1.\" $NetBSD: sysctl.3,v 1.170 2006/05/16 00:08:24 elad Exp $ 2.\" 3.\" Copyright (c) 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)sysctl.3 8.4 (Berkeley) 5/9/95 31.\" 32.Dd April 26, 2006 33.Dt SYSCTL 3 34.Os 35.Sh NAME 36.Nm sysctl , 37.Nm sysctlbyname , 38.Nm sysctlgetmibinfo , 39.Nm sysctlnametomib 40.Nd get or set system information 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In sys/param.h 45.In sys/sysctl.h 46.Ft int 47.Fn sysctl "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" \ 48"const void *newp" "size_t newlen" 49.Ft int 50.Fn sysctlbyname "const char *sname" "void *oldp" "size_t *oldlenp" \ 51"void *newp" "size_t newlen" 52.Ft int 53.Fn sysctlgetmibinfo "const char *sname" "int *name" "u_int *namelenp" \ 54"char *cname" "size_t *csz" "struct sysctlnode **rnode" "int v" 55.Ft int 56.Fn sysctlnametomib "const char *sname" "int *name" "size_t *namelenp" 57.Sh DESCRIPTION 58The 59.Nm 60function retrieves system information and allows processes with 61appropriate privileges to set system information. 62The information available from 63.Nm 64consists of integers, strings, and tables. 65Information may be retrieved and set from the command interface 66using the 67.Xr sysctl 8 68utility. 69.Pp 70Unless explicitly noted below, 71.Nm 72returns a consistent snapshot of the data requested. 73Consistency is obtained by locking the destination 74buffer into memory so that the data may be copied out without blocking. 75Calls to 76.Nm 77are serialized to avoid deadlock. 78.Pp 79The state is described using a ``Management Information Base'' (MIB) 80style name, listed in 81.Fa name , 82which is a 83.Fa namelen 84length array of integers. 85.Pp 86The 87.Fn sysctlbyname 88function accepts a string representation of a MIB entry and internally 89maps it to the appropriate numeric MIB representation. 90Its semantics are otherwise no different from 91.Fn sysctl . 92.Pp 93The information is copied into the buffer specified by 94.Fa oldp . 95The size of the buffer is given by the location specified by 96.Fa oldlenp 97before the call, 98and that location gives the amount of data copied after a successful call. 99If the amount of data available is greater 100than the size of the buffer supplied, 101the call supplies as much data as fits in the buffer provided 102and returns with the error code ENOMEM. 103If the old value is not desired, 104.Fa oldp 105and 106.Fa oldlenp 107should be set to 108.Dv NULL . 109.Pp 110The size of the available data can be determined by calling 111.Nm 112with a 113.Dv NULL 114parameter for 115.Fa oldp . 116The size of the available data will be returned in the location pointed to by 117.Fa oldlenp . 118For some operations, the amount of space may change often. 119For these operations, 120the system attempts to round up so that the returned size is 121large enough for a call to return the data shortly thereafter. 122.Pp 123To set a new value, 124.Fa newp 125is set to point to a buffer of length 126.Fa newlen 127from which the requested value is to be taken. 128If a new value is not to be set, 129.Fa newp 130should be set to 131.Dv NULL 132and 133.Fa newlen 134set to 0. 135.Pp 136The 137.Fn sysctlnametomib 138function can be used to map the string representation of a MIB entry 139to the numeric version. 140The 141.Fa name 142argument should point to an array of integers large enough to hold the 143MIB, and 144.Fa namelenp 145should indicate the number of integer slots available. 146Following a successful translation, the size_t indicated by 147.Fa namelenp 148will be changed to show the number of slots consumed. 149.Pp 150The 151.Fn sysctlgetmibinfo 152function performs name translation similar to 153.Fn sysctlnametomib , 154but also canonicalizes the name (or returns the first erroneous token 155from the string being parsed) into the space indicated by 156.Fa cname 157and 158.Fa csz . 159.Fa csz 160should indicate the size of the buffer pointed to by 161.Fa cname 162and on return, will indicate the size of the returned string including 163the trailing 164.Sq nul 165character. 166.Pp 167The 168.Fa rnode 169and 170.Fa v 171arguments to 172.Fn sysctlgetmibinfo 173are used to provide a tree for it to parse into, and to get back 174either a pointer to, or a copy of, the terminal node. 175If 176.Fa rnode 177is 178.Dv NULL , 179.Fn sysctlgetmibinfo 180uses its own internal tree for parsing, and checks it against the 181kernel at each call, to make sure that the name-to-number mapping is 182kept up to date. 183The 184.Fa v 185argument is ignored in this case. 186If 187.Fa rnode 188is not 189.Dv NULL 190but the pointer it references is, on a successful return, 191.Fa rnode 192will be adjusted to point to a copy of the terminal node. 193The 194.Fa v 195argument indicates which version of the 196.Nm 197node structure the caller wants. 198The application must later 199.Fn free 200this copy. 201If neither 202.Fa rnode 203nor the pointer it references are 204.Dv NULL , 205the pointer is used as the address of a tree over which the parsing is 206done. 207In this last case, the tree is not checked against the kernel, no 208refreshing of the mappings is performed, and the value given by 209.Fa v 210must agree with the version indicated by the tree. 211It is recommended that applications always use 212.Dv SYSCTL_VERSION 213as the value for 214.Fa v , 215as defined in the include file 216.Pa sys/sysctl.h . 217.Pp 218The top level names are defined with a CTL_ prefix in 219.Aq Pa sys/sysctl.h , 220and are as follows. 221The next and subsequent levels down are found in the include files 222listed here, and described in separate sections below. 223.Pp 224.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 225.It Sy Name Next level names Description 226.It CTL\_KERN sys/sysctl.h High kernel limits 227.It CTL\_VM uvm/uvm_param.h Virtual memory 228.It CTL\_VFS sys/mount.h Filesystem 229.It CTL\_NET sys/socket.h Networking 230.It CTL\_DEBUG sys/sysctl.h Debugging 231.It CTL\_HW sys/sysctl.h Generic CPU, I/O 232.It CTL\_MACHDEP sys/sysctl.h Machine dependent 233.It CTL\_USER sys/sysctl.h User-level 234.It CTL\_DDB sys/sysctl.h In-kernel debugger 235.It CTL\_PROC sys/sysctl.h Per-process 236.It CTL\_VENDOR ? Vendor specific 237.It CTL\_EMUL sys/sysctl.h Emulation settings 238.It CTL\_SECURITY sys/sysctl.h Security settings 239.El 240.Pp 241For example, the following retrieves the maximum number of processes allowed 242in the system: 243.Bd -literal -offset indent -compact 244int mib[2], maxproc; 245size_t len; 246.sp 247mib[0] = CTL_KERN; 248mib[1] = KERN_MAXPROC; 249len = sizeof(maxproc); 250sysctl(mib, 2, \*[Am]maxproc, \*[Am]len, NULL, 0); 251.Ed 252.sp 253To retrieve the standard search path for the system utilities: 254.Bd -literal -offset indent -compact 255int mib[2]; 256size_t len; 257char *p; 258.sp 259mib[0] = CTL_USER; 260mib[1] = USER_CS_PATH; 261sysctl(mib, 2, NULL, \*[Am]len, NULL, 0); 262p = malloc(len); 263sysctl(mib, 2, p, \*[Am]len, NULL, 0); 264.Ed 265.Sh CTL_DEBUG 266The debugging variables vary from system to system. 267A debugging variable may be added or deleted without need to recompile 268.Nm 269to know about it. 270Each time it runs, 271.Nm 272gets the list of debugging variables from the kernel and 273displays their current values. 274The system defines twenty 275.Va ( struct ctldebug ) 276variables named 277.Dv debug0 278through 279.Dv debug19 . 280They are declared as separate variables so that they can be 281individually initialized at the location of their associated variable. 282The loader prevents multiple use of the same variable by issuing errors 283if a variable is initialized in more than one place. 284For example, to export the variable 285.Dv dospecialcheck 286as a debugging variable, the following declaration would be used: 287.Bd -literal -offset indent -compact 288int dospecialcheck = 1; 289struct ctldebug debug5 = { "dospecialcheck", \*[Am]dospecialcheck }; 290.Ed 291.Pp 292Note that the dynamic implementation of 293.Nm 294currently in use largely makes this particular 295.Nm 296interface obsolete. 297See 298.Xr sysctl 8 299.\" and 300.\" .Xr sysctl 9 301for more information. 302.Sh CTL_VFS 303A distinguished second level name, VFS_GENERIC, 304is used to get general information about all filesystems. 305One of its third level identifiers is VFS_MAXTYPENUM 306that gives the highest valid filesystem type number. 307Its other third level identifier is VFS_CONF that 308returns configuration information about the filesystem 309type given as a fourth level identifier. 310The remaining second level identifiers are the 311filesystem type number returned by a 312.Xr statvfs 2 313call or from VFS_CONF. 314The third level identifiers available for each filesystem 315are given in the header file that defines the mount 316argument structure for that filesystem. 317.Sh CTL_HW 318The string and integer information available for the CTL_HW level 319is detailed below. 320The changeable column shows whether a process with appropriate 321privilege may change the value. 322.Bl -column "Second level nameXXXXXX" "struct disk_sysctlXXX" -offset indent 323.It Sy Second level name Type Changeable 324.It HW\_ALIGNBYTES integer no 325.It HW\_BYTEORDER integer no 326.It HW\_CNMAGIC string yes 327.It HW\_DISKNAMES string no 328.It HW\_DISKSTATS struct no 329.It HW\_MACHINE string no 330.It HW\_MACHINE\_ARCH string no 331.It HW\_MODEL string no 332.It HW\_NCPU integer no 333.It HW\_PAGESIZE integer no 334.It HW\_PHYSMEM integer no 335.It HW\_PHYSMEM64 quad no 336.It HW\_USERMEM integer no 337.It HW\_USERMEM64 quad no 338.El 339.Pp 340.Bl -tag -width "123456" 341.It Li HW_ALIGNBYTES 342Alignment constraint for all possible data types. 343This shows the value 344.Dv ALIGNBYTES 345in 346.Pa /usr/include/machine/param.h , 347at the kernel compilation time. 348.It Li HW_BYTEORDER 349The byteorder (4,321, or 1,234). 350.It Li HW_CNMAGIC 351The console magic key sequence. 352.It Li HW_DISKNAMES 353The list of (space separated) disk device and NFS mount names on the system. 354.It Li HW_IOSTATNAMES 355A space separated list of devices that will have I/O statistics 356collected on them. 357.It Li HW_IOSTATS 358Return statistical information on the NFS mounts, disk and tape 359devices on the system. 360An array of 361.Va struct io_sysctl 362structures is returned, 363whose size depends on the current number of such objects in the system. 364The third level name is the size of the 365.Va struct io_sysctl . 366The type of object can be determined by examining the 367.Va type 368element of 369.Va struct io_sysctl . 370Which can be 371.Dv IOSTAT_DISK 372(disk drive), 373.Dv IOSTAT_TAPE 374(tape drive), or 375.Dv IOSTAT_NFS 376(NFS mount). 377.It Li HW_MACHINE 378The machine class. 379.It Li HW_MACHINE_ARCH 380The machine CPU class. 381.It Li HW_MODEL 382The machine model. 383.It Li HW_NCPU 384The number of CPUs. 385.ne 1i 386.It Li HW_PAGESIZE 387The software page size. 388.It Li HW_PHYSMEM 389The bytes of physical memory as a 32-bit integer. 390.It Li HW_PHYSMEM64 391The bytes of physical memory as a 64-bit integer. 392.It Li HW_USERMEM 393The bytes of non-kernel memory as a 32-bit integer. 394.It Li HW_USERMEM64 395The bytes of non-kernel memory as a 64-bit integer. 396.El 397.Sh CTL_KERN 398The string and integer information available for the CTL_KERN level 399is detailed below. 400The changeable column shows whether a process with appropriate 401privilege may change the value. 402The types of data currently available are process information, 403system vnodes, the open file entries, routing table entries, 404virtual memory statistics, load average history, and clock rate 405information. 406.Bl -column "KERNXPOSIXXREADERXWRITERXLOCKS" "struct clockrateXXX" -offset indent 407.It Sy Second level name Type Changeable 408.It KERN\_ARGMAX integer no 409.It KERN\_AUTONICETIME integer yes 410.It KERN\_AUTONICEVAL integer yes 411.It KERN\_BOOTTIME struct timeval no 412.It KERN\_BUFQ node not applicable 413.It KERN\_CCPU integer no 414.It KERN\_CLOCKRATE struct clockinfo no 415.It KERN\_CONSDEV integer no 416.It KERN\_CP\_ID struct no 417.It KERN\_CP\_TIME uint64_t[\|] no 418.It KERN\_DEFCORENAME string yes 419.It KERN\_DOMAINNAME string yes 420.It KERN\_DRIVERS struct kinfo_drivers no 421.It KERN\_FILE struct file no 422.It KERN\_FORKFSLEEP integer yes 423.It KERN\_FSCALE integer no 424.It KERN\_FSYNC integer no 425.It KERN\_HARDCLOCK\_TICKS integer no 426.It KERN\_HOSTID integer yes 427.It KERN\_HOSTNAME string yes 428.It KERN\_IOV\_MAX integer no 429.It KERN\_JOB\_CONTROL integer no 430.It KERN\_LABELOFFSET integer no 431.It KERN\_LABELSECTOR integer no 432.It KERN\_LOGIN\_NAME\_MAX integer no 433.It KERN\_LOGSIGEXIT integer yes 434.It KERN\_MAPPED\_FILES integer no 435.It KERN\_MAXFILES integer yes 436.It KERN\_MAXPARTITIONS integer no 437.It KERN\_MAXPHYS integer no 438.It KERN\_MAXPROC integer yes 439.It KERN\_MAXPTYS integer yes 440.It KERN\_MAXVNODES integer yes 441.It KERN\_MBUF node not applicable 442.It KERN\_MEMLOCK integer no 443.It KERN\_MEMLOCK\_RANGE integer no 444.It KERN\_MEMORY\_PROTECTION integer no 445.It KERN\_MONOTONIC\_CLOCK integer no 446.It KERN\_MSGBUF integer no 447.It KERN\_MSGBUFSIZE integer no 448.It KERN\_NGROUPS integer no 449.It KERN\_NTPTIME struct ntptimeval no 450.It KERN\_OSRELEASE string no 451.It KERN\_OSREV integer no 452.It KERN\_OSTYPE string no 453.It KERN\_PIPE node not applicable 454.It KERN\_POSIX1 integer no 455.It KERN\_POSIX\_BARRIERS integer no 456.It KERN\_POSIX\_READER\_WRITER\_LOCKS integer no 457.It KERN\_POSIX\_SEMAPHORES integer no 458.It KERN\_POSIX\_SPIN\_LOCKS integer no 459.It KERN\_POSIX\_THREADS integer no 460.It KERN\_POSIX\_TIMERS integer no 461.It KERN\_PROC struct kinfo_proc no 462.It KERN\_PROC2 struct kinfo_proc2 no 463.It KERN\_PROC\_ARGS string no 464.It KERN\_PROF node not applicable 465.It KERN\_RAWPARTITION integer no 466.It KERN\_ROOT\_DEVICE string no 467.It KERN\_ROOT\_PARTITION integer no 468.It KERN\_RTC\_OFFSET integer yes 469.It KERN\_SAVED\_IDS integer no 470.It KERN\_SECURELVL integer raise only 471.It KERN\_SYNCHRONIZED\_IO integer no 472.It KERN\_SYSVIPC\_INFO node not applicable 473.It KERN\_SYSVMSG integer no 474.It KERN\_SYSVSEM integer no 475.It KERN\_SYSVSHM integer no 476.It KERN\_TIMEX struct no 477.It KERN\_TKSTAT node not applicable 478.It KERN\_URANDOM integer no 479.It KERN\_VERIEXEC node not applicable 480.It KERN\_VERSION string no 481.It KERN\_VNODE struct vnode no 482.El 483.ne 1i 484.Pp 485.Bl -tag -width "123456" 486.It Li KERN_ARGMAX 487The maximum bytes of argument to 488.Xr execve 2 . 489.It Li KERN_AUTONICETIME 490The number of seconds of CPU-time a non-root process may accumulate before 491having its priority lowered from the default to the value of KERN_AUTONICEVAL. 492If set to 0, automatic lowering of priority is not performed, and if set to \-1 493all non-root processes are immediately lowered. 494.It Li KERN_AUTONICEVAL 495The priority assigned for automatically niced processes. 496.It Li KERN_BOOTTIME 497A 498.Va struct timeval 499structure is returned. 500This structure contains the time that the system was booted. 501.It Li KERN_CCPU 502The scheduler exponential decay value. 503.It Li KERN_CLOCKRATE 504A 505.Va struct clockinfo 506structure is returned. 507This structure contains the clock, statistics clock and profiling clock 508frequencies, the number of micro-seconds per hz tick, and the clock 509skew rate. 510.It Li KERN_CONSDEV 511Console device. 512.It Li KERN_CP_ID 513Mapping of CPU number to CPU id. 514.It Li KERN_CP_TIME 515Returns an array of CPUSTATES uint64_ts. 516This array contains the 517number of clock ticks spent in different CPU states. 518On multi-processor systems, the sum across all CPUs is returned unless 519appropriate space is given for one data set for each CPU. 520Data for a specific CPU can also be obtained by adding the number of the 521CPU at the end of the MIB, enlarging it by one. 522.It Li KERN_DEFCORENAME 523Default template for the name of core dump files (see also PROC_PID_CORENAME 524in the per-process variables CTL_PROC, and 525.Xr core 5 526for format of this template). 527The default value is 528.Nm %n.core 529and can be changed with the kernel configuration option 530.Cd options DEFCORENAME 531(see 532.Xr options 4 533). 534.It Li KERN_DOMAINNAME 535Get or set the YP domain name. 536.It Li KERN_DUMP_ON_PANIC 537Perform a crash dump on system panic. 538.It Li KERN_DRIVERS 539Return an array of 540.Va struct kinfo_drivers 541that contains the name and major device numbers of all the device drivers 542in the current kernel. 543The 544.Va d_name 545field is always a NUL terminated string. 546The 547.Va d_bmajor 548field will be set to \-1 if the driver doesn't have a block device. 549.It Li KERN_FILE 550Return the entire file table. 551The returned data consists of a single 552.Va struct filelist 553followed by an array of 554.Va struct file , 555whose size depends on the current number of such objects in the system. 556.It Li KERN_FORKFSLEEP 557If 558.Xr fork 2 559system call fails due to limit on number of processes (either 560the global maxproc limit or user's one), wait for this many 561milliseconds before returning 562.Er EAGAIN 563error to process. 564Useful to keep heavily forking runaway processes in bay. 565Default zero (no sleep). 566Maximum is 20 seconds. 567.It Li KERN_FSCALE 568The kernel fixed-point scale factor. 569.It Li KERN_FSYNC 570Return 1 if the POSIX 1003.1b File Synchronization Option is available 571on this system, 572otherwise 0. 573.It Li KERN_HARDCLOCK_TICKS 574Returns the number of 575.Xr hardclock 9 576ticks. 577.It Li KERN_HOSTID 578Get or set the host id. 579.It Li KERN_HOSTNAME 580Get or set the hostname. 581.It Li KERN_IOV_MAX 582Return the maximum number of 583.Va iovec 584structures that a process has available for use with 585.Xr preadv 2 , 586.Xr pwritev 2 , 587.Xr readv 2 , 588.Xr recvmsg 2 , 589.Xr sendmsg 2 590and 591.Xr writev 2 . 592.It Li KERN_JOB_CONTROL 593Return 1 if job control is available on this system, otherwise 0. 594.It Li KERN_LABELOFFSET 595The offset within the sector specified by KERN_LABELSECTOR of the 596.Xr disklabel 5 . 597.It Li KERN_LABELSECTOR 598The sector number containing the 599.Xr disklabel 5 . 600.It Li KERN_LOGIN_NAME_MAX 601The size of the storage required for a login name, in bytes, 602including the terminating NUL. 603.It Li KERN_LOGSIGEXIT 604If this flag is non-zero, the kernel will 605.Xr log 9 606all process exits due to signals which create a 607.Xr core 5 608file, and whether the coredump was created. 609.It Li KERN_MAPPED_FILES 610Returns 1 if the POSIX 1003.1b Memory Mapped Files Option is available 611on this system, 612otherwise 0. 613.It Li KERN_MAXFILES 614The maximum number of open files that may be open in the system. 615.It Li KERN_MAXPARTITIONS 616The maximum number of partitions allowed per disk. 617.It Li KERN_MAXPHYS 618Maximum raw I/O transfer size. 619.It Li KERN_MAXPROC 620The maximum number of simultaneous processes the system will allow. 621.It Li KERN_MAXPTYS 622The maximum number of pseudo terminals. 623This value can be both raised and lowered, though it cannot 624be set lower than number of currently used ptys. 625See also 626.Xr pty 4 . 627.It Li KERN_MAXVNODES 628The maximum number of vnodes available on the system. 629This can only be raised. 630.It Li KERN_MBUF 631Return information about the mbuf control variables. 632the third level names for the mbuf variables are detailed below. 633The changeable column shows whether a process with appropriate 634privilege may change the value. 635.Bl -column "MBUFXNMBCLUSTERSXXX" "struct integerXXX" -offset indent 636.It Sy Third level name Type Changeable 637.It MBUF\_MBLOWAT integer yes 638.It MBUF\_MCLBYTES integer yes 639.It MBUF\_MCLLOWAT integer yes 640.It MBUF\_MSIZE integer yes 641.It MBUF\_NMBCLUSTERS integer yes 642.El 643.Pp 644The variables are as follows: 645.Bl -tag -width "123456" 646.It Li MBUF_MBLOWAT 647The mbuf low water mark. 648.It Li MBUF_MCLBYTES 649The mbuf cluster size. 650.It Li MBUF_MCLLOWAT 651The mbuf cluster low water mark. 652.It Li MBUF_MSIZE 653The mbuf base size. 654.It Li MBUF_NMBCLUSTERS 655The limit on the number of mbuf clusters. 656The variable can only be increased, and only increased on machines with 657direct-mapped pool pages. 658.El 659.It Li KERN_MEMLOCK 660Returns 1 if the POSIX 1003.1b Process Memory Locking Option is available 661on this system, 662otherwise 0. 663.It Li KERN_MEMLOCK_RANGE 664Returns 1 if the POSIX 1003.1b Range Memory Locking Option is available 665on this system, 666otherwise 0. 667.It Li KERN_MEMORY_PROTECTION 668Returns 1 if the POSIX 1003.1b Memory Protection Option is available 669on this system, 670otherwise 0. 671.It Li KERN_MONOTONIC_CLOCK 672Returns the standard version the implementation of the POSIX 1003.1b 673Monotonic Clock Option conforms to, 674otherwise 0. 675.It Li KERN_MSGBUF 676The kernel message buffer, rotated so that the head of the circular kernel 677message buffer is returned at the start of the buffer specified by 678.Fa oldp . 679The returned data may contain NUL bytes. 680.It Li KERN_MSGBUFSIZE 681The maximum number of characters that the kernel message buffer can hold. 682.It Li KERN_NGROUPS 683The maximum number of supplemental groups. 684.It Li KERN_NTPTIME 685A 686.Va struct ntptimeval 687structure is returned. 688This structure contains data used by the 689.Xr ntpd 8 690program. 691.It Li KERN_OSRELEASE 692The system release string. 693.It Li KERN_OSREV 694The system revision string. 695.It Li KERN_OSTYPE 696The system type string. 697.It Li KERN_PIPE 698Pipe settings. 699The third level names for the integer pipe settings is detailed below. 700The changeable column shows whether a process with appropriate 701privilege may change the value. 702.Bl -column "KERNXPIPEXFOOXXX" "integerXXX" -offset indent 703.It Sy Third level name Type Changeable 704.It KERN\_PIPE\_KVASIZ integer yes 705.It KERN\_PIPE\_MAXBIGPIPES integer yes 706.It KERN\_PIPE\_MAXKVASZ integer yes 707.It KERN\_PIPE\_LIMITKVA integer yes 708.It KERN\_PIPE\_NBIGPIPES integer yes 709.El 710.Pp 711The variables are as follows: 712.Bl -tag -width "123456" 713.It Li KERN_PIPE_KVASIZ 714Amount of kernel memory consumed by pipe buffers. 715.It Li KERN_PIPE_MAXBIGPIPES 716Maximum number of "big" pipes. 717.It Li KERN_PIPE_MAXKVASZ 718Maximum amount of kernel memory to be used for pipes. 719.It Li KERN_PIPE_LIMITKVA 720Limit for direct transfers via page loan. 721.It Li KERN_PIPE_NBIGPIPES 722Number of "big" pipes. 723.El 724.It Li KERN_POSIX1 725The version of ISO/IEC 9945 (POSIX 1003.1) with which the system 726attempts to comply. 727.It Li KERN_POSIX_BARRIERS 728The version of 729.St -p1003.1 730and its 731Barriers 732option to which the system attempts to conform, 733otherwise 0. 734.It Li KERN_POSIX_READER_WRITER_LOCKS 735The version of 736.St -p1003.1 737and its 738Read-Write Locks 739option to which the system attempts to conform, 740otherwise 0. 741.It Li KERN_POSIX_SEMAPHORES 742The version of 743.St -p1003.1 744and its 745Semaphores 746option to which the system attempts to conform, 747otherwise 0. 748.It Li KERN_POSIX_SPIN_LOCKS 749The version of 750.St -p1003.1 751and its 752Spin Locks 753option to which the system attempts to conform, 754otherwise 0. 755.It Li KERN_POSIX_THREADS 756The version of 757.St -p1003.1 758and its 759Threads 760option to which the system attempts to conform, 761otherwise 0. 762.It Li KERN_POSIX_TIMERS 763The version of 764.St -p1003.1 765and its 766Timers 767option to which the system attempts to conform, 768otherwise 0. 769.It Li KERN_PROC 770Return the entire process table, or a subset of it. 771An array of 772.Va struct kinfo_proc 773structures is returned, 774whose size depends on the current number of such objects in the system. 775The third and fourth level names are as follows: 776.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 777.It Sy Third level name Fourth level is: 778.It KERN\_PROC\_ALL None 779.It KERN\_PROC\_GID A group ID 780.It KERN\_PROC\_PID A process ID 781.It KERN\_PROC\_PGRP A process group 782.It KERN\_PROC\_RGID A real group ID 783.It KERN\_PROC\_RUID A real user ID 784.It KERN\_PROC\_SESSION A session ID 785.It KERN\_PROC\_TTY A tty device 786.It KERN\_PROC\_UID A user ID 787.El 788.It Li KERN_PROC2 789As for KERN_PROC, but an array of 790.Va struct kinfo_proc2 791structures are returned. 792The fifth level name is the size of the 793.Va struct kinfo_proc2 794and the sixth level name is the number of structures to return. 795.It Li KERN_PROC_ARGS 796Return the argv or environment strings (or the number thereof) 797of a process. 798Multiple strings are returned separated by NUL characters. 799The third level name is the process ID. 800The fourth level name is as follows: 801.Bl -column "Third level nameXXXXXX" -offset indent 802.It KERN\_PROC\_ARGV The argv strings 803.It KERN\_PROC\_ENV The environ strings 804.It KERN\_PROC\_NARGV The number of argv strings 805.It KERN\_PROC\_NENV The number of environ strings 806.El 807.It Li KERN_PROF 808Return profiling information about the kernel. 809If the kernel is not compiled for profiling, 810attempts to retrieve any of the KERN_PROF values will 811fail with EOPNOTSUPP. 812The third level names for the string and integer profiling information 813is detailed below. 814The changeable column shows whether a process with appropriate 815privilege may change the value. 816.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 817.It Sy Third level name Type Changeable 818.It GPROF\_COUNT u_short[\|] yes 819.It GPROF\_FROMS u_short[\|] yes 820.It GPROF\_GMONPARAM struct gmonparam no 821.It GPROF\_STATE integer yes 822.It GPROF\_TOS struct tostruct yes 823.El 824.Pp 825The variables are as follows: 826.Bl -tag -width "123456" 827.It Li GPROF_COUNT 828Array of statistical program counter counts. 829.It Li GPROF_FROMS 830Array indexed by program counter of call-from points. 831.It Li GPROF_GMONPARAM 832Structure giving the sizes of the above arrays. 833.It Li GPROF_STATE 834Profiling state. 835If set to GMON_PROF_ON, starts profiling. 836If set to GMON_PROF_OFF, stops profiling. 837.It Li GPROF_TOS 838Array of 839.Va struct tostruct 840describing destination of calls and their counts. 841.El 842.It Li KERN_RAWPARTITION 843The raw partition of a disk (a == 0). 844.It Li KERN_ROOT_DEVICE 845The name of the root device (e.g., 846.Dq wd0 ) . 847.It Li KERN_ROOT_PARTITION 848The root partition on the root device (a == 0). 849.It Li KERN_RTC_OFFSET 850Return the offset of real time clock from UTC in minutes. 851.It Li KERN_SAVED_IDS 852Returns 1 if saved set-group and saved set-user ID is available. 853.It Li KERN_SBMAX 854Maximum socket buffer size. 855.It Li KERN_SECURELVL 856The system security level. 857This level may be raised by processes with appropriate privilege. 858It may only be lowered by process 1. 859.It Li KERN_SOMAXKVA 860Maximum amount of kernel memory to be used for socket buffers. 861.It Li KERN_SYNCHRONIZED_IO 862Returns 1 if the POSIX 1003.1b Synchronized I/O Option is available 863on this system, 864otherwise 0. 865.It Li KERN_SYSVIPC_INFO 866Return System V style IPC configuration and run-time information. 867The third level name selects the System V style IPC facility. 868.Bl -column "KERN_SYSVIPC_MSG_INFOXXX" "struct shm_sysctl_infoXXX" -offset indent 869.It Sy Third level name Type 870.It KERN\_SYSVIPC\_MSG\_INFO struct msg_sysctl_info 871.It KERN\_SYSVIPC\_SEM\_INFO struct sem_sysctl_info 872.It KERN\_SYSVIPC\_SHM\_INFO struct shm_sysctl_info 873.El 874.Pp 875.Bl -tag -width "123456" 876.It Li KERN_SYSVIPC_MSG_INFO 877Return information on the System V style message facility. 878The 879.Sy msg_sysctl_info 880structure is defined in 881.Aq Pa sys/msg.h . 882.It Li KERN_SYSVIPC_SEM_INFO 883Return information on the System V style semaphore facility. 884The 885.Sy sem_sysctl_info 886structure is defined in 887.Aq Pa sys/sem.h . 888.It Li KERN_SYSVIPC_SHM_INFO 889Return information on the System V style shared memory facility. 890The 891.Sy shm_sysctl_info 892structure is defined in 893.Aq Pa sys/shm.h . 894.El 895.It Li KERN_SYSVMSG 896Returns 1 if System V style message queue functionality is available 897on this system, 898otherwise 0. 899.It Li KERN_SYSVSEM 900Returns 1 if System V style semaphore functionality is available 901on this system, 902otherwise 0. 903.It Li KERN_SYSVSHM 904Returns 1 if System V style share memory functionality is available 905on this system, 906otherwise 0. 907.It Li KERN_TIMEX 908Not available. 909.It Li KERN_TKSTAT 910Return information about the number of characters sent and received 911on ttys. 912The third level names for the tty statistic variables are detailed below. 913The changeable column shows whether a process 914with appropriate privilege may change the value. 915.Bl -column "KERNXTKSTATXRAWCCXXX" "struct integerXXX" -offset indent 916.It Sy Third level name Type Changeable 917.It KERN\_TKSTAT\_CANCC quad no 918.It KERN\_TKSTAT\_NIN quad no 919.It KERN\_TKSTAT\_NOUT quad no 920.It KERN\_TKSTAT\_RAWCC quad no 921.El 922.Pp 923The variables are as follows: 924.Bl -tag -width "123456" 925.It Li KERN_TKSTAT_CANCC 926The number of canonical input characters. 927.It Li KERN_TKSTAT_NIN 928The total number of input characters. 929.It Li KERN_TKSTAT_NOUT 930The total number of output characters. 931.It Li KERN_TKSTAT_RAWCC 932The number of raw input characters. 933.El 934.It Li KERN_URND 935Random integer value. 936.It Li KERN_VERIEXEC 937Tunings for Verified Exec. 938Third level names for the veriexec variables are detailed below. 939The changeable column shows whether a process with appropriate 940privilege may change the value or only raise it. 941Only the superuser can modify these variables. 942.Bl -column "VERIEXECXALGORITHMSXXX" "struct integerXXX" -offset indent 943.It Sy Third level name Type Changeable 944.It VERIEXEC\_ALGORITHMS string no 945.It VERIEXEC\_COUNT node not applicable 946.It VERIEXEC\_STRICT integer raise only 947.It VERIEXEC\_VERBOSE integer yes 948.El 949.Pp 950The variables are as follows: 951.Bl -tag -width "123456" 952.It Li VERIEXEC_ALGORITHMS 953Returns a string with the supported algorithms in Verified Exec. 954.It Li VERIEXEC_COUNT 955Variables are added to this node as new hash tables are created to 956contain Verified Exec data for a new device. 957Each variable in the node 958will have a name in the form of 959.No dev_ Ns Aq id 960where 961.Aq id 962is the device id. 963For example, the variable for the root device may be dev_0. 964The value of this 965variable will be the amount of fingerprinted files on the device. 966.It Li VERIEXEC_STRICT 967Controls the strict level of Verified Exec. 968The strict level defines how 969Verified Exec will treat various situations. 970In strict level 0, the system is in learning mode and will only warn about 971fingerprint mismatches, aswell as allow removal of fingerprinted files. 972It is the only level where fingerprints can be loaded. 973In strict level 1, the system is in IDS mode. 974It will deny access to files with mismatched fingerprints. 975In strict level 2, the system is in IPS mode. 976It has all effects of 977strict level 1, plus it will deny write access to monitored files, 978prevent their removal, and enforce access type (direct, indirect, file). 979Strict level 3 operates as lockdown mode. 980It will have all effects of 981strict level 2, but it will also prevent access to non-monitored files. 982Furthermore, it will prevent addition of new files to the system, and 983allow writing only to files opened before the strict level was raised. 984.It Li VERIEXEC_VERBOSE 985Controls the verbosity level of Verified Exec. 986If 0, only the minimal 987indication required will be given about what's happening - fingerprint 988mismatches, removal of entries from the tables, modification of a 989fingerprinted file. 990If 1, more messages will be printed (ie., when a file with a valid 991fingerprint is accessed). 992Verbose level 2 is debug mode. 993.El 994.It Li KERN_VERSION 995The system version string. 996.It Li KERN_VNODE 997Return the entire vnode table. 998Note, the vnode table is not necessarily a consistent snapshot of 999the system. 1000The returned data consists of an array whose size depends on the 1001current number of such objects in the system. 1002Each element of the array contains the kernel address of a vnode 1003.Va struct vnode * 1004followed by the vnode itself 1005.Va struct vnode . 1006.El 1007.Sh CTL_MACHDEP 1008The set of variables defined is architecture dependent. 1009Most architectures define at least the following variables. 1010.Bl -column "CONSOLE_DEVICEXXX" "integerXXX" -offset indent 1011.It Sy Second level name Type Changeable 1012.It Li CPU_CONSDEV dev_t no 1013.El 1014.Sh CTL_NET 1015The string and integer information available for the CTL_NET level 1016is detailed below. 1017The changeable column shows whether a process with appropriate 1018privilege may change the value. 1019The second and third levels are typically the protocol family and 1020protocol number, though this is not always the case. 1021.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 1022.It Sy Second level name Type Changeable 1023.It PF\_ROUTE routing messages no 1024.It PF\_INET IPv4 values yes 1025.It PF\_INET6 IPv6 values yes 1026.It PF\_KEY IPsec key management values yes 1027.El 1028.Pp 1029.Bl -tag -width "123456" 1030.It Li PF_ROUTE 1031Return the entire routing table or a subset of it. 1032The data is returned as a sequence of routing messages (see 1033.Xr route 4 1034for the header file, format and meaning). 1035The length of each message is contained in the message header. 1036.Pp 1037The third level name is a protocol number, which is currently always 0. 1038The fourth level name is an address family, which may be set to 0 to 1039select all address families. 1040The fifth and sixth level names are as follows: 1041.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 1042.It Sy Fifth level name Sixth level is: 1043.It NET\_RT\_FLAGS rtflags 1044.It NET\_RT\_DUMP None 1045.It NET\_RT\_IFLIST None 1046.El 1047.It Li PF_INET 1048Get or set various global information about the IPv4 1049.Pq Internet Protocol version 4 . 1050The third level name is the protocol. 1051The fourth level name is the variable name. 1052The currently defined protocols and names are: 1053.Bl -column "Protocol name" "Variable nameXX" "integer" "yes" -offset indent 1054.It Sy Protocol name Variable name Type Changeable 1055.It arp down integer yes 1056.It arp keep integer yes 1057.It arp prune integer yes 1058.It arp refresh integer yes 1059.It icmp errppslimit integer yes 1060.It icmp maskrepl integer yes 1061.It icmp rediraccept integer yes 1062.It icmp redirtimeout integer yes 1063.It ip allowsrcrt integer yes 1064.It ip anonportmax integer yes 1065.It ip anonportmin integer yes 1066.It ip checkinterface integer yes 1067.It ip directed-broadcast integer yes 1068.It ip do_loopback_cksum integer yes 1069.It ip forwarding integer yes 1070.It ip forwsrcrt integer yes 1071.It ip gifttl integer yes 1072.It ip grettl integer yes 1073.It ip hostzerobroadcast integer yes 1074.It ip lowportmin integer yes 1075.It ip lowportmax integer yes 1076.It ip maxfragpackets integer yes 1077.It ip mtudisc integer yes 1078.It ip mtudisctimeout integer yes 1079.It ip random_id integer yes 1080.It ip redirect integer yes 1081.It ip subnetsarelocal integer yes 1082.It ip ttl integer yes 1083.It tcp rfc1323 integer yes 1084.It tcp sendspace integer yes 1085.It tcp recvspace integer yes 1086.It tcp mssdflt integer yes 1087.It tcp syn_cache_limit integer yes 1088.It tcp syn_bucket_limit integer yes 1089.It tcp syn_cache_interval integer yes 1090.It tcp init_win integer yes 1091.It tcp init_win_local integer yes 1092.It tcp mss_ifmtu integer yes 1093.It tcp sack integer yes 1094.It tcp win_scale integer yes 1095.It tcp timestamps integer yes 1096.It tcp compat_42 integer yes 1097.It tcp cwm integer yes 1098.It tcp cwm_burstsize integer yes 1099.It tcp ack_on_push integer yes 1100.It tcp keepidle integer yes 1101.It tcp keepintvl integer yes 1102.It tcp keepcnt integer yes 1103.It tcp slowhz integer no 1104.It tcp newreno integer yes 1105.It tcp log_refused integer yes 1106.It tcp rstppslimit integer yes 1107.It tcp ident struct no 1108.It udp checksum integer yes 1109.It udp do_loopback_cksum integer yes 1110.It udp recvspace integer yes 1111.It udp sendspace integer yes 1112.El 1113.Pp 1114The variables are as follows: 1115.Bl -tag -width "123456" 1116.It Li arp.down 1117Failed ARP entry lifetime. 1118.It Li arp.keep 1119Valid ARP entry lifetime. 1120.It Li arp.prune 1121ARP cache pruning interval. 1122.It Li arp.refresh 1123ARP entry refresh interval. 1124.It Li ip.allowsrcrt 1125If set to 1, the host accepts source routed packets. 1126.It Li ip.anonportmax 1127The highest port number to use for TCP and UDP ephemeral port allocation. 1128This cannot be set to less than 1024 or greater than 65535, and must 1129be greater than 1130.Li ip.anonportmin . 1131.It Li ip.anonportmin 1132The lowest port number to use for TCP and UDP ephemeral port allocation. 1133This cannot be set to less than 1024 or greater than 65535. 1134.It Li ip.checkinterface 1135If set to non-zero, the host will reject packets addressed to it 1136that arrive on an interface not bound to that address. 1137Currently, this must be disabled if ipnat is used to translate the 1138destination address to another local interface, or if addresses 1139are added to the loopback interface instead of the interface where 1140the packets for those packets are received. 1141.It Li ip.directed-broadcast 1142If set to 1, enables directed broadcast behavior for the host. 1143.It Li ip.do_loopback_cksum 1144Perform IP checksum on loopback. 1145.It Li ip.forwarding 1146If set to 1, enables IP forwarding for the host, 1147meaning that the host is acting as a router. 1148.It Li ip.forwsrcrt 1149If set to 1, enables forwarding of source-routed packets for the host. 1150This value may only be changed if the kernel security level is less than 1. 1151.It Li ip.gifttl 1152The maximum time-to-live (hop count) value for an IPv4 packet generated by 1153.Xr gif 4 1154tunnel interface. 1155.It Li ip.grettl 1156The maximum time-to-live (hop count) value for an IPv4 packet generated by 1157.Xr gre 4 1158tunnel interface. 1159.It Li ip.hostzerobroadcast 1160All zeroes address is broadcast address. 1161.It Li ip.lowportmax 1162The highest port number to use for TCP and UDP reserved port allocation. 1163This cannot be set to less than 0 or greater than 1024, and must 1164be greater than 1165.Li ip.lowportmin . 1166.It Li ip.lowportmin 1167The lowest port number to use for TCP and UDP reserved port allocation. 1168This cannot be set to less than 0 or greater than 1024, and must 1169be smaller than 1170.Li ip.lowportmax . 1171.It Li ip.maxfragpackets 1172The maximum number of fragmented packets the node will accept. 11730 means that the node will not accept any fragmented packets. 1174\-1 means that the node will accept as many fragmented packets as it receives. 1175The flag is provided basically for avoiding possible DoS attacks. 1176.It Li ip.mtudisc 1177If set to 1, enables Path MTU Discovery (RFC 1191). 1178When Path MTU Discovery is enabled, the transmitted TCP segment 1179size will be determined by the advertised maximum segment size 1180(MSS) from the remote end, as constrained by the path MTU. 1181If MTU Discovery is disabled, the transmitted segment size will 1182never be greater than 1183.Li tcp.mssdflt 1184(the local maximum segment size). 1185.It Li ip.mtudisctimeout 1186The number of seconds in which a route added by the Path MTU 1187Discovery engine will time out. 1188When the route times out, the Path 1189MTU Discovery engine will attempt to probe a larger path MTU. 1190.It Li ip.random_id 1191Assign random ip_id values. 1192.It Li ip.redirect 1193If set to 1, ICMP redirects may be sent by the host. 1194This option is ignored unless the host is routing IP packets, 1195and should normally be enabled on all systems. 1196.It Li ip.subnetsarelocal 1197If set to 1, subnets are to be considered local addresses. 1198.It Li ip.ttl 1199The maximum time-to-live (hop count) value for an IP packet sourced by 1200the system. 1201This value applies to normal transport protocols, not to ICMP. 1202.It Li icmp.errppslimit 1203The variable specifies the maximum number of outgoing ICMP error messages, 1204per second. 1205ICMP error messages that exceeded the value are subject to rate limitation 1206and will not go out from the node. 1207Negative value disables rate limitation. 1208.It Li icmp.maskrepl 1209If set to 1, ICMP network mask requests are to be answered. 1210.It Li icmp.rediraccept 1211If set to non-zero, the host will accept ICMP redirect packets. 1212Note that routers will never accept ICMP redirect packets, 1213and the variable is meaningful on IP hosts only. 1214.It Li icmp.redirtimeout 1215The variable specifies lifetime of routing entries generated by incoming 1216ICMP redirect. 1217This defaults to 600 seconds. 1218.It Li icmp.returndatabytes 1219Number of bytes to return in an ICMP error message. 1220.It Li tcp.ack_on_push 1221If set to 1, TCP is to immediately transmit an ACK upon reception of 1222a packet with PUSH set. 1223This can avoid losing a round trip time in some rare situations, 1224but has the caveat of potentially defeating TCP's delayed ACK algorithm. 1225Use of this option is generally not recommended, but 1226the variable exists in case your configuration really needs it. 1227.It Li tcp.compat_42 1228If set to 1, enables work-arounds for bugs in the 4.2BSD TCP implementation. 1229Use of this option is not recommended, although it may be 1230required in order to communicate with extremely old TCP implementations. 1231.It Li tcp.cwm 1232If set to 1, enables use of the Hughes/Touch/Heidemann Congestion Window 1233Monitoring algorithm. 1234This algorithm prevents line-rate bursts of packets that could 1235otherwise occur when data begins flowing on an idle TCP connection. 1236These line-rate bursts can contribute to network and router congestion. 1237This can be particularly useful on World Wide Web servers 1238which support HTTP/1.1, which has lingering connections. 1239.It Li tcp.cwm_burstsize 1240The Congestion Window Monitoring allowed burst size, in terms 1241of packet count. 1242.It Li tcp.delack_ticks 1243Number of ticks to delay sending an ACK. 1244.It Li tcp.do_loopback_cksum 1245Perform TCP checksum on loopback. 1246.It Li tcp.init_win 1247A value indicating the TCP initial congestion window. 1248If this value is 0, an auto-tuning algorithm designed to use an initial 1249window of approximately 4K bytes is in use. 1250Otherwise, this value indicates a fixed number of packets. 1251.It Li tcp.init_win_local 1252Like 1253.Li tcp.init_win , 1254but used when communicating with hosts on a local network. 1255.It Li tcp.keepcnt 1256Number of keepalive probes sent before declaring a connection dead. 1257If set to zero, there is no limit; 1258keepalives will be sent until some kind of 1259response is received from the peer. 1260.It Li tcp.keepidle 1261Time a connection must be idle before keepalives are sent (if keepalives 1262are enabled for the connection). 1263See also tcp.slowhz. 1264.It Li tcp.keepintvl 1265Time after a keepalive probe is sent until, in the absence of any response, 1266another probe is sent. 1267See also tcp.slowhz. 1268.It Li tcp.log_refused 1269If set to 1, refused TCP connections to the host will be logged. 1270.It Li tcp.mss_ifmtu 1271If set to 1, TCP calculates the outgoing maximum segment size based on 1272the MTU of the appropriate interface. 1273If set to 0, it is calculated based on the greater of the MTU of the 1274interface, and the largest (non-loopback) interface MTU on the system. 1275.It Li tcp.mssdflt 1276The default maximum segment size both advertised to the peer 1277and to use when either the peer does not advertise a maximum segment size to 1278us during connection setup or Path MTU Discovery 1279.Li ( ip.mtudisc ) 1280is disabled. 1281Do not change this value unless you really know what you are doing. 1282.It Li tcp.newreno 1283If set to 1, enables the use of J. 1284Hoe's NewReno congestion control algorithm. 1285This algorithm improves the start-up behavior of TCP connections. 1286.It Li tcp.recvspace 1287The default TCP receive buffer size. 1288.It Li tcp.rfc1323 1289If set to 1, enables RFC 1323 extensions to TCP. 1290.It Li tcp.rstppslimit 1291The variable specifies the maximum number of outgoing TCP RST packets, 1292per second. 1293TCP RST packet that exceeded the value are subject to rate limitation 1294and will not go out from the node. 1295Negative value disables rate limitation. 1296.It Li tcp.sack.enable 1297If set to 1, enables RFC 2018 Selective ACKnowledgement. 1298.It Li tcp.sack.globalholes 1299Global number of TCP SACK holes. 1300.It Li tcp.sack.globalmaxholes 1301Global maximum number of TCP SACK holes. 1302.It Li tcp.sack.maxholes 1303Maximum number of TCP SACK holes allowed per connection. 1304.It Li tcp.sendspace 1305The default TCP send buffer size. 1306.It Li tcp.slowhz 1307The units for tcp.keepidle and tcp.keepintvl; those variables are in ticks 1308of a clock that ticks tcp.slowhz times per second. 1309(That is, their values 1310must be divided by the tcp.slowhz value to get times in seconds.) 1311.It Li tcp.syn_bucket_limit 1312The maximum number of entries allowed per hash bucket in the TCP 1313compressed state engine. 1314.It Li tcp.syn_cache_limit 1315The maximum number of entries allowed in the TCP compressed state 1316engine. 1317.It Li tcp.timestamps 1318If rfc1323 is enabled, a value of 1 indicates RFC 1323 time stamp options, 1319used for measuring TCP round trip times, are enabled. 1320.It Li tcp.win_scale 1321If rfc1323 is enabled, a value of 1 indicates RFC 1323 window scale options, 1322for increasing the TCP window size, are enabled. 1323.It Li udp.checksum 1324If set to 1, UDP checksums are being computed. 1325Received non-zero UDP checksums are always checked. 1326Disabling UDP checksums is strongly discouraged. 1327.It Li udp.sendspace 1328The default UDP send buffer size. 1329.It Li udp.recvspace 1330The default UDP receive buffer size. 1331.El 1332.Pp 1333For variables net.*.ipsec, please refer to 1334.Xr ipsec 4 . 1335.It Li PF_INET6 1336Get or set various global information about the IPv6 1337.Pq Internet Protocol version 6 . 1338The third level name is the protocol. 1339The fourth level name is the variable name. 1340The currently defined protocols and names are: 1341.Bl -column "Protocol name" "Variable nameXX" "integer" "yes" -offset indent 1342.It Sy Protocol name Variable name Type Changeable 1343.It icmp6 errppslimit integer yes 1344.It icmp6 mtudisc_hiwat integer yes 1345.It icmp6 mtudisc_lowat integer yes 1346.It icmp6 nd6_debug integer yes 1347.It icmp6 nd6_delay integer yes 1348.It icmp6 nd6_maxnudhint integer yes 1349.It icmp6 nd6_mmaxtries integer yes 1350.It icmp6 nd6_prune integer yes 1351.It icmp6 nd6_umaxtries integer yes 1352.It icmp6 nd6_useloopback integer yes 1353.It icmp6 nodeinfo integer yes 1354.It icmp6 rediraccept integer yes 1355.It icmp6 redirtimeout integer yes 1356.It ip6 accept_rtadv integer yes 1357.It ip6 anonportmax integer yes 1358.It ip6 anonportmin integer yes 1359.It ip6 auto_flowlabel integer yes 1360.It ip6 dad_count integer yes 1361.It ip6 defmcasthlim integer yes 1362.It ip6 forwarding integer yes 1363.It ip6 gifhlim integer yes 1364.It ip6 hlim integer yes 1365.It ip6 hdrnestlimit integer yes 1366.It ip6 kame_version string no 1367.It ip6 keepfaith integer yes 1368.It ip6 log_interval integer yes 1369.It ip6 lowportmax integer yes 1370.It ip6 lowportmin integer yes 1371.It ip6 maxfragpackets integer yes 1372.It ip6 maxfrags integer yes 1373.It ip6 redirect integer yes 1374.It ip6 rr_prune integer yes 1375.It ip6 use_deprecated integer yes 1376.It ip6 v6only integer yes 1377.It udp6 do_loopback_cksum integer yes 1378.It udp6 recvspace integer yes 1379.It udp6 sendspace integer yes 1380.El 1381.Pp 1382The variables are as follows: 1383.Bl -tag -width "123456" 1384.It Li ip6.accept_rtadv 1385If set to non-zero, the node will accept ICMPv6 router advertisement packets 1386and autoconfigures address prefixes and default routers. 1387The node must be a host 1388.Pq not a router 1389for the option to be meaningful. 1390.It Li ip6.anonportmax 1391The highest port number to use for TCP and UDP ephemeral port allocation. 1392This cannot be set to less than 1024 or greater than 65535, and must 1393be greater than 1394.Li ip6.anonportmin . 1395.It Li ip6.anonportmin 1396The lowest port number to use for TCP and UDP ephemeral port allocation. 1397This cannot be set to less than 1024 or greater than 65535. 1398.It Li ip6.auto_flowlabel 1399On connected transport protocol packets, 1400fill IPv6 flowlabel field to help intermediate routers to identify packet flows. 1401.It Li ip6.dad_count 1402The variable configures number of IPv6 DAD 1403.Pq duplicated address detection 1404probe packets. 1405The packets will be generated when IPv6 interface addresses are configured. 1406.It Li ip6.defmcasthlim 1407The default hop limit value for an IPv6 multicast packet sourced by the node. 1408This value applies to all the transport protocols on top of IPv6. 1409There are APIs to override the value, as documented in 1410.Xr ip6 4 . 1411.It Li ip6.forwarding 1412If set to 1, enables IPv6 forwarding for the node, 1413meaning that the node is acting as a router. 1414If set to 0, disables IPv6 forwarding for the node, 1415meaning that the node is acting as a host. 1416IPv6 specification defines node behavior for 1417.Dq router 1418case and 1419.Dq host 1420case quite differently, and changing this variable during operation 1421may cause serious trouble. 1422It is recommended to configure the variable at bootstrap time, 1423and bootstrap time only. 1424.It Li ip6.gifhlim 1425The maximum hop limit value for an IPv6 packet generated by 1426.Xr gif 4 1427tunnel interface. 1428.It Li ip6.hdrnestlimit 1429The number of IPv6 extension headers permitted on incoming IPv6 packets. 1430If set to 0, the node will accept as many extension headers as possible. 1431.It Li ip6.hlim 1432The default hop limit value for an IPv6 unicast packet sourced by the node. 1433This value applies to all the transport protocols on top of IPv6. 1434There are APIs to override the value, as documented in 1435.Xr ip6 4 . 1436.It Li ip6.kame_version 1437The string identifies the version of KAME IPv6 stack implemented in the kernel. 1438.It Li ip6.keepfaith 1439If set to non-zero, it enables 1440.Dq FAITH 1441TCP relay IPv6-to-IPv4 translator code in the kernel. 1442Refer 1443.Xr faith 4 1444and 1445.Xr faithd 8 1446for detail. 1447.It Li ip6.log_interval 1448The variable controls amount of logs generated by IPv6 packet 1449forwarding engine, by setting interval between log output 1450.Pq in seconds . 1451.It Li ip6.lowportmax 1452The highest port number to use for TCP and UDP reserved port allocation. 1453This cannot be set to less than 0 or greater than 1024, and must 1454be greater than 1455.Li ip6.lowportmin . 1456.It Li ip6.lowportmin 1457The lowest port number to use for TCP and UDP reserved port allocation. 1458This cannot be set to less than 0 or greater than 1024, and must 1459be smaller than 1460.Li ip6.lowportmax . 1461.It Li ip6.maxfragpackets 1462The maximum number of fragmented packets the node will accept. 14630 means that the node will not accept any fragmented packets. 1464\-1 means that the node will accept as many fragmented packets as it receives. 1465The flag is provided basically for avoiding possible DoS attacks. 1466.It Li ip6.maxfrags 1467The maximum number of fragments the node will accept. 14680 means that the node will not accept any fragments. 1469\-1 means that the node will accept as many fragments as it receives. 1470The flag is provided basically for avoiding possible DoS attacks. 1471.It Li ip6.redirect 1472If set to 1, ICMPv6 redirects may be sent by the node. 1473This option is ignored unless the node is routing IP packets, 1474and should normally be enabled on all systems. 1475.It Li ip6.rr_prune 1476The variable specifies interval between IPv6 router renumbering prefix 1477babysitting, in seconds. 1478.It Li ip6.use_deprecated 1479The variable controls use of deprecated address, specified in RFC 2462 5.5.4. 1480.It Li ip6.v6only 1481The variable specifies initial value for 1482.Dv IPV6_V6ONLY 1483socket option for 1484.Dv AF_INET6 1485socket. 1486Please refer to 1487.Xr ip6 4 1488for detail. 1489.It Li icmp6.errppslimit 1490The variable specifies the maximum number of outgoing ICMPv6 error messages, 1491per second. 1492ICMPv6 error messages that exceeded the value are subject to rate limitation 1493and will not go out from the node. 1494Negative value disables rate limitation. 1495.It Li icmp6.mtudisc_hiwat 1496.It Li icmp6.mtudisc_lowat 1497The variables define the maximum number of routing table entries, 1498created due to path MTU discovery 1499.Pq prevents denial-of-service attacks with ICMPv6 too big messages . 1500When IPv6 path MTU discovery happens, we keep path MTU information into 1501the routing table. 1502If the number of routing table entries exceed the value, 1503the kernel will not attempt to keep the path MTU information. 1504.Li icmp6.mtudisc_hiwat 1505is used when we have verified ICMPv6 too big messages. 1506.Li icmp6.mtudisc_lowat 1507is used when we have unverified ICMPv6 too big messages. 1508Verification is performed by using address/port pairs kept in connected pcbs. 1509Negative value disables the upper limit. 1510.It Li icmp6.nd6_debug 1511If set to non-zero, kernel IPv6 neighbor discovery code will generate 1512debugging messages. 1513The debug outputs are useful to diagnose IPv6 interoperability issues. 1514The flag must be set to 0 for normal operation. 1515.It Li icmp6.nd6_delay 1516The variable specifies 1517.Dv DELAY_FIRST_PROBE_TIME 1518timing constant in IPv6 neighbor discovery specification 1519.Pq RFC 2461 , 1520in seconds. 1521.It Li icmp6.nd6_maxnudhint 1522IPv6 neighbor discovery permits upper layer protocols to supply reachability 1523hints, to avoid unnecessary neighbor discovery exchanges. 1524The variable defines the number of consecutive hints the neighbor discovery 1525layer will take. 1526For example, by setting the variable to 3, neighbor discovery layer 1527will take 3 consecutive hints in maximum. 1528After receiving 3 hints, neighbor discovery layer will perform 1529normal neighbor discovery process. 1530.It Li icmp6.nd6_mmaxtries 1531The variable specifies 1532.Dv MAX_MULTICAST_SOLICIT 1533constant in IPv6 neighbor discovery specification 1534.Pq RFC 2461 . 1535.It Li icmp6.nd6_prune 1536The variable specifies interval between IPv6 neighbor cache babysitting, 1537in seconds. 1538.It Li icmp6.nd6_umaxtries 1539The variable specifies 1540.Dv MAX_UNICAST_SOLICIT 1541constant in IPv6 neighbor discovery specification 1542.Pq RFC 2461 . 1543.It Li icmp6.nd6_useloopback 1544If set to non-zero, kernel IPv6 stack will use loopback interface for 1545local traffic. 1546.It Li icmp6.nodeinfo 1547The variable enables responses to ICMPv6 node information queries. 1548If you set the variable to 0, responses will not be generated for 1549ICMPv6 node information queries. 1550Since node information queries can have a security impact, it is 1551possible to fine tune which responses should be answered. 1552Two separate bits can be set. 1553.Bl -tag -width "12345" 1554.It 1 1555Respond to ICMPv6 FQDN queries, e.g. 1556.Li ping6 -w . 1557.It 2 1558Respond to ICMPv6 node addresses queries, e.g. 1559.Li ping6 -a . 1560.El 1561.It Li icmp6.rediraccept 1562If set to non-zero, the host will accept ICMPv6 redirect packets. 1563Note that IPv6 routers will never accept ICMPv6 redirect packets, 1564and the variable is meaningful on IPv6 hosts 1565.Pq non-router 1566only. 1567.It Li icmp6.redirtimeout 1568The variable specifies lifetime of routing entries generated by incoming 1569ICMPv6 redirect. 1570.It Li udp6.do_loopback_cksum 1571Perform UDP checksum on loopback. 1572.It Li udp6.recvspace 1573Default UDP receive buffer size. 1574.It Li udp6.sendspace 1575Default UDP send buffer size. 1576.El 1577.Pp 1578We reuse net.*.tcp for 1579.Tn TCP 1580over 1581.Tn IPv6 , 1582and therefore we do not have variables net.*.tcp6. 1583Variables net.inet6.udp6 have identical meaning to net.inet.udp. 1584Please refer to 1585.Li PF_INET 1586section above. 1587For variables net.*.ipsec6, please refer to 1588.Xr ipsec 4 . 1589.It Li PF_KEY 1590Get or set various global information about the IPsec key management. 1591The third level name is the variable name. 1592The currently defined variable and names are: 1593.Bl -column "blockacq_lifetime" "integer" "yes" -offset indent 1594.It Sy Variable name Type Changeable 1595.It debug integer yes 1596.It spi_try integer yes 1597.It spi_min_value integer yes 1598.It spi_max_value integer yes 1599.It larval_lifetime integer yes 1600.It blockacq_count integer yes 1601.It blockacq_lifetime integer yes 1602.It esp_keymin integer yes 1603.It esp_auth integer yes 1604.It ah_keymin integer yes 1605.El 1606The variables are as follows: 1607.Bl -tag -width "123456" 1608.It Li debug 1609Turn on debugging message from within the kernel. 1610The value is a bitmap, as defined in 1611.Pa /usr/include/netkey/key_debug.h . 1612.It Li spi_try 1613The number of times the kernel will try to obtain an unique SPI 1614when it generates it from random number generator. 1615.It Li spi_min_value 1616Minimum SPI value when generating it within the kernel. 1617.It Li spi_max_value 1618Maximum SPI value when generating it within the kernel. 1619.It Li larval_lifetime 1620Lifetime for LARVAL SAD entries, in seconds. 1621.It Li blockacq_count 1622Number of ACQUIRE PF_KEY messages to be blocked after an ACQUIRE message. 1623It avoids flood of ACQUIRE PF_KEY from being sent from the kernel to the 1624key management daemon. 1625.It Li blockacq_lifetime 1626Lifetime of ACQUIRE PF_KEY message. 1627.It Li esp_keymin 1628Minimum ESP key length, in bits. 1629The value is used when the kernel creates proposal payload 1630on ACQUIRE PF_KEY message. 1631.It Li esp_auth 1632Whether ESP authentication should be used or not. 1633Non-zero value indicates that ESP authentication should be used. 1634The value is used when the kernel creates proposal payload 1635on ACQUIRE PF_KEY message. 1636.It Li ah_keymin 1637Minimum AH key length, in bits, 1638The value is used when the kernel creates proposal payload 1639on ACQUIRE PF_KEY message. 1640.El 1641.El 1642.Sh CTL_PROC 1643The string and integer information available for the CTL_PROC 1644is detailed below. 1645The changeable column shows whether a process with appropriate 1646privilege may change the value. 1647These values are per-process, 1648and as such may change from one process to another. 1649When a process is created, 1650the default values are inherited from its parent. 1651When a set-user-ID or set-group-ID binary is executed, the 1652value of PROC_PID_CORENAME is reset to the system default value. 1653The second level name is either the magic value PROC_CURPROC, which 1654points to the current process, or the PID of the target process. 1655.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" "yes" -offset indent 1656.It Sy Third level name Type Changeable 1657.It PROC\_PID\_CORENAME string yes 1658.It PROC\_PID\_LIMIT node not applicable 1659.It PROC\_PID\_STOPFORK int yes 1660.It PROC\_PID\_STOPEXEC int yes 1661.It PROC\_PID\_STOPEXIT int yes 1662.El 1663.Bl -tag -width "123456" 1664.Pp 1665.It Li PROC_PID_CORENAME 1666The template used for the core dump file name (see 1667.Xr core 5 1668for details). 1669The base name must either be 1670.Nm core 1671or end with the suffix ``.core'' (the super-user may set arbitrary names). 1672By default it points to KERN_DEFCORENAME. 1673.It Li PROC_PID_LIMIT 1674Return resources limits, as defined for the 1675.Xr getrlimit 2 1676and 1677.Xr setrlimit 2 1678system calls. 1679The fourth level name is one of: 1680.Bl -tag -width PROC_PID_LIMIT_MEMLOCKAA 1681.It Li PROC_PID_LIMIT_CPU 1682The maximum amount of CPU time (in seconds) to be used by each process. 1683.It Li PROC_PID_LIMIT_FSIZE 1684The largest size (in bytes) file that may be created. 1685.It Li PROC_PID_LIMIT_DATA 1686The maximum size (in bytes) of the data segment for a process; 1687this defines how far a program may extend its break with the 1688.Xr sbrk 2 1689system call. 1690.It Li PROC_PID_LIMIT_STACK 1691The maximum size (in bytes) of the stack segment for a process; 1692this defines how far a program's stack segment may be extended. 1693Stack extension is performed automatically by the system. 1694.It Li PROC_PID_LIMIT_CORE 1695The largest size (in bytes) 1696.Pa core 1697file that may be created. 1698.It Li PROC_PID_LIMIT_RSS 1699The maximum size (in bytes) to which a process's resident set size may 1700grow. 1701This imposes a limit on the amount of physical memory to be given to 1702a process; if memory is tight, the system will prefer to take memory 1703from processes that are exceeding their declared resident set size. 1704.It Li PROC_PID_LIMIT_MEMLOCK 1705The maximum size (in bytes) which a process may lock into memory 1706using the 1707.Xr mlock 2 1708function. 1709.It Li PROC_PID_LIMIT_NPROC 1710The maximum number of simultaneous processes for this user id. 1711.It Li PROC_PID_LIMIT_NOFILE 1712The maximum number of open files for this process. 1713.El 1714.Pp 1715The fifth level name is one of PROC_PID_LIMIT_TYPE_SOFT or 1716PROC_PID_LIMIT_TYPE_HARD, to select respectively the soft or hard limit. 1717Both are of type integer. 1718.It Li PROC_PID_STOPFORK 1719If non zero, the process' children will be stopped after 1720.Xr fork 2 1721calls. 1722The children is created in the SSTOP state and is never scheduled 1723for running before being stopped. 1724This feature helps attaching a process with a debugger such as 1725.Xr gdb 1 1726before it had the opportunity to actually do anything. 1727.Pp 1728This value is inherited by the process's children, and it also 1729apply to emulation specific system calls that fork a new process, such as 1730.Fn sproc 1731or 1732.Fn clone . 1733.It Li PROC_PID_STOPEXEC 1734If non zero, the process will be stopped on next 1735.Xr exec 3 1736call. 1737The process created by 1738.Xr exec 3 1739is created in the SSTOP state and is never scheduled for running 1740before being stopped. 1741This feature helps attaching a process with a debugger such as 1742.Xr gdb 1 1743before it had the opportunity to actually do anything. 1744.Pp 1745This value is inherited by the process's children. 1746.It Li PROC_PID_STOPEXIT 1747If non zero, the process will be stopped on when it has cause to exit, 1748either by way of calling 1749.Xr exit 3 , 1750.Xr _exit 2 , 1751or by the receipt of a specific signal. 1752The process is stopped before any of its resources or vm space is 1753released allowing examination of the termination state of a process 1754before it disappears. 1755This feature can be used to examine the final conditions of the 1756process's vmspace via 1757.Xr pmap 1 1758or its resource settings with 1759.Xr sysctl 8 1760before it disappears. 1761.Pp 1762This value is also inherited by the process's children. 1763.El 1764.Sh CTL_USER 1765The string and integer information available for the CTL_USER level 1766is detailed below. 1767The changeable column shows whether a process with appropriate 1768privilege may change the value. 1769.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 1770.It Sy Second level name Type Changeable 1771.It USER\_BC\_BASE\_MAX integer no 1772.It USER\_BC\_DIM\_MAX integer no 1773.It USER\_BC\_SCALE\_MAX integer no 1774.It USER\_BC\_STRING\_MAX integer no 1775.It USER\_COLL\_WEIGHTS\_MAX integer no 1776.It USER\_CS\_PATH string no 1777.It USER\_EXPR\_NEST\_MAX integer no 1778.It USER\_LINE\_MAX integer no 1779.It USER\_POSIX2\_CHAR\_TERM integer no 1780.It USER\_POSIX2\_C\_BIND integer no 1781.It USER\_POSIX2\_C\_DEV integer no 1782.It USER\_POSIX2\_FORT\_DEV integer no 1783.It USER\_POSIX2\_FORT\_RUN integer no 1784.It USER\_POSIX2\_LOCALEDEF integer no 1785.It USER\_POSIX2\_SW\_DEV integer no 1786.It USER\_POSIX2\_UPE integer no 1787.It USER\_POSIX2\_VERSION integer no 1788.It USER\_RE\_DUP\_MAX integer no 1789.It USER\_STREAM\_MAX integer no 1790.It USER\_TZNAME\_MAX integer no 1791.It USER\_ATEXIT\_MAX integer no 1792.El 1793.Bl -tag -width "123456" 1794.Pp 1795.It Li USER_BC_BASE_MAX 1796The maximum ibase/obase values in the 1797.Xr bc 1 1798utility. 1799.It Li USER_BC_DIM_MAX 1800The maximum array size in the 1801.Xr bc 1 1802utility. 1803.It Li USER_BC_SCALE_MAX 1804The maximum scale value in the 1805.Xr bc 1 1806utility. 1807.It Li USER_BC_STRING_MAX 1808The maximum string length in the 1809.Xr bc 1 1810utility. 1811.It Li USER_COLL_WEIGHTS_MAX 1812The maximum number of weights that can be assigned to any entry of 1813the LC_COLLATE order keyword in the locale definition file. 1814.It Li USER_CS_PATH 1815Return a value for the 1816.Ev PATH 1817environment variable that finds all the standard utilities. 1818.It Li USER_EXPR_NEST_MAX 1819The maximum number of expressions that can be nested within 1820parenthesis by the 1821.Xr expr 1 1822utility. 1823.It Li USER_LINE_MAX 1824The maximum length in bytes of a text-processing utility's input 1825line. 1826.It Li USER_POSIX2_CHAR_TERM 1827Return 1 if the system supports at least one terminal type capable of 1828all operations described in POSIX 1003.2, otherwise 0. 1829.It Li USER_POSIX2_C_BIND 1830Return 1 if the system's C-language development facilities support the 1831C-Language Bindings Option, otherwise 0. 1832.It Li USER_POSIX2_C_DEV 1833Return 1 if the system supports the C-Language Development Utilities Option, 1834otherwise 0. 1835.It Li USER_POSIX2_FORT_DEV 1836Return 1 if the system supports the FORTRAN Development Utilities Option, 1837otherwise 0. 1838.It Li USER_POSIX2_FORT_RUN 1839Return 1 if the system supports the FORTRAN Runtime Utilities Option, 1840otherwise 0. 1841.It Li USER_POSIX2_LOCALEDEF 1842Return 1 if the system supports the creation of locales, otherwise 0. 1843.It Li USER_POSIX2_SW_DEV 1844Return 1 if the system supports the Software Development Utilities Option, 1845otherwise 0. 1846.It Li USER_POSIX2_UPE 1847Return 1 if the system supports the User Portability Utilities Option, 1848otherwise 0. 1849.It Li USER_POSIX2_VERSION 1850The version of POSIX 1003.2 with which the system attempts to comply. 1851.It Li USER_RE_DUP_MAX 1852The maximum number of repeated occurrences of a regular expression 1853permitted when using interval notation. 1854.ne 1i 1855.It Li USER_STREAM_MAX 1856The minimum maximum number of streams that a process may have open 1857at any one time. 1858.It Li USER_TZNAME_MAX 1859The minimum maximum number of types supported for the name of a 1860timezone. 1861.It Li USER_ATEXIT_MAX 1862The maximum number of functions that may be registered with 1863.Xr atexit 3 . 1864.El 1865.Sh CTL_VM 1866The string and integer information available for the CTL_VM level 1867is detailed below. 1868The changeable column shows whether a process with appropriate 1869privilege may change the value. 1870.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 1871.It Sy Second level name Type Changeable 1872.It VM\_ANONMAX int yes 1873.It VM\_ANONMIN int yes 1874.It VM\_BUFCACHE int yes 1875.It VM\_BUFMEM int no 1876.It VM\_BUFMEM_HIWATER int yes 1877.It VM\_BUFMEM_LOWATER int yes 1878.It VM\_EXECMAX int yes 1879.It VM\_EXECMIN int yes 1880.It VM\_FILEMAX int yes 1881.It VM\_FILEMIN int yes 1882.It VM\_LOADAVG struct loadavg no 1883.It VM\_MAXSLP int no 1884.It VM\_METER struct vmtotal no 1885.It VM\_NKMEMPAGES int no 1886.It VM\_USPACE int no 1887.It VM\_UVMEXP struct uvmexp no 1888.It VM\_UVMEXP2 struct uvmexp_sysctl no 1889.El 1890.Pp 1891.Bl -tag -width "123456" 1892.It Li VM_ANONMAX 1893The percentage of physical memory which will be reclaimed 1894from other types of memory usage to store anonymous application data. 1895.It Li VM_ANONMIN 1896The percentage of physical memory which will be always be available for 1897anonymous application data. 1898.It Li VM_BUFCACHE 1899The percentage of kernel memory which will be available 1900for the buffer cache. 1901.It Li VM_BUFMEM 1902The amount of kernel memory that is being used by the buffer cache. 1903.It Li VM_BUFMEM_LOWATER 1904The minimum amount of kernel memory to reserve for the 1905buffer cache. 1906.It Li VM_BUFMEM_HIWATER 1907The maximum amount of kernel memory to be used for the 1908buffer cache. 1909.It Li VM_EXECMAX 1910The percentage of physical memory which will be reclaimed 1911from other types of memory usage to store cached executable data. 1912.It Li VM_EXECMIN 1913The percentage of physical memory which will be always be available for 1914cached executable data. 1915.It Li VM_FILEMAX 1916The percentage of physical memory which will be reclaimed 1917from other types of memory usage to store cached file data. 1918.It Li VM_FILEMIN 1919The percentage of physical memory which will be always be available for 1920cached file data. 1921.It Li VM_LOADAVG 1922Return the load average history. 1923The returned data consists of a 1924.Va struct loadavg . 1925.It Li VM_MAXSLP 1926The value of the maxslp kernel global variable. 1927.It Li VM_METER 1928Return system wide virtual memory statistics. 1929The returned data consists of a 1930.Va struct vmtotal . 1931.It Li VM_USPACE 1932The number of bytes allocated for each kernel stack. 1933.It Li VM_UVMEXP 1934Return system wide virtual memory statistics. 1935The returned data consists of a 1936.Va struct uvmexp . 1937.It Li VM_UVMEXP2 1938Return system wide virtual memory statistics. 1939The returned data consists of a 1940.Va struct uvmexp_sysctl . 1941.El 1942.Sh CTL_DDB 1943The integer information available for the CTL_DDB level is detailed below. 1944The changeable column shows whether a process with appropriate 1945privilege may change the value. 1946.Bl -column "DBCTL_TABSTOPSXXX" "integerXXX" -offset indent 1947.It Sy Second level name Type Changeable 1948.It DBCTL\_RADIX integer yes 1949.It DBCTL\_MAXOFF integer yes 1950.It DBCTL\_LINES integer yes 1951.It DBCTL\_TABSTOPS integer yes 1952.It DBCTL\_ONPANIC integer yes 1953.It DBCTL\_FROMCONSOLE integer yes 1954.El 1955.Pp 1956.Bl -tag -width "123456" 1957.It Li DBCTL_RADIX 1958The input and output radix. 1959.It Li DBCTL_MAXOFF 1960The maximum symbol offset. 1961.It Li DBCTL_LINES 1962Number of display lines. 1963.It Li DBCTL_TABSTOPS 1964Tab width. 1965.It Li DBCTL_ONPANIC 1966If non-zero, DDB will be entered when the kernel panics. 1967.It Li DBCTL_FROMCONSOLE 1968If not zero, DDB may be entered by sending a break on a serial 1969console or by a special key sequence on a graphics console. 1970.El 1971.Pp 1972These MIB nodes are also available as variables from within the DDB. 1973See 1974.Xr ddb 4 1975for more details. 1976.Sh CTL_SECURITY 1977The security level contains various security-related settings for 1978the system. Available settings are detailed below. 1979.Pp 1980.Bl -tag -width "123456" 1981.It Li security.curtain 1982If non-zero, will filter return objects according to the user-id 1983requesting information about them, preventing from users any 1984access to objects they don't own. 1985.Pp 1986At the moment, it affects 1987.Xr ps 1 , 1988.Xr netstat 1 1989(for 1990.Dv PF_INET , 1991.Dv PF_INET6 , 1992and 1993.Dv PF_UNIX 1994PCBs), and 1995.Xr w 1 . 1996.It Li security.pax 1997Settings for PaX -- exploit mitigation features. 1998.Pp 1999.Bl -tag -width "123456" 2000.It Li security.pax.mprotect.enable 2001Enable PaX MPROTECT restrictions. 2002.Pp 2003These are 2004.Xr mprotect 2 2005restrictions to better enforce a W^X policy. The value of this 2006knob must be non-zero for PaX MPROTECT to be enabled, even if a 2007process is already marked with 2008.Em P_PAXMPROTECT . 2009.It Li security.pax.mprotect.global_protection 2010Specifies the default global policy for programs without an 2011explicit enable/disable flag. 2012.Pp 2013When non-zero, all programs will get the PaX MPROTECT restrictions, 2014except those exempted with 2015.Xr paxctl 1 . 2016Otherwise, all programs will not get the PaX MPROTECT restrictions, 2017except those specifically marked as such with 2018.Xr paxctl 1. 2019.El 2020.It Li security.setid_core 2021Settings related to set-id processes coredumps. 2022By default, set-id processes do not dump core in situations where 2023other processes would. 2024The settings in this node allows an administrator to change this 2025behavior. 2026.Pp 2027.Bl -tag -width "123456" 2028.It Li security.setid_core.dump 2029If non-zero, set-id processes will dump core. 2030.It Li security.setid_core.group 2031The group-id for the set-id processes' coredump. 2032.It Li security.setid_core.mode 2033The mode for the set-id processes' coredump. 2034See 2035.Xr chmod 1 . 2036.It Li security.setid_core.owner 2037The user-id that will be used as the owner of the set-id processes' 2038coredump. 2039.It Li security.setid_core.path 2040The path to which set-id processes' coredumps will be saved to. 2041Same syntax as kern.defcorename. 2042.El 2043.El 2044.Sh CTL_VENDOR 2045The "vendor" toplevel name is reserved to be used by vendors who wish to 2046have their own private MIB tree. 2047Intended use is to store values under 2048.Dq vendor.\*[Lt]yourname\*[Gt].* . 2049.Sh DYNAMIC OPERATIONS 2050Several meta-identifiers are provided to perform operations on the 2051.Nm 2052tree itself, or support alternate means of accessing the data 2053instrumented by the 2054.Nm 2055tree. 2056.Bl -column CTLXCREATESYMXXX 2057.It Sy Name Description 2058.It CTL\_QUERY Retrieve a mapping of names to numbers below a given node 2059.It CTL\_CREATE Create a new node 2060.It CTL\_CREATESYM Create a new node by its kernel symbol 2061.It CTL\_DESTROY Destroy a node 2062.It CTL\_DESCRIBE Retrieve node descriptions 2063.El 2064.Pp 2065The core interface to all of these meta-functions is the structure 2066that the kernel uses to describe the tree internally, as defined in 2067.Aq Pa sys/sysctl.h 2068as: 2069.Pp 2070.Bd -literal 2071struct sysctlnode { 2072 uint32_t sysctl_flags; /* flags and type */ 2073 int32_t sysctl_num; /* mib number */ 2074 char sysctl_name[SYSCTL_NAMELEN]; /* node name */ 2075 uint32_t sysctl_ver; /* node's version vs. rest of tree */ 2076 uint32_t __rsvd; 2077 union { 2078 struct { 2079 uint32_t suc_csize; /* size of child node array */ 2080 uint32_t suc_clen; /* number of valid children */ 2081 struct sysctlnode* suc_child; /* array of child nodes */ 2082 } scu_child; 2083 struct { 2084 void *sud_data; /* pointer to external data */ 2085 size_t sud_offset; /* offset to data */ 2086 } scu_data; 2087 int32_t scu_alias; /* node this node refers to */ 2088 int32_t scu_idata; /* immediate "int" data */ 2089 u_quad_t scu_qdata; /* immediate "u_quad_t" data */ 2090 } sysctl_un; 2091 size_t _sysctl_size; /* size of instrumented data */ 2092 sysctlfn _sysctl_func; /* access helper function */ 2093 struct sysctlnode *sysctl_parent; /* parent of this node */ 2094 const char *sysctl_desc; /* description of node */ 2095}; 2096 2097#define sysctl_csize sysctl_un.scu_child.suc_csize 2098#define sysctl_clen sysctl_un.scu_child.suc_clen 2099#define sysctl_child sysctl_un.scu_child.suc_child 2100#define sysctl_data sysctl_un.scu_data.sud_data 2101#define sysctl_offset sysctl_un.scu_data.sud_offset 2102#define sysctl_alias sysctl_un.scu_alias 2103#define sysctl_idata sysctl_un.scu_idata 2104#define sysctl_qdata sysctl_un.scu_qdata 2105.Ed 2106.Pp 2107Querying the tree to discover the name to number mapping permits 2108dynamic discovery of all the data that the tree currently has 2109instrumented. 2110For example, to discover all the nodes below the 2111CTL_VFS node: 2112.Pp 2113.Bd -literal -offset indent -compact 2114struct sysctlnode query, vfs[128]; 2115int mib[2]; 2116size_t len; 2117.sp 2118mib[0] = CTL_VFS; 2119mib[1] = CTL_QUERY; 2120memset(\*[Am]query, 0, sizeof(query)); 2121query.sysctl_flags = SYSCTL_VERSION; 2122len = sizeof(vfs); 2123sysctl(mib, 2, \*[Am]vfs[0], \*[Am]len, \*[Am]query, sizeof(query)); 2124.Ed 2125.Pp 2126Note that a reference to an empty node with 2127.Fa sysctl_flags 2128set to 2129.Dv SYSCTL_VERSION 2130is passed to sysctl in order to indicate the version that the program 2131is using. 2132All dynamic operations passing nodes into sysctl require that the 2133version be explicitly specified. 2134.Pp 2135Creation and destruction of nodes works by constructing part of a new 2136node description (or a description of the existing node) and invoking 2137CTL_CREATE (or CTL_CREATESYM) or CTL_DESTROY at the parent of the new 2138node, with a pointer to the new node passed via the 2139.Fa new 2140and 2141.Fa newlen 2142arguments. 2143If valid values for 2144.Fa old 2145and 2146.Fa oldlenp 2147are passed, a copy of the new node once in the tree will be returned. 2148If the create operation fails because a node with the same name or MIB 2149number exists, a copy of the conflicting node will be returned. 2150.Pp 2151The minimum requirements for creating a node are setting the 2152.Fa sysctl_flags 2153to indicate the new node's type, 2154.Fa sysctl_num 2155to either the new node's number (or CTL_CREATE or CTL_CREATESYM if a 2156dynamically allocated MIB number is acceptable), 2157.Fa sysctl_size 2158to the size of the data to be instrumented (which must agree with the 2159given type), and 2160.Fa sysctl_name 2161must be set to the new node's name. 2162Nodes that are not of type 2163.Dq node 2164must also have some description of the data to be instrumented, which 2165will vary depending on what is to be instrumented. 2166.Pp 2167If existing kernel data is to be covered by this new node, its address 2168should be given in 2169.Fa sysctl_data 2170or, if CTL_CREATESYM is used, 2171.Fa sysctl_data 2172should be set to a string containing its name from the kernel's symbol 2173table. 2174If new data is to be instrumented and an initial value is available, 2175the new integer or quad type data should be placed into either 2176.Fa sysctl_idata 2177or 2178.Fa sysctl_qdata , 2179respectively, along with the SYSCTL_IMMEDIATE flag being set, or 2180.Fa sysctl_data 2181should be set to point to a copy of the new data, and the 2182SYSCTL_OWNDATA flag must be set. 2183This latter method is the only way that new string and struct type 2184nodes can be initialized. 2185Invalid kernel addresses are accepted, but any attempt to access those 2186nodes will return an error. 2187.Pp 2188The 2189.Fa sysctl_csize , 2190.Fa sysctl_clen , 2191.Fa sysctl_child , 2192.Fa sysctl_parent , 2193and 2194.Fa sysctl_alias 2195members are used by the kernel to link the tree together and must be 2196.Dv NULL 2197or 0. 2198Nodes created in this manner cannot have helper functions, so 2199.Fa sysctl_func 2200must also be 2201.Dv NULL . 2202If the 2203.Fa sysctl_ver 2204member is non-zero, it must match either the version of the parent or 2205the version at the root of the MIB or an error is returned. 2206This can be used to ensure that nodes are only added or removed from a 2207known state of the tree. 2208Note: It may not be possible to determine the version at the root 2209of the tree. 2210.Pp 2211This example creates a new subtree and adds a node to it that controls the 2212.Fa audiodebug 2213kernel variable, thereby making it tunable at at any time, without 2214needing to use 2215.Xr ddb 4 2216or 2217.Xr kvm 3 2218to alter the kernel's memory directly. 2219.Pp 2220.Bd -literal -offset indent -compact 2221struct sysctlnode node; 2222int mib[2]; 2223size_t len; 2224.sp 2225mib[0] = CTL_CREATE; /* create at top-level */ 2226len = sizeof(node); 2227memset(\*[Am]node, 0, len); 2228node.sysctl_flags = SYSCTL_VERSION|CTLFLAG_READWRITE|CTLTYPE_NODE; 2229snprintf(node.sysctl_name, sizeof(node.sysctl_name), "local"); 2230node.sysctl_num = CTL_CREATE; /* request dynamic MIB number */ 2231sysctl(\*[Am]mib[0], 1, \*[Am]node, \*[Am]len, \*[Am]node, len); 2232.sp 2233mib[0] = node.sysctl_num; /* use new MIB number */ 2234mib[1] = CTL_CREATESYM; /* create at second level */ 2235len = sizeof(node); 2236memset(\*[Am]node, 0, len); 2237node.sysctl_flags = SYSCTL_VERSION|CTLFLAG_READWRITE|CTLTYPE_INT; 2238snprintf(node.sysctl_name, sizeof(node.sysctl_name), "audiodebug"); 2239node.sysctl_num = CTL_CREATE; 2240node.sysctl_data = "audiodebug"; /* kernel symbol to be used */ 2241sysctl(\*[Am]mib[0], 2, NULL, NULL, \*[Am]node, len); 2242.Ed 2243.Pp 2244The process for deleting nodes is similar, but less data needs to 2245be supplied. 2246Only the 2247.Fa sysctl_num 2248field 2249needs to be filled in; almost all other fields must be left blank. 2250The 2251.Fa sysctl_name 2252and/or 2253.Fa sysctl_ver 2254fields can be filled in with the name and version of the existing node 2255as additional checks on what will be deleted. 2256If all the given data fail to match any node, nothing will be deleted. 2257If valid values for 2258.Fa old 2259and 2260.Fa oldlenp 2261are supplied and a node is deleted, a copy of what was in the MIB tree 2262will be returned. 2263.Pp 2264This sample code shows the deletion of the two nodes created in the 2265above example: 2266.Pp 2267.Bd -literal -offset indent -compact 2268int mib[2]; 2269.sp 2270len = sizeof(node); 2271memset(\*[Am]node, 0, len); 2272node.sysctl_flags = SYSCTL_VERSION; 2273.sp 2274mib[0] = 3214; /* assumed number for "local" */ 2275mib[1] = CTL_DESTROY; 2276node.sysctl_num = 3215; /* assumed number for "audiodebug" */ 2277sysctl(\*[Am]mib[0], 2, NULL, NULL, \*[Am]node, len); 2278.sp 2279mib[0] = CTL_DESTROY; 2280node.sysctl_num = 3214; /* now deleting "local" */ 2281sysctl(\*[Am]mib[0], 1, NULL, NULL, \*[Am]node, len); 2282.Ed 2283.Pp 2284Descriptions of each of the nodes can also be retrieved, if they are 2285available. 2286Descriptions can be retrieved in bulk at each level or on a per-node 2287basis. 2288The layout of the buffer into which the descriptions are returned is a 2289series of variable length structures, each of which describes its own 2290size. 2291The length indicated includes the terminating 2292.Sq nul 2293character. 2294Nodes that have no description or where the description is not 2295available are indicated by an empty string. 2296The 2297.Fa descr_ver 2298will match the 2299.Fa sysctl_ver 2300value for a given node, so that descriptions for nodes whose number 2301have been recycled can be detected and ignored or discarded. 2302.Pp 2303.Bd -literal 2304struct sysctldesc { 2305 int32_t descr_num; /* mib number of node */ 2306 uint32_t descr_ver; /* version of node */ 2307 uint32_t descr_len; /* length of description string */ 2308 char descr_str[1]; /* not really 1...see above */ 2309}; 2310.Ed 2311.Pp 2312The 2313.Fn NEXT_DESCR 2314macro can be used to skip to the next description in the retrieved 2315list. 2316.Pp 2317.Bd -literal -offset indent -compact 2318struct sysctlnode desc; 2319struct sysctldesc *d; 2320char buf[1024]; 2321int mib[2]; 2322size_t len; 2323.sp 2324/* retrieve kern-level descriptions */ 2325mib[0] = CTL_KERN; 2326mib[1] = CTL_DESCRIBE; 2327d = (struct sysctldesc *)\*[Am]buf[0]; 2328len = sizeof(buf); 2329sysctl(mib, 2, d, \*[Am]len, NULL, 0); 2330while ((caddr_t)d \*[Lt] (caddr_t)\*[Am]buf[len]) { 2331 printf("node %d: %.*s\\n", d-\*[Gt]descr_num, d-\*[Gt]descr_len, 2332 d-\*[Gt]descr_str); 2333 d = NEXT_DESCR(d); 2334} 2335.sp 2336/* retrieve description for kern.securelevel */ 2337memset(\*[Am]desc, 0, sizeof(desc)); 2338desc.sysctl_flags = SYSCTL_VERSION; 2339desc.sysctl_num = KERN_SECURELEVEL; 2340d = (struct sysctldesc *)\*[Am]buf[0]; 2341len = sizeof(buf); 2342sysctl(mib, 2, d, \*[Am]len, \*[Am]desc, sizeof(desc)); 2343printf("kern.securelevel: %.*s\\n", d-\*[Gt]descr_len, d-\*[Gt]descr_str); 2344.Ed 2345.Pp 2346Descriptions can also be set as follows, subject to the following rules: 2347.Pp 2348.Bl -bullet -compact 2349.It 2350The kernel securelevel is at zero or lower 2351.It 2352The caller has super-user privileges 2353.It 2354The node does not currently have a description 2355.It 2356The node is not marked as 2357.Dq permanent 2358.El 2359.Pp 2360.Bd -literal -offset indent -compact 2361struct sysctlnode desc; 2362int mib[2]; 2363.sp 2364/* presuming the given top-level node was just added... */ 2365mib[0] = 3214; /* mib numbers taken from previous examples */ 2366mib[1] = CTL_DESCRIBE; 2367memset(\*[Am]desc, 0, sizeof(desc)); 2368desc.sysctl_flags = SYSCTL_VERSION; 2369desc.sysctl_num = 3215; 2370desc.sysctl_desc = "audio debug control knob"; 2371sysctl(mib, 2, NULL, NULL, \*[Am]desc, sizeof(desc)); 2372.Ed 2373.Pp 2374Upon successfully setting a description, the new description will be 2375returned in the space indicated by the 2376.Fa oldp 2377and 2378.Fa oldlenp 2379arguments. 2380.Pp 2381The 2382.Fa sysctl_flags 2383field in the struct sysctlnode contains the sysctl version, node type 2384information, and a number of flags. 2385The macros 2386.Fn SYSCTL_VERS , 2387.Fn SYSCTL_TYPE , 2388and 2389.Fn SYSCTL_FLAGS 2390can be used to access the different fields. 2391Valid flags are: 2392.Bl -column CTLFLAGXPERMANENTXXX 2393.It Sy Name Description 2394.It CTLFLAG\_READONLY Node is read-only 2395.It CTLFLAG\_READONLY1 Node becomes read-only at securelevel 1 2396.It CTLFLAG\_READONLY2 Node becomes read-only at securelevel 2 2397.It CTLFLAG\_READWRITE Node is writable by the superuser 2398.It CTLFLAG\_ANYWRITE Node is writable by anyone 2399.It CTLFLAG\_PRIVATE Node is readable only by the superuser 2400.It CTLFLAG\_PERMANENT Node cannot be removed (cannot be set by 2401processes) 2402.It CTLFLAG\_OWNDATA Node owns data and does not instrument 2403existing data 2404.It CTLFLAG\_IMMEDIATE Node contains instrumented data and does not 2405instrument existing data 2406.It CTLFLAG\_HEX Node's contents should be displayed in a hexadecimal 2407form 2408.It CTLFLAG\_ROOT Node is the root of a tree (cannot be set at 2409any time) 2410.It CTLFLAG\_ANYNUMBER Node matches any MIB number (cannot be set by 2411processes) 2412.It CTLFLAG\_HIDDEN Node not displayed by default 2413.It CTLFLAG\_ALIAS Node refers to a sibling node (cannot be set 2414by processes) 2415.It CTLFLAG\_OWNDESC Node owns its own description string space 2416.El 2417.Sh RETURN VALUES 2418If the call to 2419.Nm 2420is successful, the number of bytes copied out is returned. 2421Otherwise \-1 is returned and 2422.Va errno 2423is set appropriately. 2424.Sh FILES 2425.Bl -tag -width \*[Lt]netinet6/udp6Xvar.h\*[Gt] -compact 2426.It Aq Pa sys/sysctl.h 2427definitions for top level identifiers, second level kernel and hardware 2428identifiers, and user level identifiers 2429.It Aq Pa sys/socket.h 2430definitions for second level network identifiers 2431.It Aq Pa sys/gmon.h 2432definitions for third level profiling identifiers 2433.It Aq Pa uvm/uvm_param.h 2434definitions for second level virtual memory identifiers 2435.It Aq Pa netinet/in.h 2436definitions for third level IPv4/v6 identifiers and 2437fourth level IPv4/v6 identifiers 2438.It Aq Pa netinet/icmp_var.h 2439definitions for fourth level ICMP identifiers 2440.It Aq Pa netinet/icmp6.h 2441definitions for fourth level ICMPv6 identifiers 2442.It Aq Pa netinet/tcp_var.h 2443definitions for fourth level TCP identifiers 2444.It Aq Pa netinet/udp_var.h 2445definitions for fourth level UDP identifiers 2446.It Aq Pa netinet6/udp6_var.h 2447definitions for fourth level IPv6 UDP identifiers 2448.It Aq Pa netinet6/ipsec.h 2449definitions for fourth level IPsec identifiers 2450.It Aq Pa netkey/key_var.h 2451definitions for third level PF_KEY identifiers 2452.It Aq Pa machine/cpu.h 2453definitions for second level machdep identifiers 2454.El 2455.Sh ERRORS 2456The following errors may be reported: 2457.Bl -tag -width Er 2458.It Bq Er EFAULT 2459The buffer 2460.Fa name , 2461.Fa oldp , 2462.Fa newp , 2463or length pointer 2464.Fa oldlenp 2465contains an invalid address, or the requested value is temporarily 2466unavailable. 2467.It Bq Er EINVAL 2468The 2469.Fa name 2470array is zero or greater than CTL_MAXNAME. 2471.It Bq Er EINVAL 2472A non-null 2473.Fa newp 2474is given and its specified length in 2475.Fa newlen 2476is too large or too small, or the given value is not acceptable for 2477the given node. 2478.It Bq Er ENOMEM 2479The length pointed to by 2480.Fa oldlenp 2481is too short to hold the requested value. 2482.It Bq Er EISDIR 2483The 2484.Fa name 2485array specifies an intermediate rather than terminal name. 2486.It Bq Er ENOTDIR 2487The 2488.Fa name 2489array specifies a node below a node that addresses data. 2490.It Bq Er ENOENT 2491The 2492.Fa name 2493array specifies a node that does not exist in the tree. 2494.It Bq Er ENOENT 2495An attempt was made to destroy a node that does not exist, or to 2496create or destroy a node below a node that does not exist. 2497.It Bq Er ENOTEMPTY 2498An attempt was made to destroy a node that still has children. 2499.It Bq Er EOPNOTSUPP 2500The 2501.Fa name 2502array specifies a value that is unknown or a meta-operation was 2503attempted that the requested node does not support. 2504.It Bq Er EPERM 2505An attempt is made to set a read-only value. 2506.It Bq Er EPERM 2507A process without appropriate privilege attempts to set a value or to 2508create or destroy a node. 2509.It Bq Er EPERM 2510An attempt to change a value protected by the current kernel security 2511level is made. 2512.El 2513.Sh SEE ALSO 2514.Xr ipsec 4 , 2515.Xr tcp 4 , 2516.Xr sysctl 8 2517.\" .Xr sysctl 9 2518.Sh HISTORY 2519The 2520.Nm 2521function first appeared in 2522.Bx 4.4 . 2523