netstat(8) — Linux manual page

NAME | SYNOPSIS | NOTES | DESCRIPTION | OPTIONS | OUTPUT | FILES | SEE ALSO | BUGS | AUTHORS | COLOPHON

NETSTAT(8)         Linux System Administrator's Manual        NETSTAT(8)

NAME         top

       netstat - Print network connections, routing tables, interface
       statistics, masquerade connections, and multicast memberships

SYNOPSIS         top

       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]

NOTES         top

       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.

DESCRIPTION         top

       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.

OPTIONS         top

   --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.

OUTPUT         top

   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)

FILES         top

       /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

SEE ALSO         top

       route(8), ifconfig(8), iptables(8), proc(5), ss(8), ip(8)

BUGS         top

       Occasionally strange information may appear if a socket changes
       as it is viewed. This is unlikely to occur.

AUTHORS         top

       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>

COLOPHON         top

       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 2021-04-01.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-03-25.)  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                      2014-10-07                     NETSTAT(8)

Pages that refer to this page: networks(5)proc(5)icmp(7)arp(8)ifconfig(8)netcap(8)rarp(8)route(8)traceroute(8)