netstat - show network status
netstat [-an] [-f address-family] [system [core]]
netstat [-Mnrsv] [-f address-family] [-p protocol] [system [core]]
netstat [-gin] [-I interface] [interval] [system [core]]
netstat displays statistics for network interfaces and protocols, as
well as the contents of various network-related data structures. The
output format varies according to the options selected. Some options
are ignored when used in combination with other options.
Generally, the netstat command takes one of the three forms shown
+ The first form of the command displays a list of active
sockets for each protocol.
+ The second form displays the contents of one of the other
network data structures according to the option selected.
+ The third form displays configuration information for each
network interface. It also displays network traffic data on
configured network interfaces, optionally updated at each
interval, measured in seconds.
Options are interpreted as follows:
-a Show the state of all sockets, including
passive sockets used by server processes. When
netstat is used without any options only active
sockets are shown. This option does not show
the state of X.25 programmatic access sockets.
The option is ignored if the -g, -i, -I, -M,
-p, -r, -s or interval option is specified.
-f address-family Show statistics or address control block for
only the specified address-family. The
following address families are recognized: inet
for AF_INET, and unix for AF_UNIX. This option
applies to the -a and -s options.
-g Show multicast information for network
interfaces. Only the address family AF_INET is
recognized by this option. This option may be
combined with the -i option to display both
kinds of information. The option is ignored if
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the -p option is specified.
-i Show the state of network interfaces. Only the
interfaces that have been configured with an IP
address or the plumb option using the ifconfig
command are shown. The output includes both
the primary and logical interfaces. (See
ifconfig(1M)). The counts for Ipkts and Opkts
fields are for IP packets only. This option is
ignored if the -p option is specified.
-I interface Show information about the specified interface
only. This option applies to the -g and -i
-M Show the multicast routing tables. When -s is
used with the -M option, netstat displays
multicast routing statistics instead. This
option is ignored if the -p option is
-n Show network addresses as numbers. Normally,
netstat interprets addresses and attempts to
display them symbolically. This option applies
to the -a, -i, -r and -v options.
-p protocol Show statistics for the specified protocol.
The following protocols are recognized: tcp,
udp, ip, icmp, and igmp.
-r Show the routing tables. When -v is used with
the -r option, netstat also displays the
network masks in the route entries. When -s is
used with the -r option, netstat displays
routing statistics instead. This option is
ignored if the -g, -i, -I, -p or interval
option is specified.
-s Show statistics for all protocols. When this
option is used with the -M option, netstat
displays multicast routing statistics instead.
This option is ignored if the -g, -i, -I, -p or
interval option is specified.
-v Show additional routing information. When -v
is used with the -r option, netstat also
displays the network masks in the route
entries. This option only applies to the -r
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The arguments system and core allow substitutes for the defaults,
/stand/vmunix and /dev/kmem.
If no options are specified, netstat displays the status of only
active sockets. The display of active and passive sockets status
shows the local and remote addresses, send and receive queue sizes (in
bytes), protocol, and the internal state of the protocol. Address
formats are in two forms: host.port, or network.port if the host
portion of a socket address is zero. When known, the host and network
addresses are displayed symbolically by using gethostbyname() and
getnetbyname(), respectively (see gethostent(3N) and getnetent(3N)).
If a symbolic name for an address is unknown, the address is displayed
numerically according to the address family. For more information
regarding the Internet ``dot format'', refer to inet(3N). Unspecified
or ``wildcard'' addresses and ports appear as an asterisk (*).
The interface display provides a table of cumulative statistics
regarding packets transferred, both inbound and outbound. The network
addresses of the interface and the maximum transmission unit (MTU) are
also displayed. When the interval argument is specified, netstat
displays a running count of statistics related to network interfaces.
This display consists of a column for the first interface found during
auto-configuration and a column summarizing information for all
interfaces. To display a running count of statistics for a specific
interface, use 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
The routing table display indicates the available routes and their
status. Each route consists of a destination host or network, a
netmask and a gateway to use in forwarding packets. The Flags field
shows whether the route is up (U), whether the route is to a gateway
(G), or whether the route is a host or network route (with or without
The Netmask field shows the mask to be applied to the destination IP
address of an IP packet to be forwarded. The result will be compared
with the destination address in the route entry. If they are the same,
then the route is one of the candidates for routing this IP packet.
If there are several candidate routes, then the route with the longest
Netmask field (contiguous 1's starting from the leftmost bit position)
will be chosen. (see routing(7).)
The Gateway field shows the address of the immediate gateway for
reaching the destination. It can be the address of the outgoing
interface if the destination is on a directly connected network.
The Interface field identifies which network interface is used for the
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The Pmtu field displays the path maximum transmission unit (PMTU). If
the route is created with a static PMTU value (see route(1M)), the
corresponding PMTU value permanently overrides the interface MTU.
Otherwise, the Pmtu value is the same as the MTU of the network
interface used for the route.
-a option does not list X.25 programmatic access information.
netstat was developed by HP and the University of California,
hosts(4), networks(4), gethostent(3N), getnetent(3N), protocols(4),
route(1M), ifconfig(1M), lanscan(1M), lanadmin(1M), services(4).
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