usr.bin/netstat/netstat.1

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.\"	@(#)netstat.1	8.8 (Berkeley) 4/18/94
.\" $FreeBSD$
.\"
.Dd January 11, 2014
.Dt NETSTAT 1
.Os
.Sh NAME
.Nm netstat
.Nd show network status
.Sh DESCRIPTION
The
.Nm
command symbolically displays the contents of various network-related
data structures.
There are a number of output formats,
depending on the options for the information presented.
.Bl -tag -width indent
.It Xo
.Bk -words
.Nm
.Op Fl 46AaLnSTWx
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Display a list of active sockets
(protocol control blocks)
for each network protocol,
for a particular
.Ar protocol_family ,
or for a single
.Ar protocol .
If
.Fl A
is also present,
show the address of a protocol control block (PCB)
associated with a socket; used for debugging.
If
.Fl a
is also present,
show the state of all sockets;
normally sockets used by server processes are not shown.
If
.Fl L
is also present,
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.
If
.Fl S
is also present,
show network addresses as numbers (as with
.Fl n )
but show ports symbolically.
If
.Fl x
is present, display socket buffer and tcp timer statistics for each internet socket.
When
.Fl T
is present, display information from the TCP control block, including
retransmits, out-of-order packets received, and zero-sized windows advertised.
.It Xo
.Bk -words
.Nm
.Fl i | I Ar interface
.Op Fl 46abdhnW
.Op Fl f Ar address_family
.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 .
If
.Fl a
is also present, 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.
If
.Fl b
is also present, show the number of bytes in and out.
If
.Fl d
is also present, show the number of dropped packets.
If
.Fl h
is also present, print all counters in human readable form.
If
.Fl W
is also present, print interface names using a wider field size.
.It Xo
.Bk -words
.Nm
.Fl w Ar wait
.Op Fl I Ar interface
.Op Fl d
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl q Ar howmany
.Ek
.Xc
At intervals of
.Ar wait
seconds,
display the information regarding packet
traffic on all configured network interfaces
or a single
.Ar interface .
If
.Fl q
is also present, exit after
.Ar howmany
outputs.
If
.Fl d
is also present, show the number of dropped packets.
.It Xo
.Bk -words
.Nm
.Fl s Op Fl s
.Op Fl 46z
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Display system-wide statistics for each network protocol,
for a particular
.Ar protocol_family ,
or for a single
.Ar protocol .
If
.Fl s
is repeated, counters with a value of zero are suppressed.
If
.Fl z
is also present, reset statistic counters after displaying them.
.It Xo
.Bk -words
.Nm
.Fl i | I Ar interface Fl s
.Op Fl 46
.Op Fl f Ar protocol_family | Fl p Ar protocol
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Display per-interface statistics for each network protocol,
for a particular
.Ar protocol_family ,
or for a single
.Ar protocol .
.It Xo
.Bk -words
.Nm
.Fl m
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Show statistics recorded by the memory management routines
.Pq Xr mbuf 9 .
The network manages a private pool of memory buffers.
.It Xo
.Bk -words
.Nm
.Fl B
.Op Fl z
.Op Fl I Ar interface
.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.
.It Xo
.Bk -words
.Nm
.Fl r
.Op Fl 46AanW
.Op Fl F Ar fibnum
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Display the contents of routing tables.
When
.Fl f
is specified, a routing table for a particular
.Ar address_family
is displayed.
When
.Fl F
is specified, a routing table with the number
.Ar fibnum
is displayed.
If the specified
.Ar fibnum
is -1 or
.Fl F
is not specified,
the default routing table is displayed.
If
.Fl A
is also present,
show the contents of the internal Patricia tree
structures; used for debugging.
When
.Fl W
is also present,
show the path MTU
for each route,
and print interface
names with a wider
field size.
.It Xo
.Bk -words
.Nm
.Fl rs
.Op Fl s
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Display routing statistics.
If
.Fl s
is repeated, counters with a value of zero are suppressed.
.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
.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.
.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
.Ek
.Xc
Show multicast routing statistics.
If
.Fl s
is repeated, counters with a value of zero are suppressed.
.It Xo
.Bk -words
.Nm
.Fl Q
.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"
.El
.El
.Pp
Some options have the general meaning:
.Bl -tag -width flag
.It Fl 4
Is shorthand for
.Fl f
.Ar inet
.It Fl 6
Is shorthand for
.Fl f
.Ar inet6
.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 , 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
In certain displays, avoid truncating addresses even if this causes
some fields to overflow.
.El
.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 * .
.Pp
The interface display 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.
.Pp
The routing table display indicates 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.
.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
option.
.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 .
.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-MBUF"
.It Li R-MBUF Ta Number of mbufs in the receive queue.
.It Li S-MBUF Ta Number of mbufs in the send queue.
.It Li R-CLUS Ta Number of clusters, of any type, in the receive
queue.
.It Li S-CLUS Ta Number of clusters, of any type, in the send queue.
.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.
.El
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr nfsstat 1 ,
.Xr procstat 1 ,
.Xr ps 1 ,
.Xr sockstat 1 ,
.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 trpt 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.