netstat − Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
netstat [address_family_options] [−−tcp|−t] [−−udp|−u] [−−udplite|−U] [−−raw|−w] [−−listening|−l] [−−all|−a] [−−numeric|−n] [−−numeric−hosts] [−−numeric−ports] [−−numeric−users] [−−symbolic|−N] [−−extend|−e[−−extend|−e]] [−−timers|−o] [−−program|−p] [−−verbose|−v] [−−continuous|−c] [−−wide|−W] [delay]
netstat {−−route|−r} [address_family_options] [−−extend|−e[−−extend|−e]] [−−verbose|−v] [−−numeric|−n] [−−numeric−hosts] [−−numeric−ports] [−−numeric−users] [−−continuous|−c] [delay]
netstat {−−interfaces|−I|−i} [−−all|−a] [−−extend|−e] [−−verbose|−v] [−−program|−p] [−−numeric|−n] [−−numeric-hosts] [−−numeric-ports] [−−numeric-users] [−−continuous|−c] [delay]
netstat {−−groups|−g} [−−numeric|−n] [−−numeric−hosts] [−−numeric−ports] [−−numeric−users] [−−continuous|−c] [delay]
netstat {−−masquerade|−M} [−−extend|−e] [−−numeric|−n] [−−numeric−hosts] [−−numeric−ports] [−−numeric−users] [−−continuous|−c] [delay]
netstat {−−statistics|-s} [−−tcp|−t] [−−udp|−u] [−−udplite|−U] [−−raw|−w] [delay]
netstat {−−version|−V}
netstat {−−help|−h}
address_family_options:
[-4|−−inet] [-6|−−inet6] [−−protocol={inet,inet6,unix,ipx,ax25,netrom,ddp, ... } ] [−−unix|−x] [−−inet|−−ip|−−tcpip] [−−ax25] [−−x25] [−−rose] [−−ash] [−−ipx] [−−netrom] [−−ddp|−−appletalk] [−−econet|−−ec]
This program is obsolete. Replacement for netstat is ss. Replacement for netstat -r is ip route. Replacement for netstat -i is ip -s link. Replacement for netstat -g is ip maddr.
Netstat prints information about the Linux networking subsystem. The type of information printed is controlled by the first argument, as follows:
(none)
By default, netstat displays a list of open sockets.
If you don’t specify any address families, then the
active sockets of all configured address families will be
printed.
−−route
, −r
Display the kernel routing tables. See the description in
route(8) for details. netstat -r and route
-e produce the same output.
−−groups
, −g
Display multicast group membership information for IPv4 and
IPv6.
−−interfaces=iface
, −I=iface , −i
Display a table of all network interfaces, or the specified
iface.
−−masquerade
, −M
Display a list of masqueraded connections.
−−statistics
, −s
Display summary statistics for each protocol.
−−verbose
, −v
Tell the user what is going on by being verbose. Especially
print some useful information about unconfigured address
families.
−−wide
, −W
Do not truncate IP addresses by using output as wide as
needed. This is optional for now to not break existing
scripts.
−−numeric
, −n
Show numerical addresses instead of trying to determine
symbolic host, port or user names.
−−numeric−hosts
shows numerical host addresses but does not affect the
resolution of port or user names.
−−numeric−ports
shows numerical port numbers but does not affect the
resolution of host or user names.
−−numeric−users
shows numerical user IDs but does not affect the resolution
of host or port names.
−−protocol=family
, −A
Specifies the address families (perhaps better described as
low level protocols) for which connections are to be shown.
family is a comma (’,’) separated list of
address family keywords like inet, inet6,
unix, ipx, ax25, netrom,
econet, and ddp. This has the same effect as
using the −−inet|-4,
−−inet6|-6,
−−unix|-x,
−−ipx, −−ax25,
−−netrom, and −−ddp
options.
The address family inet (Iv4) includes raw, udp, udplite and tcp protocol sockets.
−c,
−−continuous
This will cause netstat to print the selected
information every second continuously.
−e,
−−extend
Display additional information. Use this option twice for
maximum detail.
−o,
−−timers
Include information related to networking timers.
−p,
−−program
Show the PID and name of the program to which each socket
belongs.
−l,
−−listening
Show only listening sockets. (These are omitted by
default.)
−a,
−−all
Show both listening and non-listening (for TCP this means
established connections) sockets. With the
−−interfaces option, show interfaces that
are not up
−F
Print routing information from the FIB. (This is the
default.)
−C
Print routing information from the route cache.
delay
Netstat will cycle printing through statistics every
delay seconds.
Active
Internet connections (TCP, UDP, UDPLite, raw)
Proto
The protocol (tcp, udp, udpl, raw) used by the socket.
Recv−Q
Established: The count of bytes not copied by the user
program connected to this socket. Listening: Since Kernel
2.6.18 this column contains the current syn backlog.
Send−Q
Established: The count of bytes not acknowledged by the
remote host. Listening: Since Kernel 2.6.18 this column
contains the maximum size of the syn backlog.
Local
Address
Address and port number of the local end of the socket.
Unless the −−numeric (−n)
option is specified, the socket address is resolved to its
canonical host name (FQDN), and the port number is
translated into the corresponding service name.
Foreign
Address
Address and port number of the remote end of the socket.
Analogous to "Local Address."
State
The state of the socket. Since there are no states in raw
mode and usually no states used in UDP and UDPLite, this
column may be left blank. Normally this can be one of
several values:
ESTABLISHED
The socket has an established connection.
SYN_SENT
The socket is actively attempting to establish a connection.
SYN_RECV
A connection request has been received from the network.
FIN_WAIT1
The socket is closed, and the connection is shutting down.
FIN_WAIT2
Connection is closed, and the socket is waiting for a shutdown from the remote end.
TIME_WAIT
The socket is waiting after close to handle packets still in the network.
|
CLOSE |
The socket is not being used. |
CLOSE_WAIT
The remote end has shut down, waiting for the socket to close.
LAST_ACK
The remote end has shut down, and the socket is closed. Waiting for acknowledgement.
|
LISTEN |
The socket is listening for incoming connections. Such sockets are not included in the output unless you specify the −−listening (−l) or −−all (−a) option. |
CLOSING
Both sockets are shut down but we still don’t have all our data sent.
UNKNOWN
The state of the socket is unknown.
User
The username or the user id (UID) of the owner of the
socket.
PID/Program
name
Slash-separated pair of the process id (PID) and process
name of the process that owns the socket.
−−program causes this column to be
included. You will also need superuser privileges to
see this information on sockets you don’t own. This
identification information is not yet available for IPX
sockets.
Timer
(this needs to be written)
Active UNIX
domain Sockets
Proto
The protocol (usually unix) used by the socket.
RefCnt
The reference count (i.e. attached processes via this
socket).
Flags
The flags displayed is SO_ACCEPTON (displayed as
ACC), SO_WAITDATA (W) or SO_NOSPACE
(N). SO_ACCECPTON is used on unconnected sockets if
their corresponding processes are waiting for a connect
request. The other flags are not of normal interest.
Type
There are several types of socket access:
SOCK_DGRAM
The socket is used in Datagram (connectionless) mode.
SOCK_STREAM
This is a stream (connection) socket.
SOCK_RAW
The socket is used as a raw socket.
SOCK_RDM
This one serves reliably-delivered messages.
SOCK_SEQPACKET
This is a sequential packet socket.
SOCK_PACKET
Raw interface access socket.
UNKNOWN
Who ever knows what the future will bring us - just fill in here :-)
State
This field will contain one of the following Keywords:
|
FREE |
The socket is not allocated |
LISTENING
The socket is listening for a connection request. Such sockets are only included in the output if you specify the −−listening (−l) or −−all (−a) option.
CONNECTING
The socket is about to establish a connection.
CONNECTED
The socket is connected.
DISCONNECTING
The socket is disconnecting.
(empty)
The socket is not connected to another one.
UNKNOWN
This state should never happen.
PID/Program
name
Process ID (PID) and process name of the process that has
the socket open. More info available in Active Internet
connections section written above.
Path
This is the path name as which the corresponding processes
attached to the socket.
Active IPX
sockets
(this needs to be done by somebody who knows it)
Active
NET/ROM sockets
(this needs to be done by somebody who knows it)
Active AX.25
sockets
(this needs to be done by somebody who knows it)
/etc/services -- The services translation file
/proc -- Mount point for the proc filesystem, which gives access to kernel status information via the following files.
/proc/net/dev -- device information
/proc/net/raw -- raw socket information
/proc/net/tcp -- TCP socket information
/proc/net/udp -- UDP socket information
/proc/net/udplite -- UDPLite socket information
/proc/net/igmp -- IGMP multicast information
/proc/net/unix -- Unix domain socket information
/proc/net/ipx -- IPX socket information
/proc/net/ax25 -- AX25 socket information
/proc/net/appletalk -- DDP (appletalk) socket information
/proc/net/nr -- NET/ROM socket information
/proc/net/route -- IP routing information
/proc/net/ax25_route -- AX25 routing information
/proc/net/ipx_route -- IPX routing information
/proc/net/nr_nodes -- NET/ROM nodelist
/proc/net/nr_neigh -- NET/ROM neighbours
/proc/net/ip_masquerade -- masqueraded connections
/proc/net/snmp -- statistics
route(8), ifconfig(8), iptables(8), proc(5) ss(8) ip(8)
Occasionally strange information may appear if a socket changes as it is viewed. This is unlikely to occur.
The netstat user interface was written by Fred Baumgarten <dc6iq@insu1.etec.uni−karlsruhe.de>, the man page basically by Matt Welsh <mdw@tc.cornell.edu>. It was updated by Alan Cox <Alan.Cox@linux.org>, updated again by Tuan Hoang <tqhoang@bigfoot.com>. The man page and the command included in the net−tools package is totally rewritten by Bernd Eckenfels <ecki@linux.de>. UDPLite options were added by Brian Micek <bmicek@gmail.com>