NAME [Toc] [Back]
netstat - show network status
SYNOPSIS [Toc] [Back]
netstat [-an] [-f address-family] [system]
netstat [-an] [-f address-family] [system [core]] # PA-RISC only
netstat [-Mnrsv] [-f address-family] [-p protocol] [system]
netstat [-Mnrsv] [-f address-family] [-p protocol] [system [core]]
# PA-RISC only
netstat [-ginw] [-I interface] [interval] [system]
netstat [-ginw] [-I interface] [interval] [system [core]] # PA-RISC
DESCRIPTION [Toc] [Back]
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 or invalid 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
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for AF_INET, inet6 for AF_INET6, and unix for
AF_UNIX. This option with AF_UNIX applies to
the -a and -s options. This option with
AF_INET or AF_INET6 applies to the -a, -i, -n,
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
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. By
default, when the -f option is not specified,
netstat shows the state of interfaces
configured with either IPv4 or IPv6 addresses.
An exception is when the user has not
configured any IPv6 address on any interface,
netstat does not display the state of the IPv6
-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, igmp, ipv6, and icmpv6.
-r Show the routing tables. When -v is used with
the -r option, netstat also displays the
network masks in the route entries. This
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option is ignored if the -g, -i, -I, -p or
interval option is specified and is invalid if
the -s 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 and is invalid if
the -r 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
-w Show the output in wide format. This option
displays all the fields in the output with
their maximum resolution in a single line.
Thus, the output can be worked upon with textprocessing
tools. This option works only with
the -i option and will be ignored when used
with any other option.
The system argument allows substitution for the default value
/stand/vmunix. On PA-RISC systems only, the core argument allows
substitution for the default value /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.
Note: The send and receive queue size displayed is usually zero. These
fields are displayed only for backward compatibility purposes.
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)) for IPv4, and getnameinfo() for IPv6 (see
getaddrinfo(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'' for IPv4
addresses, refer to inet(3N). For more information regarding the
Internet ``colon format'' for IPv6 addresses, refer to inet6(3N).
Unspecified or ``wildcard'' addresses and ports appear as an asterisk
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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 left-most
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
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.
The Prefix field is for IPv6 only. Its format is similar to the CIDR
notation in IPv4. The prefix is an integer between 0 and 128
inclusive. It specifies how many of the leftmost contiguous bits of
the address comprise the prefix. A host route has a prefix of 128. A
default route has a prefix of 0 (see route(1M)). The prefix is also
used in selecting a route to forward an IPv6 packet.
DEPENDENCIES [Toc] [Back]
-a option does not list X.25 programmatic access information.
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AUTHOR [Toc] [Back]
netstat was developed by HP and the University of California,
SEE ALSO [Toc] [Back]
ifconfig(1M), lanscan(1M), lanadmin(1M), route(1M), inet(3N),
inet6(3N), gethostent(3N), getnetent(3N), getaddrinfo(3N). hosts(4),
networks(4), protocols(4), services(4), routing(7).
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