illumos: manual page: netstat.8

NETSTAT(8) Maintenance Commands and Procedures NETSTAT(8)

NAME

netstat - show network status

SYNOPSIS

netstat [-anuvR] [-f address_family] [-P protocol]

netstat -g [-nv] [-f address_family]

netstat -p [-n] [-f address_family]

netstat -s [-f address_family] [-P protocol]
[-T u | d ] [interval [count]]

netstat -m [-T u | d ] [-v] [interval [count]]

netstat -i [-I interface] [-acn] [-f address_family]
[-T u | d ] [interval [count]]

netstat -r [-acnvR] [-f address_family | filter]

netstat -M [-cns] [-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, depending 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 arguments)
displays a list of active sockets for each protocol.

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 connected 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.

-c

Print IPv4 networks using CIDR (x.y.z.a/NN) notation with the -i, -r,
and -M options. IPv6 networks default to this, but due to backward
compatibility, IPv4 ones do not without this flag. A noncontiguous
IPv4 netmask will print "/NM" if this flag is enabled.

-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 supported.

outif:{name|ifIndex|any|none}

Selects an 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(8).

dst:{ip-address[/mask]|any|none}

Selects a 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 output interface of either hme0 or
hme1, and excludes all other routes.

-g

Show the multicast group memberships for all interfaces. If the -v
option is included, source-specific membership information is also
displayed. See DISPLAYS, below.

-i

Show the state of the interfaces that are used for IP traffic.
Normally this shows statistics for the physical interfaces. When
combined with the -a option, this will also report information for
the logical interfaces. See ifconfig(8).

-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. If you have
not set up a multicast route, -ra might not show any multicast
routing entries, although the kernel will derive such an entry if
needed.

-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.

-T u | d

Display a time stamp.

Specify u for a printed representation of the internal representation
of time. See time(2). Specify d for standard date format. See
date(1).

-u

For each network endpoint show the list of processes which currently
have an open file descriptor pointing to that endpoint. For each
process in that list, show the username, process ID and associated
program; the information may be truncated. Where multiple processes
are associated with an endpoint, a line will be output for each
process.

While the system gathers this information, the processes associated
with a given endpoint may change. If such a change occurs, it may not
be reflected in the output.

-v

Verbose. Show additional information for the sockets, STREAMS memory
statistics, routing table, and multicast group memberships. In
conjunction with the -u flag, show the arguments with which the
process was started; these may be truncated.

-I interface

Show the state of a particular interface. interface can be any valid
interface such as hme0 or eri0. Normally, the status and statistics
for physical interfaces 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, 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.

-R

This modifier displays extended security attributes for sockets and
routing table entries. The -R modifier is available only if the
system is configured with the Solaris Trusted Extensions feature.

With -r only, this option displays the routing entries' gateway
security attributes. See route(8) for more information on security
attributes.

When displaying socket information using the first form of the
command, this option displays additional information for Multi-Level
Port(MLP) sockets. This includes:

o The label for the peer if the socket is connected.

o The following flags can be appended to the socket's
"State" output:

P
The socket is a MLP on zone-private IP addresses.

S
The socket is a MLP on IP addresses shared between
zones.

OPERANDS

interval
Display 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 accumulated since last
reboot.

The following options support interval: -i, -m, -s and -Ms.
Some values are configuration parameters and are just
redisplayed at each interval.

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 an asterisk (*). For more
information regarding the Internet naming conventions, refer to inet(4P)
and inet6(4P).

For SCTP sockets, because an endpoint can be represented by multiple
addresses, the verbose option (-v) displays the list of all the local and
remote addresses.

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.

SCTP Sockets
The possible state values for SCTP sockets are as follows:

CLOSED
Closed. The socket is not being used.

LISTEN
Listening for incoming associations.

ESTABLISHED
Association has been established.

COOKIE_WAIT
INIT has been sent to the peer, awaiting
acknowledgment.

COOKIE_ECHOED
State cookie from the INIT-ACK has been sent to the
peer, awaiting acknowledgement.

SHUTDOWN_PENDING
SHUTDOWN has been received from the upper layer,
awaiting acknowledgement of all outstanding DATA
from the peer.

SHUTDOWN_SENT
All outstanding data has been acknowledged in the
SHUTDOWN_SENT state. SHUTDOWN has been sent to the
peer, awaiting acknowledgement.

SHUTDOWN_RECEIVED
SHUTDOWN has been received from the peer, awaiting
acknowledgement of all outstanding DATA.

SHUTDOWN_ACK_SENT
All outstanding data has been acknowledged in the
SHUTDOWN_RECEIVED state. SHUTDOWN_ACK has been sent
to the peer.

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(8). 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(8)), the network to which the
interface is attached, addresses for each interface, and counter
associated 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 physical interface(s), counts for
input packets and output packets 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 eri0 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. These flags are as follows:

U
Indicates route is up.

G
Route is to a gateway.

H
Route is to a host and not a network.

M
Redundant route established with the -multirt option.

S
Route was established using the -setsrc option.

D
Route was created dynamically by a redirect.

If the -a option is specified, there will be routing entries with the
following flags:

A
Combined routing and address resolution entries.

B
Broadcast addresses.

L
Local addresses for the host.

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 interface 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 (IPv4 only).

BUSY
The interface is busy with a DHCP transaction.

PRIMARY
The interface is the primary interface. See dhcpinfo(1) and
ifconfig(8).

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

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(8) 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.

Previous versions of netstat had undocumented methods for reporting
kernel statistics published using the kstat(4D) facility. This
functionality has been removed. Use kstat(8) instead.

netstat restricts its output to information that is relevant to the zone
in which netstat runs. (This is true for both shared-IP and exclusive-IP
zones.)

July 12, 2016 NETSTAT(8)