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netstat(1)
NAME
netstat - Displays network statistics.
SYNOPSIS
netstat [-Arn|[-Aan][-f address_family][-p protocol]] [interval]
netstat [-adHimMnrstuv] [-f address_family] [-p protocol] [interval]
netstat [-ntdz] [-I interface [-c | -s]] [interval]
The netstat command displays network-related data in various formats.
OPTIONS
-a Displays the state of sockets related to the Internet protocol.
Includes sockets for processes such as servers that are currently
listening at a socket but are otherwise inactive.
-A Displays either the address of any protocol control blocks associated
with sockets or the addresses of routing table entries with bitmasks.
Typically, this option is used for debugging.
-d Displays the number of dropped packets; for use with the -I interface
or -i options. You can also specify an interval argument (in seconds).
-f address_family
Limits reports to the specified address family. The address families
that can be specified might include the following:
inet
Specifies reports of the AF_INET family, if present in the kernel.
unix
Specifies reports of the AF_UNIX family, if present in the kernel.
all Lists information about all address families in the system.
any Lists information about any address families in the system.
-H Displays the current ARP table (behaves like arp -a).
-i Displays the state of configured interfaces. (Interfaces that are
statically configured into the system, but not located at system
startup, are not shown.)
When used with the -a option, it displays IP and link-level addresses
associated with the interfaces.
You can use the -i option to retrieve your system's hardware address.
-I interface
Displays information about the specified interface.
-I interface -c
Displays the current access filter for the specified network interface.
See ifaccess.conf(4) for more information.
-I interface -s
Displays the DNA Data Link Layer counters for the specified network
interface and the adapter's status and characteristics. See Network
Administration for a description of the display fields.
-m Displays information about memory allocated to data structures
associated with network operations.
-M Displays Internet protocol multicast routing information. When used
with the -s option, it displays IP multicast statistics.
-n Displays network address in numerical format with network masks in CIDR
format. When this option is not specified, the address is displayed as
hostname and port number. This option can be used with any of the
display formats.
-pprotocol
Displays statistics for protocol, which you can specify as a well known
name or an alias. Supported protocol names and their aliases are listed
in /etc/protocols. A null listing (0) means that there is no data to
report. If routines to report statistics for a specified protocol are
not implemented on this system, netstat reports that the protocol is
unknown.
-r Displays the host's routing tables. When used with the -s option, shows
the host's routing statistics instead of routing tables.
-s Displays statistics for each protocol.
-t Displays timer information; for use with the -I interface or -i
options.
-u Displays information about domain sockets (UNIX domain).
-v Displays more verbose output when specified with the -r option. In
this case, route metric values are displayed.
-z Sets the network interface counters to zero. This option must be
specified with the -I interface option. In addition, you must be
superuser to use this option.
DESCRIPTION
The interval argument specifies in seconds the interval for updating and
displaying information. The first line of the display shows cumulative
statistics; subsequent lines show statistics recorded during interval.
Default Display
When used without options, the netstat command displays a list of active
sockets for each protocol. The default display shows the following items:
· Local and remote addresses
· Send and receive queue sizes (in bytes)
· Protocol
· State
Address formats are of the form host.port or network.port if a socket's
address specifies a network but no specific host address. The host and
network address are displayed symbolically unless -n is specified.
Interface Display
The network interface display format provides a table of cumulative
statistics for the following:
· Interface name
· Maximum Transmission Unit (MTU)
· Network Address
· Packets received (Ipkts)
· Packets received in error (Ierrs)
· Packets transferred (Opkts)
· Outgoing packets in error (Oerrs)
· Collisions
Note that the collisions item has different meanings for different
network interfaces.
· Drops (optional with -d)
· Timers (optional with -t)
Routing Table Display
A route consists of a destination host or network and a gateway to use when
forwarding packets. Direct routes are created automatically for each
interface attached to the local host when you issue the ifconfig command.
Routes can be modified automatically in response to the prevailing
condition of the network.
The routing-table display format indicates available routes and the status
of each in the following fields:
Flags
Displays the state of the route as one or more of the following:
U Up, or available.
G This route is to a gateway.
H This route is to a host
D This route was dynamically created by a redirect.
M This route was modified by a redirect.
S This is a static route that was created by the route command.
R This is a reject route that was created by the route command.
refcnt
Gives the current number of active uses for the route. Connection-
oriented protocols hold on to a single route for the duration of a
connection; connectionless protocols obtain routes in the process of
sending to a destination.
use Provides a count of the number of packets sent using the route.
interface
Indicates the network interface used for the route.
When the -v option is specified, the routing table display includes the
route metrics. An asterisk (*) indicates the metric is locked. See
route(8) for additional information on routing.
EXAMPLES
1. To show the state of the configured interfaces, enter:
$ netstat -i
2. To show the routing tables, enter:
$ netstat -r
The resulting display looks like the following:
Routing Tables
Destination Gateway Flags Refs Use Interface
Netmasks:
Inet 255.255.255.0
Route Tree for Protocol Family 2:
default 16.55.5.5 UG 13 38618 ln0
localhost 16.55.5.4 UH 2 29 lo0
ethernet 16.55.5.3 U 98 66760 ln0
(Output may be formatted differently on your system.)
3. To show the routing tables with network addresses, enter:
$ netstat -rn
The resulting display looks like the following:
Routing tables
Destination Gateway Flags Refs Use Interface
Netmasks:
Inet 0.0.0.0
Inet 255.0.0.0
Inet 255.255.0.0
Inet 255.255.252.0
Inet 255.255.255.0
Inet 255.255.255.224
Route Tree for Protocol Family 2:
default 16.140.28.1 UG 0 6004465 tu0
16.140.128/24 16.140.128.198 U 4 181451 tu0
127.0.0.1 127.0.0.1 UH 0 0 lo0
194.224/16 127.0.0.1 UG 0 3 lo0
194.226/16 127.0.0.1 UGR 0 0 lo0
198.119.1/24 198.119.19.76 U 1 867 le0
198.119.19.64/27 198.119.19.76 U 0 1 le0
198.119.64.80 198.119.19.24 UGH 0 0 le0
130.200/16 16.140.128.1 UG 0 0 tu0
4. To produce the default display for network connections, enter:
netstat
The resulting display might include the following headings:
Active Internet connections
Proto Recv-Q Send-Q Local Address Foreign Address (state)
5. To set the ln0 interface counters to zero, enter:
netstat -Iln0 -z
SEE ALSO
Commands: vmstat(1), route(8)
Network Administration