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NetBSD 6.1.5 - man page for netstat (netbsd section 1)

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 network-related data
     structures.  There are a number of output formats, depending on the options for the informa-
     tion 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 structures
     according to the option selected.	Using the third form, with a wait interval specified,
     netstat will continuously display the information 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 lis-
	   tening to a specific interface, use the -I option.  If the -s option is present, show
	   the current bpf(4) statistics.

     -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 recognized: 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, multicast addresses currently in use are shown for each Eth-
	   ernet 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 symbolically).  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 proto-
	   col 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 symbolically).

     -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 con-
	   junction with it.  This flag might be removed at any time; do not rely on its pres-
	   ence.

     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
     network but no specific host address.  When known the host and network addresses are dis-
     played 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 information regarding the
     Internet ``dot format,'' refer to inet(3)).  Unspecified, or ``wildcard'', addresses and
     ports appear as ``*''.  You can use the fstat(1) command to find out which process or pro-
     cesses hold references to a socket.

     The interface display provides a table of cumulative statistics regarding packets trans-
     ferred, errors, and collisions.  The network addresses of the interface and the maximum
     transmission unit (``mtu'') are also displayed.

     The routing table display indicates the available routes and their status.  Each route con-
     sists 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 provides 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 discovery 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 run-
     ning 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 com-
     patibility.  This display consists of a column for the primary interface (the first inter-
     face found during autoconfiguration) and a column summarizing information for all inter-
     faces.  The primary interface may be replaced with another interface with the -I option.
     The first line of each screen of information 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 indi-
     cates the status of the immediate mode.  The fourth character indicates whether the peer
     will have the ability to see the packets sent.  And the fifth character 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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