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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | NOTES | DESCRIPTION | OPTIONS | OUTPUT | FILES | SEE ALSO | BUGS | AUTHORS | COLOPHON |
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NETSTAT(8) Linux System Administrator's Manual NETSTAT(8)
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:
(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, -i
Display a table of all network interfaces and their respective
reception and transmission errors counters.
--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, 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.
-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. 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).
-l, --listening
Show only listening sockets. (These are omitted by default.)
-a, --all
Show both listening and non-listening 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.
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
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.
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
/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]>
This page is part of the net-tools (networking utilities)
project. Information about the project can be found at
⟨http://net-tools.sourceforge.net/⟩. If you have a bug report for
this manual page, see ⟨http://net-tools.sourceforge.net/⟩. This
page was obtained from the project's upstream Git repository
⟨git://git.code.sf.net/p/net-tools/code⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2023-06-29.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
net-tools 2014-10-07 NETSTAT(8)
Pages that refer to this page: networks(5), proc(5), proc_pid_net(5), icmp(7), arp(8), ifconfig(8), netcap(8), rarp(8), route(8), traceroute(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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