NETSTAT(1) BSD General Commands Manual NETSTAT(1)
netstat -- show network status
netstat [-AaLlnW] [-f address_family | -p protocol]
netstat [-gilns] [-v] [-f address_family] [-I interface]
netstat -i | -I interface [-w wait] [-c queue] [-abdgqRtS]
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]
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 inter-
faces. 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-
-a With the default display, show the state of all sockets; normally sockets used by server processes are not shown. With the routing ta-
ble 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.
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.
Limit statistics or address control block reports to those of the specified address family. The following address families are recog-
nized: 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 man-
agement 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.
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 specified 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 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.
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 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. More detailed information about the
route metrics are displayed with -ll for TCP round trip times -lll for all metrics. Use the -z flags to display only entries with non-
zero RTT values. (``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. For security reasons, root
privileges are required to read TCP statistics and in the absence of such privileges all TCP counters will be reported as zero.
-S Show interface link status and interface state information about the specified interface. This option requires specifying an interface
with -I option.
-v Increase verbosity level.
-W In certain displays, avoid truncating addresses even if this causes some fields to overflow.
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.
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 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 numeri-
cally, 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
SYN_RCVD: The socket has passively received a connection request from a
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
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
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 gate-
way to use in forwarding packets. The flags field shows a collection of information about the route stored as binary choices. The individ-
ual 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 sin-
gle 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. 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 inter-
faces or protocols. An obsolete version of this option used a numeric parameter with no option, and is currently supported for backward com-
patibility. By default, this display summarizes information for all interfaces. Information for a specific interface may be displayed with
the -I option.
nfsstat(1), ps(1), inet(4), unix(4), hosts(5), networks(5), protocols(5), route(8), services(5), iostat(8),
The netstat command appeared in 4.2BSD.
IPv6 support was added by WIDE/KAME project.
The notion of errors is ill-defined.
Darwin June 15, 2001 Darwin