netstat - Print network connections, routing tables, interface statistics,
masquerade connections, and multicast memberships
netstat [
address_family_options] [
--tcp|
-t]
[
--udp|
-u] [
--udplite|
-U]
[
--sctp|
-S] [
--raw|
-w] [
--l2cap|
-2]
[
--rfcomm|
-f] [
--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]
netstat {
--route|
-r} [
address_family_options]
[
--extend|
-e[
--extend|
-e]]
[
--verbose|
-v] [
--numeric|
-n]
[
--numeric-hosts] [
--numeric-ports] [
--numeric-users]
[
--continuous|
-c]
netstat {
--interfaces|
-i} [
--all|
-a]
[
--extend|
-e[
--extend|
-e]]
[
--verbose|
-v] [
--program|
-p]
[
--numeric|
-n] [
--numeric-hosts] [
--numeric-ports]
[
--numeric-users] [
--continuous|
-c]
netstat {
--groups|
-g} [
--numeric|
-n]
[
--numeric-hosts] [
--numeric-ports] [
--numeric-users]
[
--continuous|
-c]
netstat {
--masquerade|
-M} [
--extend|
-e]
[
--numeric|
-n] [
--numeric-hosts] [
--numeric-ports]
[
--numeric-users] [
--continuous|
-c]
netstat {
--statistics|
-s} [
--tcp|
-t]
[
--udp|
-u] [
--udplite|
-U]
[
--sctp|
-S] [
--raw|
-w]
netstat {
--version|
-V}
netstat {
--help|
-h}
address_family_options:
[
-4|
--inet] [
-6|
--inet6]
[
--protocol={
inet,
inet6,
unix,
ipx,
ax25,
netrom,
ddp,
bluetooth,
... } ] [
--unix|
-x] [
--inet|
--ip|
--tcpip]
[
--ax25] [
--x25] [
--rose] [
--ash]
[
--bluetooth] [
--ipx] [
--netrom]
[
--ddp|
--appletalk] [
--econet|
--ec]
This program is mostly 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:
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.
Display the kernel routing tables. See the description in
route(8) for
details.
netstat -r and
route -e produce the same output.
Display multicast group membership information for IPv4 and IPv6.
Display a table of all network interfaces.
Display a list of masqueraded connections.
Display summary statistics for each protocol.
Tell the user what is going on by being verbose. Especially print some useful
information about unconfigured address families.
Do not truncate IP addresses by using output as wide as needed. This is optional
for now to not break existing scripts.
Show numerical addresses instead of trying to determine symbolic host, port or
user names.
shows numerical host addresses but does not affect the resolution of port or
user names.
shows numerical port numbers but does not affect the resolution of host or user
names.
shows numerical user IDs but does not affect the resolution of host or port
names.
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,
ddp, and
bluetooth. This has the same effect as using the
--inet|
-4,
--inet6|
-6,
--unix|
-x,
--ipx,
--ax25,
--netrom,
--ddp, and
--bluetooth options.
The address family
inet (Iv4) includes raw, udp, udplite and tcp protocol
sockets.
The address family
bluetooth (Iv4) includes l2cap and rfcomm protocol
sockets.
This will cause
netstat to print the selected information every second
continuously.
Display additional information. Use this option twice for maximum detail.
Include information related to networking timers.
Show the PID and name of the program to which each socket belongs. A hyphen is
shown if the socket belongs to the kernel (e.g. a kernel service, or the
process has exited but the socket hasn't finished closing yet).
Show only listening sockets. (These are omitted by default.)
Show both listening and non-listening sockets. With the
--interfaces
option, show interfaces that are not up
Print routing information from the FIB. (This is the default.)
Print routing information from the route cache.
The protocol (tcp, udp, udpl, raw) used by the socket.
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.
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.
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.
Address and port number of the remote end of the socket. Analogous to
"Local Address".
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.
The username or the user id (UID) of the owner of the socket.
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.
TCP timer associated with this socket. The format is timer(a/b/c). The timer is
one of the following values:
- off
- There is no timer set for this socket.
- on
- The retransmission timer is active for the socket.
- keepalive
- The keepalive timer is active for the socket.
- timewait
- The connection is closing and the timewait timer is active
for the socket.
The values in the brackets:
- a
- Timer value.
- b
- Number of retransmissions sent.
- c
- Number of keepalives sent.
The protocol (usually unix) used by the socket.
The reference count (i.e. attached processes via this socket).
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.
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 :-)
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.
Process ID (PID) and process name of the process that has the socket open. More
info available in
Active Internet connections section written above.
This is the path name as which the corresponding processes attached to the
socket.
(this needs to be done by somebody who knows it)
(this needs to be done by somebody who knows it)
(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
/sys/kernel/debug/bluetooth/l2cap -- Bluetooth L2CAP information
/sys/kernel/debug/bluetooth/rfcomm -- Bluetooth serial 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
<
[email protected]>, the man page basically by Matt
Welsh <
[email protected]>. It was updated by Alan Cox
<
[email protected]>, updated again by Tuan Hoang
<
[email protected]>. The man page and the command included in the
net-tools package is totally rewritten by Bernd Eckenfels
<
[email protected]>. UDPLite options were added by Brian Micek
<
[email protected]>