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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 [-bdghiLlmnqrSsTtv] [-f address_family] [-M core] [-N system]
     netstat [-dn] [-I interface] [-M core] [-N system] [-w wait]
     netstat [-M core] [-N system] [-p protocol]
     netstat [-M core] [-N system] [-p protocol] -P pcbaddr
     netstat [-i] [-I Interface] [-p protocol]
     netstat [-is] [-f address_family] [-I Interface]
     netstat [-s] [-I Interface] -B

DESCRIPTION
     The netstat command symbolically displays the contents of various net‐
     work-related data structures.  There are a number of output formats,
     depending 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 fifth and
     sixth forms display per interface statistics for the specified protocol
     or address family.

     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 default display, show the current bpf(4) peers.  To show
	   only the peers listening to a specific interface, use the -I
	   option.  If the -s option is present, show the current bpf(4) sta‐
	   tistics.

     -b	   With the interface display (option -i), show bytes in and out,
	   instead of packets in and out.

     -d	   With either interface display (option -i or an interval, as
	   described 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; inet6, for AF_INET6; arp, for AF_ARP;
	   ns, for AF_NS; iso, for AF_ISO; atalk, for AF_APPLETALK; mpls, for
	   AF_MPLS; and local or unix, for AF_LOCAL.

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

     -I interface
	   Show information about the specified interface; used with a wait
	   interval as described below.	 If the -f address_family option (with
	   the -s option) or the -p protocol option is present, show per-
	   interface statistics on the interface for the specified
	   address_family or protocol, respectively.

     -h	   When used with -b in combination with either -i or -I, output
	   "human-readable" byte counts.

     -i	   Show the state of interfaces which have been auto-configured
	   (interfaces 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
	   interface and for each IP interface address.	 Multicast addresses
	   are shown on separate lines following the interface address with
	   which they are associated.  If the -f address_family option (with
	   the -s option) or the -p protocol option is present, show per-
	   interface statistics on all interfaces for the specified
	   address_family or protocol, respectively.

     -L	   Don't show link-level routes (e.g., IPv4 ARP or IPv6 neighbour
	   cache).

     -l	   With the -g option, display wider fields for the IPv6 multicast
	   routing table "Origin" and "Group" columns.

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

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

     -N	   Extract the name list from the specified system instead of the
	   default /netbsd.

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

     -P pcbaddr
	   Dump the contents of the protocol control block (PCB) located at
	   kernel virtual address pcbaddr.  This address may be obtained using
	   the -A flag.	 The default protocol is TCP, but may be overridden
	   using the -p flag.

     -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.  A null response typically
	   means that there are no interesting numbers to report.  The program
	   will complain if protocol is unknown or if there is no statistics
	   routine for it.

     -q	   Show software interrupt queue setting/statistics for all protocols.

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

     -S	   Show network addresses as numbers (as with -n, but show ports sym‐
	   bolically).

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

     -T	   Show MPLS Tags for the routing tables.  If multiple tags exists,
	   they will be comma separated, first tag being the BoS one.

     -t	   With the -i option, display the current value of the watchdog timer
	   function.

     -v	   Show extra (verbose) detail for the routing tables (-r), or avoid
	   truncation of long addresses.

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

     -X	   Force use of sysctl(3) when retrieving information.	Some features
	   of netstat may not be (fully) supported when using sysctl(3).  This
	   flag forces the use of the latter regardless, and emits a message
	   if a not yet fully supported feature is used in conjunction with
	   it.	This flag might be removed at any time; do not rely on its
	   presence.

     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
     ``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
     addresses 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 numerically, according to the address family.  For more informa‐
     tion regarding the Internet ``dot format,'' refer to inet(3)).  Unspeci‐
     fied, or ``wildcard'', addresses and ports appear as ``*''.  You can use
     the fstat(1) command to find out which process or processes hold refer‐
     ences to a socket.

     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
     information 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
     B	     RTF_BLACKHOLE    Just discard pkts (during updates)
     C	     RTF_CLONING      Generate new routes on use
     c	     RTF_CLONED	      Cloned routes (generated from RTF_CLONING)
     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)
     p	     RTF_ANNOUNCE     Link level proxy
     R	     RTF_REJECT	      Host or net unreachable
     S	     RTF_STATIC	      Manually added
     U	     RTF_UP	      Route usable
     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
     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 pro‐
     vides a count of the number of packets sent using that route.  The mtu
     entry shows the mtu associated with that route.  This mtu value is used
     as the basis for the TCP maximum segment size.  The 'L' flag appended to
     the mtu value indicates that the value is locked, and that path mtu dis‐
     covery is turned off for that route.  A ‘-’ indicates that the mtu for
     this route has not been set, and a default TCP maximum segment size will
     be used.  The interface entry indicates the network interface used 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.  This dis‐
     play consists of a column for the primary interface (the first interface
     found during autoconfiguration) and a column summarizing information for
     all interfaces.  The primary interface may be replaced with another
     interface with the -I option.  The first line of each screen of informa‐
     tion contains a summary since the system was last rebooted.  Subsequent
     lines of output show values accumulated over the preceding interval.

     The first character of the flags column in the -B option shows the status
     of the bpf(4) descriptor which has three different values: Idle ('I'),
     Waiting ('W') and Timed Out ('T').	 The second character indicates
     whether the promisc flag is set.  The third character indicates the sta‐
     tus of the immediate mode.	 The fourth character indicates whether the
     peer will have the ability to see the packets sent.  And the fifth char‐
     acter shows the header complete flag status.

SEE ALSO
     fstat(1), nfsstat(1), ps(1), sockstat(1), vmstat(1), inet(3), bpf(4),
     hosts(5), networks(5), protocols(5), services(5), iostat(8), trpt(8)

HISTORY
     The netstat command appeared in 4.2BSD.  IPv6 support was added by
     WIDE/KAME project.

BUGS
     The notion of errors is ill-defined.

BSD			       October 20, 2012				   BSD
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