NETSTAT(1) OpenBSD Reference Manual NETSTAT(1)NAMEnetstat - show network status
SYNOPSISnetstat [-Aan] [-f address_family] [-p protocol] [-M core] [-N system]
netstat [-bdFgilmnqrstu] [-f address_family] [-p protocol] [-M core]
[-N system] [-T tableid]
netstat [-bdn] [-c count] [-I interface] [-M core] [-N system] [-w wait]
netstat [-v] [-M core] [-N system] -P pcbaddr
netstat [-s] [-M core] [-N system] [-p protocol]
netstat [-a] [-f address_family] [-p protocol] [-i | -I interface]
netstat [-W interface]
DESCRIPTION
The netstat command symbolically displays the contents of various
network-related data structures. There are a number of output formats,
depending on the options for the information presented.
The first form of the command displays a list of active sockets for each
protocol. The second form presents the contents of one of the other
network data structures according to the option selected. Using the
third form, with a wait interval specified, netstat will continuously
display the information regarding packet traffic on the configured
network interfaces. The fourth form displays internals of the protocol
control block (PCB) and the socket structure. The fifth form displays
statistics about the named protocol. The sixth form displays per
interface statistics for the specified address family. The final form
displays per interface statistics for the specified wireless (802.11)
device.
The options are as follows:
-A With the default display, show the address of any protocol
control blocks associated with sockets; used for debugging, e.g.
with the -P flag.
-a With the default display, show the state of all sockets; normally
sockets used by server processes are not shown. With the
interface display (options -I or -i), show multicast addresses.
-b With the interface display (options -I or -i), show bytes in and
out, instead of packet statistics.
-c count
Display count updates, then exit. This option has no effect
unless -w is specified as well.
-d With either the interface display (options -I or -i) or an
interval (option -w), show the number of dropped packets.
-F When showing routes, only show routes whose gateway are in the
same address family as the destination.
-f address_family
Limit statistics or address control block reports to those of the
specified address_family.
The following address families are recognized:
Address Family Constant Description
atalk AF_APPLETALK AppleTalk
encap PF_KEY IPsec
inet AF_INET IP Version 4
inet6 AF_INET6 IP Version 6
local AF_LOCAL Local to Host (i.e., pipes)
mpls AF_MPLS MPLS
pflow PF_FLOW pflow data export
unix AF_UNIX Local to Host (i.e., pipes)
-g Show information related to multicast (group address) routing.
By default, show the IP multicast virtual-interface and routing
tables. If the -s option is also present, show multicast routing
statistics.
-I interface
Show information about the specified interface; used with a wait
interval as described below.
If the -a option is also present, multicast addresses currently
in use are shown for the given interface and for each IP
interface address. Multicast addresses are shown on separate
lines following the interface address with which they are
associated.
If the -f address_family option (with the -s option) is present,
show per-interface statistics on the given interface for the
specified address_family.
-i Show the state of interfaces which have been auto-configured
(interfaces statically configured into a system but not located
at boot-time are not shown).
If the -a option is also present, multicast addresses currently
in use are shown for each Ethernet interface and for each IP
interface address. Multicast addresses are shown on separate
lines following the interface address with which they are
associated.
If the -f address_family option (with the -s option) is present,
show per-interface statistics on all interfaces for the specified
address_family.
-l With the -g option, display wider fields for the IPv6 multicast
routing table "Origin" and "Group" columns.
-M core
Extract values associated with the name list from the specified
core instead of the running kernel.
-m Show statistics recorded by the memory management routines (the
network manages a private pool of memory buffers).
-N system
Extract the name list from the specified system instead of the
running kernel.
-n Show network addresses as numbers (normally netstat interprets
addresses and attempts to display them symbolically). This
option may be used with any of the display formats.
-P pcbaddr
Display the contents of the socket or protocol control block
(PCB) located at the kernel virtual address pcbaddr. PCB
addresses can be obtained using the -A flag. When used with the
-v option, also print socket, domain and protocol specific
structures.
-p protocol
Restrict the output to protocol, which is either a well-known
name for a protocol or an alias for it. Some protocol names and
aliases are listed in the file /etc/protocols. The program will
complain if protocol is unknown. If the -s option is specified,
the per-protocol statistics are displayed. Otherwise the states
of the matching sockets are shown.
-q Only show interfaces that have seen packets (or bytes if -b is
specified).
-r Show the routing tables. If the -s option is also specified,
show routing statistics instead. When used with the -v option,
also print routing labels.
-s Show per-protocol statistics. If this option is repeated,
counters with a value of zero are suppressed.
-T tableid
Select an alternate routing table to modify or query. Table 0 is
the default table.
-t With the -i option, display the current value of the watchdog
timer function.
-u Limit statistics or address control block reports to the AF_UNIX
address family.
-v Show extra (verbose) detail for the routing tables (-r), or avoid
truncation of long addresses. When used with the -P option, also
print socket, domain and protocol specific structures.
-W interface
(IEEE 802.11 devices only) Show per-interface IEEE 802.11
wireless statistics.
-w wait
Show network interface statistics at intervals of wait seconds.
The default display, for active sockets, shows the local and remote
addresses, send and receive queue sizes (in bytes), protocol, and the
internal state of the protocol.
Address formats are of the form ``host.port'' or ``network.port'' if a
socket's address specifies a network but no specific host address. When
known, the host and network addresses are displayed symbolically
according to the databases /etc/hosts and /etc/networks, respectively.
If a symbolic name for an address is unknown, or if the -n option is
specified, the address is printed numerically, according to the address
family.
For more information regarding the Internet ``dot format'', refer to
inet(3). Unspecified or ``wildcard'' addresses and ports appear as a
single `*'. If a local port number is registered as being in use for RPC
by portmap(8), its RPC service name or RPC service number will be printed
in ``[]'' immediately after the port number.
The interface display provides a table of cumulative statistics regarding
packets transferred, errors, and collisions. The network addresses of
the interface and the maximum transmission unit (MTU) are also displayed.
The routing table display indicates the available routes and their
status. Each route consists of a destination host or network and a
gateway to use in forwarding packets. If the destination is a network in
numeric format, the netmask (in /24 style format) is appended. The flags
field shows a collection of information about the route stored as binary
choices. The individual flags are discussed in more detail in the
route(8) and route(4) manual pages.
The mapping between letters and flags is:
1 RTF_PROTO1 Protocol specific routing flag #1.
2 RTF_PROTO2 Protocol specific routing flag #2.
3 RTF_PROTO3 Protocol specific routing flag #3.
B RTF_BLACKHOLE Just discard pkts (during updates).
C RTF_CLONING Generate new routes on use.
c RTF_CLONED Cloned routes (generated from RTF_CLONING).
D RTF_DYNAMIC Created dynamically (by redirect).
G RTF_GATEWAY Destination requires forwarding by intermediary.
H RTF_HOST Host entry (net otherwise).
L RTF_LLINFO Valid protocol to link address translation.
M RTF_MODIFIED Modified dynamically (by redirect).
P RTF_MPATH Multipath route.
R RTF_REJECT Host or net unreachable.
S RTF_STATIC Manually added.
T RTF_MPLS MPLS route.
U RTF_UP Route usable.
X RTF_XRESOLVE External daemon translates proto to link
address.
Direct 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 refcnt field gives the current number of active uses of
the route. Connection oriented protocols normally hold on to a single
route for the duration of a connection while connectionless protocols
obtain a route while sending to the same destination. The use field
provides a count of the number of packets sent using that route. The MTU
entry shows the MTU associated with that route. This MTU value is used
as the basis for the TCP maximum segment size (MSS). The `L' flag
appended to the MTU value indicates that the value is locked, and that
path MTU discovery is turned off for that route. A `-' indicates that
the MTU for this route has not been set, and a default TCP maximum
segment size will be used. The interface entry indicates the network
interface utilized for the route.
When netstat is invoked with the -w option and a wait interval argument,
it displays a running count of statistics related to network interfaces.
An obsolescent version of this option used a numeric parameter with no
option, and is currently supported for backward compatibility. This
display consists of a column for the primary interface (the first
interface found during autoconfiguration) and a column summarizing
information for all interfaces. The primary interface may be replaced
with another interface with 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
interval.
SEE ALSOfstat(1), nfsstat(1), ps(1), systat(1), tcpbench(1), top(1), inet(3),
netintro(4), route(4), hosts(5), networks(5), protocols(5), services(5),
iostat(8), portmap(8), pstat(8), route(8), tcpdrop(8), trpt(8), vmstat(8)HISTORY
The netstat command appeared in 4.2BSD. IPv6 support was added by
WIDE/KAME project.
BUGS
B The notion of errors is ill-defined.
OpenBSD 4.9 October 30, 2010 OpenBSD 4.9
