Content-type: text/html Man page of netstat

netstat

Section: User Commands (1)
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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

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. 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. Displays the number of dropped packets; for use with the -I interface or -i options. You can also specify an interval argument (in seconds). Limits reports to the specified address family. The address families that can be specified might include the following: Specifies reports of the AF_INET family, if present in the kernel. Specifies reports of the AF_UNIX family, if present in the kernel. Lists information about all address families in the system. Lists information about any address families in the system. Displays the current ARP table (behaves like arp -a). 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. Displays information about the specified interface. Displays the current access filter for the specified network interface. See ifaccess.conf(4) for more information. 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. Displays information about memory allocated to data structures associated with network operations. Displays Internet protocol multicast routing information. When used with the -s option, it displays IP multicast statistics. 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. 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. Displays the host's routing tables. When used with the -s option, shows the host's routing statistics instead of routing tables. Displays statistics for each protocol. Displays timer information; for use with the -I interface or -i options. Displays information about domain sockets (UNIX domain). Displays more verbose output when specified with the -r option. In this case, route metric values are displayed. 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: Displays the state of the route as one or more of the following: Up, or available. This route is to a gateway. This route is to a host This route was dynamically created by a redirect. This route was modified by a redirect. This is a static route that was created by the route command. This is a reject route that was created by the route command. 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. Provides a count of the number of packets sent using the route. 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

To show the state of the configured interfaces, enter: $ netstat -i 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.) 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 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) To set the ln0 interface counters to zero, enter: netstat -Iln0 -z

 

SEE ALSO

Commands:  vmstat(1), route(8)

Network Administration


 

Index

NAME
SYNOPSIS
OPTIONS
DESCRIPTION
Default Display
Interface Display
Routing Table Display
EXAMPLES
SEE ALSO

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Time: 02:43:02 GMT, October 02, 2010