `max-child-per-ip` can be used to limit such attacks.
By default, TCP wrappers are enabled.
Consult man:hosts_access[5] for more information on placing TCP restrictions on various inetd invoked daemons.
[[network-nfs]]
== Network File System (NFS)
FreeBSD supports the Network File System (NFS), which allows a server to share directories and files with clients over a network.
With NFS, users and programs can access files on remote systems as if they were stored locally.
NFS has many practical uses.
Some of the more common uses include:
* Data that would otherwise be duplicated on each client can be kept in a single location and accessed by clients on the network.
* Several clients may need access to the [.filename]#/usr/ports/distfiles# directory. Sharing that directory allows for quick access to the source files without having to download them to each client.
* On large networks, it is often more convenient to configure a central NFS server on which all user home directories are stored. Users can log into a client anywhere on the network and have access to their home directories.
* Administration of NFS exports is simplified. For example, there is only one file system where security or backup policies must be set.
* Removable media storage devices can be used by other machines on the network. This reduces the number of devices throughout the network and provides a centralized location to manage their security. It is often more convenient to install software on multiple machines from a centralized installation media.
NFS consists of a server and one or more clients.
The client remotely accesses the data that is stored on the server machine.
In order for this to function properly, a few processes have to be configured and running.
These daemons must be running on the server:
[.informaltable]
[cols="1,1", frame="none", options="header"]
|===
| Daemon
| Description
|nfsd
|The NFS daemon which services requests from NFS clients.
|mountd
|The NFS mount daemon which carries out requests received from nfsd.
|rpcbind
| This daemon allows NFS clients to discover which port the NFS server is using.
|===
Running man:nfsiod[8] on the client can improve performance, but is not required.
[[network-configuring-nfs]]
=== Configuring the Server
The file systems which the NFS server will share are specified in [.filename]#/etc/exports#.
Each line in this file specifies a file system to be exported, which clients have access to that file system, and any access options.
When adding entries to this file, each exported file system, its properties, and allowed hosts must occur on a single line.
If no clients are listed in the entry, then any client on the network can mount that file system.
The following [.filename]#/etc/exports# entries demonstrate how to export file systems.
The examples can be modified to match the file systems and client names on the reader's network.
There are many options that can be used in this file, but only a few will be mentioned here.
See man:exports[5] for the full list of options.
This example shows how to export [.filename]#/cdrom# to three hosts named _alpha_, _bravo_, and _charlie_:
[.programlisting]
....
/cdrom -ro alpha bravo charlie
....
The `-ro` flag makes the file system read-only, preventing clients from making any changes to the exported file system.
This example assumes that the host names are either in DNS or in [.filename]#/etc/hosts#.
Refer to man:hosts[5] if the network does not have a DNS server.
The next example exports [.filename]#/home# to three clients by IP address.
This can be useful for networks without DNS or [.filename]#/etc/hosts# entries.
The `-alldirs` flag allows subdirectories to be mount points.
In other words, it will not automatically mount the subdirectories, but will permit the client to mount the directories that are required as needed.
[.programlisting]
....
/usr/home -alldirs 10.0.0.2 10.0.0.3 10.0.0.4
....
This next example exports [.filename]#/a# so that two clients from different domains may access that file system.
The `-maproot=root` allows `root` on the remote system to write data on the exported file system as `root`.
If `-maproot=root` is not specified, the client's `root` user will be mapped to the server's `nobody` account and will be subject to the access limitations defined for `nobody`.
[.programlisting]
....
/a -maproot=root host.example.com box.example.org
....
A client can only be specified once per file system.
For example, if [.filename]#/usr# is a single file system, these entries would be invalid as both entries specify the same host:
[.programlisting]
....
# Invalid when /usr is one file system
/usr/src client
/usr/ports client
....
The correct format for this situation is to use one entry:
[.programlisting]
....
/usr/src /usr/ports client
....
The following is an example of a valid export list, where [.filename]#/usr# and [.filename]#/exports# are local file systems:
[.programlisting]
....
# Export src and ports to client01 and client02, but only
# client01 has root privileges on it
/usr/src /usr/ports -maproot=root client01
/usr/src /usr/ports client02
# The client machines have root and can mount anywhere
# on /exports. Anyone in the world can mount /exports/obj read-only
/exports -alldirs -maproot=root client01 client02
/exports/obj -ro
....
To enable the processes required by the NFS server at boot time, add these options to [.filename]#/etc/rc.conf#:
[.programlisting]
....
rpcbind_enable="YES"
nfs_server_enable="YES"
mountd_enable="YES"
....
The server can be started now by running this command:
[source,shell]
....
# service nfsd start
....
Whenever the NFS server is started, mountd also starts automatically.
However, mountd only reads [.filename]#/etc/exports# when it is started.
To make subsequent [.filename]#/etc/exports# edits take effect immediately, force mountd to reread it:
[source,shell]
....
# service mountd reload
....
Refer to man:nfsv4[4] for a description of an NFS Version 4 setup.
=== Configuring the Client
To enable NFS clients, set this option in each client's [.filename]#/etc/rc.conf#:
[.programlisting]
....
nfs_client_enable="YES"
....
Then, run this command on each NFS client:
[source,shell]
....
# service nfsclient start
....
The client now has everything it needs to mount a remote file system.
In these examples, the server's name is `server` and the client's name is `client`.
To mount [.filename]#/home# on `server` to the [.filename]#/mnt# mount point on `client`:
[source,shell]
....
# mount server:/home /mnt
....
The files and directories in [.filename]#/home# will now be available on `client`, in the [.filename]#/mnt# directory.
To mount a remote file system each time the client boots, add it to [.filename]#/etc/fstab#:
[.programlisting]
....
server:/home /mnt nfs rw 0 0
....
Refer to man:fstab[5] for a description of all available options.
=== Locking
Some applications require file locking to operate correctly.
To enable locking, add these lines to [.filename]#/etc/rc.conf# on both the client and server:
[.programlisting]
....
rpc_lockd_enable="YES"
rpc_statd_enable="YES"
....
Then start the applications:
[source,shell]
....
# service lockd start
# service statd start
....
If locking is not required on the server, the NFS client can be configured to lock locally by including `-L` when running mount.
Refer to man:mount_nfs[8] for further details.
[[network-autofs]]
=== Automating Mounts with man:autofs[5]
[NOTE]
====
The man:autofs[5] automount facility is supported starting with FreeBSD 10.1-RELEASE.
To use the automounter functionality in older versions of FreeBSD, use man:amd[8] instead.
This chapter only describes the man:autofs[5] automounter.
====
The man:autofs[5] facility is a common name for several components that, together, allow for automatic mounting of remote and local filesystems whenever a file or directory within that file system is accessed.
It consists of the kernel component, man:autofs[5], and several userspace applications: man:automount[8], man:automountd[8] and man:autounmountd[8].
It serves as an alternative for man:amd[8] from previous FreeBSD releases.
amd is still provided for backward compatibility purposes, as the two use different map formats; the one used by autofs is the same as with other SVR4 automounters, such as the ones in Solaris, MacOS X, and Linux.
The man:autofs[5] virtual filesystem is mounted on specified mountpoints by man:automount[8], usually invoked during boot.
Whenever a process attempts to access a file within the man:autofs[5] mountpoint, the kernel will notify man:automountd[8] daemon and pause the triggering process.
The man:automountd[8] daemon will handle kernel requests by finding the proper map and mounting the filesystem according to it, then signal the kernel to release blocked process.
The man:autounmountd[8] daemon automatically unmounts automounted filesystems after some time, unless they are still being used.
The primary autofs configuration file is [.filename]#/etc/auto_master#. It assigns individual maps to top-level mounts.
For an explanation of [.filename]#auto_master# and the map syntax, refer to man:auto_master[5].
There is a special automounter map mounted on [.filename]#/net#.
When a file is accessed within this directory, man:autofs[5] looks up the corresponding remote mount and automatically mounts it.
For instance, an attempt to access a file within [.filename]#/net/foobar/usr# would tell man:automountd[8] to mount the [.filename]#/usr# export from the host `foobar`.
.Mounting an Export with man:autofs[5]
[example]
====
In this example, `showmount -e` shows the exported file systems that can be mounted from the NFS server, `foobar`:
[source,shell]
....
% showmount -e foobar
Exports list on foobar:
/usr 10.10.10.0
/a 10.10.10.0
% cd /net/foobar/usr
....
====
The output from `showmount` shows [.filename]#/usr# as an export.
When changing directories to [.filename]#/host/foobar/usr#, man:automountd[8] intercepts the request and attempts to resolve the hostname `foobar`.
If successful, man:automountd[8] automatically mounts the source export.
To enable man:autofs[5] at boot time, add this line to [.filename]#/etc/rc.conf#:
[.programlisting]
....
autofs_enable="YES"
....
Then man:autofs[5] can be started by running:
[source,shell]
....
# service automount start
# service automountd start
# service autounmountd start
....
The man:autofs[5] map format is the same as in other operating systems.
Information about this format from other sources can be useful, like the http://web.archive.org/web/20160813071113/http://images.apple.com/business/docs/Autofs.pdf[Mac OS X document].
Consult the man:automount[8], man:automountd[8], man:autounmountd[8], and man:auto_master[5] manual pages for more information.
[[network-nis]]
== Network Information System (NIS)
Network Information System (NIS) is designed to centralize administration of UNIX(R)-like systems such as Solaris(TM), HP-UX, AIX(R), Linux, NetBSD, OpenBSD, and FreeBSD.
NIS was originally known as Yellow Pages but the name was changed due to trademark issues.
This is the reason why NIS commands begin with `yp`.
NIS is a Remote Procedure Call (RPC)-based client/server system that allows a group of machines within an NIS domain to share a common set of configuration files.
This permits a system administrator to set up NIS client systems with only minimal configuration data and to add, remove, or modify configuration data from a single location.
FreeBSD uses version 2 of the NIS protocol.
=== NIS Terms and Processes
Table 28.1 summarizes the terms and important processes used by NIS:
.NIS Terminology
[cols="1,1", frame="none", options="header"]
|===
| Term
| Description
|NIS domain name
|NIS servers and clients share an NIS domain name. Typically, this name does not have anything to do with DNS.
|man:rpcbind[8]
|This service enables RPC and must be running in order to run an NIS server or act as an NIS client.
|man:ypbind[8]
|This service binds an NIS client to its NIS server. It will take the NIS domain name and use RPC to connect to the server. It is the core of client/server communication in an NIS environment. If this service is not running on a client machine, it will not be able to access the NIS server.
|man:ypserv[8]
|This is the process for the NIS server. If this service stops running, the server will no longer be able to respond to NIS requests so hopefully, there is a slave server to take over. Some non-FreeBSD clients will not try to reconnect using a slave server and the ypbind process may need to be restarted on these clients.
|man:rpc.yppasswdd[8]
|This process only runs on NIS master servers. This daemon allows NIS clients to change their NIS passwords. If this daemon is not running, users will have to login to the NIS master server and change their passwords there.
|===
=== Machine Types
There are three types of hosts in an NIS environment:
* NIS master server
+
This server acts as a central repository for host configuration information and maintains the authoritative copy of the files used by all of the NIS clients.
The [.filename]#passwd#, [.filename]#group#, and other various files used by NIS clients are stored on the master server.
While it is possible for one machine to be an NIS master server for more than one NIS domain, this type of configuration will not be covered in this chapter as it assumes a relatively small-scale NIS environment.
* NIS slave servers
+
NIS slave servers maintain copies of the NIS master's data files in order to provide redundancy.
Slave servers also help to balance the load of the master server as NIS clients always attach to the NIS server which responds first.
* NIS clients
+
NIS clients authenticate against the NIS server during log on.
Information in many files can be shared using NIS.
The [.filename]#master.passwd#, [.filename]#group#, and [.filename]#hosts# files are commonly shared via NIS.
Whenever a process on a client needs information that would normally be found in these files locally, it makes a query to the NIS server that it is bound to instead.
=== Planning Considerations
This section describes a sample NIS environment which consists of 15 FreeBSD machines with no centralized point of administration.
Each machine has its own [.filename]#/etc/passwd# and [.filename]#/etc/master.passwd#.
These files are kept in sync with each other only through manual intervention.
Currently, when a user is added to the lab, the process must be repeated on all 15 machines.
The configuration of the lab will be as follows:
[.informaltable]
[cols="1,1,1", frame="none", options="header"]
|===
| Machine name
| IP address
| Machine role
|`ellington`
|`10.0.0.2`
|NIS master
|`coltrane`
|`10.0.0.3`
|NIS slave
|`basie`
|`10.0.0.4`
|Faculty workstation
|`bird`
|`10.0.0.5`
|Client machine
|`cli[1-11]`
|`10.0.0.[6-17]`
|Other client machines
|===
If this is the first time an NIS scheme is being developed, it should be thoroughly planned ahead of time.
Regardless of network size, several decisions need to be made as part of the planning process.
==== Choosing a NIS Domain Name
When a client broadcasts its requests for info, it includes the name of the NIS domain that it is part of.
This is how multiple servers on one network can tell which server should answer which request.
Think of the NIS domain name as the name for a group of hosts.
Some organizations choose to use their Internet domain name for their NIS domain name.
This is not recommended as it can cause confusion when trying to debug network problems.
The NIS domain name should be unique within the network and it is helpful if it describes the group of machines it represents.
For example, the Art department at Acme Inc. might be in the "acme-art" NIS domain.
This example will use the domain name `test-domain`.
However, some non-FreeBSD operating systems require the NIS domain name to be the same as the Internet domain name.
If one or more machines on the network have this restriction, the Internet domain name _must_ be used as the NIS domain name.
==== Physical Server Requirements
There are several things to keep in mind when choosing a machine to use as a NIS server.
Since NIS clients depend upon the availability of the server, choose a machine that is not rebooted frequently.
The NIS server should ideally be a stand alone machine whose sole purpose is to be an NIS server.
If the network is not heavily used, it is acceptable to put the NIS server on a machine running other services.
However, if the NIS server becomes unavailable, it will adversely affect all NIS clients.
=== Configuring the NIS Master Server
The canonical copies of all NIS files are stored on the master server.
The databases used to store the information are called NIS maps.
In FreeBSD, these maps are stored in [.filename]#/var/yp/[domainname]# where [.filename]#[domainname]# is the name of the NIS domain.
Since multiple domains are supported, it is possible to have several directories, one for each domain.
Each domain will have its own independent set of maps.
NIS master and slave servers handle all NIS requests through man:ypserv[8].
This daemon is responsible for receiving incoming requests from NIS clients, translating the requested domain and map name to a path to the corresponding database file, and transmitting data from the database back to the client.
Setting up a master NIS server can be relatively straight forward, depending on environmental needs.
Since FreeBSD provides built-in NIS support, it only needs to be enabled by adding the following lines to [.filename]#/etc/rc.conf#:
[.programlisting]
....
nisdomainname="test-domain" <.>
nis_server_enable="YES" <.>
nis_yppasswdd_enable="YES" <.>
....
<.> This line sets the NIS domain name to `test-domain`.
<.> This automates the start up of the NIS server processes when the system boots.
<.> This enables the man:rpc.yppasswdd[8] daemon so that users can change their NIS password from a client machine.
Care must be taken in a multi-server domain where the server machines are also NIS clients.
It is generally a good idea to force the servers to bind to themselves rather than allowing them to broadcast bind requests and possibly become bound to each other.
Strange failure modes can result if one server goes down and others are dependent upon it.
Eventually, all the clients will time out and attempt to bind to other servers, but the delay involved can be considerable and the failure mode is still present since the servers might bind to each other all over again.
A server that is also a client can be forced to bind to a particular server by adding these additional lines to [.filename]#/etc/rc.conf#:
[.programlisting]
....
nis_client_enable="YES" <.>
nis_client_flags="-S test-domain,server" <.>
....
<.> This enables running client stuff as well.
<.> This line sets the NIS domain name to `test-domain` and bind to itself.
After saving the edits, type `/etc/netstart` to restart the network and apply the values defined in [.filename]#/etc/rc.conf#.
Before initializing the NIS maps, start man:ypserv[8]:
[source,shell]
....
# service ypserv start
....
==== Initializing the NIS Maps
NIS maps are generated from the configuration files in [.filename]#/etc# on the NIS master, with one exception: [.filename]#/etc/master.passwd#.
This is to prevent the propagation of passwords to all the servers in the NIS domain.
Therefore, before the NIS maps are initialized, configure the primary password files:
[source,shell]
....
# cp /etc/master.passwd /var/yp/master.passwd
# cd /var/yp
# vi master.passwd
....
It is advisable to remove all entries for system accounts as well as any user accounts that do not need to be propagated to the NIS clients, such as the `root` and any other administrative accounts.
[NOTE]
====
Ensure that the [.filename]#/var/yp/master.passwd# is neither group or world readable by setting its permissions to `600`.
====
After completing this task, initialize the NIS maps.
FreeBSD includes the man:ypinit[8] script to do this.
When generating maps for the master server, include `-m` and specify the NIS domain name:
[source,shell]
....
ellington# ypinit -m test-domain
Server Type: MASTER Domain: test-domain
Creating an YP server will require that you answer a few questions.
Questions will all be asked at the beginning of the procedure.
Do you want this procedure to quit on non-fatal errors? [y/n: n] n
Ok, please remember to go back and redo manually whatever fails.
If not, something might not work.
At this point, we have to construct a list of this domains YP servers.
rod.darktech.org is already known as master server.
Please continue to add any slave servers, one per line. When you are
done with the list, type a <control D>.
master server : ellington
next host to add: coltrane
next host to add: ^D
The current list of NIS servers looks like this:
ellington
coltrane
Is this correct? [y/n: y] y
[..output from map generation..]
NIS Map update completed.
ellington has been setup as an YP master server without any errors.
....
This will create [.filename]#/var/yp/Makefile# from [.filename]#/var/yp/Makefile.dist#.
By default, this file assumes that the environment has a single NIS server with only FreeBSD clients.
Since `test-domain` has a slave server, edit this line in [.filename]#/var/yp/Makefile# so that it begins with a comment (`+#+`):
[.programlisting]
....
NOPUSH = "True"
....
==== Adding New Users
Every time a new user is created, the user account must be added to the master NIS server and the NIS maps rebuilt.
Until this occurs, the new user will not be able to login anywhere except on the NIS master.
For example, to add the new user `jsmith` to the `test-domain` domain, run these commands on the master server:
[source,shell]
....
# pw useradd jsmith
# cd /var/yp
# make test-domain
....
The user could also be added using `adduser jsmith` instead of `pw useradd smith`.
=== Setting up a NIS Slave Server
To set up an NIS slave server, log on to the slave server and edit [.filename]#/etc/rc.conf# as for the master server.
Do not generate any NIS maps, as these already exist on the master server.
When running `ypinit` on the slave server, use `-s` (for slave) instead of `-m` (for master).
This option requires the name of the NIS master in addition to the domain name, as seen in this example:
[source,shell]
....
coltrane# ypinit -s ellington test-domain
Server Type: SLAVE Domain: test-domain Master: ellington
Creating an YP server will require that you answer a few questions.
Questions will all be asked at the beginning of the procedure.
Do you want this procedure to quit on non-fatal errors? [y/n: n] n
Ok, please remember to go back and redo manually whatever fails.
If not, something might not work.
There will be no further questions. The remainder of the procedure
should take a few minutes, to copy the databases from ellington.
Transferring netgroup...
ypxfr: Exiting: Map successfully transferred
Transferring netgroup.byuser...
ypxfr: Exiting: Map successfully transferred
Transferring netgroup.byhost...
ypxfr: Exiting: Map successfully transferred
Transferring master.passwd.byuid...
ypxfr: Exiting: Map successfully transferred
Transferring passwd.byuid...
ypxfr: Exiting: Map successfully transferred
Transferring passwd.byname...
ypxfr: Exiting: Map successfully transferred
Transferring group.bygid...
ypxfr: Exiting: Map successfully transferred
Transferring group.byname...
ypxfr: Exiting: Map successfully transferred
Transferring services.byname...
ypxfr: Exiting: Map successfully transferred
Transferring rpc.bynumber...
ypxfr: Exiting: Map successfully transferred
Transferring rpc.byname...
ypxfr: Exiting: Map successfully transferred
Transferring protocols.byname...
ypxfr: Exiting: Map successfully transferred
Transferring master.passwd.byname...
ypxfr: Exiting: Map successfully transferred
Transferring networks.byname...
ypxfr: Exiting: Map successfully transferred
Transferring networks.byaddr...
ypxfr: Exiting: Map successfully transferred
Transferring netid.byname...
ypxfr: Exiting: Map successfully transferred
Transferring hosts.byaddr...
ypxfr: Exiting: Map successfully transferred
Transferring protocols.bynumber...
ypxfr: Exiting: Map successfully transferred
Transferring ypservers...
ypxfr: Exiting: Map successfully transferred
Transferring hosts.byname...
ypxfr: Exiting: Map successfully transferred
coltrane has been setup as an YP slave server without any errors.
Remember to update map ypservers on ellington.
....
This will generate a directory on the slave server called [.filename]#/var/yp/test-domain# which contains copies of the NIS master server's maps.
Adding these [.filename]#/etc/crontab# entries on each slave server will force the slaves to sync their maps with the maps on the master server:
[.programlisting]
....
20 * * * * root /usr/libexec/ypxfr passwd.byname
21 * * * * root /usr/libexec/ypxfr passwd.byuid
....
These entries are not mandatory because the master server automatically attempts to push any map changes to its slaves.
However, since clients may depend upon the slave server to provide correct password information, it is recommended to force frequent password map updates.
This is especially important on busy networks where map updates might not always complete.
To finish the configuration, run `/etc/netstart` on the slave server in order to start the NIS services.
=== Setting Up an NIS Client
An NIS client binds to an NIS server using man:ypbind[8].
This daemon broadcasts RPC requests on the local network.
These requests specify the domain name configured on the client.
If an NIS server in the same domain receives one of the broadcasts, it will respond to ypbind, which will record the server's address.
If there are several servers available, the client will use the address of the first server to respond and will direct all of its NIS requests to that server.
The client will automatically ping the server on a regular basis to make sure it is still available.
If it fails to receive a reply within a reasonable amount of time, ypbind will mark the domain as unbound and begin broadcasting again in the hopes of locating another server.
To configure a FreeBSD machine to be an NIS client:
[.procedure]
====
. Edit [.filename]#/etc/rc.conf# and add the following lines in order to set the NIS domain name and start man:ypbind[8] during network startup:
+
[.programlisting]
....
nisdomainname="test-domain"
nis_client_enable="YES"
....
. To import all possible password entries from the NIS server, use `vipw` to remove all user accounts except one from [.filename]#/etc/master.passwd#. When removing the accounts, keep in mind that at least one local account should remain and this account should be a member of `wheel`. If there is a problem with NIS, this local account can be used to log in remotely, become the superuser, and fix the problem. Before saving the edits, add the following line to the end of the file:
+
[.programlisting]
....
+:::::::::
....
+
This line configures the client to provide anyone with a valid account in the NIS server's password maps an account on the client.
There are many ways to configure the NIS client by modifying this line.
One method is described in <<network-netgroups>>.
For more detailed reading, refer to the book `Managing NFS and NIS`, published by O'Reilly Media.
. To import all possible group entries from the NIS server, add this line to [.filename]#/etc/group#:
+
[.programlisting]
....
+:*::
....
====
To start the NIS client immediately, execute the following commands as the superuser:
[source,shell]
....
# /etc/netstart
# service ypbind start
....
After completing these steps, running `ypcat passwd` on the client should show the server's [.filename]#passwd# map.
=== NIS Security
Since RPC is a broadcast-based service, any system running ypbind within the same domain can retrieve the contents of the NIS maps.
To prevent unauthorized transactions, man:ypserv[8] supports a feature called "securenets" which can be used to restrict access to a given set of hosts.
By default, this information is stored in [.filename]#/var/yp/securenets#, unless man:ypserv[8] is started with `-p` and an alternate path.
This file contains entries that consist of a network specification and a network mask separated by white space.
Lines starting with `+"#"+` are considered to be comments.
A sample [.filename]#securenets# might look like this:
[.programlisting]
....
# allow connections from local host -- mandatory
127.0.0.1 255.255.255.255
# allow connections from any host
# on the 192.168.128.0 network
192.168.128.0 255.255.255.0
# allow connections from any host
# between 10.0.0.0 to 10.0.15.255
# this includes the machines in the testlab
10.0.0.0 255.255.240.0
....
If man:ypserv[8] receives a request from an address that matches one of these rules, it will process the request normally.
If the address fails to match a rule, the request will be ignored and a warning message will be logged.
If the [.filename]#securenets# does not exist, `ypserv` will allow connections from any host.
crossref:security[tcpwrappers,"TCP Wrapper"] is an alternate mechanism for providing access control instead of [.filename]#securenets#.
While either access control mechanism adds some security, they are both vulnerable to "IP spoofing" attacks.
All NIS-related traffic should be blocked at the firewall.
Servers using [.filename]#securenets# may fail to serve legitimate NIS clients with archaic TCP/IP implementations.
Some of these implementations set all host bits to zero when doing broadcasts or fail to observe the subnet mask when calculating the broadcast address.
While some of these problems can be fixed by changing the client configuration, other problems may force the retirement of these client systems or the abandonment of [.filename]#securenets#.
The use of TCP Wrapper increases the latency of the NIS server.
The additional delay may be long enough to cause timeouts in client programs, especially in busy networks with slow NIS servers.
If one or more clients suffer from latency, convert those clients into NIS slave servers and force them to bind to themselves.
==== Barring Some Users
In this example, the `basie` system is a faculty workstation within the NIS domain.
The [.filename]#passwd# map on the master NIS server contains accounts for both faculty and students.
This section demonstrates how to allow faculty logins on this system while refusing student logins.
To prevent specified users from logging on to a system, even if they are present in the NIS database, use `vipw` to add `-_username_` with the correct number of colons towards the end of [.filename]#/etc/master.passwd# on the client, where _username_ is the username of a user to bar from logging in.
The line with the blocked user must be before the `+` line that allows NIS users.
In this example, `bill` is barred from logging on to `basie`:
[source,shell]
....
basie# cat /etc/master.passwd
root:[password]:0:0::0:0:The super-user:/root:/bin/csh
toor:[password]:0:0::0:0:The other super-user:/root:/bin/sh
daemon:*:1:1::0:0:Owner of many system processes:/root:/usr/sbin/nologin
operator:*:2:5::0:0:System &:/:/usr/sbin/nologin
bin:*:3:7::0:0:Binaries Commands and Source,,,:/:/usr/sbin/nologin
tty:*:4:65533::0:0:Tty Sandbox:/:/usr/sbin/nologin
kmem:*:5:65533::0:0:KMem Sandbox:/:/usr/sbin/nologin
games:*:7:13::0:0:Games pseudo-user:/usr/games:/usr/sbin/nologin
news:*:8:8::0:0:News Subsystem:/:/usr/sbin/nologin
man:*:9:9::0:0:Mister Man Pages:/usr/share/man:/usr/sbin/nologin
bind:*:53:53::0:0:Bind Sandbox:/:/usr/sbin/nologin
uucp:*:66:66::0:0:UUCP pseudo-user:/var/spool/uucppublic:/usr/libexec/uucp/uucico
xten:*:67:67::0:0:X-10 daemon:/usr/local/xten:/usr/sbin/nologin
pop:*:68:6::0:0:Post Office Owner:/nonexistent:/usr/sbin/nologin
nobody:*:65534:65534::0:0:Unprivileged user:/nonexistent:/usr/sbin/nologin
-bill:::::::::
+:::::::::
basie#
....
[[network-netgroups]]
=== Using Netgroups
Barring specified users from logging on to individual systems becomes unscaleable on larger networks and quickly loses the main benefit of NIS: _centralized_ administration.
Netgroups were developed to handle large, complex networks with hundreds of users and machines.
Their use is comparable to UNIX(R) groups, where the main difference is the lack of a numeric ID and the ability to define a netgroup by including both user accounts and other netgroups.
To expand on the example used in this chapter, the NIS domain will be extended to add the users and systems shown in Tables 28.2 and 28.3:
.Additional Users
[cols="1,1", frame="none", options="header"]
|===
| User Name(s)
| Description
|`alpha`, `beta`
|IT department employees
|`charlie`, `delta`
|IT department apprentices
|`echo`, `foxtrott`, `golf`, ...
|employees
|`able`, `baker`, ...
|interns
|===
.Additional Systems
[cols="1,1", frame="none", options="header"]
|===
| Machine Name(s)
| Description
|`war`, `death`, `famine`, `pollution`
|Only IT employees are allowed to log onto these servers.
|`pride`, `greed`, `envy`, `wrath`, `lust`, `sloth`
|All members of the IT department are allowed to login onto these servers.
|`one`, `two`, `three`, `four`, ...
|Ordinary workstations used by employees.
|`trashcan`
|A very old machine without any critical data. Even interns are allowed to use this system.
|===
When using netgroups to configure this scenario, each user is assigned to one or more netgroups and logins are then allowed or forbidden for all members of the netgroup.
When adding a new machine, login restrictions must be defined for all netgroups.
When a new user is added, the account must be added to one or more netgroups.
If the NIS setup is planned carefully, only one central configuration file needs modification to grant or deny access to machines.
The first step is the initialization of the NIS`netgroup` map.
In FreeBSD, this map is not created by default.
On the NIS master server, use an editor to create a map named [.filename]#/var/yp/netgroup#.
This example creates four netgroups to represent IT employees, IT apprentices, employees, and interns:
[.programlisting]
....
IT_EMP (,alpha,test-domain) (,beta,test-domain)
IT_APP (,charlie,test-domain) (,delta,test-domain)
USERS (,echo,test-domain) (,foxtrott,test-domain) \
(,golf,test-domain)
INTERNS (,able,test-domain) (,baker,test-domain)
....
Each entry configures a netgroup. The first column in an entry is the name of the netgroup.
Each set of parentheses represents either a group of one or more users or the name of another netgroup.
When specifying a user, the three comma-delimited fields inside each group represent:
. The name of the host(s) where the other fields representing the user are valid. If a hostname is not specified, the entry is valid on all hosts.
. The name of the account that belongs to this netgroup.
. The NIS domain for the account. Accounts may be imported from other NIS domains into a netgroup.
If a group contains multiple users, separate each user with whitespace.
Additionally, each field may contain wildcards.
See man:netgroup[5] for details.
Netgroup names longer than 8 characters should not be used.
The names are case sensitive and using capital letters for netgroup names is an easy way to distinguish between user, machine and netgroup names.
Some non-FreeBSD NIS clients cannot handle netgroups containing more than 15 entries.
This limit may be circumvented by creating several sub-netgroups with 15 users or fewer and a real netgroup consisting of the sub-netgroups, as seen in this example:
[.programlisting]
....
BIGGRP1 (,joe1,domain) (,joe2,domain) (,joe3,domain) [...]
BIGGRP2 (,joe16,domain) (,joe17,domain) [...]
BIGGRP3 (,joe31,domain) (,joe32,domain)
BIGGROUP BIGGRP1 BIGGRP2 BIGGRP3
....
Repeat this process if more than 225 (15 times 15) users exist within a single netgroup.
To activate and distribute the new NIS map:
[source,shell]
....
ellington# cd /var/yp
ellington# make
....
This will generate the three NIS maps [.filename]#netgroup#, [.filename]#netgroup.byhost# and [.filename]#netgroup.byuser#.
Use the map key option of man:ypcat[1] to check if the new NIS maps are available:
[source,shell]
....
ellington% ypcat -k netgroup
ellington% ypcat -k netgroup.byhost
ellington% ypcat -k netgroup.byuser
....
The output of the first command should resemble the contents of [.filename]#/var/yp/netgroup#.
The second command only produces output if host-specific netgroups were created.
The third command is used to get the list of netgroups for a user.
To configure a client, use man:vipw[8] to specify the name of the netgroup.
For example, on the server named `war`, replace this line:
[.programlisting]
....
+:::::::::
....
with
[.programlisting]
....
+@IT_EMP:::::::::
....
This specifies that only the users defined in the netgroup `IT_EMP` will be imported into this system's password database and only those users are allowed to login to this system.
This configuration also applies to the `~` function of the shell and all routines which convert between user names and numerical user IDs.
In other words, `cd ~_user_` will not work, `ls -l` will show the numerical ID instead of the username, and `find . -user joe -print` will fail with the message `No such user`.
To fix this, import all user entries without allowing them to login into the servers.
This can be achieved by adding an extra line:
[.programlisting]
....
+:::::::::/usr/sbin/nologin
....
This line configures the client to import all entries but to replace the shell in those entries with [.filename]#/usr/sbin/nologin#.
Make sure that extra line is placed _after_ `+@IT_EMP:::::::::`.
Otherwise, all user accounts imported from NIS will have [.filename]#/usr/sbin/nologin# as their login shell and no one will be able to login to the system.
To configure the less important servers, replace the old `+:::::::::` on the servers with these lines:
[.programlisting]
....
+@IT_EMP:::::::::
+@IT_APP:::::::::
+:::::::::/usr/sbin/nologin
....
The corresponding lines for the workstations would be:
[.programlisting]
....
+@IT_EMP:::::::::
+@USERS:::::::::
+:::::::::/usr/sbin/nologin
....
NIS supports the creation of netgroups from other netgroups which can be useful if the policy regarding user access changes.
One possibility is the creation of role-based netgroups.
For example, one might create a netgroup called `BIGSRV` to define the login restrictions for the important servers, another netgroup called `SMALLSRV` for the less important servers, and a third netgroup called `USERBOX` for the workstations.
Each of these netgroups contains the netgroups that are allowed to login onto these machines.
The new entries for the NIS`netgroup` map would look like this:
[.programlisting]
....
BIGSRV IT_EMP IT_APP
SMALLSRV IT_EMP IT_APP ITINTERN
USERBOX IT_EMP ITINTERN USERS
....
This method of defining login restrictions works reasonably well when it is possible to define groups of machines with identical restrictions.
Unfortunately, this is the exception and not the rule.
Most of the time, the ability to define login restrictions on a per-machine basis is required.
Machine-specific netgroup definitions are another possibility to deal with the policy changes.
In this scenario, the [.filename]#/etc/master.passwd# of each system contains two lines starting with "+".
The first line adds a netgroup with the accounts allowed to login onto this machine and the second line adds all other accounts with [.filename]#/usr/sbin/nologin# as shell.
It is recommended to use the "ALL-CAPS" version of the hostname as the name of the netgroup:
[.programlisting]
....
+@BOXNAME:::::::::
+:::::::::/usr/sbin/nologin
....
Once this task is completed on all the machines, there is no longer a need to modify the local versions of [.filename]#/etc/master.passwd# ever again.
All further changes can be handled by modifying the NIS map.
Here is an example of a possible `netgroup` map for this scenario:
[.programlisting]
....
# Define groups of users first
IT_EMP (,alpha,test-domain) (,beta,test-domain)
IT_APP (,charlie,test-domain) (,delta,test-domain)
DEPT1 (,echo,test-domain) (,foxtrott,test-domain)
DEPT2 (,golf,test-domain) (,hotel,test-domain)
DEPT3 (,india,test-domain) (,juliet,test-domain)
ITINTERN (,kilo,test-domain) (,lima,test-domain)
D_INTERNS (,able,test-domain) (,baker,test-domain)
#
# Now, define some groups based on roles
USERS DEPT1 DEPT2 DEPT3
BIGSRV IT_EMP IT_APP
SMALLSRV IT_EMP IT_APP ITINTERN
USERBOX IT_EMP ITINTERN USERS
#
# And a groups for a special tasks
# Allow echo and golf to access our anti-virus-machine
SECURITY IT_EMP (,echo,test-domain) (,golf,test-domain)
#
# machine-based netgroups
# Our main servers
WAR BIGSRV
FAMINE BIGSRV
# User india needs access to this server
POLLUTION BIGSRV (,india,test-domain)
#
# This one is really important and needs more access restrictions
DEATH IT_EMP
#
# The anti-virus-machine mentioned above
ONE SECURITY
#
# Restrict a machine to a single user
TWO (,hotel,test-domain)
# [...more groups to follow]
....
It may not always be advisable to use machine-based netgroups.
When deploying a couple of dozen or hundreds of systems, role-based netgroups instead of machine-based netgroups may be used to keep the size of the NIS map within reasonable limits.
=== Password Formats
NIS requires that all hosts within an NIS domain use the same format for encrypting passwords.
If users have trouble authenticating on an NIS client, it may be due to a differing password format.
In a heterogeneous network, the format must be supported by all operating systems, where DES is the lowest common standard.
To check which format a server or client is using, look at this section of [.filename]#/etc/login.conf#:
[.programlisting]
....
default:\
:passwd_format=des:\
:copyright=/etc/COPYRIGHT:\
[Further entries elided]
....
In this example, the system is using the DES format for password hashing.
Other possible values include `blf` for Blowfish, `md5` for MD5, `sha256` and `sha512` for SHA-256 and SHA-512 respectively.
For more information and the up to date list of what is available on your system, consult the man:crypt[3] manpage.
If the format on a host needs to be edited to match the one being used in the NIS domain, the login capability database must be rebuilt after saving the change:
[source,shell]
....
# cap_mkdb /etc/login.conf
....
[NOTE]
====
The format of passwords for existing user accounts will not be updated until each user changes their password _after_ the login capability database is rebuilt.
====
[[network-ldap]]
== Lightweight Directory Access Protocol (LDAP)
The Lightweight Directory Access Protocol (LDAP) is an application layer protocol used to access, modify, and authenticate objects using a distributed directory information service.
Think of it as a phone or record book which stores several levels of hierarchical, homogeneous information.
It is used in Active Directory and OpenLDAP networks and allows users to access to several levels of internal information utilizing a single account.
For example, email authentication, pulling employee contact information, and internal website authentication might all make use of a single user account in the LDAP server's record base.
This section provides a quick start guide for configuring an LDAP server on a FreeBSD system.
It assumes that the administrator already has a design plan which includes the type of information to store, what that information will be used for, which users should have access to that information, and how to secure this information from unauthorized access.
=== LDAP Terminology and Structure
LDAP uses several terms which should be understood before starting the configuration.
All directory entries consist of a group of _attributes_.
Each of these attribute sets contains a unique identifier known as a _Distinguished Name_ (DN) which is normally built from several other attributes such as the common or _Relative Distinguished Name_ (RDN).
Similar to how directories have absolute and relative paths, consider a DN as an absolute path and the RDN as the relative path.
An example LDAP entry looks like the following.
This example searches for the entry for the specified user account (`uid`), organizational unit (`ou`), and organization (`o`):
[source,shell]
....
% ldapsearch -xb "uid=trhodes,ou=users,o=example.com"
# extended LDIF
#
# LDAPv3
# base <uid=trhodes,ou=users,o=example.com> with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#
# trhodes, users, example.com
dn: uid=trhodes,ou=users,o=example.com
mail: trhodes@example.com
cn: Tom Rhodes
uid: trhodes
telephoneNumber: (123) 456-7890
# search result
search: 2
result: 0 Success
# numResponses: 2
# numEntries: 1
....
This example entry shows the values for the `dn`, `mail`, `cn`, `uid`, and `telephoneNumber` attributes.
The cn attribute is the RDN.
More information about LDAP and its terminology can be found at http://www.openldap.org/doc/admin24/intro.html[http://www.openldap.org/doc/admin24/intro.html].
[[ldap-config]]
=== Configuring an LDAP Server
FreeBSD does not provide a built-in LDAP server.
Begin the configuration by installing package:net/openldap-server[] package or port:
[source,shell]
....
# pkg install openldap-server
....
There is a large set of default options enabled in the extref:{linux-users}[package, software].
Review them by running `pkg info openldap-server`.
If they are not sufficient (for example if SQL support is needed), please consider recompiling the port using the appropriate crossref:ports[ports-using,framework].
The installation creates the directory [.filename]#/var/db/openldap-data# to hold the data.
The directory to store the certificates must be created:
[source,shell]
....
# mkdir /usr/local/etc/openldap/private
....
The next phase is to configure the Certificate Authority.
The following commands must be executed from [.filename]#/usr/local/etc/openldap/private#.
This is important as the file permissions need to be restrictive and users should not have access to these files.
More detailed information about certificates and their parameters can be found in crossref:security[openssl,"OpenSSL"].
To create the Certificate Authority, start with this command and follow the prompts:
[source,shell]
....
# openssl req -days 365 -nodes -new -x509 -keyout ca.key -out ../ca.crt
....
The entries for the prompts may be generic _except_ for the `Common Name`.
This entry must be _different_ than the system hostname.
If this will be a self signed certificate, prefix the hostname with `CA` for Certificate Authority.
The next task is to create a certificate signing request and a private key.
Input this command and follow the prompts:
[source,shell]
....
# openssl req -days 365 -nodes -new -keyout server.key -out server.csr
....
During the certificate generation process, be sure to correctly set the `Common Name` attribute.
The Certificate Signing Request must be signed with the Certificate Authority in order to be used as a valid certificate:
[source,shell]
....
# openssl x509 -req -days 365 -in server.csr -out ../server.crt -CA ../ca.crt -CAkey ca.key -CAcreateserial
....
The final part of the certificate generation process is to generate and sign the client certificates:
[source,shell]
....
# openssl req -days 365 -nodes -new -keyout client.key -out client.csr
# openssl x509 -req -days 3650 -in client.csr -out ../client.crt -CA ../ca.crt -CAkey ca.key
....
Remember to use the same `Common Name` attribute when prompted.
When finished, ensure that a total of eight (8) new files have been generated through the proceeding commands.
The daemon running the OpenLDAP server is [.filename]#slapd#.
Its configuration is performed through [.filename]#slapd.ldif#: the old [.filename]#slapd.conf# has been deprecated by OpenLDAP.
http://www.openldap.org/doc/admin24/slapdconf2.html[Configuration examples] for [.filename]#slapd.ldif# are available and can also be found in [.filename]#/usr/local/etc/openldap/slapd.ldif.sample#.
Options are documented in slapd-config(5).
Each section of [.filename]#slapd.ldif#, like all the other LDAP attribute sets, is uniquely identified through a DN.
Be sure that no blank lines are left between the `dn:` statement and the desired end of the section.
In the following example, TLS will be used to implement a secure channel.
The first section represents the global configuration:
[.programlisting]
....
#
# See slapd-config(5) for details on configuration options.
# This file should NOT be world readable.
#
dn: cn=config
objectClass: olcGlobal
cn: config
#
#
# Define global ACLs to disable default read access.
#
olcArgsFile: /var/run/openldap/slapd.args
olcPidFile: /var/run/openldap/slapd.pid
olcTLSCertificateFile: /usr/local/etc/openldap/server.crt
olcTLSCertificateKeyFile: /usr/local/etc/openldap/private/server.key
olcTLSCACertificateFile: /usr/local/etc/openldap/ca.crt
#olcTLSCipherSuite: HIGH
olcTLSProtocolMin: 3.1
olcTLSVerifyClient: never
....
The Certificate Authority, server certificate and server private key files must be specified here.
It is recommended to let the clients choose the security cipher and omit option `olcTLSCipherSuite` (incompatible with TLS clients other than [.filename]#openssl#). Option `olcTLSProtocolMin` lets the server require a minimum security level: it is recommended.
While verification is mandatory for the server, it is not for the client: `olcTLSVerifyClient: never`.
The second section is about the backend modules and can be configured as follows:
[.programlisting]
....
#
# Load dynamic backend modules:
#
dn: cn=module,cn=config
objectClass: olcModuleList
cn: module
olcModulepath: /usr/local/libexec/openldap
olcModuleload: back_mdb.la
#olcModuleload: back_bdb.la
#olcModuleload: back_hdb.la
#olcModuleload: back_ldap.la
#olcModuleload: back_passwd.la
#olcModuleload: back_shell.la
....
The third section is devoted to load the needed `ldif` schemas to be used by the databases: they are essential.
[.programlisting]
....
dn: cn=schema,cn=config
objectClass: olcSchemaConfig
cn: schema
include: file:///usr/local/etc/openldap/schema/core.ldif
include: file:///usr/local/etc/openldap/schema/cosine.ldif
include: file:///usr/local/etc/openldap/schema/inetorgperson.ldif
include: file:///usr/local/etc/openldap/schema/nis.ldif
....
Next, the frontend configuration section:
[.programlisting]
....
# Frontend settings
#
dn: olcDatabase={-1}frontend,cn=config
objectClass: olcDatabaseConfig
objectClass: olcFrontendConfig
olcDatabase: {-1}frontend
olcAccess: to * by * read
#
# Sample global access control policy:
# Root DSE: allow anyone to read it
# Subschema (sub)entry DSE: allow anyone to read it
# Other DSEs:
# Allow self write access
# Allow authenticated users read access
# Allow anonymous users to authenticate
#
#olcAccess: to dn.base="" by * read
#olcAccess: to dn.base="cn=Subschema" by * read
#olcAccess: to *
# by self write
# by users read
# by anonymous auth
#
# if no access controls are present, the default policy
# allows anyone and everyone to read anything but restricts
# updates to rootdn. (e.g., "access to * by * read")
#
# rootdn can always read and write EVERYTHING!
#
olcPasswordHash: {SSHA}
# {SSHA} is already the default for olcPasswordHash
....
Another section is devoted to the _configuration backend_, the only way to later access the OpenLDAP server configuration is as a global super-user.
[.programlisting]
....
dn: olcDatabase={0}config,cn=config
objectClass: olcDatabaseConfig
olcDatabase: {0}config
olcAccess: to * by * none
olcRootPW: {SSHA}iae+lrQZILpiUdf16Z9KmDmSwT77Dj4U
....
The default administrator username is `cn=config`.
Type [.filename]#slappasswd# in a shell, choose a password and use its hash in `olcRootPW`.
If this option is not specified now, before [.filename]#slapd.ldif# is imported, no one will be later able to modify the _global configuration_ section.
The last section is about the database backend:
[.programlisting]
....
#######################################################################
# LMDB database definitions
#######################################################################
#
dn: olcDatabase=mdb,cn=config
objectClass: olcDatabaseConfig
objectClass: olcMdbConfig
olcDatabase: mdb
olcDbMaxSize: 1073741824
olcSuffix: dc=domain,dc=example
olcRootDN: cn=mdbadmin,dc=domain,dc=example
# Cleartext passwords, especially for the rootdn, should
# be avoided. See slappasswd(8) and slapd-config(5) for details.
# Use of strong authentication encouraged.
olcRootPW: {SSHA}X2wHvIWDk6G76CQyCMS1vDCvtICWgn0+
# The database directory MUST exist prior to running slapd AND
# should only be accessible by the slapd and slap tools.
# Mode 700 recommended.
olcDbDirectory: /var/db/openldap-data
# Indices to maintain
olcDbIndex: objectClass eq
....
This database hosts the _actual contents_ of the LDAP directory.
Types other than `mdb` are available.
Its super-user, not to be confused with the global one, is configured here: a (possibly custom) username in `olcRootDN` and the password hash in `olcRootPW`; [.filename]#slappasswd# can be used as before.
This http://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=tree;f=tests/data/regressions/its8444;h=8a5e808e63b0de3d2bdaf2cf34fecca8577ca7fd;hb=HEAD[repository] contains four examples of [.filename]#slapd.ldif#.
To convert an existing [.filename]#slapd.conf# into [.filename]#slapd.ldif#, refer to http://www.openldap.org/doc/admin24/slapdconf2.html[this page] (please note that this may introduce some unuseful options).
When the configuration is completed, [.filename]#slapd.ldif# must be placed in an empty directory.
It is recommended to create it as:
[source,shell]
....
# mkdir /usr/local/etc/openldap/slapd.d/
....
Import the configuration database:
[source,shell]
....
# /usr/local/sbin/slapadd -n0 -F /usr/local/etc/openldap/slapd.d/ -l /usr/local/etc/openldap/slapd.ldif
....
Start the [.filename]#slapd# daemon:
[source,shell]
....
# /usr/local/libexec/slapd -F /usr/local/etc/openldap/slapd.d/
....
Option `-d` can be used for debugging, as specified in slapd(8).
To verify that the server is running and working:
[source,shell]
....
# ldapsearch -x -b '' -s base '(objectclass=*)' namingContexts
# extended LDIF
#
# LDAPv3
# base <> with scope baseObject
# filter: (objectclass=*)
# requesting: namingContexts
#
#
dn:
namingContexts: dc=domain,dc=example
# search result
search: 2
result: 0 Success
# numResponses: 2
# numEntries: 1
....
The server must still be trusted.
If that has never been done before, follow these instructions.
Install the OpenSSL package or port:
[source,shell]
....
# pkg install openssl
....
From the directory where [.filename]#ca.crt# is stored (in this example, [.filename]#/usr/local/etc/openldap#), run:
[source,shell]
....
# c_rehash .
....
Both the CA and the server certificate are now correctly recognized in their respective roles.
To verify this, run this command from the [.filename]#server.crt# directory:
[source,shell]
....
# openssl verify -verbose -CApath . server.crt
....
If [.filename]#slapd# was running, restart it.
As stated in [.filename]#/usr/local/etc/rc.d/slapd#, to properly run [.filename]#slapd# at boot the following lines must be added to [.filename]#/etc/rc.conf#:
[.programlisting]
....
slapd_enable="YES"
slapd_flags='-h "ldapi://%2fvar%2frun%2fopenldap%2fldapi/
ldap://0.0.0.0/"'
slapd_sockets="/var/run/openldap/ldapi"
slapd_cn_config="YES"
....
[.filename]#slapd# does not provide debugging at boot.
Check [.filename]#/var/log/debug.log#, [.filename]#dmesg -a# and [.filename]#/var/log/messages# for this purpose.
The following example adds the group `team` and the user `john` to the `domain.example` LDAP database, which is still empty.
First, create the file [.filename]#domain.ldif#:
[source,shell]
....
# cat domain.ldif
dn: dc=domain,dc=example
objectClass: dcObject
objectClass: organization
o: domain.example
dc: domain
dn: ou=groups,dc=domain,dc=example
objectClass: top
objectClass: organizationalunit
ou: groups
dn: ou=users,dc=domain,dc=example
objectClass: top
objectClass: organizationalunit
ou: users
dn: cn=team,ou=groups,dc=domain,dc=example
objectClass: top
objectClass: posixGroup
cn: team
gidNumber: 10001
dn: uid=john,ou=users,dc=domain,dc=example
objectClass: top
objectClass: account
objectClass: posixAccount
objectClass: shadowAccount
cn: John McUser
uid: john
uidNumber: 10001
gidNumber: 10001
homeDirectory: /home/john/
loginShell: /usr/bin/bash
userPassword: secret
....
See the OpenLDAP documentation for more details.
Use [.filename]#slappasswd# to replace the plain text password `secret` with a hash in `userPassword`.
The path specified as `loginShell` must exist in all the systems where `john` is allowed to login.
Finally, use the `mdb` administrator to modify the database:
[source,shell]
....
# ldapadd -W -D "cn=mdbadmin,dc=domain,dc=example" -f domain.ldif
....
Modifications to the _global configuration_ section can only be performed by the global super-user.
For example, assume that the option `olcTLSCipherSuite: HIGH:MEDIUM:SSLv3` was initially specified and must now be deleted.
First, create a file that contains the following:
[source,shell]
....
# cat global_mod
dn: cn=config
changetype: modify
delete: olcTLSCipherSuite
....
Then, apply the modifications:
[source,shell]
....
# ldapmodify -f global_mod -x -D "cn=config" -W
....
When asked, provide the password chosen in the _configuration backend_ section.
The username is not required: here, `cn=config` represents the DN of the database section to be modified.
Alternatively, use `ldapmodify` to delete a single line of the database, `ldapdelete` to delete a whole entry.
If something goes wrong, or if the global super-user cannot access the configuration backend, it is possible to delete and re-write the whole configuration:
[source,shell]
....
# rm -rf /usr/local/etc/openldap/slapd.d/
....
[.filename]#slapd.ldif# can then be edited and imported again.
Please, follow this procedure only when no other solution is available.
This is the configuration of the server only.
The same machine can also host an LDAP client, with its own separate configuration.
[[network-dhcp]]
== Dynamic Host Configuration Protocol (DHCP)
The Dynamic Host Configuration Protocol (DHCP) allows a system to connect to a network in order to be assigned the necessary addressing information for communication on that network.
FreeBSD includes the OpenBSD version of `dhclient` which is used by the client to obtain the addressing information.
FreeBSD does not install a DHCP server, but several servers are available in the FreeBSD Ports Collection.
The DHCP protocol is fully described in http://www.freesoft.org/CIE/RFC/2131/[RFC 2131].
Informational resources are also available at http://www.isc.org/downloads/dhcp/[isc.org/downloads/dhcp/].
This section describes how to use the built-in DHCP client.
It then describes how to install and configure a DHCP server.
[NOTE]
====
In FreeBSD, the man:bpf[4] device is needed by both the DHCP server and DHCP client.
This device is included in the [.filename]#GENERIC# kernel that is installed with FreeBSD.
Users who prefer to create a custom kernel need to keep this device if DHCP is used.
It should be noted that [.filename]#bpf# also allows privileged users to run network packet sniffers on that system.
====
=== Configuring a DHCP Client
DHCP client support is included in the FreeBSD installer, making it easy to configure a newly installed system to automatically receive its networking addressing information from an existing DHCP server.
Refer to crossref:bsdinstall[bsdinstall-post,"Accounts, Time Zone, Services and Hardening"] for examples of network configuration.
When `dhclient` is executed on the client machine, it begins broadcasting requests for configuration information.
By default, these requests use UDP port 68.
The server replies on UDP port 67, giving the client an IP address and other relevant network information such as a subnet mask, default gateway, and DNS server addresses.
This information is in the form of a DHCP "lease" and is valid for a configurable time.
This allows stale IP addresses for clients no longer connected to the network to automatically be reused.
DHCP clients can obtain a great deal of information from the server.
An exhaustive list may be found in man:dhcp-options[5].
By default, when a FreeBSD system boots, its DHCP client runs in the background, or _asynchronously_.
Other startup scripts continue to run while the DHCP process completes, which speeds up system startup.
Background DHCP works well when the DHCP server responds quickly to the client's requests.
However, DHCP may take a long time to complete on some systems.
If network services attempt to run before DHCP has assigned the network addressing information, they will fail.
Using DHCP in _synchronous_ mode prevents this problem as it pauses startup until the DHCP configuration has completed.
This line in [.filename]#/etc/rc.conf# is used to configure background or asynchronous mode:
[.programlisting]
....
ifconfig_fxp0="DHCP"
....
This line may already exist if the system was configured to use DHCP during installation.
Replace the _fxp0_ shown in these examples with the name of the interface to be dynamically configured, as described in crossref:config[config-network-setup,“Setting Up Network Interface Cards”].
To instead configure the system to use synchronous mode, and to pause during startup while DHCP completes, use "`SYNCDHCP`":
[.programlisting]
....
ifconfig_fxp0="SYNCDHCP"
....
Additional client options are available.
Search for `dhclient` in man:rc.conf[5] for details.
The DHCP client uses the following files:
* [.filename]#/etc/dhclient.conf#
+
The configuration file used by `dhclient`.
Typically, this file contains only comments as the defaults are suitable for most clients.
This configuration file is described in man:dhclient.conf[5].
* [.filename]#/sbin/dhclient#
+
More information about the command itself can be found in man:dhclient[8].
* [.filename]#/sbin/dhclient-script#
+
The FreeBSD-specific DHCP client configuration script.
It is described in man:dhclient-script[8], but should not need any user modification to function properly.
* [.filename]#/var/db/dhclient.leases.interface#
+
The DHCP client keeps a database of valid leases in this file, which is written as a log and is described in man:dhclient.leases[5].
[[network-dhcp-server]]
=== Installing and Configuring a DHCP Server
This section demonstrates how to configure a FreeBSD system to act as a DHCP server using the Internet Systems Consortium (ISC) implementation of the DHCP server.
This implementation and its documentation can be installed using the package:net/isc-dhcp44-server[] package or port.
The installation of package:net/isc-dhcp44-server[] installs a sample configuration file.
Copy [.filename]#/usr/local/etc/dhcpd.conf.example# to [.filename]#/usr/local/etc/dhcpd.conf# and make any edits to this new file.
The configuration file is comprised of declarations for subnets and hosts which define the information that is provided to DHCP clients.
For example, these lines configure the following:
[.programlisting]
....
option domain-name "example.org";<.>
option domain-name-servers ns1.example.org;<.>
option subnet-mask 255.255.255.0;<.>
default-lease-time 600;<.>
max-lease-time 72400;<.>
ddns-update-style none;<.>
subnet 10.254.239.0 netmask 255.255.255.224 {
range 10.254.239.10 10.254.239.20;<.>
option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;<.>
}
host fantasia {
hardware ethernet 08:00:07:26:c0:a5;<.>
fixed-address fantasia.fugue.com;<.>
}
....
<.> This option specifies the default search domain that will be provided to clients. Refer to man:resolv.conf[5] for more information.
<.> This option specifies a comma separated list of DNS servers that the client should use. They can be listed by their Fully Qualified Domain Names (FQDN), as seen in the example, or by their IP addresses.
<.> The subnet mask that will be provided to clients.
<.> The default lease expiry time in seconds. A client can be configured to override this value.
<.> The maximum allowed length of time, in seconds, for a lease. Should a client request a longer lease, a lease will still be issued, but it will only be valid for `max-lease-time`.
<.> The default of `none` disables dynamic DNS updates. Changing this to `interim` configures the DHCP server to update a DNS server whenever it hands out a lease so that the DNS server knows which IP addresses are associated with which computers in the network. Do not change the default setting unless the DNS server has been configured to support dynamic DNS.
<.> This line creates a pool of available IP addresses which are reserved for allocation to DHCP clients. The range of addresses must be valid for the network or subnet specified in the previous line.
<.> Declares the default gateway that is valid for the network or subnet specified before the opening `{` bracket.
<.> Specifies the hardware MAC address of a client so that the DHCP server can recognize the client when it makes a request.
<.> Specifies that this host should always be given the same IP address. Using the hostname is correct, since the DHCP server will resolve the hostname before returning the lease information.
This configuration file supports many more options.
Refer to dhcpd.conf(5), installed with the server, for details and examples.
Once the configuration of [.filename]#dhcpd.conf# is complete, enable the DHCP server in [.filename]#/etc/rc.conf#:
[.programlisting]
....
dhcpd_enable="YES"
dhcpd_ifaces="dc0"
....
Replace the `dc0` with the interface (or interfaces, separated by whitespace) that the DHCP server should listen on for DHCP client requests.
Start the server by issuing the following command:
[source,shell]
....
# service isc-dhcpd start
....
Any future changes to the configuration of the server will require the dhcpd service to be stopped and then started using man:service[8].
The DHCP server uses the following files.
Note that the manual pages are installed with the server software.
* [.filename]#/usr/local/sbin/dhcpd#
+
More information about the dhcpd server can be found in dhcpd(8).
* [.filename]#/usr/local/etc/dhcpd.conf#
+
The server configuration file needs to contain all the information that should be provided to clients, along with information regarding the operation of the server.
This configuration file is described in dhcpd.conf(5).
* [.filename]#/var/db/dhcpd.leases#
+
The DHCP server keeps a database of leases it has issued in this file, which is written as a log.
Refer to dhcpd.leases(5), which gives a slightly longer description.
* [.filename]#/usr/local/sbin/dhcrelay#
+
This daemon is used in advanced environments where one DHCP server forwards a request from a client to another DHCP server on a separate network.
If this functionality is required, install the package:net/isc-dhcp44-relay[] package or port.
The installation includes dhcrelay(8) which provides more detail.
[[network-dns]]
== Domain Name System (DNS)
Domain Name System (DNS) is the protocol through which domain names are mapped to IP addresses, and vice versa.
DNS is coordinated across the Internet through a somewhat complex system of authoritative root, Top Level Domain (TLD), and other smaller-scale name servers, which host and cache individual domain information.
It is not necessary to run a name server to perform DNS lookups on a system.
The following table describes some of the terms associated with DNS:
.DNS Terminology
[cols="1,1", frame="none", options="header"]
|===
| Term
| Definition
|Forward DNS
|Mapping of hostnames to IP addresses.
|Origin
|Refers to the domain covered in a particular zone file.
|Resolver
|A system process through which a machine queries a name server for zone information.
|Reverse DNS
|Mapping of IP addresses to hostnames.
|Root zone
|The beginning of the Internet zone hierarchy. All zones fall under the root zone, similar to how all files in a file system fall under the root directory.
|Zone
|An individual domain, subdomain, or portion of the DNS administered by the same authority.
|===
Examples of zones:
* `.` is how the root zone is usually referred to in documentation.
* `org.` is a Top Level Domain (TLD) under the root zone.
* `example.org.` is a zone under the `org.`TLD.
* `1.168.192.in-addr.arpa` is a zone referencing all IP addresses which fall under the `192.168.1.*`IP address space.
As one can see, the more specific part of a hostname appears to its left.
For example, `example.org.` is more specific than `org.`, as `org.` is more specific than the root zone.
The layout of each part of a hostname is much like a file system: the [.filename]#/dev# directory falls within the root, and so on.
=== Reasons to Run a Name Server
Name servers generally come in two forms: authoritative name servers, and caching (also known as resolving) name servers.
An authoritative name server is needed when:
* One wants to serve DNS information to the world, replying authoritatively to queries.
* A domain, such as `example.org`, is registered and IP addresses need to be assigned to hostnames under it.
* An IP address block requires reverse DNS entries (IP to hostname).
* A backup or second name server, called a slave, will reply to queries.
A caching name server is needed when:
* A local DNS server may cache and respond more quickly than querying an outside name server.
When one queries for `www.FreeBSD.org`, the resolver usually queries the uplink ISP's name server, and retrieves the reply.
With a local, caching DNS server, the query only has to be made once to the outside world by the caching DNS server.
Additional queries will not have to go outside the local network, since the information is cached locally.
=== DNS Server Configuration
Unbound is provided in the FreeBSD base system.
By default, it will provide DNS resolution to the local machine only.
While the base system package can be configured to provide resolution services beyond the local machine, it is recommended that such requirements be addressed by installing Unbound from the FreeBSD Ports Collection.
To enable Unbound, add the following to [.filename]#/etc/rc.conf#:
[.programlisting]
....
local_unbound_enable="YES"
....
Any existing nameservers in [.filename]#/etc/resolv.conf# will be configured as forwarders in the new Unbound configuration.
[NOTE]
====
If any of the listed nameservers do not support DNSSEC, local DNS resolution will fail.
Be sure to test each nameserver and remove any that fail the test.
The following command will show the trust tree or a failure for a nameserver running on `192.168.1.1`:
[source,shell]
....
% drill -S FreeBSD.org @192.168.1.1
....
====
Once each nameserver is confirmed to support DNSSEC, start Unbound:
[source,shell]
....
# service local_unbound onestart
....
This will take care of updating [.filename]#/etc/resolv.conf# so that queries for DNSSEC secured domains will now work.
For example, run the following to validate the FreeBSD.org DNSSEC trust tree:
[source,shell]
....
% drill -S FreeBSD.org
;; Number of trusted keys: 1
;; Chasing: freebsd.org. A
DNSSEC Trust tree:
freebsd.org. (A)
|---freebsd.org. (DNSKEY keytag: 36786 alg: 8 flags: 256)
|---freebsd.org. (DNSKEY keytag: 32659 alg: 8 flags: 257)
|---freebsd.org. (DS keytag: 32659 digest type: 2)
|---org. (DNSKEY keytag: 49587 alg: 7 flags: 256)
|---org. (DNSKEY keytag: 9795 alg: 7 flags: 257)
|---org. (DNSKEY keytag: 21366 alg: 7 flags: 257)
|---org. (DS keytag: 21366 digest type: 1)
| |---. (DNSKEY keytag: 40926 alg: 8 flags: 256)
| |---. (DNSKEY keytag: 19036 alg: 8 flags: 257)
|---org. (DS keytag: 21366 digest type: 2)
|---. (DNSKEY keytag: 40926 alg: 8 flags: 256)
|---. (DNSKEY keytag: 19036 alg: 8 flags: 257)
;; Chase successful
....
[[network-apache]]
== Apache HTTP Server
The open source Apache HTTP Server is the most widely used web server.
FreeBSD does not install this web server by default, but it can be installed from the package:www/apache24[] package or port.
This section summarizes how to configure and start version 2._x_ of the Apache HTTP Server on FreeBSD.
For more detailed information about Apache 2.X and its configuration directives, refer to http://httpd.apache.org/[httpd.apache.org].
=== Configuring and Starting Apache
In FreeBSD, the main Apache HTTP Server configuration file is installed as [.filename]#/usr/local/etc/apache2x/httpd.conf#, where _x_ represents the version number.
This ASCII text file begins comment lines with a `+#+`.
The most frequently modified directives are:
`ServerRoot "/usr/local"`::
Specifies the default directory hierarchy for the Apache installation.
Binaries are stored in the [.filename]#bin# and [.filename]#sbin# subdirectories of the server root and configuration files are stored in the [.filename]#etc/apache2x# subdirectory.
`ServerAdmin you@example.com`::
Change this to the email address to receive problems with the server.
This address also appears on some server-generated pages, such as error documents.
`ServerName www.example.com:80`::
Allows an administrator to set a hostname which is sent back to clients for the server.
For example, `www` can be used instead of the actual hostname.
If the system does not have a registered DNS name, enter its IP address instead.
If the server will listen on an alternate report, change `80` to the alternate port number.
`DocumentRoot "/usr/local/www/apache2_x_/data"`::
The directory where documents will be served from.
By default, all requests are taken from this directory, but symbolic links and aliases may be used to point to other locations.
It is always a good idea to make a backup copy of the default Apache configuration file before making changes.
When the configuration of Apache is complete, save the file and verify the configuration using `apachectl`.
Running `apachectl configtest` should return `Syntax OK`.
To launch Apache at system startup, add the following line to [.filename]#/etc/rc.conf#:
[.programlisting]
....
apache24_enable="YES"
....
If Apache should be started with non-default options, the following line may be added to [.filename]#/etc/rc.conf# to specify the needed flags:
[.programlisting]
....
apache24_flags=""
....
If apachectl does not report configuration errors, start `httpd` now:
[source,shell]
....
# service apache24 start
....
The `httpd` service can be tested by entering `http://_localhost_` in a web browser, replacing _localhost_ with the fully-qualified domain name of the machine running `httpd`.
The default web page that is displayed is [.filename]#/usr/local/www/apache24/data/index.html#.
The Apache configuration can be tested for errors after making subsequent configuration changes while `httpd` is running using the following command:
[source,shell]
....
# service apache24 configtest
....
[NOTE]
====
It is important to note that `configtest` is not an man:rc[8] standard, and should not be expected to work for all startup scripts.
====
=== Virtual Hosting
Virtual hosting allows multiple websites to run on one Apache server.
The virtual hosts can be _IP-based_ or _name-based_.
IP-based virtual hosting uses a different IP address for each website.
Name-based virtual hosting uses the clients HTTP/1.1 headers to figure out the hostname, which allows the websites to share the same IP address.
To setup Apache to use name-based virtual hosting, add a `VirtualHost` block for each website.
For example, for the webserver named `www.domain.tld` with a virtual domain of `www.someotherdomain.tld`, add the following entries to [.filename]#httpd.conf#:
[.programlisting]
....
<VirtualHost *>
ServerName www.domain.tld
DocumentRoot /www/domain.tld
</VirtualHost>
<VirtualHost *>
ServerName www.someotherdomain.tld
DocumentRoot /www/someotherdomain.tld
</VirtualHost>
....
For each virtual host, replace the values for `ServerName` and `DocumentRoot` with the values to be used.
For more information about setting up virtual hosts, consult the official Apache documentation at: http://httpd.apache.org/docs/vhosts/[http://httpd.apache.org/docs/vhosts/].
=== Apache Modules
Apache uses modules to augment the functionality provided by the basic server.
Refer to http://httpd.apache.org/docs/current/mod/[http://httpd.apache.org/docs/current/mod/] for a complete listing of and the configuration details for the available modules.
In FreeBSD, some modules can be compiled with the package:www/apache24[] port.
Type `make config` within [.filename]#/usr/ports/www/apache24# to see which modules are available and which are enabled by default.
If the module is not compiled with the port, the FreeBSD Ports Collection provides an easy way to install many modules.
This section describes three of the most commonly used modules.
==== SSL support
At one in point in time, support for SSL inside of Apache required a secondary module called [.filename]#mod_ssl#.
This is no longer the case and the default install of Apache comes with SSL built into the web server.
An example of how to enable support for SSL websites is available in the installed file, [.filename]#httpd-ssl.conf# inside of the [.filename]#/usr/local/etc/apache24/extra# directory
Inside this directory is also a sample file called named [.filename]#ssl.conf-sample#.
It is recommended that both files be evaluated to properly set up secure websites in the Apache web server.
After the configuration of SSL is complete, the following line must be uncommented in the main [.filename]#http.conf# to activate the changes on the next restart or reload of Apache:
[.programlisting]
....
#Include etc/apache24/extra/httpd-ssl.conf
....
[WARNING]
====
SSL version two and version three have known vulnerability issues.
It is highly recommended TLS version 1.2 and 1.3 be enabled in place of the older SSL options.
This can be accomplished by setting the following options in the [.filename]#ssl.conf#:
====
[.programlisting]
....
SSLProtocol all -SSLv3 -SSLv2 +TLSv1.2 +TLSv1.3
SSLProxyProtocol all -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
....
To complete the configuration of SSL in the web server, uncomment the following line to ensure that the configuration will be pulled into Apache during restart or reload:
[.programlisting]
....
# Secure (SSL/TLS) connections
Include etc/apache24/extra/httpd-ssl.conf
....
The following lines must also be uncommented in the [.filename]#httpd.conf# to fully support SSL in Apache:
[.programlisting]
....
LoadModule authn_socache_module libexec/apache24/mod_authn_socache.so
LoadModule socache_shmcb_module libexec/apache24/mod_socache_shmcb.so
LoadModule ssl_module libexec/apache24/mod_ssl.so
....
The next step is to work with a certificate authority to have the appropriate certificates installed on the system.
This will set up a chain of trust for the site and prevent any warnings of self-signed certificates.
==== [.filename]#mod_perl#
The [.filename]#mod_perl# module makes it possible to write Apache modules in Perl.
In addition, the persistent interpreter embedded in the server avoids the overhead of starting an external interpreter and the penalty of Perl start-up time.
The [.filename]#mod_perl# can be installed using the package:www/mod_perl2[] package or port.
Documentation for using this module can be found at http://perl.apache.org/docs/2.0/index.html[http://perl.apache.org/docs/2.0/index.html].
==== [.filename]#mod_php#
_PHP: Hypertext Preprocessor_ (PHP) is a general-purpose scripting language that is especially suited for web development.
Capable of being embedded into HTML, its syntax draws upon C, Java(TM), and Perl with the intention of allowing web developers to write dynamically generated webpages quickly.
Support for PHP for Apache and any other feature written in the language, can be added by installing the appropriate port.
For all supported versions, search the package database using `pkg`:
[source,shell]
....
# pkg search php
....
A list will be displayed including the versions and additional features they provide.
The components are completely modular, meaning features are enabled by installing the appropriate port.
To install PHP version 7.4 for Apache, issue the following command:
[source,shell]
....
# pkg install mod_php74
....
If any dependency packages need to be installed, they will be installed as well.
By default, PHP will not be enabled.
The following lines will need to be added to the Apache configuration file located in [.filename]#/usr/local/etc/apache24# to make it active:
[.programlisting]
....
<FilesMatch "\.php$">
SetHandler application/x-httpd-php
</FilesMatch>
<FilesMatch "\.phps$">
SetHandler application/x-httpd-php-source
</FilesMatch>
....
In addition, the `DirectoryIndex` in the configuration file will also need to be updated and Apache will either need to be restarted or reloaded for the changes to take effect.
Support for many of the PHP features may also be installed by using `pkg`.
For example, to install support for XML or SSL, install their respective ports:
[source,shell]
....
# pkg install php74-xml php74-openssl
....
As before, the Apache configuration will need to be reloaded for the changes to take effect, even in cases where it was just a module install.
To perform a graceful restart to reload the configuration, issue the following command:
[source,shell]
....
# apachectl graceful
....
Once the install is complete, there are two methods of obtaining the installed PHP support modules and the environmental information of the build.
The first is to install the full PHP binary and running the command to gain the information:
[source,shell]
....
# pkg install php74
....
[source,shell]
....
# php -i |less
....
It is necessary to pass the output to a pager, such as the `more` or `less` to easier digest the amount of output.
Finally, to make any changes to the global configuration of PHP there is a well documented file installed into [.filename]#/usr/local/etc/php.ini#.
At the time of install, this file will not exist because there are two versions to choose from, one is [.filename]#php.ini-development# and the other is [.filename]#php.ini-production#.
These are starting points to assist administrators in their deployment.
==== HTTP2 Support
Apache support for the HTTP2 protocol is included by default when installing the port with `pkg`.
The new version of HTTP includes many improvements over the previous version, including utilizing a single connection to a website, reducing overall roundtrips of TCP connections.
Also, packet header data is compressed and HTTP2 requires encryption by default.
When Apache is configured to only use HTTP2, web browsers will require secure, encrypted HTTPS connections.
When Apache is configured to use both versions, HTTP1.1 will be considered a fall back option if any issues arise during the connection.
While this change does require administrators to make changes, they are positive and equate to a more secure Internet for everyone.
The changes are only required for sites not currently implementing SSL and TLS.
[NOTE]
====
This configuration depends on the previous sections, including TLS support.
It is recommended those instructions be followed before continuing with this configuration.
====
Start the process by enabling the http2 module by uncommenting the line in [.filename]#/usr/local/etc/apache24/httpd.conf# and replace the mpm_prefork module with mpm_event as the former does not support HTTP2.
[.programlisting]
....
LoadModule http2_module libexec/apache24/mod_http2.so
LoadModule mpm_event_module libexec/apache24/mod_mpm_event.so
....
[NOTE]
====
There is a separate [.filename]#mod_http2# port that is available.
It exists to deliver security and bug fixes quicker than the module installed with the bundled [.filename]#apache24# port.
It is not required for HTTP2 support but is available.
When installed, the [.filename]#mod_h2.so# should be used in place of [.filename]#mod_http2.so# in the Apache configuration.
====
There are two methods to implement HTTP2 in Apache; one way is globally for all sites and each VirtualHost running on the system.
To enable HTTP2 globally, add the following line under the ServerName directive:
[.programlisting]
....
Protocols h2 http/1.1
....
[NOTE]
====
To enable HTTP2 over plaintext, use h2h2chttp/1.1 in the [.filename]#httpd.conf#.
====
Having the h2c here will allow plaintext HTTP2 data to pass on the system but is not recommended.
In addition, using the http/1.1 here will allow fallback to the HTTP1.1 version of the protocol should it be needed by the system.
To enable HTTP2 for individual VirtualHosts, add the same line within the VirtualHost directive in either [.filename]#httpd.conf# or [.filename]#httpd-ssl.conf#.
Reload the configuration using the `apachectl`[parameter]#reload# command and test the configuration either by using either of the following methods after visiting one of the hosted pages:
[source,shell]
....
# grep "HTTP/2.0" /var/log/httpd-access.log
....
This should return something similar to the following:
[.programlisting]
....
192.168.1.205 - - [18/Oct/2020:18:34:36 -0400] "GET / HTTP/2.0" 304 -
192.0.2.205 - - [18/Oct/2020:19:19:57 -0400] "GET / HTTP/2.0" 304 -
192.0.0.205 - - [18/Oct/2020:19:20:52 -0400] "GET / HTTP/2.0" 304 -
192.0.2.205 - - [18/Oct/2020:19:23:10 -0400] "GET / HTTP/2.0" 304 -
....
The other method is using the web browser's built in site debugger or `tcpdump`; however, using either method is beyond the scope of this document.
Support for HTTP2 reverse proxy connections by using the [.filename]#mod_proxy_http2.so# module.
When configuring the ProxyPass or RewriteRules [P] statements, they should use h2:// for the connection.
=== Dynamic Websites
In addition to mod_perl and mod_php, other languages are available for creating dynamic web content.
These include Django and Ruby on Rails.
==== Django
Django is a BSD-licensed framework designed to allow developers to write high performance, elegant web applications quickly.
It provides an object-relational mapper so that data types are developed as Python objects.
A rich dynamic database-access API is provided for those objects without the developer ever having to write SQL.
It also provides an extensible template system so that the logic of the application is separated from the HTML presentation.
Django depends on [.filename]#mod_python#, and an SQL database engine.
In FreeBSD, the package:www/py-django[] port automatically installs [.filename]#mod_python# and supports the PostgreSQL, MySQL, or SQLite databases, with the default being SQLite.
To change the database engine, type `make config` within [.filename]#/usr/ports/www/py-django#, then install the port.
Once Django is installed, the application will need a project directory along with the Apache configuration in order to use the embedded Python interpreter.
This interpreter is used to call the application for specific URLs on the site.
To configure Apache to pass requests for certain URLs to the web application, add the following to [.filename]#httpd.conf#, specifying the full path to the project directory:
[.programlisting]
....
<Location "/">
SetHandler python-program
PythonPath "['/dir/to/the/django/packages/'] + sys.path"
PythonHandler django.core.handlers.modpython
SetEnv DJANGO_SETTINGS_MODULE mysite.settings
PythonAutoReload On
PythonDebug On
</Location>
....
Refer to https://docs.djangoproject.com[https://docs.djangoproject.com] for more information on how to use Django.
==== Ruby on Rails
Ruby on Rails is another open source web framework that provides a full development stack.
It is optimized to make web developers more productive and capable of writing powerful applications quickly.
On FreeBSD, it can be installed using the package:www/rubygem-rails[] package or port.
Refer to http://guides.rubyonrails.org[http://guides.rubyonrails.org] for more information on how to use Ruby on Rails.
[[network-ftp]]
== File Transfer Protocol (FTP)
The File Transfer Protocol (FTP) provides users with a simple way to transfer files to and from an FTP server.
FreeBSD includes FTP server software, ftpd, in the base system.
FreeBSD provides several configuration files for controlling access to the FTP server.
This section summarizes these files.
Refer to man:ftpd[8] for more details about the built-in FTP server.
=== Configuration
The most important configuration step is deciding which accounts will be allowed access to the FTP server.
A FreeBSD system has a number of system accounts which should not be allowed FTP access.
The list of users disallowed any FTP access can be found in [.filename]#/etc/ftpusers#. By default, it includes system accounts.
Additional users that should not be allowed access to FTP can be added.
In some cases it may be desirable to restrict the access of some users without preventing them completely from using FTP.
This can be accomplished be creating [.filename]#/etc/ftpchroot# as described in man:ftpchroot[5].
This file lists users and groups subject to FTP access restrictions.
To enable anonymous FTP access to the server, create a user named `ftp` on the FreeBSD system.
Users will then be able to log on to the FTP server with a username of `ftp` or `anonymous`.
When prompted for the password, any input will be accepted, but by convention, an email address should be used as the password.
The FTP server will call man:chroot[2] when an anonymous user logs in, to restrict access to only the home directory of the `ftp` user.
There are two text files that can be created to specify welcome messages to be displayed to FTP clients.
The contents of [.filename]#/etc/ftpwelcome# will be displayed to users before they reach the login prompt.
After a successful login, the contents of [.filename]#/etc/ftpmotd# will be displayed.
Note that the path to this file is relative to the login environment, so the contents of [.filename]#~ftp/etc/ftpmotd# would be displayed for anonymous users.
Once the FTP server has been configured, set the appropriate variable in [.filename]#/etc/rc.conf# to start the service during boot:
[.programlisting]
....
ftpd_enable="YES"
....
To start the service now:
[source,shell]
....
# service ftpd start
....
Test the connection to the FTP server by typing:
[source,shell]
....
% ftp localhost
....
The ftpd daemon uses man:syslog[3] to log messages.
By default, the system log daemon will write messages related to FTP in [.filename]#/var/log/xferlog#.
The location of the FTP log can be modified by changing the following line in [.filename]#/etc/syslog.conf#:
[.programlisting]
....
ftp.info /var/log/xferlog
....
[NOTE]
====
Be aware of the potential problems involved with running an anonymous FTP server.
In particular, think twice about allowing anonymous users to upload files.
It may turn out that the FTP site becomes a forum for the trade of unlicensed commercial software or worse.
If anonymous FTP uploads are required, then verify the permissions so that these files cannot be read by other anonymous users until they have been reviewed by an administrator.
====
[[network-samba]]
== File and Print Services for Microsoft(R) Windows(R) Clients (Samba)
Samba is a popular open source software package that provides file and print services using the SMB/CIFS protocol.
This protocol is built into Microsoft(R) Windows(R) systems.
It can be added to non-Microsoft(R) Windows(R) systems by installing the Samba client libraries.
The protocol allows clients to access shared data and printers.
These shares can be mapped as a local disk drive and shared printers can be used as if they were local printers.
On FreeBSD, the Samba client libraries can be installed using the package:net/samba413[] port or package.
The client provides the ability for a FreeBSD system to access SMB/CIFS shares in a Microsoft(R) Windows(R) network.
A FreeBSD system can also be configured to act as a Samba server by installing the same package:net/samba413[] port or package.
This allows the administrator to create SMB/CIFS shares on the FreeBSD system which can be accessed by clients running Microsoft(R) Windows(R) or the Samba client libraries.
=== Server Configuration
Samba is configured in [.filename]#/usr/local/etc/smb4.conf#.
This file must be created before Samba can be used.
A simple [.filename]#smb4.conf# to share directories and printers with Windows(R) clients in a workgroup is shown here.
For more complex setups involving LDAP or Active Directory, it is easier to use man:samba-tool[8] to create the initial [.filename]#smb4.conf#.
[.programlisting]
....
[global]
workgroup = WORKGROUP
server string = Samba Server Version %v
netbios name = ExampleMachine
wins support = Yes
security = user
passdb backend = tdbsam
# Example: share /usr/src accessible only to 'developer' user
[src]
path = /usr/src
valid users = developer
writable = yes
browsable = yes
read only = no
guest ok = no
public = no
create mask = 0666
directory mask = 0755
....
==== Global Settings
Settings that describe the network are added in [.filename]#/usr/local/etc/smb4.conf#:
`workgroup`::
The name of the workgroup to be served.
`netbios name`::
The NetBIOS name by which a Samba server is known.
By default, it is the same as the first component of the host's DNS name.
`server string`::
The string that will be displayed in the output of `net view` and some other networking tools that seek to display descriptive text about the server.
`wins support`::
Whether Samba will act as a WINS server.
Do not enable support for WINS on more than one server on the network.
==== Security Settings
The most important settings in [.filename]#/usr/local/etc/smb4.conf# are the security model and the backend password format.
These directives control the options:
`security`::
The most common settings are `security = share` and `security = user`.
If the clients use usernames that are the same as their usernames on the FreeBSD machine, user level security should be used.
This is the default security policy and it requires clients to first log on before they can access shared resources.
+
In share level security, clients do not need to log onto the server with a valid username and password before attempting to connect to a shared resource.
This was the default security model for older versions of Samba.
`passdb backend`::
Samba has several different backend authentication models.
Clients may be authenticated with LDAP, NIS+, an SQL database, or a modified password file.
The recommended authentication method, `tdbsam`, is ideal for simple networks and is covered here.
For larger or more complex networks, `ldapsam` is recommended.
`smbpasswd` was the former default and is now obsolete.
==== Samba Users
FreeBSD user accounts must be mapped to the `SambaSAMAccount` database for Windows(R) clients to access the share.
Map existing FreeBSD user accounts using man:pdbedit[8]:
[source,shell]
....
# pdbedit -a -u username
....
This section has only mentioned the most commonly used settings.
Refer to the https://wiki.samba.org[Official Samba Wiki] for additional information about the available configuration options.
=== Starting Samba
To enable Samba at boot time, add the following line to [.filename]#/etc/rc.conf#:
[.programlisting]
....
samba_server_enable="YES"
....
To start Samba now:
[source,shell]
....
# service samba_server start
Performing sanity check on Samba configuration: OK
Starting nmbd.
Starting smbd.
....
Samba consists of three separate daemons.
Both the nmbd and smbd daemons are started by `samba_enable`.
If winbind name resolution is also required, set:
[.programlisting]
....
winbindd_enable="YES"
....
Samba can be stopped at any time by typing:
[source,shell]
....
# service samba_server stop
....
Samba is a complex software suite with functionality that allows broad integration with Microsoft(R) Windows(R) networks.
For more information about functionality beyond the basic configuration described here, refer to https://www.samba.org[https://www.samba.org].
[[network-ntp]]
== Clock Synchronization with NTP
Over time, a computer's clock is prone to drift.
This is problematic as many network services require the computers on a network to share the same accurate time.
Accurate time is also needed to ensure that file timestamps stay consistent.
The Network Time Protocol (NTP) is one way to provide clock accuracy in a network.
FreeBSD includes man:ntpd[8] which can be configured to query other NTP servers to synchronize the clock on that machine or to provide time services to other computers in the network.
This section describes how to configure ntpd on FreeBSD.
Further documentation can be found in [.filename]#/usr/share/doc/ntp/# in HTML format.
=== NTP Configuration
On FreeBSD, the built-in ntpd can be used to synchronize a system's clock.
ntpd is configured using man:rc.conf[5] variables and [.filename]#/etc/ntp.conf#, as detailed in the following sections.
ntpd communicates with its network peers using UDP packets.
Any firewalls between your machine and its NTP peers must be configured to allow UDP packets in and out on port 123.
==== The [.filename]#/etc/ntp.conf# file
ntpd reads [.filename]#/etc/ntp.conf# to determine which NTP servers to query.
Choosing several NTP servers is recommended in case one of the servers becomes unreachable or its clock proves unreliable.
As ntpd receives responses, it favors reliable servers over the less reliable ones.
The servers which are queried can be local to the network, provided by an ISP, or selected from an http://support.ntp.org/bin/view/Servers/WebHome[ online list of publicly accessible NTP servers].
When choosing a public NTP server, select one that is geographically close and review its usage policy.
The `pool` configuration keyword selects one or more servers from a pool of servers.
An http://support.ntp.org/bin/view/Servers/NTPPoolServers[ online list of publicly accessible NTP pools] is available, organized by geographic area.
In addition, FreeBSD provides a project-sponsored pool, `0.freebsd.pool.ntp.org`.
.Sample [.filename]#/etc/ntp.conf#
[example]
====
This is a simple example of an [.filename]#ntp.conf# file.
It can safely be used as-is; it contains the recommended `restrict` options for operation on a publicly-accessible network connection.
[.programlisting]
....
# Disallow ntpq control/query access. Allow peers to be added only
# based on pool and server statements in this file.
restrict default limited kod nomodify notrap noquery nopeer
restrict source limited kod nomodify notrap noquery
# Allow unrestricted access from localhost for queries and control.
restrict 127.0.0.1
restrict ::1
# Add a specific server.
server ntplocal.example.com iburst
# Add FreeBSD pool servers until 3-6 good servers are available.
tos minclock 3 maxclock 6
pool 0.freebsd.pool.ntp.org iburst
# Use a local leap-seconds file.
leapfile "/var/db/ntpd.leap-seconds.list"
....
====
The format of this file is described in man:ntp.conf[5].
The descriptions below provide a quick overview of just the keywords used in the sample file above.
By default, an NTP server is accessible to any network host.
The `restrict` keyword controls which systems can access the server.
Multiple `restrict` entries are supported, each one refining the restrictions given in previous statements.
The values shown in the example grant the local system full query and control access, while allowing remote systems only the ability to query the time.
For more details, refer to the `Access Control Support` subsection of man:ntp.conf[5].
The `server` keyword specifies a single server to query.
The file can contain multiple server keywords, with one server listed on each line.
The `pool` keyword specifies a pool of servers.
ntpd will add one or more servers from this pool as needed to reach the number of peers specified using the `tos minclock` value.
The `iburst` keyword directs ntpd to perform a burst of eight quick packet exchanges with a server when contact is first established, to help quickly synchronize system time.
The `leapfile` keyword specifies the location of a file containing information about leap seconds.
The file is updated automatically by man:periodic[8].
The file location specified by this keyword must match the location set in the `ntp_db_leapfile` variable in [.filename]#/etc/rc.conf#.
==== NTP entries in [.filename]#/etc/rc.conf#
Set `ntpd_enable=YES` to start ntpd at boot time.
Once `ntpd_enable=YES` has been added to [.filename]#/etc/rc.conf#, ntpd can be started immediately without rebooting the system by typing:
[source,shell]
....
# service ntpd start
....
Only `ntpd_enable` must be set to use ntpd.
The [.filename]#rc.conf# variables listed below may also be set as needed.
Set `ntpd_sync_on_start=YES` to allow ntpd to step the clock any amount, one time at startup.
Normally ntpd will log an error message and exit if the clock is off by more than 1000 seconds.
This option is especially useful on systems without a battery-backed realtime clock.
Set `ntpd_oomprotect=YES` to protect the ntpd daemon from being killed by the system attempting to recover from an Out Of Memory (OOM) condition.
Set `ntpd_config=` to the location of an alternate [.filename]#ntp.conf# file.
Set `ntpd_flags=` to contain any other ntpd flags as needed, but avoid using these flags which are managed internally by [.filename]#/etc/rc.d/ntpd#:
* `-p` (pid file location)
* `-c` (set `ntpd_config=` instead)
==== ntpd and the unpriveleged `ntpd` user
ntpd on FreeBSD can start and run as an unpriveleged user.
Doing so requires the man:mac_ntpd[4] policy module.
The [.filename]#/etc/rc.d/ntpd# startup script first examines the NTP configuration.
If possible, it loads the `mac_ntpd` module, then starts ntpd as unpriveleged user `ntpd` (user id 123).
To avoid problems with file and directory access, the startup script will not automatically start ntpd as `ntpd` when the configuration contains any file-related options.
The presence of any of the following in `ntpd_flags` requires manual configuration as described below to run as the `ntpd` user:
* -f or --driftfile
* -i or --jaildir
* -k or --keyfile
* -l or --logfile
* -s or --statsdir
The presence of any of the following keywords in [.filename]#ntp.conf# requires manual configuration as described below to run as the `ntpd` user:
* crypto
* driftfile
* key
* logdir
* statsdir
To manually configure ntpd to run as user `ntpd` you must:
* Ensure that the `ntpd` user has access to all the files and directories specified in the configuration.
* Arrange for the `mac_ntpd` module to be loaded or compiled into the kernel. See man:mac_ntpd[4] for details.
* Set `ntpd_user="ntpd"` in [.filename]#/etc/rc.conf#
=== Using NTP with a PPP Connection
ntpd does not need a permanent connection to the Internet to function properly.
However, if a PPP connection is configured to dial out on demand, NTP traffic should be prevented from triggering a dial out or keeping the connection alive.
This can be configured with `filter` directives in [.filename]#/etc/ppp/ppp.conf#. For example:
[.programlisting]
....
set filter dial 0 deny udp src eq 123
# Prevent NTP traffic from initiating dial out
set filter dial 1 permit 0 0
set filter alive 0 deny udp src eq 123
# Prevent incoming NTP traffic from keeping the connection open
set filter alive 1 deny udp dst eq 123
# Prevent outgoing NTP traffic from keeping the connection open
set filter alive 2 permit 0/0 0/0
....
For more details, refer to the `PACKET FILTERING` section in man:ppp[8] and the examples in [.filename]#/usr/share/examples/ppp/#.
[NOTE]
====
Some Internet access providers block low-numbered ports, preventing NTP from functioning since replies never reach the machine.
====
[[network-iscsi]]
== iSCSI Initiator and Target Configuration
iSCSI is a way to share storage over a network.
Unlike NFS, which works at the file system level, iSCSI works at the block device level.
In iSCSI terminology, the system that shares the storage is known as the _target_.
The storage can be a physical disk, or an area representing multiple disks or a portion of a physical disk.
For example, if the disk(s) are formatted with ZFS, a zvol can be created to use as the iSCSI storage.
The clients which access the iSCSI storage are called _initiators_.
To initiators, the storage available through iSCSI appears as a raw, unformatted disk known as a LUN.
Device nodes for the disk appear in [.filename]#/dev/# and the device must be separately formatted and mounted.
FreeBSD provides a native, kernel-based iSCSI target and initiator.
This section describes how to configure a FreeBSD system as a target or an initiator.
[[network-iscsi-target]]
=== Configuring an iSCSI Target
To configure an iSCSI target, create the [.filename]#/etc/ctl.conf# configuration file, add a line to [.filename]#/etc/rc.conf# to make sure the man:ctld[8] daemon is automatically started at boot, and then start the daemon.
The following is an example of a simple [.filename]#/etc/ctl.conf# configuration file.
Refer to man:ctl.conf[5] for a more complete description of this file's available options.
[.programlisting]
....
portal-group pg0 {
discovery-auth-group no-authentication
listen 0.0.0.0
listen [::]
}
target iqn.2012-06.com.example:target0 {
auth-group no-authentication
portal-group pg0
lun 0 {
path /data/target0-0
size 4G
}
}
....
The first entry defines the `pg0` portal group.
Portal groups define which network addresses the man:ctld[8] daemon will listen on.
The `discovery-auth-group no-authentication` entry indicates that any initiator is allowed to perform iSCSI target discovery without authentication.
Lines three and four configure man:ctld[8] to listen on all IPv4 (`listen 0.0.0.0`) and IPv6 (`listen [::]`) addresses on the default port of 3260.
It is not necessary to define a portal group as there is a built-in portal group called `default`.
In this case, the difference between `default` and `pg0` is that with `default`, target discovery is always denied, while with `pg0`, it is always allowed.
The second entry defines a single target.
Target has two possible meanings: a machine serving iSCSI or a named group of LUNs.
This example uses the latter meaning, where `iqn.2012-06.com.example:target0` is the target name.
This target name is suitable for testing purposes.
For actual use, change `com.example` to the real domain name, reversed.
The `2012-06` represents the year and month of acquiring control of that domain name, and `target0` can be any value.
Any number of targets can be defined in this configuration file.
The `auth-group no-authentication` line allows all initiators to connect to the specified target and `portal-group pg0` makes the target reachable through the `pg0` portal group.
The next section defines the LUN.
To the initiator, each LUN will be visible as a separate disk device.
Multiple LUNs can be defined for each target.
Each LUN is identified by a number, where LUN 0 is mandatory.
The `path /data/target0-0` line defines the full path to a file or zvol backing the LUN.
That path must exist before starting man:ctld[8].
The second line is optional and specifies the size of the LUN.
Next, to make sure the man:ctld[8] daemon is started at boot, add this line to [.filename]#/etc/rc.conf#:
[.programlisting]
....
ctld_enable="YES"
....
To start man:ctld[8] now, run this command:
[source,shell]
....
# service ctld start
....
As the man:ctld[8] daemon is started, it reads [.filename]#/etc/ctl.conf#.
If this file is edited after the daemon starts, use this command so that the changes take effect immediately:
[source,shell]
....
# service ctld reload
....
==== Authentication
The previous example is inherently insecure as it uses no authentication, granting anyone full access to all targets.
To require a username and password to access targets, modify the configuration as follows:
[.programlisting]
....
auth-group ag0 {
chap username1 secretsecret
chap username2 anothersecret
}
portal-group pg0 {
discovery-auth-group no-authentication
listen 0.0.0.0
listen [::]
}
target iqn.2012-06.com.example:target0 {
auth-group ag0
portal-group pg0
lun 0 {
path /data/target0-0
size 4G
}
}
....
The `auth-group` section defines username and password pairs.
An initiator trying to connect to `iqn.2012-06.com.example:target0` must first specify a defined username and secret.
However, target discovery is still permitted without authentication.
To require target discovery authentication, set `discovery-auth-group` to a defined `auth-group` name instead of `no-authentication`.
It is common to define a single exported target for every initiator.
As a shorthand for the syntax above, the username and password can be specified directly in the target entry:
[.programlisting]
....
target iqn.2012-06.com.example:target0 {
portal-group pg0
chap username1 secretsecret
lun 0 {
path /data/target0-0
size 4G
}
}
....
[[network-iscsi-initiator]]
=== Configuring an iSCSI Initiator
[NOTE]
====
The iSCSI initiator described in this section is supported starting with FreeBSD 10.0-RELEASE.
To use the iSCSI initiator available in older versions, refer to man:iscontrol[8].
====
The iSCSI initiator requires that the man:iscsid[8] daemon is running.
This daemon does not use a configuration file.
To start it automatically at boot, add this line to [.filename]#/etc/rc.conf#:
[.programlisting]
....
iscsid_enable="YES"
....
To start man:iscsid[8] now, run this command:
[source,shell]
....
# service iscsid start
....
Connecting to a target can be done with or without an [.filename]#/etc/iscsi.conf# configuration file.
This section demonstrates both types of connections.
==== Connecting to a Target Without a Configuration File
To connect an initiator to a single target, specify the IP address of the portal and the name of the target:
[source,shell]
....
# iscsictl -A -p 10.10.10.10 -t iqn.2012-06.com.example:target0
....
To verify if the connection succeeded, run `iscsictl` without any arguments.
The output should look similar to this:
[.programlisting]
....
Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Connected: da0
....
In this example, the iSCSI session was successfully established, with [.filename]#/dev/da0# representing the attached LUN.
If the `iqn.2012-06.com.example:target0` target exports more than one LUN, multiple device nodes will be shown in that section of the output:
[source,shell]
....
Connected: da0 da1 da2.
....
Any errors will be reported in the output, as well as the system logs.
For example, this message usually means that the man:iscsid[8] daemon is not running:
[.programlisting]
....
Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Waiting for iscsid(8)
....
The following message suggests a networking problem, such as a wrong IP address or port:
[.programlisting]
....
Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.11 Connection refused
....
This message means that the specified target name is wrong:
[.programlisting]
....
Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Not found
....
This message means that the target requires authentication:
[.programlisting]
....
Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Authentication failed
....
To specify a CHAP username and secret, use this syntax:
[source,shell]
....
# iscsictl -A -p 10.10.10.10 -t iqn.2012-06.com.example:target0 -u user -s secretsecret
....
==== Connecting to a Target with a Configuration File
To connect using a configuration file, create [.filename]#/etc/iscsi.conf# with contents like this:
[.programlisting]
....
t0 {
TargetAddress = 10.10.10.10
TargetName = iqn.2012-06.com.example:target0
AuthMethod = CHAP
chapIName = user
chapSecret = secretsecret
}
....
The `t0` specifies a nickname for the configuration file section.
It will be used by the initiator to specify which configuration to use.
The other lines specify the parameters to use during connection.
The `TargetAddress` and `TargetName` are mandatory, whereas the other options are optional.
In this example, the CHAP username and secret are shown.
To connect to the defined target, specify the nickname:
[source,shell]
....
# iscsictl -An t0
....
Alternately, to connect to all targets defined in the configuration file, use:
[source,shell]
....
# iscsictl -Aa
....
To make the initiator automatically connect to all targets in [.filename]#/etc/iscsi.conf#, add the following to [.filename]#/etc/rc.conf#:
[.programlisting]
....
iscsictl_enable="YES"
iscsictl_flags="-Aa"
....
|