Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

netstat(1) [ultrix man page]

netstat(1)						      General Commands Manual							netstat(1)

       netstat - show network status

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

       The command displays the contents of network-related data structures symbolically.  Depending on the options supplied to there are a number
       of output formats.

       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.  The third form, with an interval specified, continuously displays the
       information regarding packet traffic on the configured network interfaces.  The fourth form displays the Digital Network Architecture (DNA)
       Ethernet  Data  Link  Layer counters for an Ethernet interface, or the DNA Fiber Distributed Data Interface (FDDI) Data Link Layer counters
       for an FDDI interface. It also presents the FDDI adapter's status and characteristics for the FDDI interface.

       If no options are specified, displays the state of all active sockets from those using any of the protocols listed in

       The arguments, system and core allow substitutes for the defaults and

       If an interval is specified, display the information regarding packet traffic on the configured network	interfaces  continuously,  pausing
       interval seconds before refreshing the screen.

       There  are  a  number of display formats, depending on the information presented.  The default display, for active sockets, shows the local
       and remote addresses, send and receive queue sizes (in bytes), protocol, and, optionally, the internal state of the protocol.

       Address formats are either 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 and respectively.  If a symbolic name for
       an address is unknown, or if the -n option is specified, the address is printed in the Internet dot format.  Refer to for more  information
       regarding this format.  Unspecified, or wildcard, addresses and ports appear as an asterisk (*).

       The interface display provides a table of cumulative statistics regarding packets transferred, errors, and collisions.  The network address
       (currently Internet specific) 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 (for example, U if up), whether the route is to a gate-
       way (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 connec-
       tionless  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 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 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 information
       contains a summary since the system was last rebooted.  Subsequent lines of output show values accumulated over the preceding interval.

       -A		   Displays the address of any associated protocol control blocks; used for debugging.

       -a		   Displays the information for all sockets.  Normally sockets used by server processes are not shown.

       -f address_family   Limits  statistics or address control block reports to those of the specified address family.  Recognized address fami-
			   lies are inet, for AF_INET, and unix, for AF_UNIX.

       -h		   Displays the state of the IMP host table.

       -I interface	   Shows information only about this interface.  Used with an interval displayed below.

       -I interface -s	   Displays the DNA Ethernet Data Link Layer counters for an Ethernet interface.  Displays the DNA FDDI  Data  Link  Layer
			   counters, adapter's status and characteristics for an FDDI interface.

       -i		   Displays  status  information  for autoconfigured interfaces .  Interfaces statically configured into a system, but not
			   located at boot time are not shown.

       -m		   Displays information for the memory management routines The network manages a private share of memory.

       -n		   Displays network addresses as numbers.  Normally interprets addresses and attempts to display them symbolically.

       -r		   Displays the routing tables.  When -s is also present, shows routing statistics instead.

       -s		   Displays per-protocol statistics.

       -t		   Displays time until interface watchdog routine starts up (used only in conjunction with -i option).

See Also
       iostat(1), vmstat(1), hosts(5), networks(5), protocols(5), services(5), trpt(8c)

Man Page