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NETSTAT(1)		  BSD General Commands Manual		    NETSTAT(1)

NAME
     netstat --	show network status

SYNOPSIS
     netstat [-Aan] [-f	address_family]	[-M core] [-N system]
     netstat [-bdghimnrs] [-f address_family] [-M core]	[-N system]
     netstat [-bdn] [-I	interface] [-M core] [-N system] [-w wait]
     netstat [-p protocol] [-M core] [-N system]

DESCRIPTION
     The netstat command symbolically displays the contents of various net-
     work-related data structures.  There are a	number of output formats, de-
     pending on	the options for	the information	presented.  The	first form of
     the command displays a list of active sockets for each protocol.  The
     second form presents the contents of one of the other network data	struc-
     tures according to	the option selected.  Using the	third form, with a
     wait interval specified, netstat will continuously	display	the informa-
     tion regarding packet traffic on the configured network interfaces.  The
     fourth form displays statistics about the named protocol.

     The options have the following meaning:

     -A	   With	the default display, show the address of any protocol control
	   blocks associated with sockets; used	for debugging.

     -a	   With	the default display, show the state of all sockets; normally
	   sockets used	by server processes are	not shown.

     -b	   With	the interface display (option -i , as described	below),	show
	   the number of bytes in and out.

     -d	   With	either interface display (option -i or an interval, as de-
	   scribed below), show	the number of dropped packets.

     -f	address_family
	   Limit statistics or address control block reports to	those of the
	   specified address family.  The following address families are rec-
	   ognized: inet, for AF_INET, ipx, for	AF_IPX,	atalk, for
	   AF_APPLETALK	(ddp), and unix, for AF_UNIX.

     -g	   Show	information related to multicast (group	address) routing.  By
	   default, show the IP	Multicast virtual-interface and	routing	ta-
	   bles.  If the -s option is also present, show multicast routing
	   statistics.

     -h	   Show	the state of the IMP host table	(obsolete).

     -I	interface
	   Show	information about the specified	interface; used	with a wait
	   interval as described below.

     -i	   Show	the state of interfaces	which have been	auto-configured	(in-
	   terfaces statically configured into a system, but not located at
	   boot	time are not shown).  If the -a	options	is also	present, mul-
	   ticast addresses currently in use are shown for each	Ethernet in-
	   terface and for each	IP interface address.  Multicast addresses are
	   shown on separate lines following the interface address with	which
	   they	are associated.

     -M	   Extract values associated with the name list	from the specified
	   core	instead	of the default /dev/kmem.

     -m	   Show	statistics recorded by the memory management routines (the
	   network manages a private pool of memory buffers).

     -N	   Extract the name list from the specified system instead of the de-
	   fault /kernel.

     -n	   Show	network	addresses as numbers (normally netstat interprets ad-
	   dresses and attempts	to display them	symbolically).	This option
	   may be used with any	of the display formats.

     -p	protocol
	   Show	statistics about protocol, which is either a well-known	name
	   for a protocol or an	alias for it.  Some protocol names and aliases
	   are listed in the file /etc/protocols.  The special protocol	name
	   ``bdg'' is used to show bridging statistics.	 A null	response typi-
	   cally means that there are no interesting numbers to	report.	 The
	   program will	complain if protocol is	unknown	or if there is no sta-
	   tistics routine for it.

     -s	   Show	per-protocol statistics.  If this option is repeated, counters
	   with	a value	of zero	are suppressed.

     -r	   Show	the routing tables.  When -s is	also present, show routing
	   statistics instead.

     -w	wait
	   Show	network	interface statistics at	intervals of wait seconds.

     The default display, for active sockets, shows the	local and remote ad-
     dresses, send and receive queue sizes (in bytes), protocol, and the in-
     ternal state of the protocol.  Address formats are	of the form
     ``host.port'' or ``network.port'' if a socket's address specifies a net-
     work but no specific host address.	 When known the	host and network ad-
     dresses are displayed symbolically	according to the data bases /etc/hosts
     and /etc/networks,	respectively.  If a symbolic name for an address is
     unknown, or if the	-n option is specified,	the address is printed numeri-
     cally, according to the address family.  For more information regarding
     the Internet ``dot	format,'' refer	to inet(3)).  Unspecified, or ``wild-
     card'', addresses and ports appear	as ``*''.

     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 (``mtu'') are also	dis-
     played.

     The routing table display indicates the available routes and their	sta-
     tus.  Each	route consists of a destination	host or	network	and a gateway
     to	use in forwarding packets.  The	flags field shows a collection of in-
     formation about the route stored as binary	choices.  The individual flags
     are discussed in more detail in the route(8) and route(4) manual pages.
     The mapping between letters and flags is:

     1	     RTF_PROTO1	      Protocol specific	routing	flag #1
     2	     RTF_PROTO2	      Protocol specific	routing	flag #2
     3	     RTF_PROTO3	      Protocol specific	routing	flag #3
     B	     RTF_BLACKHOLE    Just discard pkts	(during	updates)
     b	     RTF_BROADCAST    The route	represents a broadcast address
     C	     RTF_CLONING      Generate new routes on use
     c	     RTF_PRCLONING    Protocol-specified generate new routes on	use
     D	     RTF_DYNAMIC      Created dynamically (by redirect)
     G	     RTF_GATEWAY      Destination requires forwarding by intermediary
     H	     RTF_HOST	      Host entry (net otherwise)
     L	     RTF_LLINFO	      Valid protocol to	link address translation
     M	     RTF_MODIFIED     Modified dynamically (by redirect)
     R	     RTF_REJECT	      Host or net unreachable
     S	     RTF_STATIC	      Manually added
     U	     RTF_UP	      Route usable
     W	     RTF_WASCLONED    Route was	generated as a result of cloning
     X	     RTF_XRESOLVE     External daemon translates proto to link address

     Direct routes are created for each	interface attached to the local	host;
     the gateway field for such	entries	shows the address of the outgoing in-
     terface.  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 en-
     try indicates the network interface utilized for the route.

     When netstat is invoked with the -w option	and a 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	de-
     fault, this display summarizes information	for all	interfaces.  Informa-
     tion for a	specific interface may be displayed with the -I	option.

SEE ALSO
     nfsstat(1), ps(1),	hosts(5), networks(5), protocols(5), services(5),
     iostat(8),	trpt(8), vmstat(8)

HISTORY
     The netstat command appeared in 4.2BSD.

BUGS
     The notion	of errors is ill-defined.

4.2 Berkeley Distribution	April 18, 1994	     4.2 Berkeley Distribution

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | BUGS

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