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HTML rendering created 2026-01-16 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 | BUGS | SEE ALSO | 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|-ee] [--timers|-o]
[--program|-p] [--verbose|-v] [--continuous|-c]
[--wide|-W]
netstat {--route|-r} [address_family_options] [--extend|-e|-ee]
[--verbose|-v] [--numeric|-n] [--numeric-hosts]
[--numeric-ports] [--numeric-users] [--continuous|-c]
netstat {--interfaces|-i} [--all|-a] [--extend|-e] [--numeric|-n]
[--numeric-hosts] [--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]
[--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.
Invocation Mode
The type of information printed is controlled by the first argu‐
ment, 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 respec‐
tive reception and transmission errors counters. Without
the --extended option it produces same output as ifconfig
-s, otherwise the detailed list.
--masquerade, -M
Display a list of masqueraded connections.
--statistics, -s
Display summary (SNMP) 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 addresses by using output as wide as need‐
ed. 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 res‐
olution of port or user names.
--numeric-ports
shows numerical port numbers but does not affect the reso‐
lution 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 Family
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, --in‐
et6|-6, --unix|-x, --ipx, --ax25, --netrom, --ddp, and
--bluetooth options.
The address family inet (IPv4) includes raw, udp, udplite
and tcp protocol sockets.
The address family bluetooth includes l2cap and rfcomm pro‐
tocol 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 de‐
fault.)
-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 de‐
fault.)
-C Print routing information from the route cache. (The cache
is no longer provided with Linux kernel 3.6).
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 pro‐
gram connected to this socket.
Listening: Since Kernel 2.6.18 this column contains the
current accept queue.
Send-Q Established: The count of bytes not acknowledged by the re‐
mote 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 ser‐
vice 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 sev‐
eral 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 net‐
work.
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) op‐
tion.
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 sock‐
et.
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 sock‐
et).
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)
Kernel Interface table (-i)
Output format depends on the --extended flag. if not specified
the output is compatible to the short ifconfig -s statistics ta‐
ble, otherwise the detailed interface list is used. Both docu‐
mented in ifconfig(8).
Kernel IP routing table (-r)
Output format depends on the --extended flags. If not specified
the output is the same as route -e. If one is specified, the out‐
put is the same as route default format. If the extended option
is specified twice, the output is same as route -ee. All three
documented in route(8).
/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
Occasionally strange information may appear if a socket changes as
it is viewed. This is unlikely to occur.
The performance when listing large number of sockets on busy
servers is low, use the netlink(7) based ss(8) command instead.
Homepage of the net-tools project:
⟨https://net-tools.sourceforge.io⟩
route(8), ifconfig(8), iptables(8), ss(8), ip(8)
proc(5)
The netstat user interface was written by Fred Baumgarten
<dc6iq@insu1.etec.uni-karlsruhe.de>, the man page by Matt Welsh
<mdw@tc.cornell.edu>. It was updated by Alan Cox
<Alan.Cox@linux.org>, Tuan Hoang <tqhoang@bigfoot.com>, and Bernd
Eckenfels <net-tools@lina.inka.de>. UDPLite options were added by
Brian Micek <bmicek@gmail.com>.
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 2026-01-16. (At that
time, the date of the most recent commit that was found in the
repository was 2025-12-12.) 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
man-pages@man7.org
net-tools 2025-09-10 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 2026-01-16 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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