4.3BSD - /usr/man/cat1/netstat.0

NETSTAT(1)                                                          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 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
       structures according to the option selected.   Using  the  third  form,
       with  an  interval  specified,  netstat  will  continuously display the
       information regarding packet traffic on the configured  network  inter‐
       faces.

       The options have the following meaning:

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

       -a     With the default display, show the state of  all  sockets;  nor‐
              mally 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 inter���
              val as described below.

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

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

       -s     Show per-protocol statistics.

       -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  infor‐
       mation  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 statistics regard‐
       ing 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 sta‐
       tus.  Each route consists of a destination host or network and a  gate‐
       way  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 out‐
       going 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 pro‐
       tocols  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  run‐
       ning  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 infor‐
       mation contains a summary since the system was last  rebooted.   Subse‐
       quent lines of output show values accumulated over the preceding inter‐
       val.

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 something else
       for the IMP.


4.2 Berkeley Distribution         May 8, 1986                       NETSTAT(1)