2.11BSD#431 - /usr/man/cat1/netstat.0

NETSTAT(1)	    UNIX Programmer's Manual	       NETSTAT(1)


NAME
     netstat - show network status

SYNOPSIS
     netstat [ -Aan ] [ -f address_family ] [ system ] [ core ]
     netstat [ -himnrs ] [ -f address_family ] [ system ] [ core
     ]
     netstat [ -n ] [ -I interface ] interval [ system ] [ core ]

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 an interval specified, netstat will con-
     tinuously display the information regarding packet traffic
     on the configured network interfaces.

     The options have the following meaning:

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

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

     -h   Show the state of the IMP host table.

     -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).

     -I interface
	  Show information only about this interface; used with
	  an interval as described below.

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

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

     -s   Show per-protocol statistics.


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NETSTAT(1)	    UNIX Programmer's Manual	       NETSTAT(1)


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

     -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, ns,
	  for AF_NS, and unix, for AF_UNIX.

     The arguments, system and core allow substitutes for the
     defaults ``/vmunix'' and ``/dev/kmem''.

     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
     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 information regarding the
     Internet ``dot format,'' refer to inet(3N).  Unspecified, or
     ``wildcard'', addresses and ports appear as ``*''.

     The interface display provides a table of cumulative statis-
     tics regarding packets transferred, 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 consists of a destination host or
     network and a gateway to use in forwarding packets.  The
     flags field shows the state of the route (``U'' if ``up''),
     whether the route is to a gateway (``G''), and whether the
     route was created dynamically by a redirect (``D'').  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.

     When netstat is invoked with an interval argument, it
     displays a running count of statistics related to network
     interfaces.  This display consists of a column for the pri-
     mary interface (the first interface found during


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NETSTAT(1)	    UNIX Programmer's Manual	       NETSTAT(1)


     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 information contains a summary since the sys-
     tem was last rebooted.  Subsequent lines of output show
     values accumulated over the preceding interval.

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

BUGS
     The notion of errors is ill-defined.  Collisions mean some-
     thing else for the IMP.


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