usr.bin/netstat/netstat.1

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.Dd August 14, 2023
.Dt NETSTAT 1
.Os
.Sh NAME
.Nm netstat
.Nd show network status and statistics
.Sh SYNOPSIS
.Bk -words
.Bl -tag -width "netstat"
.It Nm
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46AaCLnPRSTWx
.Op Fl f Ar protocol_family | Fl p Ar protocol
.It Nm Fl i | I Ar interface
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46abdhnW
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.It Nm Fl w Ar wait
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl I Ar interface
.Op Fl 46d
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl q Ar howmany
.It Nm Fl s
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46sz
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.It Nm Fl i | I Ar interface Fl s
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46s
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.It Nm Fl m
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl M Ar core
.Op Fl N Ar system
.It Nm Fl B
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl z
.Op Fl I Ar interface
.It Nm Fl r
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46nW
.Op Fl F Ar fibnum
.Op Fl f Ar address_family
.It Nm Fl rs
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl s
.Op Fl M Ar core
.Op Fl N Ar system
.It Nm Fl g
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46W
.Op Fl f Ar address_family
.It Nm Fl gs
.Op Fl j Ar jail
.Op Fl -libxo
.Op Fl 46s
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.It Nm Fl Q
.Op Fl j Ar jail
.Op Fl -libxo
.El
.Ek
.Sh DESCRIPTION
The
.Nm
command shows the contents of various network-related
data structures.
The arguments passed determine which of the below output formats the
command uses.
.Bl -tag -width indent
.It Xo
.Bk -words
.Nm
.Op Fl 46AaCLnRSTWx
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl j Ar jail
.Ek
.Xc
Display a list of active sockets
(protocol control blocks)
for each network protocol.
.Pp
The default display for active sockets shows the local
and remote addresses, send and receive queue sizes (in bytes), protocol,
and the internal state of the protocol.
Address formats are of the form
.Dq host.port
or
.Dq network.port
if a socket's address specifies a network but no specific host address.
When known, the host and network addresses are displayed symbolically
according to the databases
.Xr hosts 5
and
.Xr networks 5 ,
respectively.
If a symbolic name for an address is unknown, or if
the
.Fl n
option is specified, the address is printed numerically, according
to the address family.
For more information regarding
the Internet IPv4
.Dq dot format ,
refer to
.Xr inet 3 .
Unspecified,
or
.Dq wildcard ,
addresses and ports appear as
.Dq Li * .
.Bl -tag -width indent
.It Fl -libxo
Generate output via
.Xr libxo 3
in a selection of different human and machine readable formats.
See
.Xr xo_parse_args 3
for details on command line arguments.
.It Fl 4
Show IPv4 only.
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only.
See
.Sx GENERAL OPTIONS .
.It Fl A
Show the address of a protocol control block (PCB)
associated with a socket; used for debugging.
.It Fl a
Show the state of all sockets;
normally sockets used by server processes are not shown.
.It Fl c
Show the used TCP stack for each session.
.It Fl C
Show the congestion control algorithm and diagnostic information of TCP sockets.
.It Fl L
Show the size of the various listen queues.
The first count shows the number of unaccepted connections,
the second count shows the amount of unaccepted incomplete connections,
and the third count is the maximum number of queued connections.
.It Fl n
Do not resolve numeric addresses and port numbers to names.
See
.Sx GENERAL OPTIONS .
.It Fl P
Display the log ID for each socket.
.It Fl R
Display the flowid and flowtype for each socket.
flowid is a 32 bit hardware specific identifier for each flow.
flowtype defines which protocol fields are hashed to produce the id.
A complete listing is available in
.Pa sys/mbuf.h
under
.Dv M_HASHTYPE_* .
.It Fl S
Show network addresses as numbers (as with
.Fl n )
but show ports symbolically.
.It Fl T
Display diagnostic information from the TCP control block.
Fields include the number of packets requiring retransmission,
received out-of-order, and those advertising a zero-sized window.
.It Fl W
Avoid truncating addresses even if this causes some fields to overflow.
.It Fl x
Display socket buffer and TCP timer statistics for each
internet socket.
.Pp
The
.Fl x
flag causes
.Nm
to output all the information recorded about data
stored in the socket buffers.
The fields are:
.Bl -column ".Li R-HIWA"
.It Li R-HIWA Ta Receive buffer high water mark, in bytes.
.It Li S-HIWA Ta Send buffer high water mark, in bytes.
.It Li R-LOWA Ta Receive buffer low water mark, in bytes.
.It Li S-LOWA Ta Send buffer low water mark, in bytes.
.It Li R-BCNT Ta Receive buffer byte count.
.It Li S-BCNT Ta Send buffer byte count.
.It Li R-BMAX Ta Maximum bytes that can be used in the receive buffer.
.It Li S-BMAX Ta Maximum bytes that can be used in the send buffer.
.It Li rexmt Ta Time, in seconds, to fire Retransmit Timer, or 0 if not armed.
.It Li persist Ta Time, in seconds, to fire Retransmit Persistence, or 0 if not armed.
.It Li keep Ta Time, in seconds, to fire Keep Alive, or 0 if not armed.
.It Li 2msl Ta Time, in seconds, to fire 2*msl TIME_WAIT Timer, or 0 if not armed.
.It Li delack Ta Time, in seconds, to fire Delayed ACK Timer, or 0 if not armed.
.It Li rcvtime Ta Time, in seconds, since last packet received.
.El
.It Fl f Ar protocol_family
Filter by
.Ar protocol_family .
See
.Sx GENERAL OPTIONS .
.It Fl p Ar protocol
Filter by
.Ar protocol .
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl i | I Ar interface
.Op Fl 46abdhnW
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Show the state of all network interfaces or a single
.Ar interface
which have been auto-configured
(interfaces statically configured into a system, but not
located at boot time are not shown).
An asterisk
.Pq Dq Li *
after an interface name indicates that the interface is
.Dq down .
.Pp
When
.Nm
is invoked with
.Fl i
.Pq all interfaces
or
.Fl I Ar interface ,
it provides a table of cumulative
statistics regarding packets transferred, errors, and collisions.
The network addresses of the interface
and the maximum transmission unit
.Pq Dq mtu
are also displayed.
If both
.Fl i
and
.Fl I
are specified,
.Fl I
overrides any instances of
.Fl i .
.Bl -tag -width indent
.It Fl 4
Show IPv4 only.
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only.
See
.Sx GENERAL OPTIONS .
.It Fl a
Multicast addresses currently in use are shown
for each Ethernet interface and for each IP interface address.
Multicast addresses are shown on separate lines following the interface
address with which they are associated.
.It Fl b
Show the number of bytes in and out.
.It Fl d
Show the number of dropped packets.
.It Fl h
Print all counters in human readable form.
.It Fl n
Do not resolve numeric addresses and port numbers to names.
See
.Sx GENERAL OPTIONS .
.It Fl W
Avoid truncating addresses even if this causes some fields to overflow.
See
.Sx GENERAL OPTIONS .
However, in most cases field widths are determined automatically with the
.Fl i
option, and this option has little effect.
.It Fl f Ar protocol_family
Filter by
.Ar protocol_family .
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl w Ar wait
.Op Fl I Ar interface
.Op Fl 46d
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl q Ar howmany
.Op Fl j Ar jail
.Ek
.Xc
At intervals of
.Ar wait
seconds, display the information regarding packet traffic on all
configured network interfaces or a single
.Ar interface .
.Pp
When
.Nm
is invoked with the
.Fl w
option and a
.Ar wait
interval argument, it displays a running count of statistics related to
network interfaces.
An obsolescent version of this option used a numeric parameter
with no option, and is currently supported for backward compatibility.
By default, this display summarizes information for all interfaces.
Information for a specific interface may be displayed with the
.Fl I Ar interface
option.
.Bl -tag -width indent
.It Fl I Ar interface
Only show information regarding
.Ar interface
.It Fl 4
Show IPv4 only.
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only.
See
.Sx GENERAL OPTIONS .
.It Fl d
Show the number of dropped packets.
.It Fl M
Use an alternative core.
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image.
See
.Sx GENERAL OPTIONS .
.It Fl q
Exit after
.Ar howmany
outputs.
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl s
.Op Fl 46sz
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Display system-wide statistics for each network protocol.
.Bl -tag -width indent
.It Fl 4
Show IPv4 only.
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only.
See
.Sx GENERAL OPTIONS .
.It Fl s
If
.Fl s
is repeated, counters with a value of zero are suppressed.
.It Fl z
Reset statistic counters after displaying them.
.It Fl f Ar protocol_family
Filter by
.Ar protocol_family .
See
.Sx GENERAL OPTIONS .
.It Fl p Ar protocol
Filter by
.Ar protocol .
See
.Sx GENERAL OPTIONS .
.It Fl M
Use an alternative core.
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl i | I Ar interface Fl s
.Op Fl 46s
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Display per-interface statistics for each network protocol.
If both
.Fl i
and
.Fl I
are specified,
.Fl I
overrides any instances of
.Fl i .
.Bl -tag -width indent
.It Fl 4
Show IPv4 only
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only
See
.Sx GENERAL OPTIONS .
.It Fl s
If
.Fl s
is repeated, counters with a value of zero are suppressed.
.It Fl f Ar protocol_family
Filter by
.Ar protocol_family .
See
.Sx GENERAL OPTIONS .
.It Fl p Ar protocol
Filter by
.Ar protocol .
See
.Sx GENERAL OPTIONS .
.It Fl M
Use an alternative core
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl m
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Show statistics recorded by the memory management routines
.Pq Xr mbuf 9 .
The network manages a private pool of memory buffers.
.Bl -tag -width indent
.It Fl M
Use an alternative core
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl B
.Op Fl z
.Op Fl I Ar interface
.Op Fl j Ar jail
.Ek
.Xc
Show statistics about
.Xr bpf 4
peers.
This includes information like
how many packets have been matched, dropped and received by the
bpf device, also information about current buffer sizes and device
states.
.Pp
The
.Xr bpf 4
flags displayed when
.Nm
is invoked with the
.Fl B
option represent the underlying parameters of the bpf peer.
Each flag is
represented as a single lower case letter.
The mapping between the letters and flags in order of appearance are:
.Bl -column ".Li i"
.It Li p Ta Set if listening promiscuously
.It Li i Ta Dv BIOCIMMEDIATE No has been set on the device
.It Li f Ta Dv BIOCGHDRCMPLT No status: source link addresses are being
filled automatically
.It Li s Ta Dv BIOCGSEESENT No status: see packets originating locally and
remotely on the interface.
.It Li a Ta Packet reception generates a signal
.It Li l Ta Dv BIOCLOCK No status: descriptor has been locked
.El
.Pp
For more information about these flags, please refer to
.Xr bpf 4 .
.Bl -tag -width indent
.It Fl z
Reset statistic counters after displaying them.
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl r
.Op Fl 46AnW
.Op Fl F Ar fibnum
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Display the contents of routing tables.
.Pp
When
.Nm
is invoked with the routing table option
.Fl r ,
it lists the available routes and their status.
Each route consists of a destination host or network, and a gateway to use
in forwarding packets.
The flags field shows a collection of information about the route stored
as binary choices.
The individual flags are discussed in more detail in the
.Xr route 8
and
.Xr route 4
manual pages.
The mapping between letters and flags is:
.Bl -column ".Li W" ".Dv RTF_WASCLONED"
.It Li 1 Ta Dv RTF_PROTO1 Ta "Protocol specific routing flag #1"
.It Li 2 Ta Dv RTF_PROTO2 Ta "Protocol specific routing flag #2"
.It Li 3 Ta Dv RTF_PROTO3 Ta "Protocol specific routing flag #3"
.It Li B Ta Dv RTF_BLACKHOLE Ta "Just discard pkts (during updates)"
.It Li b Ta Dv RTF_BROADCAST Ta "The route represents a broadcast address"
.It Li D Ta Dv RTF_DYNAMIC Ta "Created dynamically (by redirect)"
.It Li G Ta Dv RTF_GATEWAY Ta "Destination requires forwarding by intermediary"
.It Li H Ta Dv RTF_HOST Ta "Host entry (net otherwise)"
.It Li L Ta Dv RTF_LLINFO Ta "Valid protocol to link address translation"
.It Li M Ta Dv RTF_MODIFIED Ta "Modified dynamically (by redirect)"
.It Li R Ta Dv RTF_REJECT Ta "Host or net unreachable"
.It Li S Ta Dv RTF_STATIC Ta "Manually added"
.It Li U Ta Dv RTF_UP Ta "Route usable"
.It Li X Ta Dv RTF_XRESOLVE Ta "External daemon translates proto to link address"
.El
.Pp
Direct routes are created for each
interface attached to the local host;
the gateway field for such entries shows the address of the outgoing interface.
The refcnt field gives the
current number of active uses of the route.
Connection oriented
protocols normally hold on to a single route for the duration of
a connection while connectionless protocols obtain a route while sending
to the same destination.
The use field provides a count of the number of packets
sent using that route.
The interface entry indicates the network interface utilized for the route.
.Bl -tag -width indent
.It Fl 4
Show IPv4 only.
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only.
See
.Sx GENERAL OPTIONS .
.It Fl n
Do not resolve numeric addresses and port numbers to names.
See
.Sx GENERAL OPTIONS .
.It Fl W
Show the path MTU for each route, and print interface names with a
wider field size.
.It Fl F
Display the routing table with the number
.Ar fibnum .
If the specified
.Ar fibnum
is -1 or
.Fl F
is not specified,
the default routing table is displayed.
.It Fl f
Display the routing table for a particular
.Ar address_family .
.It Fl M
Use an alternative core
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl rs
.Op Fl s
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Display routing statistics.
.Bl -tag -width indent
.It Fl s
If
.Fl s
is repeated, counters with a value of zero are suppressed.
.It Fl M
Use an alternative core
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl g
.Op Fl 46W
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Display the contents of the multicast virtual interface tables,
and multicast forwarding caches.
Entries in these tables will appear only when the kernel is
actively forwarding multicast sessions.
This option is applicable only to the
.Cm inet
and
.Cm inet6
address families.
.Bl -tag -width indent
.It Fl 4
Show IPv4 only
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only
See
.Sx GENERAL OPTIONS .
.It Fl W
Avoid truncating addresses even if this causes some fields to overflow.
.It Fl f Ar protocol_family
Filter by
.Ar protocol_family .
See
.Sx GENERAL OPTIONS .
.It Fl M
Use an alternative core
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl gs
.Op Fl 46s
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl j Ar jail
.Ek
.Xc
Show multicast routing statistics.
.Bl -tag -width indent
.It Fl 4
Show IPv4 only
See
.Sx GENERAL OPTIONS .
.It Fl 6
Show IPv6 only
See
.Sx GENERAL OPTIONS .
.It Fl s
If
.Fl s
is repeated, counters with a value of zero are suppressed.
.It Fl f Ar protocol_family
Filter by
.Ar protocol_family .
See
.Sx GENERAL OPTIONS .
.It Fl M
Use an alternative core
See
.Sx GENERAL OPTIONS .
.It Fl N
Use an alternative kernel image
See
.Sx GENERAL OPTIONS .
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.It Xo
.Bk -words
.Nm
.Fl Q
.Op Fl j Ar jail
.Ek
.Xc
Show
.Xr netisr 9
statistics.
The flags field shows available ISR handlers:
.Bl -column ".Li W" ".Dv NETISR_SNP_FLAGS_DRAINEDCPU"
.It Li C Ta Dv NETISR_SNP_FLAGS_M2CPUID Ta "Able to map mbuf to cpu id"
.It Li D Ta Dv NETISR_SNP_FLAGS_DRAINEDCPU  Ta "Has queue drain handler"
.It Li F Ta Dv NETISR_SNP_FLAGS_M2FLOW Ta "Able to map mbuf to flow id"
.It Fl j Ar jail
Run inside a jail.
See
.Sx GENERAL OPTIONS .
.El
.El
.Ss GENERAL OPTIONS
Some options have the general meaning:
.Bl -tag -width flag
.It Fl 4
Is shorthand for
.Fl f
.Ar inet
.Pq Show only IPv4
.It Fl 6
Is shorthand for
.Fl f
.Ar inet6
.Pq Show only IPv6
.It Fl f Ar address_family , Fl p Ar protocol
Limit display to those records
of the specified
.Ar address_family
or a single
.Ar protocol .
The following address families and protocols are recognized:
.Pp
.Bl -tag -width ".Cm netgraph , ng Pq Dv AF_NETGRAPH" -compact
.It Em Family
.Em Protocols
.It Cm inet Pq Dv AF_INET
.Cm divert , icmp , igmp , ip , ipsec , pim, sctp , tcp , udp
.It Cm inet6 Pq Dv AF_INET6
.Cm icmp6 , ip6 , ipsec6 , rip6 , sctp , tcp , udp
.It Cm pfkey Pq Dv PF_KEY
.Cm pfkey
.It Cm netgraph , ng Pq Dv AF_NETGRAPH
.Cm ctrl , data
.It Cm unix Pq Dv AF_UNIX
.It Cm link Pq Dv AF_LINK
.El
.Pp
The program will complain if
.Ar protocol
is unknown or if there is no statistics routine for it.
.It Fl M
Extract values associated with the name list from the specified core
instead of the default
.Pa /dev/kmem .
.It Fl N
Extract the name list from the specified system instead of the default,
which is the kernel image the system has booted from.
.It Fl n
Show network addresses and ports as numbers.
Normally
.Nm
attempts to resolve addresses and ports,
and display them symbolically.
.It Fl W
Wider output; expand address fields, etc, to avoid truncation.
Non-numeric values such as domain names may still be truncated; use the
.Fl n
option if necessary to avoid ambiguity.
.It Fl j Ar jail
Perform the actions inside the
.Ar jail .
This allows network state to be accessed even if the
.Cm netstat
binary is not available in the
.Ar jail .
.El
.Sh EXAMPLES
Show packet traffic information (packets, bytes, errors, packet drops, etc) for
interface re0 updated every 2 seconds and exit after 5 outputs:
.Bd -literal -offset indent
$ netstat -w 2 -q 5 -I re0
.Ed
.Pp
Show statistics for ICMP on any interface:
.Bd -literal -offset indent
$ netstat -s -p icmp
.Ed
.Pp
Show routing tables:
.Bd -literal -offset indent
$ netstat -r
.Ed
.Pp
Same as above, but without resolving numeric addresses and port numbers to
names:
.Bd -literal -offset indent
$ netstat -rn
.Ed
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr nfsstat 1 ,
.Xr procstat 1 ,
.Xr ps 1 ,
.Xr sockstat 1 ,
.Xr libxo 3 ,
.Xr xo_parse_args 3 ,
.Xr bpf 4 ,
.Xr inet 4 ,
.Xr route 4 ,
.Xr unix 4 ,
.Xr hosts 5 ,
.Xr networks 5 ,
.Xr protocols 5 ,
.Xr services 5 ,
.Xr iostat 8 ,
.Xr route 8 ,
.Xr vmstat 8 ,
.Xr mbuf 9
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.2 .
.Pp
IPv6 support was added by WIDE/KAME project.
.Sh BUGS
The notion of errors is ill-defined.