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NETSTAT(1)                BSD General Commands Manual               NETSTAT(1)

NAME
     netstat -- show network status

SYNOPSIS
     netstat [-AaLlnW] [-f address_family | -p protocol]
     netstat [-gilns] [-v] [-f address_family] [-I interface]
     netstat -i | -I interface [-w wait] [-c queue] [-abdgqRt]
     netstat -s [-s] [-f address_family | -p protocol] [-w wait]
     netstat -i | -I interface -s [-f address_family | -p protocol]
     netstat -m [-m]
     netstat -r [-Aaln] [-f address_family]
     netstat -rs [-s]

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 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 a wait interval specified, netstat will continuously display the information
     regarding packet traffic on the configured network interfaces.  The fourth form displays statistics for
     the specified protocol or address family. If a wait interval is specified, the protocol information
     over the last interval seconds will be displayed.  The fifth form displays per-interface statistics for
     the specified protocol or address family.  The sixth form displays mbuf(9) statistics.  The seventh
     form displays routing table for the specified address family.  The eighth form displays routing statis-tics. statistics.
     tics.

     The options have the following meaning:

     -A    With the default display, show the address of any protocol control blocks associated with sockets
           and the flow hash; used for debugging.

     -a    With the default display, show the state of all sockets; normally sockets used by server pro-cesses processes
           cesses are not shown. With the routing table display (option -r, as described below), show proto-col-cloned protocol-cloned
           col-cloned routes (routes generated by a RTF_PRCLONING parent route); normally these routes are
           not shown.

     -b    With the interface display (option -i, as described below), show the number of bytes in and out.

     -c queue
           With the queue statistics (option -q, as described below), show only those for the specified
           queue.

     -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 and unix, for
           AF_UNIX.

     -g    Show information related to multicast (group address) membership.  If the -s option is also
           present, show extended interface group management statistics.  If the -v option is specified,
           show link-layer memberships; they are suppressed by default.  Source lists for each group will
           also be printed.  Specifiying -v twice will print the control plane timers for each interface and
           the source list counters for each group.  If the -i is specified, only that interface will be
           shown.  If the -f is specified, only information for the address family will be displayed.

     -I interface
           Show information about the specified interface; used with a wait interval as described below.  If
           the -s option is present, show per-interface protocol statistics on the interface for the speci-fied specified
           fied address_family or protocol, or for all protocol families.

     -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 Ethernet interface and for each IP inter-face interface
           face address.  Multicast addresses are shown on separate lines following the interface address
           with which they are associated.  If the -s option is present, show per-interface statistics on
           all interfaces for the specified address_family or protocol, or for all protocol families.

     -L    Show the size of the various listen queues.  The first count shows the number of unaccepted con-nections. connections.
           nections.  The second count shows the amount of unaccepted incomplete connections.  The third
           count is the maximum number of queued connections.

     -l    Print full IPv6 address.

     -m    Show statistics recorded by the memory management routines (the network stack manages a private
           pool of memory buffers). More detailed information about the buffers, which includes their cache
           related statistics, can be obtained by using -mm or -m -m option.

     -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.

     -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.  The special protocol
           name ``bdg'' is used to show bridging statistics.  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 network interface send queue statistics.  By default all queues are displayed, unless speci-fied specified
           fied with -c.  This option requires specifying an interface with -I option.  More detailed infor-mation information
           mation about the queues, which includes their queueing algorithm related statistics, can be
           obtained by using -qq or -q -q option.

     -r    Show the routing tables.  Use with -a to show protocol-cloned routes.  When -s is also present,
           show routing statistics instead.  When -l is also present, netstat assumes more columns are there
           and the maximum transmission unit (``mtu'') are also displayed.

     -R    Show reachability information.  Use with -i to show link-layer reachability information for a
           given interface.

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

     -v    Increase verbosity level.

     -W    In certain displays, avoid truncating addresses even if this causes some fields to overflow.

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

     -x    Show extended link-layer reachability information in addition to that shown by the -R flag.

OUTPUT
     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.  If known, the host and network addresses are displayed symbolically according to the data-bases databases
     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 ``*''.

     Internet domain socket states:

     CLOSED:  The socket is not in use.

     LISTEN:  The socket is listening for incoming connections.  Unconnected
     listening sockets like these are only displayed when using the -a option.

     SYN_SENT:  The socket is actively trying to establish a connection to a
     remote peer.

     SYN_RCVD:  The socket has passively received a connection request from a
     remote peer.

     ESTABLISHED:  The socket has an established connection between a local
     application and a remote peer.

     CLOSE_WAIT:  The socket connection has been closed by the remote peer,
     and the system is waiting for the local application to close its half of
     the connection.

     LAST_ACK:  The socket connection has been closed by the remote peer, the
     local application has closed its half of the connection, and the system
     is waiting for the remote peer to acknowledge the close.

     FIN_WAIT_1:  The socket connection has been closed by the local
     application, the remote peer has not yet acknowledged the close, and the
     system is waiting for it to close its half of the connection.

     FIN_WAIT_2:  The socket connection has been closed by the local
     application, the remote peer has acknowledged the close, and the system
     is waiting for it to close its half of the connection.

     CLOSING:  The socket connection has been closed by the local application
     and the remote peer simultaneously, and the remote peer has not yet
     acknowledged the close attempt of the local application.

     TIME_WAIT:  The socket connection has been closed by the local
     application, the remote peer has closed its half of the connection, and
     the system is waiting to be sure that the remote peer received the last
     acknowledgement.

     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 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 a col-lection collection
     lection 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
     3       RTF_PROTO3       Protocol specific routing flag #3
     B       RTF_BLACKHOLE    Just discard packets (during updates)
     b       RTF_BROADCAST    The route represents a broadcast address
     C       RTF_CLONING      Generate new routes on use
     c       RTF_PRCLONING    Protocol-specified generate new routes on use
     D       RTF_DYNAMIC      Created dynamically (by redirect)
     G       RTF_GATEWAY      Destination requires forwarding by intermediary
     H       RTF_HOST         Host entry (net otherwise)
     I       RTF_IFSCOPE      Route is associated with an interface scope
     i       RTF_IFREF        Route is holding a reference to the interface
     L       RTF_LLINFO       Valid protocol to link address translation
     M       RTF_MODIFIED     Modified dynamically (by redirect)
     m       RTF_MULTICAST    The route represents a multicast address
     R       RTF_REJECT       Host or net unreachable
     r       RTF_ROUTER       Host is a default router
     S       RTF_STATIC       Manually added
     U       RTF_UP           Route usable
     W       RTF_WASCLONED    Route was generated as a result of cloning
     X       RTF_XRESOLVE     External daemon translates proto to link address
     Y       RTF_PROXY        Proxying; cloned routes will not be scoped

     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 desti-nation. destination.
     nation.  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.  A route which is marked with the
     RTF_IFSCOPE flag is instantiated for the corresponding interface.  A cloning route which is marked with
     the RTF_PROXY flag will not generate new routes that are associated with its interface scope.

     When netstat is invoked with the -w option and a wait interval argument, it displays a running count of
     statistics related to network interfaces or protocols.  An obsolete version of this option used a
     numeric parameter with no option, and is currently supported for backward compatibility.  By default,
     this display summarizes information for all interfaces.  Information for a specific interface may be
     displayed with the -I option.

SEE ALSO
     nfsstat(1), ps(1), inet(4), unix(4), hosts(5), networks(5), protocols(5), route(8), services(5),
     iostat(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.

Darwin                           June 15, 2001                          Darwin

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