netstat(1M)
NAME
netstat - show network status
SYNOPSIS
netstat [-anv] [-f address_family] [-P protocol]
netstat -g [-n] [-f address_family]
netstat -p [-n] [-f address_family]
netstat -s [-f address_family] [-P protocol]
netstat -m [-v]
netstat -i [-I interface] [-an] [-f address_family] [inter-
val [count]]
netstat -r [-anv] [-f address_family | filter]
netstat -M [-ns] [-f address_family]
netstat -D [-I interface] [-f address_family]
DESCRIPTION
The netstat command displays the contents of certain
network-related data structures in various formats, depend-
ing on the options you select.
The netstat command has the several forms shown in the
SYNOPSIS section, above, listed as follows:
o The first form of the command (with no required argu-
ments) displays a list of active sockets for each pro-
tocol.
o The second, third, and fourth forms (-g, -p, and -s
options) display information from various network data
structures.
o The fifth form (-m option) displays STREAMS memory
statistics.
o The sixth form (-i option) shows the state of the
interfaces.
o The seventh form (-r option) displays the routing
table.
o The eighth form (-M option) displays the multicast
routing table.
o The ninth form (-D option) displays the state of DHCP
on one or all interfaces.
These forms are described in greater detail below.
With no arguments (the first form), netstat displays con-
nected sockets for PF_INET, PF_INET6, and PF_UNIX, unless
modified otherwise by the -f option.
OPTIONS
-a Show the state of all sockets, all routing table
entries, or all interfaces, both physical and logical.
Normally, listener sockets used by server processes
are not shown. Under most conditions, only interface,
host, network, and default routes are shown and only
the status of physical interfaces is shown.
-f address_family
Limit all displays to those of the specified
address_family. The value of address_family can be one
of the following:
inet For the AF_INET address family showing IPv4
information.
inet6 For the AF_INET6 address family showing IPv6
information.
unix For the AF_UNIX address family.
-f filter
With -r only, limit the display of routes to those
matching the specified filter. A filter rule consists
of a "keyword:value" pair. The known keywords and the
value syntax are:
af:{inet|inet6|unix|number}
Selects an address family. This is identical to
-f address_family and both syntaxes are sup-
ported.
{inif|outif}:{name|ifIndex|any|none}
Selects an input or output interface. You can
specify the interface by name (such as hme0) or
by ifIndex number (for example, 2). If any is
used, the filter matches all routes having a
specified interface (anything other than null).
If none is used, the filter matches all routes
having a null interface. Note that you can view
the index number (ifIndex) for an interface with
the -a option of ifconfig(1M).
{src|dst}:{ip-address[/mask]|any|none}
Selects a source or destination IP address. If
specified with a mask length, then any routes
with matching or longer (more specific) masks
are selected. If any is used, then all but
addresses but 0 are selected. If none is used,
then address 0 is selected.
flags:[+ -]?[ABDGHLMSU]+
Selects routes tagged with the specified flags.
By default, the flags as specified must be set
in order to match. With a leading +, the flags
specified must be set but others are ignored.
With a leading -, the flags specified must not
be set and others are permitted.
You can specify multiple instances of -f to specify multiple
filters. For example:
% netstat -nr -f outif:hme0 -f outif:hme1 -f dst:10.0.0.0/8
The preceding command displays routes within network
10.0.0.0/8, with mask length 8 or greater, and an out-
put interface of either hme0 or hme1, and excludes all
other routes.
-g Show the multicast group memberships for all inter-
faces. See DISPLAYS, below.
-i Show the state of the interfaces that are used for IP
traffic. Normally this shows statistics for the physi-
cal interfaces. When combined with the -a option, this
will also report information for the logical inter-
faces. See ifconfig(1M).
-m Show the STREAMS memory statistics.
-n Show network addresses as numbers. netstat normally
displays addresses as symbols. This option may be used
with any of the display formats.
-p Show the net to media tables. See DISPLAYS, below.
-r Show the routing tables. Normally, only interface,
host, network, and default routes are shown, but when
this option is combined with the -a option, all routes
will be displayed, including cache.
-s Show per-protocol statistics. When used with the -M
option, show multicast routing statistics instead.
When used with the -a option, per-interface statistics
will be displayed, when available, in addition to
statistics global to the system. See DISPLAYS, below.
-v Verbose. Show additional information for the sockets,
STREAMS memory statistics, and the routing table.
-I interface
Show the state of a particular interface. interface
can be any valid interface such as hme0 or le0. Nor-
mally, the status and statistics for physical inter-
faces are displayed. When this option is combined with
the -a option, information for the logical interfaces
is also reported.
-M Show the multicast routing tables. When used with the
-s option, show multicast routing statistics instead.
-P protocol
Limit display of statistics or state of all sockets to
those applicable to protocol. The protocol can be one
of ip, ipv6, icmp, icmpv6, igmp, udp, tcp, rawip.
rawip can also be specified as raw. The command
accepts protocol options only as all lowercase.
-D Show the status of DHCP configured interfaces.
OPERANDS
interval
Display interface statistics accumulated since last
display every interval seconds, repeating forever,
unless count is specified. When invoked with interval,
the first row of netstat output shows statistics accu-
mulated since last reboot.
count Display interface statistics the number of times
specified by count, at the interval specified by
interval.
DISPLAYS
Active Sockets (First Form)
The display for each active socket shows the local and
remote address, the send and receive queue sizes (in bytes),
the send and receive windows (in bytes), and the internal
state of the protocol.
The symbolic format normally used to display socket
addresses is either
hostname.port
when the name of the host is specified, or
network.port
if a socket address specifies a network but no specific
host.
The numeric host address or network number associated with
the socket is used to look up the corresponding symbolic
hostname or network name in the hosts or networks database.
If the network or hostname for an address is not known, or
if the -n option is specified, the numerical network address
is shown. Unspecified, or "wildcard", addresses and ports
appear as "*". For more information regarding the Internet
naming conventions, refer to inet(7P) and inet6(7P).
TCP Sockets
The possible state values for TCP sockets are as follows:
BOUND Bound, ready to connect or listen.
CLOSED
Closed. The socket is not being used.
CLOSING
Closed, then remote shutdown; awaiting acknowledgment.
CLOSE_WAIT
Remote shutdown; waiting for the socket to close.
ESTABLISHED
Connection has been established.
FIN_WAIT_1
Socket closed; shutting down connection.
FIN_WAIT_2
Socket closed; waiting for shutdown from remote.
IDLE Idle, opened but not bound.
LAST_ACK
Remote shutdown, then closed; awaiting acknowledgment.
LISTEN
Listening for incoming connections.
SYN_RECEIVED
Initial synchronization of the connection under way.
SYN_SENT
Actively trying to establish connection.
TIME_WAIT
Wait after close for remote shutdown retransmission.
Network Data Structures (Second Through Fifth Forms)
The form of the display depends upon which of the -g, -m,
-p, or -s options you select.
-g Displays the list of multicast group membership.
-m Displays the memory usage, for example, STREAMS mblks.
-p Displays the net to media mapping table. For IPv4, the
address resolution table is displayed. See arp(1M).
For IPv6, the neighbor cache is displayed.
-s Displays the statistics for the various protocol
layers.
The statistics use the MIB specified variables. The defined
values for ipForwarding are:
forwarding(1)
Acting as a gateway.
not-forwarding(2)
Not acting as a gateway.
The IPv6 and ICMPv6 protocol layers maintain per-interface
statistics. If the -a option is specified with the -s
option, then the per-interface statistics as well as the
total sums are displayed. Otherwise, just the sum of the
statistics are shown.
For the second, third, and fourth forms of the command, you
must specify at least -g, -p, or -s. You can specify any
combination of these options. You can also specify -m (the
fifth form) with any set of the -g, -p, and -s options. If
you specify more than one of these options, netstat displays
the information for each one of them.
Interface Status (Sixth Form)
The interface status display lists information for all
current interfaces, one interface per line. If an interface
is specified using the -I option, it displays information
for only the specified interface.
The list consists of the interface name, mtu (maximum
transmission unit, or maximum packet size)(see
ifconfig(1M)), the network to which the interface is
attached, addresses for each interface, and counter associ-
ated with the interface. The counters show the number of
input packets, input errors, output packets, output errors,
and collisions, respectively. For Point-to-Point interfaces,
the Net/Dest field is the name or address on the other side
of the link.
If the -a option is specified with either the -i option or
the -I option, then the output includes names of the physi-
cal interface(s), counts for input packets and output pack-
ets for each logical interface, plus additional information.
If the -n option is specified, the list displays the IP
address instead of the interface name.
If an optional interval is specified, the output will be
continually displayed in interval seconds until interrupted
by the user or until count is reached. See OPERANDS.
The physical interface is specified using the -I option.
When used with the interval operand, output for the -I
option has the following format:
input le0 output input (Total) output
packets errs packets errs colls packets errs packets errs colls
227681 0 659471 1 502 261331 0 99597 1 502
10 0 0 0 0 10 0 0 0 0
8 0 0 0 0 8 0 0 0 0
10 0 2 0 0 10 0 2 0 0
If the input interface is not specified, the first interface
of address family inet or inet6 will be displayed.
Routing Table (Seventh Form)
The routing table display lists the available routes and the
status of each. Each route consists of a destination host or
network, and a gateway to use in forwarding packets. The
flags column shows the status of the route (U if "up"),
whether the route is to a gateway (G), whether it is a
redundant route established with the -multirt option (M),
whether the route was established using the -setsrc option
(S), and whether the route was created dynamically by a
redirect (D). If the -a option is specified, there will be
routing entries with flags for combined routing and address
resolution entries (A), broadcast addresses (B), and the
local addresses for the host (L).
Interface 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 use column displays the number of packets sent using a
combined routing and address resolution (A) or a broadcast
(B) route. For a local (L) route, this count is the number
of packets received, and for all other routes it is the
number of times the routing entry has been used to create a
new combined route and address resolution entry.
The interface entry indicates the network interface utilized
for the route.
Multicast Routing Tables (Eighth Form)
The multicast routing table consists of the virtual inter-
face table and the actual routing table.
DHCP Interface Information (Ninth Form)
The DHCP interface information consists of the interface
name, its current state, lease information, packet counts,
and a list of flags.
The states correlate with the specifications set forth in
RFC 2131.
Lease information includes:
o when the lease began;
o when lease renewal will begin; and
o when the lease will expire.
The flags currently defined include:
BOOTP The interface has a lease obtained through BOOTP.
BUSY The interface is busy with a DHCP transaction.
PRIMARY
The interface is the primary interface. See
dhcpinfo(1).
FAILED
The interface is in failure state and must be
manually restarted.
Packet counts are maintained for the number of packets sent,
the number of packets received, and the number of lease
offers declined by the DHCP client. All three counters are
initialized to zero and then incremented while obtaining a
lease. The counters are reset when the period of lease
renewal begins for the interface. Thus, the counters
represent either the number of packets sent, received, and
declined while obtaining the current lease, or the number of
packets sent, received, and declined while attempting to
obtain a future lease.
FILES
/etc/default/inet_type
DEFAULT_IP setting
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
SEE ALSO
arp(1M), dhcpinfo(1), dhcpagent(1M), ifconfig(1M),
iostat(1M), mibiisa(1M), savecore(1M), vmstat(1M), hosts(4),
inet_type(4), networks(4), protocols(4), services(4), attri-
butes(5), inet(7P), inet6(7P)
Droms, R., RFC 2131, Dynamic Host Configuration Protocol,
Network Working Group, March 1997.
NOTES
When displaying interface information, netstat honors the
DEFAULT_IP setting in /etc/default/inet_type. If it is set
to IP_VERSION4, then netstat will omit information relating
to IPv6 interfaces, statistics, connections, routes and the
like.
However, you can override the DEFAULT_IP setting in
/etc/default/inet_type on the command-line. For example, if
you have used the command-line to explicitly request IPv6
information by using the inet6 address family or one of the
IPv6 protocols, it will override the DEFAULT_IP setting.
If you need to examine network status information following
a kernel crash, use the mdb(1) utility on the savecore(1M)
output.
The netstat utility obtains TCP statistics from the system
by opening /dev/tcp and issuing queries. Because of this,
netstat might display an extra, unused connection in IDLE
state when reporting connection status.
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