NAME
sysctl
—
system information variables
DESCRIPTION
The sysctl(3) library function and the sysctl(8) utility are used to get and set values of system variables, maintained by the kernel. The variables are organized in a tree and identified by a sequence of numbers, conventionally separated by dots with the topmost identifier at the left side. The numbers have corresponding text names. The sysctlnametomib(3) function or the-M
argument to the sysctl(8) utility can be used to convert the text
representation to the numeric one.
The individual sysctl variables are described below, both the textual and numeric form where applicable. The textual names can be used as argument to the sysctl(8) utility and in the file /etc/sysctl.conf. The numeric names are usually defined as preprocessor constants and are intended for use by programs. Every such constant expands to one integer, which identifies the sysctl variable relative to the upper level of the tree. See the sysctl(3) manual page for programming examples.
Top level names
The top level names are defined with a CTL_
prefix in <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.
Name | Constant | Next level names | Description |
kern | CTL_KERN |
<sys/sysctl.h> |
High kernel limits |
vm | CTL_VM |
<uvm/uvm_param.h> |
Virtual memory |
vfs | CTL_VFS |
<sys/mount.h> |
Filesystem |
net | CTL_NET |
<sys/socket.h> |
Networking |
debug | CTL_DEBUG |
<sys/sysctl.h> |
Debugging |
hw | CTL_HW |
<sys/sysctl.h> |
Generic CPU, I/O |
machdep | CTL_MACHDEP |
<sys/sysctl.h> |
Machine dependent |
user | CTL_USER |
<sys/sysctl.h> |
User-level |
ddb | CTL_DDB |
<sys/sysctl.h> |
In-kernel debugger |
proc | CTL_PROC |
<sys/sysctl.h> |
Per-process |
vendor | CTL_VENDOR |
? | Vendor specific |
emul | CTL_EMUL |
<sys/sysctl.h> |
Emulation settings |
security | CTL_SECURITY |
<sys/sysctl.h> |
Security settings |
The debug.* subtree
The debugging variables vary from system to system. A debugging
variable may be added or deleted without need to recompile
sysctl
to know about it. Each time it runs,
sysctl
gets the list of debugging variables from the
kernel and displays their current values. The system defines twenty
(struct ctldebug) variables named
debug0
through 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
dospecialcheck as a debugging variable, the following
declaration would be used:
int dospecialcheck = 1; struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck };
Note that the dynamic implementation of
sysctl
currently in use largely makes this
particular sysctl
interface obsolete. See
sysctl(8) for more information.
The vfs.* subtree
A distinguished second level name,
vfs.generic
(VFS_GENERIC
),
is used to get general information about all file systems. It has the
following third level identifiers:
vfs.generic.maxtypenum
(VFS_MAXTYPENUM
)- The highest valid file system type number.
vfs.generic.conf
(VFS_CONF
)- Returns configuration information about the file system type given as a fourth level identifier.
vfs.generic.usermount
(VFS_USERMOUNT
)- Determines if non superuser mounts are allowed, defaults to
0
. vfs.generic.magiclinks
(VFS_MAGICLINKS
)- Controls if expansion of variables is going to be performed on pathnames
or not. Defaults to no variable expansion,
0
. Variables are of the form@name
and the variables supported are described in symlink(7) under “MAGIC SYMLINKS”.
A second level name for controlling the wapbl(4) (Write Ahead Physical Block Logging file system journalling) capabilities with the following third level identifiers:
vfs.wapbl.flush_disk_cache
- Controls whether to attempt to flush the disk cache on each commit. It defaults to 1 and it should always be on to ensure integrity of file system metadata in the event of a power loss. For slow disks, turning it off can improve performance.
vfs.wapbl.verbose_commit
- For each transaction log commit, print the number of bytes written and the time it took to commit as seconds.nanoseconds.
The remaining second level identifiers are the file system names,
identified by the type number returned by a
statvfs(2) call or from vfs.generic.conf
.
The third level identifiers available for each file system are given in the header file that defines the mount argument structure for that file system.
The hw.* subtree
The string and integer information available for the
hw
level is detailed below. The changeable column
shows whether a process with appropriate privilege may change the value.
Second level name | Type | Changeable |
hw.alignbytes | integer | no |
hw.byteorder | integer | no |
hw.cnmagic | string | yes |
hw.disknames | string | no |
hw.diskstats | struct | no |
hw.machine | string | no |
hw.machine_arch | string | no |
hw.model | string | no |
hw.ncpu | integer | no |
hw.ncpuonline | integer | no |
hw.pagesize | integer | no |
hw.physmem | integer | no |
hw.physmem64 | quad | no |
hw.usermem | integer | no |
hw.usermem64 | quad | no |
hw.alignbytes
(HW_ALIGNBYTES
)- Alignment constraint for all possible data types. This shows the value
ALIGNBYTES
in<machine/param.h>
, at the kernel compilation time. hw.byteorder
(HW_BYTEORDER
)- The byteorder (4321, or 1234).
hw.cnmagic
(HW_CNMAGIC
)- The console magic key sequence.
hw.disknames
(HW_DISKNAMES
)- The list of (space separated) disk device names on the system.
hw.iostatnames
(HW_IOSTATNAMES
)- A space separated list of devices that will have I/O statistics collected on them.
hw.iostats
(HW_IOSTATS
)- Return statistical information on the NFS mounts, disk and tape devices on
the system. An array of 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 struct
io_sysctl. The type of object can be determined by examining the
type element of struct
io_sysctl. Which can be
IOSTAT_DISK
(disk drive),IOSTAT_TAPE
(tape drive), orIOSTAT_NFS
(NFS mount). hw.machine
(HW_MACHINE
)- The machine class.
hw.machine_arch
(HW_MACHINE_ARCH
)- The machine CPU class.
hw.model
(HW_MODEL
)- The machine model.
hw.ncpu
(HW_NCPU
)- The number of CPUs configured.
hw.ncpuonline
(HW_NCPUONLINE
)- The number of CPUs online.
hw.pagesize
(HW_PAGESIZE
)- The software page size.
hw.physmem
(HW_PHYSMEM
)- The bytes of physical memory as a 32-bit integer.
hw.physmem64
(HW_PHYSMEM64
)- The bytes of physical memory as a 64-bit integer.
hw.usermem
(HW_USERMEM
)- The bytes of non-kernel memory as a 32-bit integer.
hw.usermem64
(HW_USERMEM64
)- The bytes of non-kernel memory as a 64-bit integer.
The kern.* subtree
This subtree includes data generally related to the kernel. The
string and integer information available for the
kern
level is detailed below. The changeable column
shows whether a process with appropriate privilege may change the value.
Second level name | Type | Changeable |
kern.aio_listio_max | integer | yes |
kern.aio_max | integer | yes |
kern.arandom | integer | no |
kern.argmax | integer | no |
kern.boothowto | integer | no |
kern.boottime | struct timespec | no |
kern.buildinfo | string | no |
kern.ccpu | integer | no |
kern.clockrate | struct clockinfo | no |
kern.consdev | integer | no |
kern.coredump | node | not applicable |
kern.cp_id | struct | no |
kern.cp_time | uint64_t[] | no |
kern.cryptodevallowsoft | integer | yes |
kern.defcorename | string | yes |
kern.detachall | integer | yes |
kern.domainname | string | yes |
kern.drivers | struct kinfo_drivers | no |
kern.dump_on_panic | integer | yes |
kern.expose_address | integer | yes |
kern.file | struct file | no |
kern.forkfsleep | integer | yes |
kern.fscale | integer | no |
kern.fsync | integer | no |
kern.hardclock_ticks | integer | no |
kern.hostid | integer | yes |
kern.hostname | string | yes |
kern.iov_max | integer | no |
kern.ipc | node | not applicable |
kern.job_control | integer | no |
kern.labeloffset | integer | no |
kern.labelsector | integer | no |
kern.login_name_max | integer | no |
kern.logsigexit | integer | yes |
kern.mapped_files | integer | no |
kern.maxfiles | integer | yes |
kern.maxlwp | integer | yes |
kern.maxpartitions | integer | no |
kern.maxphys | integer | no |
kern.maxproc | integer | yes |
kern.maxptys | integer | yes |
kern.maxvnodes | integer | yes |
kern.messages | integer | yes |
kern.mbuf | node | not applicable |
kern.memlock | integer | no |
kern.memlock_range | integer | no |
kern.memory_protection | integer | no |
kern.module | node | not applicable |
kern.monotonic_clock | integer | no |
kern.mqueue | node | not applicable |
kern.msgbuf | integer | no |
kern.msgbufsize | integer | no |
kern.ngroups | integer | no |
kern.ntptime | struct ntptimeval | no |
kern.osrelease | string | no |
kern.osrevision | integer | no |
kern.ostype | string | no |
kern.pipe | node | not applicable |
kern.pool | struct pool_sysctl | no |
kern.posix1version | integer | no |
kern.posix_aio | integer | no |
kern.posix_barriers | integer | no |
kern.posix_reader_writer_locks | integer | no |
kern.posix_semaphores | integer | no |
kern.posix_spin_locks | integer | no |
kern.posix_threads | integer | no |
kern.posix_timers | integer | no |
kern.proc | struct kinfo_proc | no |
kern.proc2 | struct kinfo_proc2 | no |
kern.proc_args | string | no |
kern.profiling | node | not applicable |
kern.rawpartition | integer | no |
kern.root_device | string | no |
kern.root_partition | integer | no |
kern.rtc_offset | integer | yes |
kern.saved_ids | integer | no |
kern.sbmax | integer | yes |
kern.sched | node | not applicable |
kern.securelevel | integer | raise only |
kern.somaxkva | integer | yes |
kern.sooptions | integer | yes |
kern.synchronized_io | integer | no |
kern.timecounter | node | not applicable |
kern.timex | struct | no |
kern.tkstat | node | not applicable |
kern.tty | node | not applicable |
kern.urandom | integer | no |
kern.usercrypto | integer | yes |
kern.userasymcrypto | integer | yes |
kern.veriexec | node | not applicable |
kern.version | string | no |
kern.vnode | struct vnode | no |
kern.aio_listio_max
- The maximum number of asynchronous I/O operations in a single list I/O call. Like with all variables related to aio(3), the variable may be created and removed dynamically upon loading or unloading the corresponding kernel module.
kern.aio_max
- The maximum number of asynchronous I/O operations.
kern.arandom
(KERN_ARND
)- This variable returns up to 256 bytes of random data. Multiple queries can be used to obtain an infinite amount of non-blocking cryptographically secure random data. The used random number generator (RNG) is based on arc4random(3).
kern.argmax
(KERN_ARGMAX
)- The maximum bytes of argument to execve(2).
kern.boothowto
- Flags passed from the boot loader; see reboot(2) for the meanings of the flags.
kern.boottime
(KERN_BOOTTIME
)- A struct timespec structure is returned. This structure contains the time that the system was booted. That time is defined (for this purpose) to be the time at which the kernel first started accumulating clock ticks.
kern.bufq
- This variable contains information on the
bufq(9) subsystem. Currently, the only third level name implemented
is
kern.bufq.strategies
which provides a list of buffer queue strategies currently available. kern.buildinfo
- When the kernel is built, the build environment may optionally provide arbitrary information to be stored in this variable.
kern.ccpu
(KERN_CCPU
)- The scheduler exponential decay value.
kern.clockrate
(KERN_CLOCKRATE
)- A 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. Refer to hz(9) for additional details.
kern.consdev
(KERN_CONSDEV
)- Console device.
kern.coredump
- 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.
The third level name is
kern.coredump.setid
and fourth level variables are described below.Fourth level name Type Changeable kern.coredump.setid.dump integer yes kern.coredump.setid.group integer yes kern.coredump.setid.mode integer yes kern.coredump.setid.owner integer yes kern.coredump.setid.path string yes kern.coredump.setid.dump
- If non-zero, set-id processes will dump core.
kern.coredump.setid.group
- The group-id for the set-id processes' coredump.
kern.coredump.setid.mode
- The mode for the set-id processes' coredump. See chmod(1).
kern.coredump.setid.owner
- The user-id that will be used as the owner of the set-id processes' coredump.
kern.coredump.setid.path
- The path to which set-id processes' coredumps will be saved to. Same syntax as kern.defcorename.
kern.cp_id
(KERN_CP_ID
)- Mapping of CPU number to CPU id.
kern.cp_time
(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. kern.cryptodevallowsoft
- This variable controls userland access to hardware versus software transforms in the crypto(4) system. The available values are as follows:
kern.defcorename
(KERN_DEFCORENAME
)- Default template for the name of core dump files (see also
proc.pid.corename
in the per-process variablesproc.*
, and core(5) for format of this template). The default value is %n.core and can be changed with the kernel configuration optionoptions DEFCORENAME
(see options(4) ). kern.detachall
- Detach all devices at shutdown.
kern.domainname
(KERN_DOMAINNAME
)- Get or set the YP domain name.
kern.drivers
(KERN_DRIVERS
)- Return an array of struct kinfo_drivers that contains the name and major device numbers of all the device drivers in the current kernel. The d_name field is always a NUL terminated string. The d_bmajor field will be set to -1 if the driver doesn't have a block device.
kern.expose_address
- Expose kernel addresses in
sysctl(3) calls used by
fstat(1) and
sockstat(1). If it is set to
0
access is not allowed. If it is set to1
then only processes that have opened /dev/kmem can have access. If it is set to2
every process is allowed. Defaults to0
forKASLR
kernels and1
otherwise. Allowing general access renders KASLR ineffective; allowing only kmem accessing programs weakens KASLR if those programs can be subverted to leak the addresses. kern.dump_on_panic
(KERN_DUMP_ON_PANIC
)- Perform a crash dump on system panic(9).
kern.file
(KERN_FILE
)- Return the entire file table. The returned data consists of a single struct filelist followed by an array of struct file, whose size depends on the current number of such objects in the system.
kern.forkfsleep
(KERN_FORKFSLEEP
)- If 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
EAGAIN
error to process. Useful to keep heavily forking runaway processes in bay. Default zero (no sleep). Maximum is 20 seconds. kern.fscale
(KERN_FSCALE
)- The kernel fixed-point scale factor.
kern.fsync
(KERN_FSYNC
)- Return 1 if the IEEE Std 1003.1b-1993 (“POSIX.1b”) File Synchronization Option is available on this system, otherwise 0.
kern.hardclock_ticks
(KERN_HARDCLOCK_TICKS
)- Returns the number of hardclock(9) ticks.
kern.hist
- This variable contains kernel history data if the kernel was configured
for any of the options
UVHMIST
,USB_DEBUG
,BIOHIST
, orSCDEBUG
. (See options(4) for more details.) The third-level names correspond to each available history table. The values of the history tables are in an internal format, and can be decoded by the vmstat(1) utility's-U
and-u
options; the-l
option can be used to see which tables are available. kern.hostid
(KERN_HOSTID
)- Get or set the host identifier. This is aimed to replace the legacy gethostid(3) and sethostid(3) system calls.
kern.hostname
(KERN_HOSTNAME
)- Get or set the hostname(1).
kern.iov_max
(KERN_IOV_MAX
)- Return the maximum number of iovec structures that a process has available for use with preadv(2), pwritev(2), readv(2), recvmsg(2), sendmsg(2) and writev(2).
kern.ipc
(KERN_SYSVIPC
)- Return information about the SysV IPC parameters. The third level names
for the ipc variables are detailed below.
Third level name Type Changeable kern.ipc.sysvmsg integer no kern.ipc.sysvsem integer no kern.ipc.sysvshm integer no kern.ipc.sysvipc_info struct no kern.ipc.shmmax integer yes kern.ipc.shmmni integer yes kern.ipc.shmseg integer yes kern.ipc.shmmaxpgs integer yes kern.ipc.shm_use_phys integer yes kern.ipc.msgmni integer yes kern.ipc.msgseg integer yes kern.ipc.semmni integer yes kern.ipc.semmns integer yes kern.ipc.semmnu integer yes kern.ipc.sysvmsg
(KERN_SYSVIPC_MSG
)- Returns 1 if System V style message queue functionality is available on this system, otherwise 0.
kern.ipc.sysvsem
(KERN_SYSVIPC_SEM
)- Returns 1 if System V style semaphore functionality is available on this system, otherwise 0.
kern.ipc.sysvshm
(KERN_SYSVIPC_SHM
)- Returns 1 if System V style share memory functionality is available on this system, otherwise 0.
kern.ipc.sysvipc_info
(KERN_SYSVIPC_INFO
)- Return System V style IPC configuration and run-time information. The
fourth level name selects the System V style IPC facility.
Fourth level name Type KERN_SYSVIPC_MSG_INFO struct msg_sysctl_info KERN_SYSVIPC_SEM_INFO struct sem_sysctl_info KERN_SYSVIPC_SHM_INFO struct shm_sysctl_info KERN_SYSVIPC_MSG_INFO
- Return information on the System V style message facility. The
msg_sysctl_info
structure is defined in
<sys/msg.h>
. KERN_SYSVIPC_SEM_INFO
- Return information on the System V style semaphore facility. The
sem_sysctl_info
structure is defined in
<sys/sem.h>
. KERN_SYSVIPC_SHM_INFO
- Return information on the System V style shared memory facility.
The
shm_sysctl_info
structure is defined in
<sys/shm.h>
.
kern.ipc.shmmax
(KERN_SYSVIPC_SHMMAX
)- Max shared memory segment size in bytes.
kern.ipc.shmmni
(KERN_SYSVIPC_SHMMNI
)- Max number of shared memory identifiers.
kern.ipc.shmseg
(KERN_SYSVIPC_SHMSEG
)- Max shared memory segments per process.
kern.ipc.shmmaxpgs
(KERN_SYSVIPC_SHMMAXPGS
)- Max amount of shared memory in pages.
kern.ipc.shm_use_phys
(KERN_SYSVIPC_SHMUSEPHYS
)- Locking of shared memory in physical memory. If 0, memory can be swapped out, otherwise it will be locked in physical memory.
kern.ipc.msgmni
- Max number of message queue identifiers.
kern.ipc.msgseg
- Max number of number of message segments.
kern.ipc.semmni
- Max number of number of semaphore identifiers.
kern.ipc.semmns
- Max number of number of semaphores in system.
kern.ipc.semmnu
- Max number of undo structures in system.
kern.job_control
(KERN_JOB_CONTROL
)- Return 1 if job control is available on this system, otherwise 0.
kern.labeloffset
(KERN_LABELOFFSET
)- The offset within the sector specified by
KERN_LABELSECTOR
of the disklabel(5). kern.labelsector
(KERN_LABELSECTOR
)- The sector number containing the disklabel(5).
kern.login_name_max
(KERN_LOGIN_NAME_MAX
)- The size of the storage required for a login name, in bytes, including the terminating NUL.
kern.logsigexit
(KERN_LOGSIGEXIT
)- If this flag is non-zero, the kernel will log(9) all process exits due to signals which create a core(5) file, and whether the coredump was created.
kern.mapped_files
(KERN_MAPPED_FILES
)- Returns 1 if the IEEE Std 1003.1b-1993 (“POSIX.1b”) Memory Mapped Files Option is available on this system, otherwise 0.
kern.maxfiles
(KERN_MAXFILES
)- The maximum number of open files that may be open in the system.
kern.maxpartitions
(KERN_MAXPARTITIONS
)- The maximum number of partitions allowed per disk.
kern.maxlwp
- The maximum number of Lightweight Processes (threads) the system allows per uid.
kern.maxphys
(KERN_MAXPHYS
)- Maximum raw I/O transfer size.
kern.maxproc
(KERN_MAXPROC
)- The maximum number of simultaneous processes the system will allow.
kern.maxptys
(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 pty(4).
kern.maxvnodes
(KERN_MAXVNODES
)- The maximum number of vnodes available on the system. This can only be raised.
kern.mbuf
(KERN_MBUF
)- Return information about the mbuf control variables. Mbufs are data
structures which store network packets and other data structures in the
networking code, see
mbuf(9). 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.
Third level name Type Changeable kern.mbuf.mblowat integer yes kern.mbuf.mclbytes integer yes kern.mbuf.mcllowat integer yes kern.mbuf.msize integer yes kern.mbuf.nmbclusters integer yes The variables are as follows:
kern.mbuf.mblowat
(MBUF_MBLOWAT
)- The mbuf low water mark.
kern.mbuf.mclbytes
(MBUF_MCLBYTES
)- The mbuf cluster size.
kern.mbuf.mcllowat
(MBUF_MCLLOWAT
)- The mbuf cluster low water mark.
kern.mbuf.msize
(MBUF_MSIZE
)- The mbuf base size.
kern.mbuf.nmbclusters
(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.
kern.memlock
(KERN_MEMLOCK
)- Returns 1 if the IEEE Std 1003.1b-1993 (“POSIX.1b”) Process Memory Locking Option is available on this system, otherwise 0.
kern.memlock_range
(KERN_MEMLOCK_RANGE
)- Returns 1 if the IEEE Std 1003.1b-1993 (“POSIX.1b”) Range Memory Locking Option is available on this system, otherwise 0.
kern.memory_protection
(KERN_MEMORY_PROTECTION
)- Returns 1 if the IEEE Std 1003.1b-1993 (“POSIX.1b”) Memory Protection Option is available on this system, otherwise 0.
kern.messages
- Kernel console message verbosity. See
⟨sys/reboot.h⟩
Value Verbosity sys/reboot.h equivalent 0 Silent AB_SILENT 1 Quiet AB_QUIET 2 Normal AB_NORMAL 3 Verbose AB_VERBOSE 4 Debug AB_DEBUG kern.module
- Settings related to kernel modules. The third level names for the settings
are described below.
Third level name Type Changeable kern.module.autoload integer yes kern.module.autotime integer yes kern.module.verbose boolean yes The variables are as follows:
kern.module.autoload
- A boolean that controls whether kernel modules are loaded automatically. See module(7) for additional details.
kern.module.autotime
- An integer that controls the delay before an attempt is made to automatically unload a module that was auto-loaded. Setting this value to zero disables the auto-unload function.
kern.module.verbose
- A boolean that enables or disables verbose debug messages related to kernel modules.
kern.monotonic_clock
(KERN_MONOTONIC_CLOCK
)- Returns the standard version the implementation of the IEEE Std 1003.1b-1993 (“POSIX.1b”) Monotonic Clock Option conforms to, otherwise 0.
kern.mqueue
- Settings related to POSIX message queues; see
mqueue(3). This node is created dynamically when the corresponding
kernel module is loaded. The third level names for the settings are
described below.
Third level name Type Changeable kern.mqueue.mq_open_max integer yes kern.mqueue.mq_prio_max integer yes kern.mqueue.mq_max_msgsize integer yes kern.mqueue.mq_def_maxmsg integer yes kern.mqueue.mq_max_maxmsg integer yes The variables are:
kern.mqueue.mq_open_max
- The maximum number of message queue descriptors any single process can open.
kern.mqueue.mq_prio_max
- The maximum priority of a message.
kern.mqueue.mq_max_msgsize
- The maximum size of a message in a message queue.
kern.mqueue.mq_def_maxmsg
- The default maximum message count.
kern.mqueue.mq_max_maxmsg
- The maximum number of messages in a message queue.
kern.msgbuf
(KERN_MSGBUF
)- The kernel message buffer, rotated so that the head of the circular kernel message buffer is at the start of the returned data. The returned data may contain NUL bytes.
kern.msgbufsize
(KERN_MSGBUFSIZE
)- The maximum number of characters that the kernel message buffer can hold.
kern.ngroups
(KERN_NGROUPS
)- The maximum number of supplemental groups.
kern.ntptime
(KERN_NTPTIME
)- A struct ntptimeval structure is returned. This structure contains data used by the ntpd(8) program.
kern.osrelease
(KERN_OSRELEASE
)- The system release string.
kern.osrevision
(KERN_OSREV
)- The system revision string.
kern.ostype
(KERN_OSTYPE
)- The system type string.
kern.pipe
(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.
Third level name Type Changeable kern.pipe.kvasiz integer yes kern.pipe.maxbigpipes integer yes kern.pipe.maxkvasz integer yes kern.pipe.limitkva integer yes kern.pipe.nbigpipes integer yes The variables are as follows:
kern.pipe.kvasiz
(KERN_PIPE_KVASIZ
)- Amount of kernel memory consumed by pipe buffers.
kern.pipe.maxbigpipes
(KERN_PIPE_MAXBIGPIPES
)- Maximum number of “big” pipes.
kern.pipe.maxkvasz
(KERN_PIPE_MAXKVASZ
)- Maximum amount of kernel memory to be used for pipes.
kern.pipe.limitkva
(KERN_PIPE_LIMITKVA
)- Limit for direct transfers via page loan.
kern.pipe.nbigpipes
(KERN_PIPE_NBIGPIPES
)- Number of “big” pipes.
kern.pool
- Provides statistics about the pool(9) and pool_cache(9) subsystems.
kern.posix1version
(KERN_POSIX1
)- The version of ISO/IEC 9945 (IEEE Std 1003.1 (“POSIX.1”)) with which the system attempts to comply.
kern.posix_aio
- The version of IEEE Std 1003.1 (“POSIX.1”) and its Asynchronous I/O option to which the system attempts to conform.
kern.posix_barriers
(KERN_POSIX_BARRIERS
)- The version of IEEE Std 1003.1 (“POSIX.1”) and its Barriers option to which the system attempts to conform, otherwise 0.
kern.posix_reader_writer_locks
(KERN_POSIX_READER_WRITER_LOCKS
)- The version of IEEE Std 1003.1 (“POSIX.1”) and its Read-Write Locks option to which the system attempts to conform, otherwise 0.
kern.posix_semaphores
(KERN_POSIX_SEMAPHORES
)- The version of IEEE Std 1003.1 (“POSIX.1”) and its Semaphores option to which the system attempts to conform, otherwise 0.
kern.posix_spin_locks
(KERN_POSIX_SPIN_LOCKS
)- The version of IEEE Std 1003.1 (“POSIX.1”) and its Spin Locks option to which the system attempts to conform, otherwise 0.
kern.posix_threads
(KERN_POSIX_THREADS
)- The version of IEEE Std 1003.1 (“POSIX.1”) and its Threads option to which the system attempts to conform, otherwise 0.
kern.posix_timers
(KERN_POSIX_TIMERS
)- The version of IEEE Std 1003.1 (“POSIX.1”) and its Timers option to which the system attempts to conform, otherwise 0.
kern.proc
(KERN_PROC
)- Return the entire process table, or a subset of it. An array of
struct kinfo_proc structures is returned, whose size
depends on the current number of such objects in the system. The third and
fourth level numeric names are as follows:
Third level name Fourth level is: KERN_PROC_ALL None KERN_PROC_GID A group ID KERN_PROC_PID A process ID KERN_PROC_PGRP A process group KERN_PROC_RGID A real group ID KERN_PROC_RUID A real user ID KERN_PROC_SESSION A session ID KERN_PROC_TTY A tty device KERN_PROC_UID A user ID kern.proc2
(KERN_PROC2
)- As for
KERN_PROC
, but an array of struct kinfo_proc2 structures are returned. The fifth level name is the size of the struct kinfo_proc2 and the sixth level name is the number of structures to return. kern.proc_args
(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:
KERN_PROC_ARGV
The argv strings KERN_PROC_ENV
The environ strings KERN_PROC_NARGV
The number of argv strings KERN_PROC_NENV
The number of environ strings KERN_PROC_PATHNAME
The full pathname of the executable KERN_PROC_CWD
The current working directory kern.profiling
(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 withEOPNOTSUPP
. 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.Third level name Type Changeable kern.profiling.count u_short[] yes kern.profiling.froms u_short[] yes kern.profiling.gmonparam struct gmonparam no kern.profiling.state integer yes kern.profiling.tos struct tostruct yes The variables are as follows:
kern.profiling.count
(GPROF_COUNT
)- Array of statistical program counter counts.
kern.profiling.froms
(GPROF_FROMS
)- Array indexed by program counter of call-from points.
kern.profiling.gmonparams
(GPROF_GMONPARAM
)- Structure giving the sizes of the above arrays.
kern.profiling.state
(GPROF_STATE
)- Profiling state. If set to
GMON_PROF_ON
, starts profiling. If set toGMON_PROF_OFF
, stops profiling. kern.profiling.tos
(GPROF_TOS
)- Array of struct tostruct describing destination of calls and their counts.
kern.rawpartition
(KERN_RAWPARTITION
)- The raw partition of a disk (a == 0).
kern.root_device
(KERN_ROOT_DEVICE
)- The name of the root device (e.g., “wd0”).
kern.root_partition
(KERN_ROOT_PARTITION
)- The root partition on the root device (a == 0).
kern.rtc_offset
(KERN_RTC_OFFSET
)- Return the offset of real time clock from UTC in minutes.
kern.saved_ids
(KERN_SAVED_IDS
)- Returns 1 if saved set-group and saved set-user ID is available.
kern.sbmax
(KERN_SBMAX
)- Maximum socket buffer size in bytes.
kern.securelevel
(KERN_SECURELVL
)- See secmodel_securelevel(9).
kern.sched
(dynamic
)- Influence the scheduling of LWPs, their priorisation and how they are
distributed on and moved between CPUs.
Third level name Type Changeable kern.sched.cacheht_time integer yes kern.sched.balance_period integer yes kern.sched.average_weight integer yes kern.sched.min_catch integer yes kern.sched.timesoftints integer yes kern.sched.kpreempt_pri integer yes kern.sched.upreempt_pri integer yes kern.sched.maxts integer yes kern.sched.mints integer yes kern.sched.name string no kern.sched.rtts integer no kern.sched.pri_min integer no kern.sched.pri_max integer no The variables are as follows:
kern.sched.cacheht_time
(dynamic
)- Cache hotness time in which a LWP is kept on one particular CPU and not moved to another CPU. This reduces the overhead of flushing and reloading caches. Defaults to 3ms. Needs to be given in “hz” units, see mstohz(9).
kern.sched.balance_period
(dynamic
)- Interval at which the CPU queues are checked for re-balancing. Defaults to 300ms. Needs to be given in “hz” units, see mstohz(9).
kern.sched.average_weight
(dynamic
)- Can be used to influence how likely LWPs are to be migrated from one CPU's queue of LWPs that are ready to run to a different, idle CPU. The value gives the percentage for weighting the average count of migratable threads from the past against the current number of migratable threads. A small value gives more weight to the past, a larger values more weight on the current situation. Defaults to 50 and must be between 0 and 100.
kern.sched.min_catch
(dynamic
)- Minimum count of migratable (runable) threads for catching (stealing) from another CPU. Defaults to 1 but can be increased to decrease chance of thread migration between CPUs.
kern.sched.timesoftints
(dynamic
)- Enable tracking of CPU time for soft interrupts as part of a LWP's real execution time. Set to a non-zero value to enable, and see ps(1) for printing CPU times.
kern.sched.kpreempt_pri
(dynamic
)- Minimum priority to trigger kernel preemption.
kern.sched.upreempt_pri
(dynamic
)- Minimum priority to trigger user preemption.
kern.sched.maxts
(dynamic
)- Scheduler specific maximal time quantum (in milliseconds). Must be set
to a value larger than “mints” and between 10 and
“hz” as given by the
kern.clockrate
sysctl. Provided by the M2 scheduler. kern.sched.mints
(dynamic
)- Scheduler specific minimal time quantum (in milliseconds). Must be set to a value smaller than “maxts” and between 1 and “hz” as given by the “kern.clockrate” sysctl. Provided by the M2 scheduler.
kern.sched.name
(dynamic
)- Scheduler name. Provided both by the M2 and the 4BSD scheduler.
kern.sched.rtts
(dynamic
)- Fixed scheduler specific round-robin time quantum in milliseconds. Provided both by the M2 and the 4BSD scheduler.
kern.sched.pri_min
(dynamic
)- Minimal POSIX real-time priority. See sched(3).
kern.sched.pri_max
(dynamic
)- Maximal POSIX real-time priority. See sched(3).
kern.somaxkva
(KERN_SOMAXKVA
)- Maximum amount of kernel memory to be used for socket buffers in bytes.
kern.sooptions
- Set the default socket option flags for socket(2) creation. See setsockopt(2) for a list of supported flags.
kern.synchronized_io
(KERN_SYNCHRONIZED_IO
)- Returns 1 if the IEEE Std 1003.1b-1993 (“POSIX.1b”) Synchronized I/O Option is available on this system, otherwise 0.
kern.timecounter
(dynamic
)- Display and control the timecounter source of the system.
Third level name Type Changeable kern.timecounter.choice string no kern.timecounter.hardware string yes kern.timecounter.timestepwarnings integer yes The variables are as follows:
kern.timecounter.choice
(dynamic
)- The list of available timecounters with their quality and frequency.
kern.timecounter.hardware
(dynamic
)- The currently selected timecounter source.
kern.timecounter.timestepwarnings
(dynamic
)- If non-zero display a message each time the time is stepped.
kern.timex
(KERN_TIMEX
)- Not available.
kern.tkstat
(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.
Third level name Type Changeable kern.tkstat.cancc quad no kern.tkstat.nin quad no kern.tkstat.nout quad no kern.tkstat.rawcc quad no The variables are as follows:
kern.tkstat.cancc
(KERN_TKSTAT_CANCC
)- The number of canonical input characters.
kern.tkstat.nin
(KERN_TKSTAT_NIN
)- The total number of input characters.
kern.tkstat.nout
(KERN_TKSTAT_NOUT
)- The total number of output characters.
kern.tkstat.rawcc
(KERN_TKSTAT_RAWCC
)- The number of raw input characters.
kern.tty
- The third level names for the tty setup variables are detailed below. The
changeable column shows whether a process with appropriate privilege may
change the value.
Third level name Type Changeable kern.tty.qsize int yes The variables are as follows:
kern.tty.qsize
- Control/display the size of the default input and output queues
selected during tty creation. Is converted to a power of two and its
range is between
1024
and65536
.
kern.uidinfo
- Resource usage for the current user.
Third level name Type Changeable kern.uidinfo.proccnt integer no kern.uidinfo.lwpcnt integer no kern.uidinfo.lockcnt integer no kern.uidinfo.semcnt integer no kern.uidinfo.sbsize integer no kern.uidinfo.proccnt
- Returns the number of active processes for the current user.
kern.uidinfo.lwpcnt
- Returns the number of active threads for the current user; the first thread of each process is not counted.
kern.uidinfo.lockcnt
- Number of locks held by the current user.
kern.uidinfo.semcnt
- Number of semaphores held by the current user.
kern.uidinfo.sbsize
- Number of bytes in socket buffers allocated to the current user.
kern.urandom
(KERN_URND
)- Random integer value.
kern.usercrypto
- When enabled, allows userland to open(2) the /dev/crypto special device, used by the crypto(4) system.
kern.userasymcrypto
- Enables or disables the use of software asymmetric crypto support in the crypto(4) system.
kern.veriexec
- Runtime information for
veriexec(8).
Third level name Type Changeable kern.veriexec.algorithms string no kern.veriexec.count node not applicable kern.veriexec.strict integer yes kern.veriexec.verbose integer yes kern.veriexec.algorithms
- Returns a string with the supported algorithms in Veriexec.
kern.veriexec.count
- Sub-nodes are added to this node as new mounts are monitored by Veriexec. Each mount will be under its own tableN node. Under each node there will be three variables, indicating the mount point, the file system type, and the number of entries.
kern.veriexec.strict
- Controls the strict level of Veriexec. See security(7) for more information on each level's implications.
kern.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.
kern.version
(KERN_VERSION
)- The system version string.
kern.vnode
(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 struct vnode * followed by the vnode itself struct vnode.
The machdep.* subtree
The set of variables defined is architecture dependent. Most architectures define at least the following variables.
Second level name | Type | Changeable |
machdep.booted_kernel |
string | no |
The net.* subtree
The string and integer information available for the
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.
Second level name | Type | Changeable |
net.route | routing messages | no |
net.inet | IPv4 values | yes |
net.inet6 | IPv6 values | yes |
net.key | IPsec key management values | yes |
net.route
(PF_ROUTE
)- Return the entire routing table or a subset of it. The data is returned as
a sequence of routing messages (see
route(4) for the header file, format and meaning). The length of
each message is contained in the message header.
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:
Fifth level name Sixth level is: NET_RT_FLAGS rtflags NET_RT_DUMP None NET_RT_IFLIST None net.inet
(PF_INET
)- Get or set various global information about the IPv4 (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:
Protocol Variable Type Changeable arp down integer yes arp keep integer yes arp log_movements integer yes arp log_permanent_modify integer yes arp log_unknown_network integer yes arp log_wrong_iface integer yes carp allow integer yes carp preempt integer yes carp log integer yes carp arpbalance integer yes icmp errppslimit integer yes icmp maskrepl integer yes icmp rediraccept integer yes icmp redirtimeout integer yes icmp bmcastecho integer yes ip allowsrcrt integer yes ip anonportalgo.selected string yes ip anonportalgo.available string yes ip anonportalgo.reserve struct yes ip anonportmax integer yes ip anonportmin integer yes ip checkinterface integer yes ip dad_count integer yes ip directed-broadcast integer yes ip do_loopback_cksum integer yes ip forwarding integer yes ip forwsrcrt integer yes ip gifttl integer yes ip grettl integer yes ip hashsize integer yes ip hostzerobroadcast integer yes ip lowportmin integer yes ip lowportmax integer yes ip maxflows integer yes ip maxfragpackets integer yes ip mtudisc integer yes ip mtudisctimeout integer yes ip random_id integer yes ip redirect integer yes ip subnetsarelocal integer yes ip ttl integer yes tcp rfc1323 integer yes tcp sendspace integer yes tcp recvspace integer yes tcp mssdflt integer yes tcp syn_cache_limit integer yes tcp syn_bucket_limit integer yes tcp syn_cache_interval integer yes tcp init_win integer yes tcp init_win_local integer yes tcp mss_ifmtu integer yes tcp win_scale integer yes tcp timestamps integer yes tcp cwm integer yes tcp cwm_burstsize integer yes tcp ack_on_push integer yes tcp keepidle integer yes tcp keepintvl integer yes tcp keepcnt integer yes tcp slowhz integer no tcp keepinit integer yes tcp log_refused integer yes tcp rstppslimit integer yes tcp ident struct no tcp drop struct no tcp sack.enable integer yes tcp sack.globalholes integer no tcp sack.globalmaxholes integer yes tcp sack.maxholes integer yes tcp ecn.enable integer yes tcp ecn.maxretries integer yes tcp congctl.selected string yes tcp congctl.available string yes tcp abc.enable integer yes tcp abc.aggressive integer yes udp checksum integer yes udp do_loopback_cksum integer yes udp recvspace integer yes udp sendspace integer yes The variables are as follows:
arp.down
- Failed ARP entry lifetime.
arp.keep
- Valid ARP entry lifetime.
carp.allow
- If set to 0, incoming carp(4) packets will not be processed. If set to any other value, processing will occur. Enabled by default.
carp.arpbalance
- If set to any value other than 0, the ARP balancing functionality of carp(4) is enabled. When ARP requests are received for an IP address which is part of any virtual host, carp will hash the source IP in the ARP request to select one of the virtual hosts from the set of all the virtual hosts which have that IP address. The master of that host will respond with the correct virtual MAC address. Disabled by default.
carp.log
- If set to any value other than 0, carp(4) will log errors. Disabled by default.
carp.preempt
- If set to 0, carp(4) will not attempt to become master if it is receiving advertisements from another active master. If set to any other value, carp will become master of the virtual host if it believes it can send advertisements more frequently than the current master. Disabled by default.
ip.allowsrcrt
- If set to 1, the host accepts source routed packets.
ip.anonportalgo.available
- The available RFC 6056 port randomization algorithms.
ip.anonportalgo.reserve
- A bitmask of ports that will not be used during anonymous or privileged port selection.
ip.anonportalgo.selected
- The currently selected RFC 6056 port randomization algorithm.
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
ip.anonportmin
. 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.
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 NAT 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.
ip.dad_count
- The number of arp(4) probes sent for Address Conflict Detection. Set to 0 to disable this.
ip.directed-broadcast
- If set to 1, enables directed broadcast behavior for the host.
ip.do_loopback_cksum
- Perform IP checksum on loopback.
ip.forwarding
- If set to 1, enables IP forwarding for the host, meaning that the host is acting as a router.
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.
ip.gifttl
- The maximum time-to-live (hop count) value for an IPv4 packet generated by gif(4) tunnel interface.
ip.grettl
- The maximum time-to-live (hop count) value for an IPv4 packet generated by gre(4) tunnel interface.
ip.hashsize
- The size of IPv4 Fast Forward hash table. This value must be a power
of 2 (64, 256...). A larger hash table size results in fewer
collisions. Also see
ip.maxflows
. ip.hostzerobroadcast
- All zeroes address is broadcast address.
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
ip.lowportmin
. 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
ip.lowportmax
. ip.maxflows
- IPv4 Fast Forwarding is enabled by default. If set to 0, IPv4 Fast
Forwarding is disabled.
ip.maxflows
controls the maximum amount of flows which can be created. The default value is 256. 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.
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
tcp.mssdflt
(the local maximum segment size). 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.
ip.random_id
- Assign random ip_id values.
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.
ip.subnetsarelocal
- If set to 1, subnets are to be considered local addresses.
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.
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.
icmp.maskrepl
- If set to 1, ICMP network mask requests are to be answered.
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.
icmp.redirtimeout
- The variable specifies lifetime of routing entries generated by incoming ICMP redirect. This defaults to 600 seconds.
icmp.returndatabytes
- Number of bytes to return in an ICMP error message.
icmp.bmcastecho
- If set to 1, enables responding to ICMP echo or timestamp request to the broadcast address.
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.
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.
tcp.cwm_burstsize
- The Congestion Window Monitoring allowed burst size, in terms of packet count.
tcp.delack_ticks
- Number of ticks to delay sending an ACK.
tcp.do_loopback_cksum
- Perform TCP checksum on loopback.
tcp.init_win
- A value indicating the TCP initial congestion window. The valid range is 0 to 10 (maximum specified by RFC6928), with a default of 4 (approximately 4K per RFC3390).
tcp.init_win_local
- Like
tcp.init_win
, but used when communicating with hosts on a local network. 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.
tcp.keepidle
- Time a connection must be idle before keepalives are sent (if keepalives are enabled for the connection). See also tcp.slowhz.
tcp.keepintvl
- Time after a keepalive probe is sent until, in the absence of any response, another probe is sent. See also tcp.slowhz.
tcp.log_refused
- If set to 1, refused TCP connections to the host will be logged.
tcp.keepinit
- Timeout in seconds during connection establishment.
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.
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
(
ip.mtudisc
) is disabled. Do not change this value unless you really know what you are doing. tcp.recvspace
- The default TCP receive buffer size.
tcp.rfc1323
- If set to 1, enables RFC 1323 extensions to TCP.
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.
tcp.ident
- Return the user ID of a connected socket pair. (RFC1413 Identification Protocol lookups.)
tcp.drop
- Drop a TCP socket pair connection.
tcp.sack.enable
- If set to 1, enables RFC 2018 Selective ACKnowledgement.
tcp.sack.globalholes
- Global number of TCP SACK holes.
tcp.sack.globalmaxholes
- Global maximum number of TCP SACK holes.
tcp.sack.maxholes
- Maximum number of TCP SACK holes allowed per connection.
tcp.ecn.enable
- If set to 1, enables RFC 3168 Explicit Congestion Notification.
tcp.ecn.maxretries
- Number of times to retry sending the ECN-setup packet.
tcp.sendspace
- The default TCP send buffer size.
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.)
tcp.syn_bucket_limit
- The maximum number of entries allowed per hash bucket in the TCP compressed state engine.
tcp.syn_cache_limit
- The maximum number of entries allowed in the TCP compressed state engine.
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.
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.
tcp.congctl.available
- The available TCP congestion control algorithms.
tcp.congctl.selected
- The currently selected TCP congestion control algorithm.
tcp.abc.enable
- If set to 1, use RFC 3465 Appropriate Byte Counting (ABC). If set to 0, use traditional Packet Counting.
tcp.abc.aggressive
- Choose the L parameter found in RFC 3465. L is the maximum cwnd increase for an ack during slow start. If set to 1, use L=2*SMSS. If set to 0, use L=1*SMSS. It has no effect unless tcp.abc.enable is set to 1.
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.
udp.recvspace
- The default UDP receive buffer size.
udp.sendspace
- The default UDP send buffer size.
For variables net.*.ipsec, please refer to ipsec(4).
net.inet6
(PF_INET6
)- Get or set various global information about the IPv6 (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:
Protocol Variable Type Changeable icmp6 errppslimit integer yes icmp6 mtudisc_hiwat integer yes icmp6 mtudisc_lowat integer yes icmp6 nd6_debug integer yes icmp6 nd6_delay integer yes icmp6 nd6_maxnudhint integer yes icmp6 nd6_mmaxtries integer yes icmp6 nd6_prune integer yes icmp6 nd6_umaxtries integer yes icmp6 nd6_useloopback integer yes icmp6 nodeinfo integer yes icmp6 rediraccept integer yes icmp6 redirtimeout integer yes ip6 accept_rtadv integer yes ip6 addctlpolicy struct in6_addrpolicy no ip6 anonportalgo.selected string yes ip6 anonportalgo.available string yes ip6 anonportalgo.reserve struct yes ip6 anonportmax integer yes ip6 anonportmin integer yes ip6 auto_flowlabel integer yes ip6 dad_count integer yes ip6 defmcasthlim integer yes ip6 forwarding integer yes ip6 gifhlim integer yes ip6 hashsize integer yes ip6 hlim integer yes ip6 hdrnestlimit integer yes ip6 kame_version string no ip6 keepfaith integer yes ip6 log_interval integer yes ip6 lowportmax integer yes ip6 lowportmin integer yes ip6 maxdynroutes integer yes ip6 maxifprefixes integer yes ip6 maxifdefrouters integer yes ip6 maxflows integer yes ip6 maxfragpackets integer yes ip6 maxfrags integer yes ip6 neighborgcthresh integer yes ip6 redirect integer yes ip6 rr_prune integer yes ip6 use_deprecated integer yes ip6 v6only integer yes udp6 do_loopback_cksum integer yes udp6 recvspace integer yes udp6 sendspace integer yes The variables are as follows:
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 (not a router) for the option to be meaningful.
ip6.anonportalgo.available
- The available RFC 6056 port randomization algorithms.
ip6.anonportalgo.reserve
- A bitmask of ports that will not be used during anonymous or privileged port selection.
ip6.anonportalgo.selected
- The currently selected RFC 6056 port randomization algorithm.
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
ip6.anonportmin
. 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.
ip6.auto_flowlabel
- On connected transport protocol packets, fill IPv6 flowlabel field to help intermediate routers to identify packet flows.
ip6.dad_count
- The variable configures number of IPv6 DAD (duplicated address detection) probe packets. The packets will be generated when IPv6 interface addresses are configured.
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 ip6(4).
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 “router” case and “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.
ip6.gifhlim
- The maximum hop limit value for an IPv6 packet generated by gif(4) tunnel interface.
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.
ip6.hashsize
- The size of IPv6 Fast Forward hash table. This value must be a power
of 2 (64, 256, ...). A larger hash table size results in fewer
collisions. Also see
ip6.maxflows
. 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 ip6(4).
ip6.kame_version
- The string identifies the version of KAME IPv6 stack implemented in the kernel.
ip6.keepfaith
- If set to non-zero, it enables “FAITH” TCP relay IPv6-to-IPv4 translator code in the kernel. Refer faith(4) and faithd(8) for detail.
ip6.log_interval
- The variable controls amount of logs generated by IPv6 packet forwarding engine, by setting interval between log output (in seconds).
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
ip6.lowportmin
. 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
ip6.lowportmax
. ip6.maxdynroutes
- Maximum number of routes created by redirect. Set it to negative to disable. The default value is 4096.
ip6.maxifprefixes
- Maximum number of prefixes created by route advertisements per interface. Set it to negative to disable. The default value is 16.
ip6.maxifdefrouters 16
- Maximum number of default routers created by route advertisements per interface. Set it to negative to disable. The default value is 16.
ip6.maxflows
- IPv6 Fast Forwarding is enabled by default. If set to 0, IPv6 Fast
Forwarding is disabled.
ip6.maxflows
controls the maximum amount of flows which can be created. The default value is 256. 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.
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.
ip6.neighborgcthresh
- Maximum number of entries in neighbor cache per interface. Set to negative to disable. The default value is 2048.
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.
ip6.rr_prune
- The variable specifies interval between IPv6 router renumbering prefix babysitting, in seconds.
ip6.use_deprecated
- The variable controls use of deprecated address, specified in RFC 2462 5.5.4.
ip6.v6only
- The variable specifies initial value for
IPV6_V6ONLY
socket option forAF_INET6
socket. Please refer to ip6(4) for detail. 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.
icmp6.mtudisc_hiwat
icmp6.mtudisc_lowat
- The variables define the maximum number of routing table entries,
created due to path MTU discovery (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.
icmp6.mtudisc_hiwat
is used when we have verified ICMPv6 too big messages.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. 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.
icmp6.nd6_delay
- The variable specifies
DELAY_FIRST_PROBE_TIME
timing constant in IPv6 neighbor discovery specification (RFC 2461), in seconds. 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.
icmp6.nd6_mmaxtries
- The variable specifies
MAX_MULTICAST_SOLICIT
constant in IPv6 neighbor discovery specification (RFC 2461). icmp6.nd6_prune
- The variable specifies interval between IPv6 neighbor cache babysitting, in seconds.
icmp6.nd6_umaxtries
- The variable specifies
MAX_UNICAST_SOLICIT
constant in IPv6 neighbor discovery specification (RFC 2461). icmp6.nd6_useloopback
- If set to non-zero, kernel IPv6 stack will use loopback interface for local traffic.
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.
- 1
- Respond to ICMPv6 FQDN queries, e.g.
ping6 -w
. - 2
- Respond to ICMPv6 node addresses queries, e.g.
ping6 -a
.
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 (non-router) only.
icmp6.redirtimeout
- The variable specifies lifetime of routing entries generated by incoming ICMPv6 redirect.
udp6.do_loopback_cksum
- Perform UDP checksum on loopback.
udp6.recvspace
- Default UDP receive buffer size.
udp6.sendspace
- Default UDP send buffer size.
We reuse net.*.tcp for TCP over IPv6, and therefore we do not have variables net.*.tcp6. Variables net.inet6.udp6 have identical meaning to net.inet.udp. Please refer to
PF_INET
section above. For variables net.*.ipsec6, please refer to ipsec(4). net.key
(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:
Variable Type Changeable debug integer yes enabled integer yes used integer no spi_try integer yes spi_min_value integer yes spi_max_value integer yes larval_lifetime integer yes blockacq_count integer yes blockacq_lifetime integer yes esp_keymin integer yes esp_auth integer yes ah_keymin integer yes debug
- Turn on debugging message from within the kernel. The value is a
bitmap, as defined in
<netipsec/key_debug.h>
. enabled
- Control processing of IPsec control messages.
- 0
- Never allow IPsec processing
- 1
- Allow IPsec processing when SPD policies are present.
- 2
- Force IPsec processing even when SPD policies are not present.
used
- Based on if IPsec is enabled, and SPD rule existence, show if IPsec is being used. Note that currently once IPsec is being used, it cannot be disabled.
spi_try
- The number of times the kernel will try to obtain an unique SPI when it generates it from random number generator.
spi_min_value
- Minimum SPI value when generating it within the kernel.
spi_max_value
- Maximum SPI value when generating it within the kernel.
larval_lifetime
- Lifetime for LARVAL SAD entries, in seconds.
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.
blockacq_lifetime
- Lifetime of ACQUIRE PF_KEY message.
esp_keymin
- Minimum ESP key length, in bits. The value is used when the kernel creates proposal payload on ACQUIRE PF_KEY message.
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.
ah_keymin
- Minimum AH key length, in bits, The value is used when the kernel creates proposal payload on ACQUIRE PF_KEY message.
net.local
(PF_LOCAL
)- Get or set various global information about
AF_LOCAL
type sockets. For some variables, the third level name is the variable name:Variable Type Changeable inflight integer no deferred integer no inflight
- The number of file descriptors currently passed between processes, "in flight".
deferred
- The number of file descriptors passed between processes that have been deferred for cleanup by a kernel task.
Other variables are specific to a socket type:
Socket Type Sy Variable Type Changeable dgram pcblist struct no dgram recvspace integer yes dgram sendspace integer yes seqpacket pcblist struct no stream pcblist struct no stream recvspace integer yes stream sendspace integer yes dgram.pcblist
- The Protocol Control Block list structure for datagram sockets. Parsed by netstat(1) or sockstat(1).
dgram.recvspace
- The default datagram receive buffer size.
dgram.sendspace
- The default datagram send buffer size.
seqpacket.pcblist
- The Protocol Control Block list structure for Sequential Packet sockets. Parsed by netstat(1) or sockstat(1).
stream.pcblist
- The Protocol Control Block list structure for stream sockets. Parsed by netstat(1) or sockstat(1).
stream.recvspace
- The default stream receive buffer size.
stream.sendspace
- The default stream send buffer size.
The proc.* subtree
The string and integer information available for the
proc
level 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.
Third level name | Type | Changeable |
proc.pid.corename | string | yes |
proc.pid.rlimit | node | not applicable |
proc.pid.stopfork | int | yes |
proc.pid.stopexec | int | yes |
proc.pid.stopexit | int | yes |
proc.pid.paxflags | int | no |
proc.pid.corename
(PROC_PID_CORENAME
)- The template used for the core dump file name (see
core(5) for details). The base name must either be
core or end with the suffix
.core (the super-user may set arbitrary names). By
default it points to
KERN_DEFCORENAME
. proc.pid.rlimit
(PROC_PID_LIMIT
)- Return resources limits, as defined for the
getrlimit(2) and
setrlimit(2) system calls. The fourth level name is one of:
proc.pid.rlimit.cputime
(PROC_PID_LIMIT_CPU
)- The maximum amount of CPU time (in seconds) to be used by each process.
proc.pid.rlimit.filesize
(PROC_PID_LIMIT_FSIZE
)- The largest size (in bytes) file that may be created.
proc.pid.rlimit.datasize
(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 sbrk(2) system call.
proc.pid.rlimit.stacksize
(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.
proc.pid.rlimit.coredumpsize
(PROC_PID_LIMIT_CORE
)- The largest size (in bytes) core file that may be created.
proc.pid.rlimit.memoryuse
(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.
proc.pid.rlimit.memorylocked
(PROC_PID_LIMIT_MEMLOCK
)- The maximum size (in bytes) which a process may lock into memory using the mlock(2) function.
proc.pid.rlimit.maxproc
(PROC_PID_LIMIT_NPROC
)- The maximum number of simultaneous processes for this user id.
proc.pid.rlimit.descriptors
(PROC_PID_LIMIT_NOFILE
)- The maximum number of open files for this process.
proc.pid.rlimit.sbsize
(PROC_PID_LIMIT_SBSIZE
)- The maximum size (in bytes) of the socket buffers set by the
setsockopt(2)
SO_RCVBUF
andSO_SNDBUF
options. proc.pid.rlimit.vmemoryuse
(PROC_PID_LIMIT_AS
)- The maximum size (in bytes) which a process can obtain.
proc.pid.rlimit.maxlwp
(PROC_PID_LIMIT_NTHR
)- The maximum number of threads that cen be created and running at one time in the process. The first thread of each process is not counted against this.
The fifth level name is one of
soft
(PROC_PID_LIMIT_TYPE_SOFT
) orhard
(PROC_PID_LIMIT_TYPE_HARD
), to select respectively the soft or hard limit. Both are of type integer. proc.pid.stopfork
(PROC_PID_STOPFORK
)- If non zero, the process' children will be stopped after
fork(2) calls. The children are created in the SSTOP state and are
never scheduled for running before being stopped. This feature enables
attaching to a process with a debugger such as
gdb(1) before the process has the opportunity to actually do
anything.
This value is inherited by the process's children, and it also applies to emulation specific system calls that fork a new process, such as
sproc
() orclone
(). proc.pid.stopexec
(PROC_PID_STOPEXEC
)- If non zero, the process will be stopped on the next
exec(3) call. The process created by
exec(3) is created in the SSTOP state and is never scheduled for
running before being stopped. This feature enables attaching to a process
with a debugger such as
gdb(1) before the process has the opportunity to actually do
anything.
This value is inherited by the process's children.
proc.pid.stopexit
(PROC_PID_STOPEXIT
)- If non zero, the process will be stopped when it has cause to exit, either
by way of calling
exit(3),
_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 the process before it disappears.
This feature can be used to examine the final conditions of the process's
vmspace via pmap(1) or its resource settings with
sysctl(8) before it disappears.
This value is also inherited by the process's children.
proc.pid.paxflags
(PROC_PID_PAXFLAGS
)- This read-only variable returns the current value of the process's pax flags (see paxctl(8)).
The
user.* subtree (CTL_USER
)
The string and integer information available for the
user
level is detailed below. The changeable column
shows whether a process with appropriate privilege may change the value.
Second level name | Type | Changeable |
user.atexit_max | integer | no |
user.bc_base_max | integer | no |
user.bc_dim_max | integer | no |
user.bc_scale_max | integer | no |
user.bc_string_max | integer | no |
user.coll_weights_max | integer | no |
user.cs_path | string | no |
user.expr_nest_max | integer | no |
user.line_max | integer | no |
user.posix2_c_bind | integer | no |
user.posix2_c_dev | integer | no |
user.posix2_char_term | integer | no |
user.posix2_fort_dev | integer | no |
user.posix2_fort_run | integer | no |
user.posix2_localedef | integer | no |
user.posix2_sw_dev | integer | no |
user.posix2_upe | integer | no |
user.posix2_version | integer | no |
user.re_dup_max | integer | no |
user.stream_max | integer | no |
user.stream_max | integer | no |
user.tzname_max | integer | no |
user.atexit_max
(USER_ATEXIT_MAX
)- The maximum number of functions that may be registered with atexit(3).
user.bc_base_max
(USER_BC_BASE_MAX
)- The maximum ibase/obase values in the bc(1) utility.
user.bc_dim_max
(USER_BC_DIM_MAX
)- The maximum array size in the bc(1) utility.
user.bc_scale_max
(USER_BC_SCALE_MAX
)- The maximum scale value in the bc(1) utility.
user.bc_string_max
(USER_BC_STRING_MAX
)- The maximum string length in the bc(1) utility.
user.coll_weights_max
(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.
user.cs_path
(USER_CS_PATH
)- Return a value for the
PATH
environment variable that finds all the standard utilities. user.expr_nest_max
(USER_EXPR_NEST_MAX
)- The maximum number of expressions that can be nested within parenthesis by the expr(1) utility.
user.line_max
(USER_LINE_MAX
)- The maximum length in bytes of a text-processing utility's input line.
user.posix2_char_term
(USER_POSIX2_CHAR_TERM
)- Return 1 if the system supports at least one terminal type capable of all operations described in IEEE Std 1003.2 (“POSIX.2”), otherwise 0.
user.posix2_c_bind
(USER_POSIX2_C_BIND
)- Return 1 if the system's C-language development facilities support the C-Language Bindings Option, otherwise 0.
user.posix2_c_dev
(USER_POSIX2_C_DEV
)- Return 1 if the system supports the C-Language Development Utilities Option, otherwise 0.
user.posix2_fort_dev
(USER_POSIX2_FORT_DEV
)- Return 1 if the system supports the FORTRAN Development Utilities Option, otherwise 0.
user.posix2_fort_run
(USER_POSIX2_FORT_RUN
)- Return 1 if the system supports the FORTRAN Runtime Utilities Option, otherwise 0.
user.posix2_localedef
(USER_POSIX2_LOCALEDEF
)- Return 1 if the system supports the creation of locales, otherwise 0.
user.posix2_sw_dev
(USER_POSIX2_SW_DEV
)- Return 1 if the system supports the Software Development Utilities Option, otherwise 0.
user.posix2_upe
(USER_POSIX2_UPE
)- Return 1 if the system supports the User Portability Utilities Option, otherwise 0.
user.posix2_version
(USER_POSIX2_VERSION
)- The version of IEEE Std 1003.2 (“POSIX.2”) with which the system attempts to comply.
user.re_dup_max
(USER_RE_DUP_MAX
)- The maximum number of repeated occurrences of a regular expression permitted when using interval notation.
user.stream_max
(USER_STREAM_MAX
)- The minimum maximum number of streams that a process may have open at any one time.
user.tzname_max
(USER_TZNAME_MAX
)- The minimum maximum number of types supported for the name of a timezone.
The
vm.* subtree (CTL_VM
)
The string and integer information available for the
vm
level is detailed below. The changeable column
shows whether a process with appropriate privilege may change the value.
Second level name | Type | Changeable |
vm.anonmax | int | yes |
vm.anonmin | int | yes |
vm.bufcache | int | yes |
vm.bufmem | int | no |
vm.bufmem_hiwater | int | yes |
vm.bufmem_lowater | int | yes |
vm.execmax | int | yes |
vm.execmin | int | yes |
vm.filemax | int | yes |
vm.filemin | int | yes |
vm.loadavg | struct loadavg | no |
vm.maxslp | int | no |
vm.nkmempages | int | no |
vm.uspace | int | no |
vm.uvmexp | struct uvmexp | no |
vm.uvmexp2 | struct uvmexp_sysctl | no |
vm.vmmeter | struct vmtotal | no |
vm.proc.map | struct kinfo_vmentry | no |
vm.guard_size | unsigned int | no |
vm.thread_guard_size | unsigned int | yes |
vm.anonmax
(VM_ANONMAX
)- The percentage of physical memory which will be reclaimed from other types of memory usage to store anonymous application data.
vm.anonmin
(VM_ANONMIN
)- The percentage of physical memory which will be always be available for anonymous application data.
vm.bufcache
(VM_BUFCACHE
)- The percentage of physical memory which will be available for the buffer cache.
vm.bufmem
(VM_BUFMEM
)- The amount of kernel memory that is being used by the buffer cache.
vm.bufmem_lowater
(VM_BUFMEM_LOWATER
)- The minimum amount of kernel memory to reserve for the buffer cache.
vm.bufmem_hiwater
(VM_BUFMEM_HIWATER
)- The maximum amount of kernel memory to be used for the buffer cache.
vm.execmax
(VM_EXECMAX
)- The percentage of physical memory which will be reclaimed from other types of memory usage to store cached executable data.
vm.execmin
(VM_EXECMIN
)- The percentage of physical memory which will be always be available for cached executable data.
vm.filemax
(VM_FILEMAX
)- The percentage of physical memory which will be reclaimed from other types of memory usage to store cached file data.
vm.filemin
(VM_FILEMIN
)- The percentage of physical memory which will be always be available for cached file data.
vm.loadavg
(VM_LOADAVG
)- Return the load average history. The returned data consists of a struct loadavg.
vm.maxslp
(VM_MAXSLP
)- The value of the maxslp kernel global variable.
vm.vmmeter
(VM_METER
)- Return system wide virtual memory statistics. The returned data consists of a struct vmtotal.
- vm.user_va0_disable
- A flag which controls whether user processes can map virtual address 0.
vm.proc.map
(VM_PROC
)- The third level is
VM_PROC_MAP
, the fourth is the pid of the process to display the vm object entries for, and the fifth is the size of struct kinfo_vmentry. Returns an array of struct kinfo_vmentry objects. vm.uspace
(VM_USPACE
)- The number of bytes allocated for each kernel stack.
vm.uvmexp
(VM_UVMEXP
)- Return system wide virtual memory statistics. The returned data consists of a struct uvmexp.
vm.uvmexp2
(VM_UVMEXP2
)- Return system wide virtual memory statistics. The returned data consists of a struct uvmexp_sysctl.
vm.guard_size
- Return system wide guard size for the main thread of a program.
vm.thread_guard_size
- Return system wide default size for the guard area of all other threads of a program.
The
ddb.* subtree (CTL_DDB
)
The information available for the ddb
level is detailed below. The changeable column shows whether a process with
appropriate privilege may change the value.
Second level name | Type | Changeable |
ddb.commandonenter | string | yes |
ddb.dumpstack | integer | yes |
ddb.fromconsole | integer | yes |
ddb.lines | integer | yes |
ddb.maxoff | integer | yes |
ddb.maxwidth | integer | yes |
ddb.onpanic | integer | yes |
ddb.panicstackframes | integer | yes |
ddb.radix | integer | yes |
ddb.tabstops | integer | yes |
ddb.tee_msgbuf | integer | yes |
ddb.commandonenter
- If not empty, the string is used as the DDB command to be executed each time DDB is entered.
ddb.dumpstack
- A value of 1 causes a stack trace to be printed on entering ddb from a panic. A value of 0 disables this behaviour. The default value is 1.
ddb.fromconsole
(DDBCTL_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.
ddb.lines
(DDBCTL_LINES
)- Number of display lines.
ddb.maxoff
(DDBCTL_MAXOFF
)- The maximum symbol offset.
ddb.maxwidth
(DDBCTL_MAXWIDTH
)- The maximum output line width.
ddb.onpanic
(DDBCTL_ONPANIC
)- If greater than zero, DDB will be entered if the kernel panics. A value of 1 causes the system to enter DDB on panic. A value of 0 causes the kernel to attempt to print a stack trace, then reboot, while a value of -1 means neither a stack trace will be printed nor DDB entered.
ddb.panicstackframes
- Number of stack frames to display on panic. Useful to avoid scrolling away
the interesting frames on a glass tty. Default value is
65535
(all frames), useful value around10
. ddb.radix
(DDBCTL_RADIX
)- The input and output radix.
ddb.tabstops
(DDBCTL_TABSTOPS
)- Tab width.
ddb.tee_msgbuf
- If not zero, DDB will output also to the kernel message buffer.
Some of these MIB nodes are also available as variables from within the debugger. See ddb(4) for more details.
The
security.* subtree (CTL_SECURITY
)
The security
level contains various
security-related settings for the system. The available second level names
are:
Second level name | Type | Changeable |
security.curtain |
integer | yes |
security.models |
node | not applicable |
security.pax |
node | not applicable |
Available settings are detailed below.
security.curtain
- If non-zero, will filter return objects according to the user ID
requesting information about them, preventing users from accessing any
objects they do not own.
At the moment, it affects ps(1), netstat(1) (for
PF_INET
,PF_INET6
, andPF_UNIX
PCBs), and w(1). security.models
- NetBSD supports pluggable security models. Every
security model used, whether if loaded as a module or built with the
system, is required to add an entry to this node with at least one
element, “name”, indicating the name of the security model.
In addition to the name, any settings and other information private to the security model will be available under this node. See secmodel(9) for more information.
security.pax
- Settings for PaX — exploit mitigation features. For more
information on any of the PaX features, please see
paxctl(8) and
security(7). The available third and fourth level names are:
Third and fourth level names Type Changeable security.pax.aslr.enabled
integer yes security.pax.aslr.global
integer yes security.pax.mprotect.enabled
integer yes security.pax.mprotect.global
integer yes security.pax.mprotect.ptrace
integer yes security.pax.segvguard.enabled
integer yes security.pax.segvguard.expiry_timeout
integer yes security.pax.segvguard.global
integer yes security.pax.segvguard.max_crashes
integer yes security.pax.segvguard.suspend_timeout
integer yes security.pax.aslr.enabled
- Enable PaX ASLR (Address Space Layout Randomization).
The value of this knob must be non-zero for PaX ASLR to be enabled, even if a program is set to explicit enable.
security.pax.aslr.global
- Specifies the default global policy for programs without an explicit
enable/disable flag.
When non-zero, all programs will get PaX ASLR, except those exempted with paxctl(8). Otherwise, all programs will not get PaX ASLR, except those specifically marked as such with paxctl(8).
security.pax.mprotect.enabled
- Enable PaX MPROTECT restrictions.
These are 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 program is set to explicit enable.
security.pax.mprotect.global
- Specifies the default global policy for programs without an explicit
enable/disable flag.
When non-zero, all programs will get the PaX MPROTECT restrictions, except those exempted with paxctl(8). Otherwise, all programs will not get the PaX MPROTECT restrictions, except those specifically marked as such with paxctl(8).
security.pax.mprotect.ptrace
- This variable allows
ptrace(2) to override PaX MPROTECT permissions. It can have the
following values:
- 0
- Does not let override any permissions.
- 1
- Disables PaX MPROTECT from processes that start executing while traced (default).
- 2
- Bypasses PaX MPROTECT for all processes being traced.
security.pax.segvguard.enabled
- Enable PaX Segvguard.
PaX Segvguard can detect and prevent certain exploitation attempts, where an attacker may try for example to brute-force function return addresses of respawning daemons.
Note: The NetBSD interface and implementation of the Segvguard is still experimental, and may change in future releases.
security.pax.segvguard.expiry_timeout
- If the max number was not reached within this timeout (in seconds), the entry will expire.
security.pax.segvguard.global
- Specifies the default global policy for programs without an explicit
enable/disable flag.
When non-zero, all programs will get the PaX Segvguard, except those exempted with paxctl(8). Otherwise, no program will get the PaX Segvguard restrictions, except those specifically marked as such with paxctl(8).
security.pax.segvguard.max_crashes
- The maximum number of segfaults a program can receive before suspension.
security.pax.segvguard.suspend_timeout
- Number of seconds to suspend a user from running a faulting program when the limit was exceeded.
The
vendor.* subtree (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 “vendor.<yourname>.*”.
SEE ALSO
HISTORY
The sysctl
variables first appeared in
4.4BSD.