summaryrefslogtreecommitdiff
path: root/lib/libc/gen/sysctl.3
blob: 5aa2e738e991efb5f8866b8947a0851a3233daff (plain)
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
.\"	$NetBSD: sysctl.3,v 1.178 2006/08/11 19:17:47 christos Exp $
.\"
.\" Copyright (c) 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)sysctl.3	8.4 (Berkeley) 5/9/95
.\"
.Dd August 10, 2006
.Dt SYSCTL 3
.Os
.Sh NAME
.Nm sysctl ,
.Nm sysctlbyname ,
.Nm sysctlgetmibinfo ,
.Nm sysctlnametomib
.Nd get or set system information
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/sysctl.h
.Ft int
.Fn sysctl "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" \
"const void *newp" "size_t newlen"
.Ft int
.Fn sysctlbyname "const char *sname" "void *oldp" "size_t *oldlenp" \
"void *newp" "size_t newlen"
.Ft int
.Fn sysctlgetmibinfo "const char *sname" "int *name" "u_int *namelenp" \
"char *cname" "size_t *csz" "struct sysctlnode **rnode" "int v"
.Ft int
.Fn sysctlnametomib "const char *sname" "int *name" "size_t *namelenp"
.Sh DESCRIPTION
The
.Nm
function retrieves system information and allows processes with
appropriate privileges to set system information.
The information available from
.Nm
consists of integers, strings, and tables.
Information may be retrieved and set from the command interface
using the
.Xr sysctl 8
utility.
.Pp
Unless explicitly noted below,
.Nm
returns a consistent snapshot of the data requested.
Consistency is obtained by locking the destination
buffer into memory so that the data may be copied out without blocking.
Calls to
.Nm
are serialized to avoid deadlock.
.Pp
The state is described using a ``Management Information Base'' (MIB)
style name, listed in
.Fa name ,
which is a
.Fa namelen
length array of integers.
.Pp
The
.Fn sysctlbyname
function accepts a string representation of a MIB entry and internally
maps it to the appropriate numeric MIB representation.
Its semantics are otherwise no different from
.Fn sysctl .
.Pp
The information is copied into the buffer specified by
.Fa oldp .
The size of the buffer is given by the location specified by
.Fa oldlenp
before the call,
and that location gives the amount of data copied after a successful call.
If the amount of data available is greater
than the size of the buffer supplied,
the call supplies as much data as fits in the buffer provided
and returns with the error code ENOMEM.
If the old value is not desired,
.Fa oldp
and
.Fa oldlenp
should be set to
.Dv NULL .
.Pp
The size of the available data can be determined by calling
.Nm
with a
.Dv NULL
parameter for
.Fa oldp .
The size of the available data will be returned in the location pointed to by
.Fa oldlenp .
For some operations, the amount of space may change often.
For these operations,
the system attempts to round up so that the returned size is
large enough for a call to return the data shortly thereafter.
.Pp
To set a new value,
.Fa newp
is set to point to a buffer of length
.Fa newlen
from which the requested value is to be taken.
If a new value is not to be set,
.Fa newp
should be set to
.Dv NULL
and
.Fa newlen
set to 0.
.Pp
The
.Fn sysctlnametomib
function can be used to map the string representation of a MIB entry
to the numeric version.
The
.Fa name
argument should point to an array of integers large enough to hold the
MIB, and
.Fa namelenp
should indicate the number of integer slots available.
Following a successful translation, the size_t indicated by
.Fa namelenp
will be changed to show the number of slots consumed.
.Pp
The
.Fn sysctlgetmibinfo
function performs name translation similar to
.Fn sysctlnametomib ,
but also canonicalizes the name (or returns the first erroneous token
from the string being parsed) into the space indicated by
.Fa cname
and
.Fa csz .
.Fa csz
should indicate the size of the buffer pointed to by
.Fa cname
and on return, will indicate the size of the returned string including
the trailing
.Sq nul
character.
.Pp
The
.Fa rnode
and
.Fa v
arguments to
.Fn sysctlgetmibinfo
are used to provide a tree for it to parse into, and to get back
either a pointer to, or a copy of, the terminal node.
If
.Fa rnode
is
.Dv NULL ,
.Fn sysctlgetmibinfo
uses its own internal tree for parsing, and checks it against the
kernel at each call, to make sure that the name-to-number mapping is
kept up to date.
The
.Fa v
argument is ignored in this case.
If
.Fa rnode
is not
.Dv NULL
but the pointer it references is, on a successful return,
.Fa rnode
will be adjusted to point to a copy of the terminal node.
The
.Fa v
argument indicates which version of the
.Nm
node structure the caller wants.
The application must later
.Fn free
this copy.
If neither
.Fa rnode
nor the pointer it references are
.Dv NULL ,
the pointer is used as the address of a tree over which the parsing is
done.
In this last case, the tree is not checked against the kernel, no
refreshing of the mappings is performed, and the value given by
.Fa v
must agree with the version indicated by the tree.
It is recommended that applications always use
.Dv SYSCTL_VERSION
as the value for
.Fa v ,
as defined in the include file
.Pa sys/sysctl.h .
.Pp
The top level names are defined with a CTL_ prefix in
.Aq Pa sys/sysctl.h ,
and are as follows.
The next and subsequent levels down are found in the include files
listed here, and described in separate sections below.
.Pp
.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent
.It Sy Name	Next level names	Description
.It CTL\_KERN	sys/sysctl.h	High kernel limits
.It CTL\_VM	uvm/uvm_param.h	Virtual memory
.It CTL\_VFS	sys/mount.h	Filesystem
.It CTL\_NET	sys/socket.h	Networking
.It CTL\_DEBUG	sys/sysctl.h	Debugging
.It CTL\_HW	sys/sysctl.h	Generic CPU, I/O
.It CTL\_MACHDEP	sys/sysctl.h	Machine dependent
.It CTL\_USER	sys/sysctl.h	User-level
.It CTL\_DDB	sys/sysctl.h	In-kernel debugger
.It CTL\_PROC	sys/sysctl.h	Per-process
.It CTL\_VENDOR	?	Vendor specific
.It CTL\_EMUL	sys/sysctl.h	Emulation settings
.It CTL\_SECURITY	sys/sysctl.h	Security settings
.El
.Pp
For example, the following retrieves the maximum number of processes allowed
in the system:
.Bd -literal -offset indent -compact
int mib[2], maxproc;
size_t len;
.sp
mib[0] = CTL_KERN;
mib[1] = KERN_MAXPROC;
len = sizeof(maxproc);
sysctl(mib, 2, \*[Am]maxproc, \*[Am]len, NULL, 0);
.Ed
.sp
To retrieve the standard search path for the system utilities:
.Bd -literal -offset indent -compact
int mib[2];
size_t len;
char *p;
.sp
mib[0] = CTL_USER;
mib[1] = USER_CS_PATH;
sysctl(mib, 2, NULL, \*[Am]len, NULL, 0);
p = malloc(len);
sysctl(mib, 2, p, \*[Am]len, NULL, 0);
.Ed
.Sh CTL_DEBUG
The debugging variables vary from system to system.
A debugging variable may be added or deleted without need to recompile
.Nm
to know about it.
Each time it runs,
.Nm
gets the list of debugging variables from the kernel and
displays their current values.
The system defines twenty
.Va ( struct ctldebug )
variables named
.Dv debug0
through
.Dv debug19 .
They are declared as separate variables so that they can be
individually initialized at the location of their associated variable.
The loader prevents multiple use of the same variable by issuing errors
if a variable is initialized in more than one place.
For example, to export the variable
.Dv dospecialcheck
as a debugging variable, the following declaration would be used:
.Bd -literal -offset indent -compact
int dospecialcheck = 1;
struct ctldebug debug5 = { "dospecialcheck", \*[Am]dospecialcheck };
.Ed
.Pp
Note that the dynamic implementation of
.Nm
currently in use largely makes this particular
.Nm
interface obsolete.
See
.Xr sysctl 8
.\" and
.\" .Xr sysctl 9
for more information.
.Sh CTL_VFS
A distinguished second level name, VFS_GENERIC,
is used to get general information about all filesystems.
One of its third level identifiers is VFS_MAXTYPENUM
that gives the highest valid filesystem type number.
Its other third level identifier is VFS_CONF that
returns configuration information about the filesystem
type given as a fourth level identifier.
The remaining second level identifiers are the
filesystem type number returned by a
.Xr statvfs 2
call or from VFS_CONF.
The third level identifiers available for each filesystem
are given in the header file that defines the mount
argument structure for that filesystem.
.Sh CTL_HW
The string and integer information available for the CTL_HW level
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "Second level nameXXXXXX" "struct disk_sysctlXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It HW\_ALIGNBYTES	integer	no
.It HW\_BYTEORDER	integer	no
.It HW\_CNMAGIC	string	yes
.It HW\_DISKNAMES	string	no
.It HW\_DISKSTATS	struct	no
.It HW\_MACHINE	string	no
.It HW\_MACHINE\_ARCH	string	no
.It HW\_MODEL	string	no
.It HW\_NCPU	integer	no
.It HW\_PAGESIZE	integer	no
.It HW\_PHYSMEM	integer	no
.It HW\_PHYSMEM64	quad	no
.It HW\_USERMEM	integer	no
.It HW\_USERMEM64	quad	no
.El
.Pp
.Bl -tag -width "123456"
.It Li HW_ALIGNBYTES
Alignment constraint for all possible data types.
This shows the value
.Dv ALIGNBYTES
in
.Pa /usr/include/machine/param.h ,
at the kernel compilation time.
.It Li HW_BYTEORDER
The byteorder (4,321, or 1,234).
.It Li HW_CNMAGIC
The console magic key sequence.
.It Li HW_DISKNAMES
The list of (space separated) disk device and NFS mount names on the system.
.It Li HW_IOSTATNAMES
A space separated list of devices that will have I/O statistics
collected on them.
.It Li HW_IOSTATS
Return statistical information on the NFS mounts, disk and tape
devices on the system.
An array of
.Va struct io_sysctl
structures is returned,
whose size depends on the current number of such objects in the system.
The third level name is the size of the
.Va struct io_sysctl .
The type of object can be determined by examining the
.Va type
element of
.Va struct io_sysctl .
Which can be
.Dv IOSTAT_DISK
(disk drive),
.Dv IOSTAT_TAPE
(tape drive), or
.Dv IOSTAT_NFS
(NFS mount).
.It Li HW_MACHINE
The machine class.
.It Li HW_MACHINE_ARCH
The machine CPU class.
.It Li HW_MODEL
The machine model.
.It Li HW_NCPU
The number of CPUs.
.ne 1i
.It Li HW_PAGESIZE
The software page size.
.It Li HW_PHYSMEM
The bytes of physical memory as a 32-bit integer.
.It Li HW_PHYSMEM64
The bytes of physical memory as a 64-bit integer.
.It Li HW_USERMEM
The bytes of non-kernel memory as a 32-bit integer.
.It Li HW_USERMEM64
The bytes of non-kernel memory as a 64-bit integer.
.El
.Sh CTL_KERN
The string and integer information available for the CTL_KERN level
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
The types of data currently available are process information,
system vnodes, the open file entries, routing table entries,
virtual memory statistics, load average history, and clock rate
information.
.Bl -column "KERNXPOSIXXREADERXWRITERXLOCKS" "struct clockrateXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It KERN\_ARGMAX	integer	no
.It KERN\_AUTONICETIME	integer	yes
.It KERN\_AUTONICEVAL	integer	yes
.It KERN\_BOOTTIME	struct timeval	no
.It KERN\_BUFQ	node	not applicable
.It KERN\_CCPU	integer	no
.It KERN\_CLOCKRATE	struct clockinfo	no
.It KERN\_CONSDEV	integer	no
.It KERN\_CP\_ID	struct	no
.It KERN\_CP\_TIME	uint64_t[\|]	no
.It KERN\_DEFCORENAME	string	yes
.It KERN\_DOMAINNAME	string	yes
.It KERN\_DRIVERS	struct kinfo_drivers	no
.It KERN\_FILE	struct file	no
.It KERN\_FORKFSLEEP	integer	yes
.It KERN\_FSCALE	integer	no
.It KERN\_FSYNC	integer	no
.It KERN\_HARDCLOCK\_TICKS	integer	no
.It KERN\_HOSTID	integer	yes
.It KERN\_HOSTNAME	string	yes
.It KERN\_IOV\_MAX	integer	no
.It KERN\_JOB\_CONTROL	integer	no
.It KERN\_LABELOFFSET	integer	no
.It KERN\_LABELSECTOR	integer	no
.It KERN\_LOGIN\_NAME\_MAX	integer	no
.It KERN\_LOGSIGEXIT	integer	yes
.It KERN\_MAPPED\_FILES	integer	no
.It KERN\_MAXFILES	integer	yes
.It KERN\_MAXPARTITIONS	integer	no
.It KERN\_MAXPHYS	integer	no
.It KERN\_MAXPROC	integer	yes
.It KERN\_MAXPTYS	integer	yes
.It KERN\_MAXVNODES	integer	yes
.It KERN\_MBUF	node	not applicable
.It KERN\_MEMLOCK	integer	no
.It KERN\_MEMLOCK\_RANGE	integer	no
.It KERN\_MEMORY\_PROTECTION	integer	no
.It KERN\_MONOTONIC\_CLOCK	integer	no
.It KERN\_MSGBUF	integer	no
.It KERN\_MSGBUFSIZE	integer	no
.It KERN\_NGROUPS	integer	no
.It KERN\_NTPTIME	struct ntptimeval	no
.It KERN\_OSRELEASE	string	no
.It KERN\_OSREV	integer	no
.It KERN\_OSTYPE	string	no
.It KERN\_PIPE	node	not applicable
.It KERN\_POSIX1	integer	no
.It KERN\_POSIX\_BARRIERS	integer	no
.It KERN\_POSIX\_READER\_WRITER\_LOCKS	integer	no
.It KERN\_POSIX\_SEMAPHORES	integer	no
.It KERN\_POSIX\_SPIN\_LOCKS	integer	no
.It KERN\_POSIX\_THREADS	integer	no
.It KERN\_POSIX\_TIMERS	integer	no
.It KERN\_PROC	struct kinfo_proc	no
.It KERN\_PROC2	struct kinfo_proc2	no
.It KERN\_PROC\_ARGS	string	no
.It KERN\_PROF	node	not applicable
.It KERN\_RAWPARTITION	integer	no
.It KERN\_ROOT\_DEVICE	string	no
.It KERN\_ROOT\_PARTITION	integer	no
.It KERN\_RTC\_OFFSET	integer	yes
.It KERN\_SAVED\_IDS	integer	no
.It KERN\_SECURELVL	integer	raise only
.It KERN\_SYNCHRONIZED\_IO	integer	no
.It KERN\_SYSVIPC\_INFO	node	not applicable
.It KERN\_SYSVMSG	integer	no
.It KERN\_SYSVSEM	integer	no
.It KERN\_SYSVSHM	integer	no
.It KERN\_TIMEX	struct	no
.It KERN\_TKSTAT	node	not applicable
.It KERN\_URANDOM	integer	no
.It KERN\_VERIEXEC	node	not applicable
.It KERN\_VERSION	string	no
.It KERN\_VNODE	struct vnode	no
.El
.ne 1i
.Pp
.Bl -tag -width "123456"
.It Li KERN_ARGMAX
The maximum bytes of argument to
.Xr execve 2 .
.It Li KERN_AUTONICETIME
The number of seconds of CPU-time a non-root process may accumulate before
having its priority lowered from the default to the value of KERN_AUTONICEVAL.
If set to 0, automatic lowering of priority is not performed, and if set to \-1
all non-root processes are immediately lowered.
.It Li KERN_AUTONICEVAL
The priority assigned for automatically niced processes.
.It Li KERN_BOOTTIME
A
.Va struct timeval
structure is returned.
This structure contains the time that the system was booted.
.It Li KERN_CCPU
The scheduler exponential decay value.
.It Li KERN_CLOCKRATE
A
.Va struct clockinfo
structure is returned.
This structure contains the clock, statistics clock and profiling clock
frequencies, the number of micro-seconds per hz tick, and the clock
skew rate.
.It Li KERN_CONSDEV
Console device.
.It Li KERN_CP_ID
Mapping of CPU number to CPU id.
.It Li KERN_CP_TIME
Returns an array of CPUSTATES uint64_ts.
This array contains the
number of clock ticks spent in different CPU states.
On multi-processor systems, the sum across all CPUs is returned unless
appropriate space is given for one data set for each CPU.
Data for a specific CPU can also be obtained by adding the number of the
CPU at the end of the MIB, enlarging it by one.
.It Li KERN_DEFCORENAME
Default template for the name of core dump files (see also PROC_PID_CORENAME
in the per-process variables CTL_PROC, and
.Xr core 5
for format of this template).
The default value is
.Nm %n.core
and can be changed with the kernel configuration option
.Cd options DEFCORENAME
(see
.Xr options 4
).
.It Li KERN_DOMAINNAME
Get or set the YP domain name.
.It Li KERN_DUMP_ON_PANIC
Perform a crash dump on system panic.
.It Li KERN_DRIVERS
Return an array of
.Va struct kinfo_drivers
that contains the name and major device numbers of all the device drivers
in the current kernel.
The
.Va d_name
field is always a NUL terminated string.
The
.Va d_bmajor
field will be set to \-1 if the driver doesn't have a block device.
.It Li KERN_FILE
Return the entire file table.
The returned data consists of a single
.Va struct filelist
followed by an array of
.Va struct file ,
whose size depends on the current number of such objects in the system.
.It Li KERN_FORKFSLEEP
If
.Xr fork 2
system call fails due to limit on number of processes (either
the global maxproc limit or user's one), wait for this many
milliseconds before returning
.Er EAGAIN
error to process.
Useful to keep heavily forking runaway processes in bay.
Default zero (no sleep).
Maximum is 20 seconds.
.It Li KERN_FSCALE
The kernel fixed-point scale factor.
.It Li KERN_FSYNC
Return 1 if the POSIX 1003.1b File Synchronization Option is available
on this system,
otherwise 0.
.It Li KERN_HARDCLOCK_TICKS
Returns the number of
.Xr hardclock 9
ticks.
.It Li KERN_HOSTID
Get or set the host id.
.It Li KERN_HOSTNAME
Get or set the hostname.
.It Li KERN_IOV_MAX
Return the maximum number of
.Va iovec
structures that a process has available for use with
.Xr preadv 2 ,
.Xr pwritev 2 ,
.Xr readv 2 ,
.Xr recvmsg 2 ,
.Xr sendmsg 2
and
.Xr writev 2 .
.It Li KERN_JOB_CONTROL
Return 1 if job control is available on this system, otherwise 0.
.It Li KERN_LABELOFFSET
The offset within the sector specified by KERN_LABELSECTOR of the
.Xr disklabel 5 .
.It Li KERN_LABELSECTOR
The sector number containing the
.Xr disklabel 5 .
.It Li KERN_LOGIN_NAME_MAX
The size of the storage required for a login name, in bytes,
including the terminating NUL.
.It Li KERN_LOGSIGEXIT
If this flag is non-zero, the kernel will
.Xr log 9
all process exits due to signals which create a
.Xr core 5
file, and whether the coredump was created.
.It Li KERN_MAPPED_FILES
Returns 1 if the POSIX 1003.1b Memory Mapped Files Option is available
on this system,
otherwise 0.
.It Li KERN_MAXFILES
The maximum number of open files that may be open in the system.
.It Li KERN_MAXPARTITIONS
The maximum number of partitions allowed per disk.
.It Li KERN_MAXPHYS
Maximum raw I/O transfer size.
.It Li KERN_MAXPROC
The maximum number of simultaneous processes the system will allow.
.It Li KERN_MAXPTYS
The maximum number of pseudo terminals.
This value can be both raised and lowered, though it cannot
be set lower than number of currently used ptys.
See also
.Xr pty 4 .
.It Li KERN_MAXVNODES
The maximum number of vnodes available on the system.
This can only be raised.
.It Li KERN_MBUF
Return information about the mbuf control variables.
the third level names for the mbuf variables are detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "MBUFXNMBCLUSTERSXXX" "struct integerXXX" -offset indent
.It Sy Third level name	Type	Changeable
.It MBUF\_MBLOWAT	integer	yes
.It MBUF\_MCLBYTES	integer	yes
.It MBUF\_MCLLOWAT	integer	yes
.It MBUF\_MSIZE	integer	yes
.It MBUF\_NMBCLUSTERS	integer	yes
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li MBUF_MBLOWAT
The mbuf low water mark.
.It Li MBUF_MCLBYTES
The mbuf cluster size.
.It Li MBUF_MCLLOWAT
The mbuf cluster low water mark.
.It Li MBUF_MSIZE
The mbuf base size.
.It Li MBUF_NMBCLUSTERS
The limit on the number of mbuf clusters.
The variable can only be increased, and only increased on machines with
direct-mapped pool pages.
.El
.It Li KERN_MEMLOCK
Returns 1 if the POSIX 1003.1b Process Memory Locking Option is available
on this system,
otherwise 0.
.It Li KERN_MEMLOCK_RANGE
Returns 1 if the POSIX 1003.1b Range Memory Locking Option is available
on this system,
otherwise 0.
.It Li KERN_MEMORY_PROTECTION
Returns 1 if the POSIX 1003.1b Memory Protection Option is available
on this system,
otherwise 0.
.It Li KERN_MONOTONIC_CLOCK
Returns the standard version the implementation of the POSIX 1003.1b
Monotonic Clock Option conforms to,
otherwise 0.
.It Li KERN_MSGBUF
The kernel message buffer, rotated so that the head of the circular kernel
message buffer is returned at the start of the buffer specified by
.Fa oldp .
The returned data may contain NUL bytes.
.It Li KERN_MSGBUFSIZE
The maximum number of characters that the kernel message buffer can hold.
.It Li KERN_NGROUPS
The maximum number of supplemental groups.
.It Li KERN_NTPTIME
A
.Va struct ntptimeval
structure is returned.
This structure contains data used by the
.Xr ntpd 8
program.
.It Li KERN_OSRELEASE
The system release string.
.It Li KERN_OSREV
The system revision string.
.It Li KERN_OSTYPE
The system type string.
.It Li KERN_PIPE
Pipe settings.
The third level names for the  integer pipe settings is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "KERNXPIPEXFOOXXX" "integerXXX" -offset indent
.It Sy Third level name Type    Changeable
.It KERN\_PIPE\_KVASIZ	integer	yes
.It KERN\_PIPE\_MAXBIGPIPES	integer	yes
.It KERN\_PIPE\_MAXKVASZ	integer	yes
.It KERN\_PIPE\_LIMITKVA	integer	yes
.It KERN\_PIPE\_NBIGPIPES	integer	yes
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li KERN_PIPE_KVASIZ
Amount of kernel memory consumed by pipe buffers.
.It Li KERN_PIPE_MAXBIGPIPES
Maximum number of "big" pipes.
.It Li KERN_PIPE_MAXKVASZ
Maximum amount of kernel memory to be used for pipes.
.It Li KERN_PIPE_LIMITKVA
Limit for direct transfers via page loan.
.It Li KERN_PIPE_NBIGPIPES
Number of "big" pipes.
.El
.It Li KERN_POSIX1
The version of ISO/IEC 9945 (POSIX 1003.1) with which the system
attempts to comply.
.It Li KERN_POSIX_BARRIERS
The version of
.St -p1003.1
and its
Barriers
option to which the system attempts to conform,
otherwise 0.
.It Li KERN_POSIX_READER_WRITER_LOCKS
The version of
.St -p1003.1
and its
Read-Write Locks
option to which the system attempts to conform,
otherwise 0.
.It Li KERN_POSIX_SEMAPHORES
The version of
.St -p1003.1
and its
Semaphores
option to which the system attempts to conform,
otherwise 0.
.It Li KERN_POSIX_SPIN_LOCKS
The version of
.St -p1003.1
and its
Spin Locks
option to which the system attempts to conform,
otherwise 0.
.It Li KERN_POSIX_THREADS
The version of
.St -p1003.1
and its
Threads
option to which the system attempts to conform,
otherwise 0.
.It Li KERN_POSIX_TIMERS
The version of
.St -p1003.1
and its
Timers
option to which the system attempts to conform,
otherwise 0.
.It Li KERN_PROC
Return the entire process table, or a subset of it.
An array of
.Va struct kinfo_proc
structures is returned,
whose size depends on the current number of such objects in the system.
The third and fourth level names are as follows:
.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent
.It Sy Third level name	Fourth level is:
.It KERN\_PROC\_ALL	None
.It KERN\_PROC\_GID	A group ID
.It KERN\_PROC\_PID	A process ID
.It KERN\_PROC\_PGRP	A process group
.It KERN\_PROC\_RGID	A real group ID
.It KERN\_PROC\_RUID	A real user ID
.It KERN\_PROC\_SESSION	A session ID
.It KERN\_PROC\_TTY	A tty device
.It KERN\_PROC\_UID	A user ID
.El
.It Li KERN_PROC2
As for KERN_PROC, but an array of
.Va struct kinfo_proc2
structures are returned.
The fifth level name is the size of the
.Va struct kinfo_proc2
and the sixth level name is the number of structures to return.
.It Li KERN_PROC_ARGS
Return the argv or environment strings (or the number thereof)
of a process.
Multiple strings are returned separated by NUL characters.
The third level name is the process ID.
The fourth level name is as follows:
.Bl -column "Third level nameXXXXXX" -offset indent
.It KERN\_PROC\_ARGV	The argv strings
.It KERN\_PROC\_ENV	The environ strings
.It KERN\_PROC\_NARGV	The number of argv strings
.It KERN\_PROC\_NENV	The number of environ strings
.El
.It Li KERN_PROF
Return profiling information about the kernel.
If the kernel is not compiled for profiling,
attempts to retrieve any of the KERN_PROF values will
fail with EOPNOTSUPP.
The third level names for the string and integer profiling information
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent
.It Sy Third level name	Type	Changeable
.It GPROF\_COUNT	u_short[\|]	yes
.It GPROF\_FROMS	u_short[\|]	yes
.It GPROF\_GMONPARAM	struct gmonparam	no
.It GPROF\_STATE	integer	yes
.It GPROF\_TOS	struct tostruct	yes
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li GPROF_COUNT
Array of statistical program counter counts.
.It Li GPROF_FROMS
Array indexed by program counter of call-from points.
.It Li GPROF_GMONPARAM
Structure giving the sizes of the above arrays.
.It Li GPROF_STATE
Profiling state.
If set to GMON_PROF_ON, starts profiling.
If set to GMON_PROF_OFF, stops profiling.
.It Li GPROF_TOS
Array of
.Va struct tostruct
describing destination of calls and their counts.
.El
.It Li KERN_RAWPARTITION
The raw partition of a disk (a == 0).
.It Li KERN_ROOT_DEVICE
The name of the root device (e.g.,
.Dq wd0 ) .
.It Li KERN_ROOT_PARTITION
The root partition on the root device (a == 0).
.It Li KERN_RTC_OFFSET
Return the offset of real time clock from UTC in minutes.
.It Li KERN_SAVED_IDS
Returns 1 if saved set-group and saved set-user ID is available.
.It Li KERN_SBMAX
Maximum socket buffer size.
.It Li KERN_SECURELVL
The system security level.
This level may be raised by processes with appropriate privilege.
It may only be lowered by process 1.
.It Li KERN_SOMAXKVA
Maximum amount of kernel memory to be used for socket buffers.
.It Li KERN_SYNCHRONIZED_IO
Returns 1 if the POSIX 1003.1b Synchronized I/O Option is available
on this system,
otherwise 0.
.It Li KERN_SYSVIPC_INFO
Return System V style IPC configuration and run-time information.
The third level name selects the System V style IPC facility.
.Bl -column "KERN_SYSVIPC_MSG_INFOXXX" "struct shm_sysctl_infoXXX" -offset indent
.It Sy Third level name	Type
.It KERN\_SYSVIPC\_MSG\_INFO	struct msg_sysctl_info
.It KERN\_SYSVIPC\_SEM\_INFO	struct sem_sysctl_info
.It KERN\_SYSVIPC\_SHM\_INFO	struct shm_sysctl_info
.El
.Pp
.Bl -tag -width "123456"
.It Li KERN_SYSVIPC_MSG_INFO
Return information on the System V style message facility.
The
.Sy msg_sysctl_info
structure is defined in
.Aq Pa sys/msg.h .
.It Li KERN_SYSVIPC_SEM_INFO
Return information on the System V style semaphore facility.
The
.Sy sem_sysctl_info
structure is defined in
.Aq Pa sys/sem.h .
.It Li KERN_SYSVIPC_SHM_INFO
Return information on the System V style shared memory facility.
The
.Sy shm_sysctl_info
structure is defined in
.Aq Pa sys/shm.h .
.El
.It Li KERN_SYSVMSG
Returns 1 if System V style message queue functionality is available
on this system,
otherwise 0.
.It Li KERN_SYSVSEM
Returns 1 if System V style semaphore functionality is available
on this system,
otherwise 0.
.It Li KERN_SYSVSHM
Returns 1 if System V style share memory functionality is available
on this system,
otherwise 0.
.It Li KERN_TIMEX
Not available.
.It Li KERN_TKSTAT
Return information about the number of characters sent and received
on ttys.
The third level names for the tty statistic variables are detailed below.
The changeable column shows whether a process
with appropriate privilege may change the value.
.Bl -column "KERNXTKSTATXRAWCCXXX" "struct integerXXX" -offset indent
.It Sy Third level name	Type	Changeable
.It KERN\_TKSTAT\_CANCC	quad	no
.It KERN\_TKSTAT\_NIN	quad	no
.It KERN\_TKSTAT\_NOUT	quad	no
.It KERN\_TKSTAT\_RAWCC	quad	no
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li KERN_TKSTAT_CANCC
The number of canonical input characters.
.It Li KERN_TKSTAT_NIN
The total number of input characters.
.It Li KERN_TKSTAT_NOUT
The total number of output characters.
.It Li KERN_TKSTAT_RAWCC
The number of raw input characters.
.El
.It Li KERN_URND
Random integer value.
.It Li KERN_VERIEXEC
Tunings for Verixec.
Third level names for the Veriexec variables are detailed below.
The changeable column shows whether a process with appropriate privilege may
change the value or only raise it.
Only the superuser can modify these variables.
.Bl -column "VERIEXECXALGORITHMSXXX" "struct integerXXX" -offset indent
.It Sy Third level name	Type	Changeable
.It VERIEXEC\_ALGORITHMS	string	no
.It VERIEXEC\_COUNT	node	not applicable
.It VERIEXEC\_STRICT	integer	raise only
.It VERIEXEC\_VERBOSE	integer	yes
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li VERIEXEC_ALGORITHMS
Returns a string with the supported algorithms in Veriexec.
.It Li VERIEXEC_COUNT
Sub-nodes are added to this node as new mounts are monitored by Veriexec.
Each mount will be under its own
.No tableN
node.
Under each node there will be three variables, indicating the mount
point, the file-system type, and the number of entries.
.It Li VERIEXEC_STRICT
Controls the strict level of Veriexec.
The strict level defines how Veriexec will treat various situations.
.Pp
In strict level 0, the system is in learning mode and will only warn about
fingerprint mismatches, as well as allow removal of fingerprinted files.
It is the only level where fingerprints can be loaded.
.Pp
In strict level 1, the system is in IDS mode.
It will deny access to files with mismatched fingerprints.
Write access to monitored files will be permitted, but once modified, further
access to them will be denied.
Monitored files cannot be removed.
If a disk will be opened for raw writing, Veriexec will invalidate all
fingerprints on that disk, if it is monitored.
.Pp
In strict level 2, the system is in IPS mode.
It has all effects of
strict level 1, plus it will deny write access to monitored files and enforce
access type (direct, indirect, file).
Execution of non-monitored files is denied.
Opening of raw disks for writing will be denied if the disk is monitored.
Attempts to write to kernel memory, either via
.Pa /dev/mem
or
.Pa /dev/kmem ,
will be denied to protect Veriexec's internal data-structures.
.Pp
Strict level 3 operates as lockdown mode.
It will have all effects of
strict level 2, but it will also prevent access to non-monitored files.
Furthermore, it will prevent addition of new files to the system, and
allow writing only to files opened before the strict level was raised.
All attempts to open a disk for raw writing will be denied.
.It Li VERIEXEC_VERBOSE
Controls the verbosity level of Veriexec.
If 0, only the minimal
indication required will be given about what's happening - fingerprint
mismatches, removal of entries from the tables, modification of a
fingerprinted file.
If 1, more messages will be printed (ie., when a file with a valid
fingerprint is accessed).
Verbose level 2 is debug mode.
.El
.It Li KERN_VERSION
The system version string.
.It Li KERN_VNODE
Return the entire vnode table.
Note, the vnode table is not necessarily a consistent snapshot of
the system.
The returned data consists of an array whose size depends on the
current number of such objects in the system.
Each element of the array contains the kernel address of a vnode
.Va struct vnode *
followed by the vnode itself
.Va struct vnode .
.It Li kern.coredump.setid
Settings related to set-id processes coredumps.
By default, set-id processes do not dump core in situations where
other processes would.
The settings in this node allows an administrator to change this
behavior.
.Pp
.Bl -tag -width "123456"
.It Li kern.coredump.setid.dump
If non-zero, set-id processes will dump core.
.It Li kern.coredump.setid.group
The group-id for the set-id processes' coredump.
.It Li kern.coredump.setid.mode
The mode for the set-id processes' coredump.
See
.Xr chmod 1 .
.It Li kern.coredump.setid.owner
The user-id that will be used as the owner of the set-id processes'
coredump.
.It Li kern.coredump.setid.path
The path to which set-id processes' coredumps will be saved to.
Same syntax as kern.defcorename.
.El
.El
.Sh CTL_MACHDEP
The set of variables defined is architecture dependent.
Most architectures define at least the following variables.
.Bl -column "CONSOLE_DEVICEXXX" "integerXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It Li CPU_CONSDEV	dev_t	no
.El
.Sh CTL_NET
The string and integer information available for the CTL_NET level
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
The second and third levels are typically the protocol family and
protocol number, though this is not always the case.
.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It PF\_ROUTE	routing messages	no
.It PF\_INET	IPv4 values	yes
.It PF\_INET6	IPv6 values	yes
.It PF\_KEY	IPsec key management values	yes
.El
.Pp
.Bl -tag -width "123456"
.It Li PF_ROUTE
Return the entire routing table or a subset of it.
The data is returned as a sequence of routing messages (see
.Xr route 4
for the header file, format and meaning).
The length of each message is contained in the message header.
.Pp
The third level name is a protocol number, which is currently always 0.
The fourth level name is an address family, which may be set to 0 to
select all address families.
The fifth and sixth level names are as follows:
.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent
.It Sy Fifth level name	Sixth level is:
.It NET\_RT\_FLAGS	rtflags
.It NET\_RT\_DUMP	None
.It NET\_RT\_IFLIST	None
.El
.It Li PF_INET
Get or set various global information about the IPv4
.Pq Internet Protocol version 4 .
The third level name is the protocol.
The fourth level name is the variable name.
The currently defined protocols and names are:
.Bl -column "Protocol name" "Variable nameXX" "integer" "yes" -offset indent
.It Sy Protocol name	Variable name	Type	Changeable
.It arp	down	integer	yes
.It arp	keep	integer	yes
.It arp	prune	integer	yes
.It arp	refresh	integer	yes
.It icmp	errppslimit	integer	yes
.It icmp	maskrepl	integer	yes
.It icmp	rediraccept	integer	yes
.It icmp	redirtimeout	integer	yes
.It ip	allowsrcrt	integer	yes
.It ip	anonportmax	integer	yes
.It ip	anonportmin	integer	yes
.It ip	checkinterface	integer	yes
.It ip	directed-broadcast	integer	yes
.It ip	do_loopback_cksum	integer	yes
.It ip	forwarding	integer	yes
.It ip	forwsrcrt	integer	yes
.It ip	gifttl	integer	yes
.It ip	grettl	integer	yes
.It ip	hostzerobroadcast	integer	yes
.It ip	lowportmin	integer	yes
.It ip	lowportmax	integer	yes
.It ip	maxfragpackets	integer	yes
.It ip	mtudisc	integer	yes
.It ip	mtudisctimeout	integer	yes
.It ip	random_id	integer	yes
.It ip	redirect	integer	yes
.It ip	subnetsarelocal	integer	yes
.It ip	ttl	integer	yes
.It tcp	rfc1323	integer	yes
.It tcp	sendspace	integer	yes
.It tcp	recvspace	integer	yes
.It tcp	mssdflt	integer	yes
.It tcp	syn_cache_limit	integer	yes
.It tcp	syn_bucket_limit	integer	yes
.It tcp	syn_cache_interval	integer	yes
.It tcp	init_win	integer	yes
.It tcp	init_win_local	integer	yes
.It tcp	mss_ifmtu	integer	yes
.It tcp	sack	integer	yes
.It tcp	win_scale	integer	yes
.It tcp	timestamps	integer	yes
.It tcp	compat_42	integer	yes
.It tcp	cwm	integer	yes
.It tcp	cwm_burstsize	integer	yes
.It tcp	ack_on_push	integer	yes
.It tcp	keepidle	integer	yes
.It tcp	keepintvl	integer	yes
.It tcp	keepcnt	integer	yes
.It tcp	slowhz	integer	no
.It tcp	newreno	integer	yes
.It tcp	log_refused	integer	yes
.It tcp	rstppslimit	integer	yes
.It tcp	ident	struct	no
.It udp	checksum	integer	yes
.It udp	do_loopback_cksum	integer	yes
.It udp	recvspace	integer	yes
.It udp	sendspace	integer	yes
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li arp.down
Failed ARP entry lifetime.
.It Li arp.keep
Valid ARP entry lifetime.
.It Li arp.prune
ARP cache pruning interval.
.It Li arp.refresh
ARP entry refresh interval.
.It Li ip.allowsrcrt
If set to 1, the host accepts source routed packets.
.It Li ip.anonportmax
The highest port number to use for TCP and UDP ephemeral port allocation.
This cannot be set to less than 1024 or greater than 65535, and must
be greater than
.Li ip.anonportmin .
.It Li ip.anonportmin
The lowest port number to use for TCP and UDP ephemeral port allocation.
This cannot be set to less than 1024 or greater than 65535.
.It Li ip.checkinterface
If set to non-zero, the host will reject packets addressed to it
that arrive on an interface not bound to that address.
Currently, this must be disabled if ipnat is used to translate the
destination address to another local interface, or if addresses
are added to the loopback interface instead of the interface where
the packets for those packets are received.
.It Li ip.directed-broadcast
If set to 1, enables directed broadcast behavior for the host.
.It Li ip.do_loopback_cksum
Perform IP checksum on loopback.
.It Li ip.forwarding
If set to 1, enables IP forwarding for the host,
meaning that the host is acting as a router.
.It Li ip.forwsrcrt
If set to 1, enables forwarding of source-routed packets for the host.
This value may only be changed if the kernel security level is less than 1.
.It Li ip.gifttl
The maximum time-to-live (hop count) value for an IPv4 packet generated by
.Xr gif 4
tunnel interface.
.It Li ip.grettl
The maximum time-to-live (hop count) value for an IPv4 packet generated by
.Xr gre 4
tunnel interface.
.It Li ip.hostzerobroadcast
All zeroes address is broadcast address.
.It Li ip.lowportmax
The highest port number to use for TCP and UDP reserved port allocation.
This cannot be set to less than 0 or greater than 1024, and must
be greater than
.Li ip.lowportmin .
.It Li ip.lowportmin
The lowest port number to use for TCP and UDP reserved port allocation.
This cannot be set to less than 0 or greater than 1024, and must
be smaller than
.Li ip.lowportmax .
.It Li ip.maxfragpackets
The maximum number of fragmented packets the node will accept.
0 means that the node will not accept any fragmented packets.
\-1 means that the node will accept as many fragmented packets as it receives.
The flag is provided basically for avoiding possible DoS attacks.
.It Li ip.mtudisc
If set to 1, enables Path MTU Discovery (RFC 1191).
When Path MTU Discovery is enabled, the transmitted TCP segment
size will be determined by the advertised maximum segment size
(MSS) from the remote end, as constrained by the path MTU.
If MTU Discovery is disabled, the transmitted segment size will
never be greater than
.Li tcp.mssdflt
(the local maximum segment size).
.It Li ip.mtudisctimeout
The number of seconds in which a route added by the Path MTU
Discovery engine will time out.
When the route times out, the Path
MTU Discovery engine will attempt to probe a larger path MTU.
.It Li ip.random_id
Assign random ip_id values.
.It Li ip.redirect
If set to 1, ICMP redirects may be sent by the host.
This option is ignored unless the host is routing IP packets,
and should normally be enabled on all systems.
.It Li ip.subnetsarelocal
If set to 1, subnets are to be considered local addresses.
.It Li ip.ttl
The maximum time-to-live (hop count) value for an IP packet sourced by
the system.
This value applies to normal transport protocols, not to ICMP.
.It Li icmp.errppslimit
The variable specifies the maximum number of outgoing ICMP error messages,
per second.
ICMP error messages that exceeded the value are subject to rate limitation
and will not go out from the node.
Negative value disables rate limitation.
.It Li icmp.maskrepl
If set to 1, ICMP network mask requests are to be answered.
.It Li icmp.rediraccept
If set to non-zero, the host will accept ICMP redirect packets.
Note that routers will never accept ICMP redirect packets,
and the variable is meaningful on IP hosts only.
.It Li icmp.redirtimeout
The variable specifies lifetime of routing entries generated by incoming
ICMP redirect.
This defaults to 600 seconds.
.It Li icmp.returndatabytes
Number of bytes to return in an ICMP error message.
.It Li tcp.ack_on_push
If set to 1, TCP is to immediately transmit an ACK upon reception of
a packet with PUSH set.
This can avoid losing a round trip time in some rare situations,
but has the caveat of potentially defeating TCP's delayed ACK algorithm.
Use of this option is generally not recommended, but
the variable exists in case your configuration really needs it.
.It Li tcp.compat_42
If set to 1, enables work-arounds for bugs in the 4.2BSD TCP implementation.
Use of this option is not recommended, although it may be
required in order to communicate with extremely old TCP implementations.
.It Li tcp.cwm
If set to 1, enables use of the Hughes/Touch/Heidemann Congestion Window
Monitoring algorithm.
This algorithm prevents line-rate bursts of packets that could
otherwise occur when data begins flowing on an idle TCP connection.
These line-rate bursts can contribute to network and router congestion.
This can be particularly useful on World Wide Web servers
which support HTTP/1.1, which has lingering connections.
.It Li tcp.cwm_burstsize
The Congestion Window Monitoring allowed burst size, in terms
of packet count.
.It Li tcp.delack_ticks
Number of ticks to delay sending an ACK.
.It Li tcp.do_loopback_cksum
Perform TCP checksum on loopback.
.It Li tcp.init_win
A value indicating the TCP initial congestion window.
If this value is 0, an auto-tuning algorithm designed to use an initial
window of approximately 4K bytes is in use.
Otherwise, this value indicates a fixed number of packets.
.It Li tcp.init_win_local
Like
.Li tcp.init_win ,
but used when communicating with hosts on a local network.
.It Li tcp.keepcnt
Number of keepalive probes sent before declaring a connection dead.
If set to zero, there is no limit;
keepalives will be sent until some kind of
response is received from the peer.
.It Li tcp.keepidle
Time a connection must be idle before keepalives are sent (if keepalives
are enabled for the connection).
See also tcp.slowhz.
.It Li tcp.keepintvl
Time after a keepalive probe is sent until, in the absence of any response,
another probe is sent.
See also tcp.slowhz.
.It Li tcp.log_refused
If set to 1, refused TCP connections to the host will be logged.
.It Li tcp.mss_ifmtu
If set to 1, TCP calculates the outgoing maximum segment size based on
the MTU of the appropriate interface.
If set to 0, it is calculated based on the greater of the MTU of the
interface, and the largest (non-loopback) interface MTU on the system.
.It Li tcp.mssdflt
The default maximum segment size both advertised to the peer
and to use when either the peer does not advertise a maximum segment size to
us during connection setup or Path MTU Discovery
.Li ( ip.mtudisc )
is disabled.
Do not change this value unless you really know what you are doing.
.It Li tcp.newreno
If set to 1, enables the use of J.
Hoe's NewReno congestion control algorithm.
This algorithm improves the start-up behavior of TCP connections.
.It Li tcp.recvspace
The default TCP receive buffer size.
.It Li tcp.rfc1323
If set to 1, enables RFC 1323 extensions to TCP.
.It Li tcp.rstppslimit
The variable specifies the maximum number of outgoing TCP RST packets,
per second.
TCP RST packet that exceeded the value are subject to rate limitation
and will not go out from the node.
Negative value disables rate limitation.
.It Li tcp.sack.enable
If set to 1, enables RFC 2018 Selective ACKnowledgement.
.It Li tcp.sack.globalholes
Global number of TCP SACK holes.
.It Li tcp.sack.globalmaxholes
Global maximum number of TCP SACK holes.
.It Li tcp.sack.maxholes
Maximum number of TCP SACK holes allowed per connection.
.It Li tcp.sendspace
The default TCP send buffer size.
.It Li tcp.slowhz
The units for tcp.keepidle and tcp.keepintvl; those variables are in ticks
of a clock that ticks tcp.slowhz times per second.
(That is, their values
must be divided by the tcp.slowhz value to get times in seconds.)
.It Li tcp.syn_bucket_limit
The maximum number of entries allowed per hash bucket in the TCP
compressed state engine.
.It Li tcp.syn_cache_limit
The maximum number of entries allowed in the TCP compressed state
engine.
.It Li tcp.timestamps
If rfc1323 is enabled, a value of 1 indicates RFC 1323 time stamp options,
used for measuring TCP round trip times, are enabled.
.It Li tcp.win_scale
If rfc1323 is enabled, a value of 1 indicates RFC 1323 window scale options,
for increasing the TCP window size, are enabled.
.It Li udp.checksum
If set to 1, UDP checksums are being computed.
Received non-zero UDP checksums are always checked.
Disabling UDP checksums is strongly discouraged.
.It Li udp.sendspace
The default UDP send buffer size.
.It Li udp.recvspace
The default UDP receive buffer size.
.El
.Pp
For variables net.*.ipsec, please refer to
.Xr ipsec 4 .
.It Li PF_INET6
Get or set various global information about the IPv6
.Pq Internet Protocol version 6 .
The third level name is the protocol.
The fourth level name is the variable name.
The currently defined protocols and names are:
.Bl -column "Protocol name" "Variable nameXX" "integer" "yes" -offset indent
.It Sy Protocol name	Variable name	Type	Changeable
.It icmp6	errppslimit	integer	yes
.It icmp6	mtudisc_hiwat	integer	yes
.It icmp6	mtudisc_lowat	integer	yes
.It icmp6	nd6_debug	integer	yes
.It icmp6	nd6_delay	integer	yes
.It icmp6	nd6_maxnudhint	integer	yes
.It icmp6	nd6_mmaxtries	integer	yes
.It icmp6	nd6_prune	integer	yes
.It icmp6	nd6_umaxtries	integer	yes
.It icmp6	nd6_useloopback	integer	yes
.It icmp6	nodeinfo	integer	yes
.It icmp6	rediraccept	integer	yes
.It icmp6	redirtimeout	integer	yes
.It ip6	accept_rtadv	integer	yes
.It ip6	anonportmax	integer	yes
.It ip6	anonportmin	integer	yes
.It ip6	auto_flowlabel	integer	yes
.It ip6	dad_count	integer	yes
.It ip6	defmcasthlim	integer	yes
.It ip6	forwarding	integer	yes
.It ip6	gifhlim	integer	yes
.It ip6	hlim	integer	yes
.It ip6	hdrnestlimit	integer	yes
.It ip6	kame_version	string	no
.It ip6	keepfaith	integer	yes
.It ip6	log_interval	integer	yes
.It ip6	lowportmax	integer	yes
.It ip6	lowportmin	integer	yes
.It ip6	maxfragpackets	integer	yes
.It ip6	maxfrags	integer	yes
.It ip6	redirect	integer	yes
.It ip6	rr_prune	integer	yes
.It ip6	use_deprecated	integer	yes
.It ip6	v6only	integer	yes
.It udp6	do_loopback_cksum	integer	yes
.It udp6	recvspace	integer	yes
.It udp6	sendspace	integer	yes
.El
.Pp
The variables are as follows:
.Bl -tag -width "123456"
.It Li ip6.accept_rtadv
If set to non-zero, the node will accept ICMPv6 router advertisement packets
and autoconfigures address prefixes and default routers.
The node must be a host
.Pq not a router
for the option to be meaningful.
.It Li ip6.anonportmax
The highest port number to use for TCP and UDP ephemeral port allocation.
This cannot be set to less than 1024 or greater than 65535, and must
be greater than
.Li ip6.anonportmin .
.It Li ip6.anonportmin
The lowest port number to use for TCP and UDP ephemeral port allocation.
This cannot be set to less than 1024 or greater than 65535.
.It Li ip6.auto_flowlabel
On connected transport protocol packets,
fill IPv6 flowlabel field to help intermediate routers to identify packet flows.
.It Li ip6.dad_count
The variable configures number of IPv6 DAD
.Pq duplicated address detection
probe packets.
The packets will be generated when IPv6 interface addresses are configured.
.It Li ip6.defmcasthlim
The default hop limit value for an IPv6 multicast packet sourced by the node.
This value applies to all the transport protocols on top of IPv6.
There are APIs to override the value, as documented in
.Xr ip6 4 .
.It Li ip6.forwarding
If set to 1, enables IPv6 forwarding for the node,
meaning that the node is acting as a router.
If set to 0, disables IPv6 forwarding for the node,
meaning that the node is acting as a host.
IPv6 specification defines node behavior for
.Dq router
case and
.Dq host
case quite differently, and changing this variable during operation
may cause serious trouble.
It is recommended to configure the variable at bootstrap time,
and bootstrap time only.
.It Li ip6.gifhlim
The maximum hop limit value for an IPv6 packet generated by
.Xr gif 4
tunnel interface.
.It Li ip6.hdrnestlimit
The number of IPv6 extension headers permitted on incoming IPv6 packets.
If set to 0, the node will accept as many extension headers as possible.
.It Li ip6.hlim
The default hop limit value for an IPv6 unicast packet sourced by the node.
This value applies to all the transport protocols on top of IPv6.
There are APIs to override the value, as documented in
.Xr ip6 4 .
.It Li ip6.kame_version
The string identifies the version of KAME IPv6 stack implemented in the kernel.
.It Li ip6.keepfaith
If set to non-zero, it enables
.Dq FAITH
TCP relay IPv6-to-IPv4 translator code in the kernel.
Refer
.Xr faith 4
and
.Xr faithd 8
for detail.
.It Li ip6.log_interval
The variable controls amount of logs generated by IPv6 packet
forwarding engine, by setting interval between log output
.Pq in seconds .
.It Li ip6.lowportmax
The highest port number to use for TCP and UDP reserved port allocation.
This cannot be set to less than 0 or greater than 1024, and must
be greater than
.Li ip6.lowportmin .
.It Li ip6.lowportmin
The lowest port number to use for TCP and UDP reserved port allocation.
This cannot be set to less than 0 or greater than 1024, and must
be smaller than
.Li ip6.lowportmax .
.It Li ip6.maxfragpackets
The maximum number of fragmented packets the node will accept.
0 means that the node will not accept any fragmented packets.
\-1 means that the node will accept as many fragmented packets as it receives.
The flag is provided basically for avoiding possible DoS attacks.
.It Li ip6.maxfrags
The maximum number of fragments the node will accept.
0 means that the node will not accept any fragments.
\-1 means that the node will accept as many fragments as it receives.
The flag is provided basically for avoiding possible DoS attacks.
.It Li ip6.redirect
If set to 1, ICMPv6 redirects may be sent by the node.
This option is ignored unless the node is routing IP packets,
and should normally be enabled on all systems.
.It Li ip6.rr_prune
The variable specifies interval between IPv6 router renumbering prefix
babysitting, in seconds.
.It Li ip6.use_deprecated
The variable controls use of deprecated address, specified in RFC 2462 5.5.4.
.It Li ip6.v6only
The variable specifies initial value for
.Dv IPV6_V6ONLY
socket option for
.Dv AF_INET6
socket.
Please refer to
.Xr ip6 4
for detail.
.It Li icmp6.errppslimit
The variable specifies the maximum number of outgoing ICMPv6 error messages,
per second.
ICMPv6 error messages that exceeded the value are subject to rate limitation
and will not go out from the node.
Negative value disables rate limitation.
.It Li icmp6.mtudisc_hiwat
.It Li icmp6.mtudisc_lowat
The variables define the maximum number of routing table entries,
created due to path MTU discovery
.Pq prevents denial-of-service attacks with ICMPv6 too big messages .
When IPv6 path MTU discovery happens, we keep path MTU information into
the routing table.
If the number of routing table entries exceed the value,
the kernel will not attempt to keep the path MTU information.
.Li icmp6.mtudisc_hiwat
is used when we have verified ICMPv6 too big messages.
.Li icmp6.mtudisc_lowat
is used when we have unverified ICMPv6 too big messages.
Verification is performed by using address/port pairs kept in connected pcbs.
Negative value disables the upper limit.
.It Li icmp6.nd6_debug
If set to non-zero, kernel IPv6 neighbor discovery code will generate
debugging messages.
The debug outputs are useful to diagnose IPv6 interoperability issues.
The flag must be set to 0 for normal operation.
.It Li icmp6.nd6_delay
The variable specifies
.Dv DELAY_FIRST_PROBE_TIME
timing constant in IPv6 neighbor discovery specification
.Pq RFC 2461 ,
in seconds.
.It Li icmp6.nd6_maxnudhint
IPv6 neighbor discovery permits upper layer protocols to supply reachability
hints, to avoid unnecessary neighbor discovery exchanges.
The variable defines the number of consecutive hints the neighbor discovery
layer will take.
For example, by setting the variable to 3, neighbor discovery layer
will take 3 consecutive hints in maximum.
After receiving 3 hints, neighbor discovery layer will perform
normal neighbor discovery process.
.It Li icmp6.nd6_mmaxtries
The variable specifies
.Dv MAX_MULTICAST_SOLICIT
constant in IPv6 neighbor discovery specification
.Pq RFC 2461 .
.It Li icmp6.nd6_prune
The variable specifies interval between IPv6 neighbor cache babysitting,
in seconds.
.It Li icmp6.nd6_umaxtries
The variable specifies
.Dv MAX_UNICAST_SOLICIT
constant in IPv6 neighbor discovery specification
.Pq RFC 2461 .
.It Li icmp6.nd6_useloopback
If set to non-zero, kernel IPv6 stack will use loopback interface for
local traffic.
.It Li icmp6.nodeinfo
The variable enables responses to ICMPv6 node information queries.
If you set the variable to 0, responses will not be generated for
ICMPv6 node information queries.
Since node information queries can have a security impact, it is
possible to fine tune which responses should be answered.
Two separate bits can be set.
.Bl -tag -width "12345"
.It 1
Respond to ICMPv6 FQDN queries, e.g.
.Li ping6 -w .
.It 2
Respond to ICMPv6 node addresses queries, e.g.
.Li ping6 -a .
.El
.It Li icmp6.rediraccept
If set to non-zero, the host will accept ICMPv6 redirect packets.
Note that IPv6 routers will never accept ICMPv6 redirect packets,
and the variable is meaningful on IPv6 hosts
.Pq non-router
only.
.It Li icmp6.redirtimeout
The variable specifies lifetime of routing entries generated by incoming
ICMPv6 redirect.
.It Li udp6.do_loopback_cksum
Perform UDP checksum on loopback.
.It Li udp6.recvspace
Default UDP receive buffer size.
.It Li udp6.sendspace
Default UDP send buffer size.
.El
.Pp
We reuse net.*.tcp for
.Tn TCP
over
.Tn IPv6 ,
and therefore we do not have variables net.*.tcp6.
Variables net.inet6.udp6 have identical meaning to net.inet.udp.
Please refer to
.Li PF_INET
section above.
For variables net.*.ipsec6, please refer to
.Xr ipsec 4 .
.It Li PF_KEY
Get or set various global information about the IPsec key management.
The third level name is the variable name.
The currently defined variable and names are:
.Bl -column "blockacq_lifetime" "integer" "yes" -offset indent
.It Sy Variable name	Type	Changeable
.It debug	integer	yes
.It spi_try	integer	yes
.It spi_min_value	integer	yes
.It spi_max_value	integer	yes
.It larval_lifetime	integer	yes
.It blockacq_count	integer	yes
.It blockacq_lifetime	integer	yes
.It esp_keymin	integer	yes
.It esp_auth	integer	yes
.It ah_keymin	integer	yes
.El
The variables are as follows:
.Bl -tag -width "123456"
.It Li debug
Turn on debugging message from within the kernel.
The value is a bitmap, as defined in
.Pa /usr/include/netkey/key_debug.h .
.It Li spi_try
The number of times the kernel will try to obtain an unique SPI
when it generates it from random number generator.
.It Li spi_min_value
Minimum SPI value when generating it within the kernel.
.It Li spi_max_value
Maximum SPI value when generating it within the kernel.
.It Li larval_lifetime
Lifetime for LARVAL SAD entries, in seconds.
.It Li blockacq_count
Number of ACQUIRE PF_KEY messages to be blocked after an ACQUIRE message.
It avoids flood of ACQUIRE PF_KEY from being sent from the kernel to the
key management daemon.
.It Li blockacq_lifetime
Lifetime of ACQUIRE PF_KEY message.
.It Li esp_keymin
Minimum ESP key length, in bits.
The value is used when the kernel creates proposal payload
on ACQUIRE PF_KEY message.
.It Li esp_auth
Whether ESP authentication should be used or not.
Non-zero value indicates that ESP authentication should be used.
The value is used when the kernel creates proposal payload
on ACQUIRE PF_KEY message.
.It Li ah_keymin
Minimum AH key length, in bits,
The value is used when the kernel creates proposal payload
on ACQUIRE PF_KEY message.
.El
.El
.Sh CTL_PROC
The string and integer information available for the CTL_PROC
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
These values are per-process,
and as such may change from one process to another.
When a process is created,
the default values are inherited from its parent.
When a set-user-ID or set-group-ID binary is executed, the
value of PROC_PID_CORENAME is reset to the system default value.
The second level name is either the magic value PROC_CURPROC, which
points to the current process, or the PID of the target process.
.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" "yes" -offset indent
.It Sy Third level name	Type	Changeable
.It PROC\_PID\_CORENAME	string	yes
.It PROC\_PID\_LIMIT	node	not applicable
.It PROC\_PID\_STOPFORK	int	yes
.It PROC\_PID\_STOPEXEC	int	yes
.It PROC\_PID\_STOPEXIT	int	yes
.El
.Bl -tag -width "123456"
.Pp
.It Li PROC_PID_CORENAME
The template used for the core dump file name (see
.Xr core 5
for details).
The base name must either be
.Nm core
or end with the suffix ``.core'' (the super-user may set arbitrary names).
By default it points to KERN_DEFCORENAME.
.It Li PROC_PID_LIMIT
Return resources limits, as defined for the
.Xr getrlimit 2
and
.Xr setrlimit 2
system calls.
The fourth level name is one of:
.Bl -tag -width PROC_PID_LIMIT_MEMLOCKAA
.It Li PROC_PID_LIMIT_CPU
The maximum amount of CPU time (in seconds) to be used by each process.
.It Li PROC_PID_LIMIT_FSIZE
The largest size (in bytes) file that may be created.
.It Li PROC_PID_LIMIT_DATA
The maximum size (in bytes) of the data segment for a process;
this defines how far a program may extend its break with the
.Xr sbrk 2
system call.
.It Li PROC_PID_LIMIT_STACK
The maximum size (in bytes) of the stack segment for a process;
this defines how far a program's stack segment may be extended.
Stack extension is performed automatically by the system.
.It Li PROC_PID_LIMIT_CORE
The largest size (in bytes)
.Pa core
file that may be created.
.It Li PROC_PID_LIMIT_RSS
The maximum size (in bytes) to which a process's resident set size may
grow.
This imposes a limit on the amount of physical memory to be given to
a process; if memory is tight, the system will prefer to take memory
from processes that are exceeding their declared resident set size.
.It Li PROC_PID_LIMIT_MEMLOCK
The maximum size (in bytes) which a process may lock into memory
using the
.Xr mlock 2
function.
.It Li PROC_PID_LIMIT_NPROC
The maximum number of simultaneous processes for this user id.
.It Li PROC_PID_LIMIT_NOFILE
The maximum number of open files for this process.
.El
.Pp
The fifth level name is one of PROC_PID_LIMIT_TYPE_SOFT or
PROC_PID_LIMIT_TYPE_HARD, to select respectively the soft or hard limit.
Both are of type integer.
.It Li PROC_PID_STOPFORK
If non zero, the process' children will be stopped after
.Xr fork 2
calls.
The children is created in the SSTOP state and is never scheduled
for running before being stopped.
This feature helps attaching a process with a debugger such as
.Xr gdb 1
before it had the opportunity to actually do anything.
.Pp
This value is inherited by the process's children, and it also
apply to emulation specific system calls that fork a new process, such as
.Fn sproc
or
.Fn clone .
.It Li PROC_PID_STOPEXEC
If non zero, the process will be stopped on next
.Xr exec 3
call.
The process created by
.Xr exec 3
is created in the SSTOP state and is never scheduled for running
before being stopped.
This feature helps attaching a process with a debugger such as
.Xr gdb 1
before it had the opportunity to actually do anything.
.Pp
This value is inherited by the process's children.
.It Li PROC_PID_STOPEXIT
If non zero, the process will be stopped on when it has cause to exit,
either by way of calling
.Xr exit 3 ,
.Xr _exit 2 ,
or by the receipt of a specific signal.
The process is stopped before any of its resources or vm space is
released allowing examination of the termination state of a process
before it disappears.
This feature can be used to examine the final conditions of the
process's vmspace via
.Xr pmap 1
or its resource settings with
.Xr sysctl 8
before it disappears.
.Pp
This value is also inherited by the process's children.
.El
.Sh CTL_USER
The string and integer information available for the CTL_USER level
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It USER\_BC\_BASE\_MAX	integer	no
.It USER\_BC\_DIM\_MAX	integer	no
.It USER\_BC\_SCALE\_MAX	integer	no
.It USER\_BC\_STRING\_MAX	integer	no
.It USER\_COLL\_WEIGHTS\_MAX	integer	no
.It USER\_CS\_PATH	string	no
.It USER\_EXPR\_NEST\_MAX	integer	no
.It USER\_LINE\_MAX	integer	no
.It USER\_POSIX2\_CHAR\_TERM	integer	no
.It USER\_POSIX2\_C\_BIND	integer	no
.It USER\_POSIX2\_C\_DEV	integer	no
.It USER\_POSIX2\_FORT\_DEV	integer	no
.It USER\_POSIX2\_FORT\_RUN	integer	no
.It USER\_POSIX2\_LOCALEDEF	integer	no
.It USER\_POSIX2\_SW\_DEV	integer	no
.It USER\_POSIX2\_UPE	integer	no
.It USER\_POSIX2\_VERSION	integer	no
.It USER\_RE\_DUP\_MAX	integer	no
.It USER\_STREAM\_MAX	integer	no
.It USER\_TZNAME\_MAX	integer	no
.It USER\_ATEXIT\_MAX	integer	no
.El
.Bl -tag -width "123456"
.Pp
.It Li USER_BC_BASE_MAX
The maximum ibase/obase values in the
.Xr bc 1
utility.
.It Li USER_BC_DIM_MAX
The maximum array size in the
.Xr bc 1
utility.
.It Li USER_BC_SCALE_MAX
The maximum scale value in the
.Xr bc 1
utility.
.It Li USER_BC_STRING_MAX
The maximum string length in the
.Xr bc 1
utility.
.It Li USER_COLL_WEIGHTS_MAX
The maximum number of weights that can be assigned to any entry of
the LC_COLLATE order keyword in the locale definition file.
.It Li USER_CS_PATH
Return a value for the
.Ev PATH
environment variable that finds all the standard utilities.
.It Li USER_EXPR_NEST_MAX
The maximum number of expressions that can be nested within
parenthesis by the
.Xr expr 1
utility.
.It Li USER_LINE_MAX
The maximum length in bytes of a text-processing utility's input
line.
.It Li USER_POSIX2_CHAR_TERM
Return 1 if the system supports at least one terminal type capable of
all operations described in POSIX 1003.2, otherwise 0.
.It Li USER_POSIX2_C_BIND
Return 1 if the system's C-language development facilities support the
C-Language Bindings Option, otherwise 0.
.It Li USER_POSIX2_C_DEV
Return 1 if the system supports the C-Language Development Utilities Option,
otherwise 0.
.It Li USER_POSIX2_FORT_DEV
Return 1 if the system supports the FORTRAN Development Utilities Option,
otherwise 0.
.It Li USER_POSIX2_FORT_RUN
Return 1 if the system supports the FORTRAN Runtime Utilities Option,
otherwise 0.
.It Li USER_POSIX2_LOCALEDEF
Return 1 if the system supports the creation of locales, otherwise 0.
.It Li USER_POSIX2_SW_DEV
Return 1 if the system supports the Software Development Utilities Option,
otherwise 0.
.It Li USER_POSIX2_UPE
Return 1 if the system supports the User Portability Utilities Option,
otherwise 0.
.It Li USER_POSIX2_VERSION
The version of POSIX 1003.2 with which the system attempts to comply.
.It Li USER_RE_DUP_MAX
The maximum number of repeated occurrences of a regular expression
permitted when using interval notation.
.ne 1i
.It Li USER_STREAM_MAX
The minimum maximum number of streams that a process may have open
at any one time.
.It Li USER_TZNAME_MAX
The minimum maximum number of types supported for the name of a
timezone.
.It Li USER_ATEXIT_MAX
The maximum number of functions that may be registered with
.Xr atexit 3 .
.El
.Sh CTL_VM
The string and integer information available for the CTL_VM level
is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It VM\_ANONMAX	int	yes
.It VM\_ANONMIN	int	yes
.It VM\_BUFCACHE	int	yes
.It VM\_BUFMEM	int	no
.It VM\_BUFMEM_HIWATER	int	yes
.It VM\_BUFMEM_LOWATER	int	yes
.It VM\_EXECMAX	int	yes
.It VM\_EXECMIN	int	yes
.It VM\_FILEMAX	int	yes
.It VM\_FILEMIN	int	yes
.It VM\_LOADAVG	struct loadavg	no
.It VM\_MAXSLP	int	no
.It VM\_METER	struct vmtotal	no
.It VM\_NKMEMPAGES	int	no
.It VM\_USPACE	int	no
.It VM\_UVMEXP	struct uvmexp	no
.It VM\_UVMEXP2	struct uvmexp_sysctl	no
.El
.Pp
.Bl -tag -width "123456"
.It Li VM_ANONMAX
The percentage of physical memory which will be reclaimed
from other types of memory usage to store anonymous application data.
.It Li VM_ANONMIN
The percentage of physical memory which will be always be available for
anonymous application data.
.It Li VM_BUFCACHE
The percentage of kernel memory which will be available
for the buffer cache.
.It Li VM_BUFMEM
The amount of kernel memory that is being used by the buffer cache.
.It Li VM_BUFMEM_LOWATER
The minimum amount of kernel memory to reserve for the
buffer cache.
.It Li VM_BUFMEM_HIWATER
The maximum amount of kernel memory to be used for the
buffer cache.
.It Li VM_EXECMAX
The percentage of physical memory which will be reclaimed
from other types of memory usage to store cached executable data.
.It Li VM_EXECMIN
The percentage of physical memory which will be always be available for
cached executable data.
.It Li VM_FILEMAX
The percentage of physical memory which will be reclaimed
from other types of memory usage to store cached file data.
.It Li VM_FILEMIN
The percentage of physical memory which will be always be available for
cached file data.
.It Li VM_LOADAVG
Return the load average history.
The returned data consists of a
.Va struct loadavg .
.It Li VM_MAXSLP
The value of the maxslp kernel global variable.
.It Li VM_METER
Return system wide virtual memory statistics.
The returned data consists of a
.Va struct vmtotal .
.It Li VM_USPACE
The number of bytes allocated for each kernel stack.
.It Li VM_UVMEXP
Return system wide virtual memory statistics.
The returned data consists of a
.Va struct uvmexp .
.It Li VM_UVMEXP2
Return system wide virtual memory statistics.
The returned data consists of a
.Va struct uvmexp_sysctl .
.El
.Sh CTL_DDB
The integer information available for the CTL_DDB level is detailed below.
The changeable column shows whether a process with appropriate
privilege may change the value.
.Bl -column "DBCTL_TABSTOPSXXX" "integerXXX" -offset indent
.It Sy Second level name	Type	Changeable
.It DBCTL\_RADIX	integer	yes
.It DBCTL\_MAXOFF	integer	yes
.It DBCTL\_LINES	integer	yes
.It DBCTL\_TABSTOPS	integer	yes
.It DBCTL\_ONPANIC	integer	yes
.It DBCTL\_FROMCONSOLE	integer	yes
.El
.Pp
.Bl -tag -width "123456"
.It Li DBCTL_RADIX
The input and output radix.
.It Li DBCTL_MAXOFF
The maximum symbol offset.
.It Li DBCTL_LINES
Number of display lines.
.It Li DBCTL_TABSTOPS
Tab width.
.It Li DBCTL_ONPANIC
If non-zero, DDB will be entered when the kernel panics.
.It Li DBCTL_FROMCONSOLE
If not zero, DDB may be entered by sending a break on a serial
console or by a special key sequence on a graphics console.
.El
.Pp
These MIB nodes are also available as variables from within the DDB.
See
.Xr ddb 4
for more details.
.Sh CTL_SECURITY
The security level contains various security-related settings for
the system. Available settings are detailed below.
.Pp
.Bl -tag -width "123456"
.It Li security.curtain
If non-zero, will filter return objects according to the user-id
requesting information about them, preventing from users any
access to objects they don't own.
.Pp
At the moment, it affects
.Xr ps 1 ,
.Xr netstat 1
(for
.Dv PF_INET ,
.Dv PF_INET6 ,
and
.Dv PF_UNIX
PCBs), and
.Xr w 1 .
.It Li security.pax
Settings for PaX -- exploit mitigation features.
.Pp
.Bl -tag -width "123456"
.It Li security.pax.mprotect.enable
Enable PaX MPROTECT restrictions.
.Pp
These are
.Xr mprotect 2
restrictions to better enforce a W^X policy. The value of this
knob must be non-zero for PaX MPROTECT to be enabled, even if a
process is already marked with
.Em P_PAXMPROTECT .
.It Li security.pax.mprotect.global_protection
Specifies the default global policy for programs without an
explicit enable/disable flag.
.Pp
When non-zero, all programs will get the PaX MPROTECT restrictions,
except those exempted with
.Xr paxctl 1  .
Otherwise, all programs will not get the PaX MPROTECT restrictions,
except those specifically marked as such with
.Xr paxctl 1 .
.El
.El
.Sh CTL_VENDOR
The "vendor" toplevel name is reserved to be used by vendors who wish to
have their own private MIB tree.
Intended use is to store values under
.Dq vendor.\*[Lt]yourname\*[Gt].* .
.Sh DYNAMIC OPERATIONS
Several meta-identifiers are provided to perform operations on the
.Nm
tree itself, or support alternate means of accessing the data
instrumented by the
.Nm
tree.
.Bl -column CTLXCREATESYMXXX
.It Sy Name	Description
.It CTL\_QUERY	Retrieve a mapping of names to numbers below a given node
.It CTL\_CREATE	Create a new node
.It CTL\_CREATESYM	Create a new node by its kernel symbol
.It CTL\_DESTROY	Destroy a node
.It CTL\_DESCRIBE	Retrieve node descriptions
.El
.Pp
The core interface to all of these meta-functions is the structure
that the kernel uses to describe the tree internally, as defined in
.Aq Pa sys/sysctl.h
as:
.Pp
.Bd -literal
struct sysctlnode {
        uint32_t sysctl_flags;          /* flags and type */
        int32_t sysctl_num;             /* mib number */
        char sysctl_name[SYSCTL_NAMELEN]; /* node name */
        uint32_t sysctl_ver;        /* node's version vs. rest of tree */
        uint32_t __rsvd;
        union {
                struct {
                        uint32_t suc_csize; /* size of child node array */
                        uint32_t suc_clen; /* number of valid children */
                        struct sysctlnode* suc_child; /* array of child nodes */
                } scu_child;
                struct {
                        void *sud_data; /* pointer to external data */
                        size_t sud_offset; /* offset to data */
                } scu_data;
                int32_t scu_alias;      /* node this node refers to */
                int32_t scu_idata;      /* immediate "int" data */
                u_quad_t scu_qdata;     /* immediate "u_quad_t" data */
        } sysctl_un;
        size_t _sysctl_size;            /* size of instrumented data */
        sysctlfn _sysctl_func;          /* access helper function */
        struct sysctlnode *sysctl_parent; /* parent of this node */
        const char *sysctl_desc;        /* description of node */
};

#define sysctl_csize    sysctl_un.scu_child.suc_csize
#define sysctl_clen     sysctl_un.scu_child.suc_clen
#define sysctl_child    sysctl_un.scu_child.suc_child
#define sysctl_data     sysctl_un.scu_data.sud_data
#define sysctl_offset   sysctl_un.scu_data.sud_offset
#define sysctl_alias    sysctl_un.scu_alias
#define sysctl_idata    sysctl_un.scu_idata
#define sysctl_qdata    sysctl_un.scu_qdata
.Ed
.Pp
Querying the tree to discover the name to number mapping permits
dynamic discovery of all the data that the tree currently has
instrumented.
For example, to discover all the nodes below the
CTL_VFS node:
.Pp
.Bd -literal -offset indent -compact
struct sysctlnode query, vfs[128];
int mib[2];
size_t len;
.sp
mib[0] = CTL_VFS;
mib[1] = CTL_QUERY;
memset(\*[Am]query, 0, sizeof(query));
query.sysctl_flags = SYSCTL_VERSION;
len = sizeof(vfs);
sysctl(mib, 2, \*[Am]vfs[0], \*[Am]len, \*[Am]query, sizeof(query));
.Ed
.Pp
Note that a reference to an empty node with
.Fa sysctl_flags
set to
.Dv SYSCTL_VERSION
is passed to sysctl in order to indicate the version that the program
is using.
All dynamic operations passing nodes into sysctl require that the
version be explicitly specified.
.Pp
Creation and destruction of nodes works by constructing part of a new
node description (or a description of the existing node) and invoking
CTL_CREATE (or CTL_CREATESYM) or CTL_DESTROY at the parent of the new
node, with a pointer to the new node passed via the
.Fa new
and
.Fa newlen
arguments.
If valid values for
.Fa old
and
.Fa oldlenp
are passed, a copy of the new node once in the tree will be returned.
If the create operation fails because a node with the same name or MIB
number exists, a copy of the conflicting node will be returned.
.Pp
The minimum requirements for creating a node are setting the
.Fa sysctl_flags
to indicate the new node's type,
.Fa sysctl_num
to either the new node's number (or CTL_CREATE or CTL_CREATESYM if a
dynamically allocated MIB number is acceptable),
.Fa sysctl_size
to the size of the data to be instrumented (which must agree with the
given type), and
.Fa sysctl_name
must be set to the new node's name.
Nodes that are not of type
.Dq node
must also have some description of the data to be instrumented, which
will vary depending on what is to be instrumented.
.Pp
If existing kernel data is to be covered by this new node, its address
should be given in
.Fa sysctl_data
or, if CTL_CREATESYM is used,
.Fa sysctl_data
should be set to a string containing its name from the kernel's symbol
table.
If new data is to be instrumented and an initial value is available,
the new integer or quad type data should be placed into either
.Fa sysctl_idata
or
.Fa sysctl_qdata ,
respectively, along with the SYSCTL_IMMEDIATE flag being set, or
.Fa sysctl_data
should be set to point to a copy of the new data, and the
SYSCTL_OWNDATA flag must be set.
This latter method is the only way that new string and struct type
nodes can be initialized.
Invalid kernel addresses are accepted, but any attempt to access those
nodes will return an error.
.Pp
The
.Fa sysctl_csize ,
.Fa sysctl_clen ,
.Fa sysctl_child ,
.Fa sysctl_parent ,
and
.Fa sysctl_alias
members are used by the kernel to link the tree together and must be
.Dv NULL
or 0.
Nodes created in this manner cannot have helper functions, so
.Fa sysctl_func
must also be
.Dv NULL .
If the
.Fa sysctl_ver
member is non-zero, it must match either the version of the parent or
the version at the root of the MIB or an error is returned.
This can be used to ensure that nodes are only added or removed from a
known state of the tree.
Note: It may not be possible to determine the version at the root
of the tree.
.Pp
This example creates a new subtree and adds a node to it that controls the
.Fa audiodebug
kernel variable, thereby making it tunable at at any time, without
needing to use
.Xr ddb 4
or
.Xr kvm 3
to alter the kernel's memory directly.
.Pp
.Bd -literal -offset indent -compact
struct sysctlnode node;
int mib[2];
size_t len;
.sp
mib[0] = CTL_CREATE;		/* create at top-level */
len = sizeof(node);
memset(\*[Am]node, 0, len);
node.sysctl_flags = SYSCTL_VERSION|CTLFLAG_READWRITE|CTLTYPE_NODE;
snprintf(node.sysctl_name, sizeof(node.sysctl_name), "local");
node.sysctl_num = CTL_CREATE;	/* request dynamic MIB number */
sysctl(\*[Am]mib[0], 1, \*[Am]node, \*[Am]len, \*[Am]node, len);
.sp
mib[0] = node.sysctl_num;	/* use new MIB number */
mib[1] = CTL_CREATESYM;		/* create at second level */
len = sizeof(node);
memset(\*[Am]node, 0, len);
node.sysctl_flags = SYSCTL_VERSION|CTLFLAG_READWRITE|CTLTYPE_INT;
snprintf(node.sysctl_name, sizeof(node.sysctl_name), "audiodebug");
node.sysctl_num = CTL_CREATE;
node.sysctl_data = "audiodebug"; /* kernel symbol to be used */
sysctl(\*[Am]mib[0], 2, NULL, NULL, \*[Am]node, len);
.Ed
.Pp
The process for deleting nodes is similar, but less data needs to
be supplied.
Only the
.Fa sysctl_num
field
needs to be filled in; almost all other fields must be left blank.
The
.Fa sysctl_name
and/or
.Fa sysctl_ver
fields can be filled in with the name and version of the existing node
as additional checks on what will be deleted.
If all the given data fail to match any node, nothing will be deleted.
If valid values for
.Fa old
and
.Fa oldlenp
are supplied and a node is deleted, a copy of what was in the MIB tree
will be returned.
.Pp
This sample code shows the deletion of the two nodes created in the
above example:
.Pp
.Bd -literal -offset indent -compact
int mib[2];
.sp
len = sizeof(node);
memset(\*[Am]node, 0, len);
node.sysctl_flags = SYSCTL_VERSION;
.sp
mib[0] = 3214;			/* assumed number for "local" */
mib[1] = CTL_DESTROY;
node.sysctl_num = 3215;		/* assumed number for "audiodebug" */
sysctl(\*[Am]mib[0], 2, NULL, NULL, \*[Am]node, len);
.sp
mib[0] = CTL_DESTROY;
node.sysctl_num = 3214;		/* now deleting "local" */
sysctl(\*[Am]mib[0], 1, NULL, NULL, \*[Am]node, len);
.Ed
.Pp
Descriptions of each of the nodes can also be retrieved, if they are
available.
Descriptions can be retrieved in bulk at each level or on a per-node
basis.
The layout of the buffer into which the descriptions are returned is a
series of variable length structures, each of which describes its own
size.
The length indicated includes the terminating
.Sq nul
character.
Nodes that have no description or where the description is not
available are indicated by an empty string.
The
.Fa descr_ver
will match the
.Fa sysctl_ver
value for a given node, so that descriptions for nodes whose number
have been recycled can be detected and ignored or discarded.
.Pp
.Bd -literal
struct sysctldesc {
        int32_t         descr_num;      /* mib number of node */
        uint32_t        descr_ver;      /* version of node */
        uint32_t        descr_len;      /* length of description string */
        char            descr_str[1];   /* not really 1...see above */
};
.Ed
.Pp
The
.Fn NEXT_DESCR
macro can be used to skip to the next description in the retrieved
list.
.Pp
.Bd -literal -offset indent -compact
struct sysctlnode desc;
struct sysctldesc *d;
char buf[1024];
int mib[2];
size_t len;
.sp
/* retrieve kern-level descriptions */
mib[0] = CTL_KERN;
mib[1] = CTL_DESCRIBE;
d = (struct sysctldesc *)\*[Am]buf[0];
len = sizeof(buf);
sysctl(mib, 2, d, \*[Am]len, NULL, 0);
while ((caddr_t)d \*[Lt] (caddr_t)\*[Am]buf[len]) {
	printf("node %d: %.*s\\n", d-\*[Gt]descr_num, d-\*[Gt]descr_len,
	    d-\*[Gt]descr_str);
	d = NEXT_DESCR(d);
}
.sp
/* retrieve description for kern.securelevel */
memset(\*[Am]desc, 0, sizeof(desc));
desc.sysctl_flags = SYSCTL_VERSION;
desc.sysctl_num = KERN_SECURELEVEL;
d = (struct sysctldesc *)\*[Am]buf[0];
len = sizeof(buf);
sysctl(mib, 2, d, \*[Am]len, \*[Am]desc, sizeof(desc));
printf("kern.securelevel: %.*s\\n", d-\*[Gt]descr_len, d-\*[Gt]descr_str);
.Ed
.Pp
Descriptions can also be set as follows, subject to the following rules:
.Pp
.Bl -bullet -compact
.It
The kernel securelevel is at zero or lower
.It
The caller has super-user privileges
.It
The node does not currently have a description
.It
The node is not marked as
.Dq permanent
.El
.Pp
.Bd -literal -offset indent -compact
struct sysctlnode desc;
int mib[2];
.sp
/* presuming the given top-level node was just added... */
mib[0] = 3214; /* mib numbers taken from previous examples */
mib[1] = CTL_DESCRIBE;
memset(\*[Am]desc, 0, sizeof(desc));
desc.sysctl_flags = SYSCTL_VERSION;
desc.sysctl_num = 3215;
desc.sysctl_desc = "audio debug control knob";
sysctl(mib, 2, NULL, NULL, \*[Am]desc, sizeof(desc));
.Ed
.Pp
Upon successfully setting a description, the new description will be
returned in the space indicated by the
.Fa oldp
and
.Fa oldlenp
arguments.
.Pp
The
.Fa sysctl_flags
field in the struct sysctlnode contains the sysctl version, node type
information, and a number of flags.
The macros
.Fn SYSCTL_VERS ,
.Fn SYSCTL_TYPE ,
and
.Fn SYSCTL_FLAGS
can be used to access the different fields.
Valid flags are:
.Bl -column CTLFLAGXPERMANENTXXX
.It Sy Name	Description
.It CTLFLAG\_READONLY	Node is read-only
.It CTLFLAG\_READONLY1	Node becomes read-only at securelevel 1
.It CTLFLAG\_READONLY2	Node becomes read-only at securelevel 2
.It CTLFLAG\_READWRITE	Node is writable by the superuser
.It CTLFLAG\_ANYWRITE	Node is writable by anyone
.It CTLFLAG\_PRIVATE	Node is readable only by the superuser
.It CTLFLAG\_PERMANENT	Node cannot be removed (cannot be set by
processes)
.It CTLFLAG\_OWNDATA	Node owns data and does not instrument
existing data
.It CTLFLAG\_IMMEDIATE	Node contains instrumented data and does not
instrument existing data
.It CTLFLAG\_HEX	Node's contents should be displayed in a hexadecimal
form
.It CTLFLAG\_ROOT	Node is the root of a tree (cannot be set at
any time)
.It CTLFLAG\_ANYNUMBER	Node matches any MIB number (cannot be set by
processes)
.It CTLFLAG\_HIDDEN	Node not displayed by default
.It CTLFLAG\_ALIAS	Node refers to a sibling node (cannot be set
by processes)
.It CTLFLAG\_OWNDESC	Node owns its own description string space
.El
.Sh RETURN VALUES
If the call to
.Nm
is successful, the number of bytes copied out is returned.
Otherwise \-1 is returned and
.Va errno
is set appropriately.
.Sh FILES
.Bl -tag -width \*[Lt]netinet6/udp6Xvar.h\*[Gt] -compact
.It Aq Pa sys/sysctl.h
definitions for top level identifiers, second level kernel and hardware
identifiers, and user level identifiers
.It Aq Pa sys/socket.h
definitions for second level network identifiers
.It Aq Pa sys/gmon.h
definitions for third level profiling identifiers
.It Aq Pa uvm/uvm_param.h
definitions for second level virtual memory identifiers
.It Aq Pa netinet/in.h
definitions for third level IPv4/v6 identifiers and
fourth level IPv4/v6 identifiers
.It Aq Pa netinet/icmp_var.h
definitions for fourth level ICMP identifiers
.It Aq Pa netinet/icmp6.h
definitions for fourth level ICMPv6 identifiers
.It Aq Pa netinet/tcp_var.h
definitions for fourth level TCP identifiers
.It Aq Pa netinet/udp_var.h
definitions for fourth level UDP identifiers
.It Aq Pa netinet6/udp6_var.h
definitions for fourth level IPv6 UDP identifiers
.It Aq Pa netinet6/ipsec.h
definitions for fourth level IPsec identifiers
.It Aq Pa netkey/key_var.h
definitions for third level PF_KEY identifiers
.It Aq Pa machine/cpu.h
definitions for second level machdep identifiers
.El
.Sh ERRORS
The following errors may be reported:
.Bl -tag -width Er
.It Bq Er EFAULT
The buffer
.Fa name ,
.Fa oldp ,
.Fa newp ,
or length pointer
.Fa oldlenp
contains an invalid address, or the requested value is temporarily
unavailable.
.It Bq Er EINVAL
The
.Fa name
array is zero or greater than CTL_MAXNAME.
.It Bq Er EINVAL
A non-null
.Fa newp
is given and its specified length in
.Fa newlen
is too large or too small, or the given value is not acceptable for
the given node.
.It Bq Er ENOMEM
The length pointed to by
.Fa oldlenp
is too short to hold the requested value.
.It Bq Er EISDIR
The
.Fa name
array specifies an intermediate rather than terminal name.
.It Bq Er ENOTDIR
The
.Fa name
array specifies a node below a node that addresses data.
.It Bq Er ENOENT
The
.Fa name
array specifies a node that does not exist in the tree.
.It Bq Er ENOENT
An attempt was made to destroy a node that does not exist, or to
create or destroy a node below a node that does not exist.
.It Bq Er ENOTEMPTY
An attempt was made to destroy a node that still has children.
.It Bq Er EOPNOTSUPP
The
.Fa name
array specifies a value that is unknown or a meta-operation was
attempted that the requested node does not support.
.It Bq Er EPERM
An attempt is made to set a read-only value.
.It Bq Er EPERM
A process without appropriate privilege attempts to set a value or to
create or destroy a node.
.It Bq Er EPERM
An attempt to change a value protected by the current kernel security
level is made.
.El
.Sh SEE ALSO
.Xr ipsec 4 ,
.Xr tcp 4 ,
.Xr sysctl 8
.\" .Xr sysctl 9
.Sh HISTORY
The
.Nm
function first appeared in
.Bx 4.4 .