usr.bin/netstat/netstat.1

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.\"	@(#)netstat.1	8.8 (Berkeley) 4/18/94
.\" $FreeBSD: src/usr.bin/netstat/netstat.1,v 1.22.2.13 2003/05/03 22:10:02 keramida Exp $
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.Dd April 21, 2018
.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 AaLlnPSW
.Op Fl c Ar cpu
.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.
.It Xo
.Bk -words
.Nm
.Fl i | I Ar interface
.Op Fl aBbdhnt
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.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 t
is also present, show the contents of watchdog timers.
If
.Fl B
is also present, the maximum buffer sizes are displayed instead
of current buffer usage.
.It Xo
.Bk -words
.Nm
.Fl w Ar wait
.Op Fl I Ar interface
.Op Fl dh
.Op Fl M Ar core
.Op Fl N Ar system
.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 d
is also present, show the number of dropped packets.
If
.Fl h
is also present, print counters in human readable form.
.It Xo
.Bk -words
.Nm
.Fl s Op Fl s
.Op Fl z
.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 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 r
.Op Fl AalnW
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Display the contents of all routing tables,
or a routing table for a particular
.Ar address_family .
If
.Fl A
is also present,
show the contents of the internal Patricia tree
structures; used for debugging.
If
.Fl a
is also present,
show protocol-cloned routes
(routes generated by an
.Dv RTF_PRCLONING
parent route);
normally these routes are not shown.
When
.Fl W
or
.Fl l
is also present,
show the path MTU,
MSL,
initial window size
and MPLS label operations
for each route.
.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 lW
.Op Fl f Ar address_family
.Op Fl M Ar core
.Op Fl N Ar system
.Ek
.Xc
Show information related to multicast (group address) routing.
By default, show the IP Multicast virtual-interface and routing tables.
.It Xo
.Bk -words
.Nm
.Fl gs
.Op Fl s
.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.
.El
.Pp
Some options have the general meaning:
.Bl -tag -width flag
.It Fl c Ar cpu
On SMP systems the route table is replicated.  This option allows
the route table for a specific cpu to be accessed and exists
primarily for debugging purposes.
.It Fl f Ar address_family , Fl f Ar protocol_family , Fl p Ar protocol
Limit display to those records
of the specified
.Ar address_family ,
.Ar protocol_family
or a single
.Ar protocol .
The following address families, protocol 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 PF_INET
.Cm carp , divert , icmp , igmp , ip , pim , tcp , udp
.It Cm inet6 Pq Dv AF_INET6 PF_INET6
.Cm carp , icmp6 , ip6 , rip6 , tcp , udp
.It Cm netgraph , ng Pq Dv AF_NETGRAPH PF_NETGRAPH
.Cm ctrl , data
.It Cm unix Pq Dv AF_UNIX PF_UNIX
.It Cm link Pq Dv AF_LINK PF_LINK
.It Cm mpls Pq Dv AF_MPLS PF_MPLS
.El
.Pp
The program will complain if
.Ar protocol
is unknown or if there is no statistics routine for it.
.It Fl l
The
.Fl l
option is equivalent to
.Fl W .
.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 P
Display additional protocol-specific information.  For TCP the current
transmit window, unacked sequence space, and RTT is displayed.
.It Fl W
Wide display.
In certain displays, add columns and 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 C Ta Dv RTF_CLONING Ta "Generate new routes on use"
.It Li c Ta Dv RTF_PRCLONING Ta "Protocol-specified generate new routes on use"
.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 m Ta Dv RTF_MPLSOPS Ta "MPLS label operations"
.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 W Ta Dv RTF_WASCLONED Ta "Route was generated as a result of cloning"
.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.
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr nfsstat 1 ,
.Xr ps 1 ,
.Xr sockstat 1 ,
.Xr carp 4 ,
.Xr inet 4 ,
.Xr inet6 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.