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 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 struc-
 tures 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 statistics.
 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 debug-
 ging.
 -a With the default display, show the state of all sockets; normally
 sockets used by server processes are not shown. With the routing
 table display (option -r, as described below), show protocol-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 rec-
 ognized: 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 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, mul-
 ticast addresses currently in use are shown for each Ethernet
 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 -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 connections. 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 typi-
 cally means that there are no interesting numbers to report. The
 program will complain if protocol is unknown or if there is no sta-
 tistics routine for it.
 -q Show network interface send queue statistics. By default all
 queues are displayed, unless specified with -c. This option
 requires specifying an interface with -I option. More detailed
 information about the queues, which includes their queueing algo-
 rithm 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 suppressed.
 -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 net-
 work but no specific host address. If known, the host and network
 addresses are displayed symbolically according to the databases
 /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 informa-
 tion regarding the Internet ``dot format'', refer to inet(3) ). Unspeci-
 fied, 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 dis-
 played.
 The routing table display indicates the available routes and their sta-
 tus. Each route consists 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
 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 destination. The use field pro-
 vides a count of the number of packets sent using that route. The inter-
 face 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 parame-
 ter with no option, and is currently supported for backward compatibil-
 ity. 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