NETSTAT linux command manual

NETSTAT(8)                Linux Programmer's Manual                NETSTAT(8)

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

       netstat  [address_family_options]  [--tcp|-t]  [--udp|-u]   [--raw|-w]
       [--listening|-l]       [--all|-a]      [--numeric|-n]      [--numeric-
       hosts][--numeric-ports][--numeric-ports]               [--symbolic|-N]
       [--extend|-e[--extend|-e]] [--timers|-o] [--program|-p] [--verbose|-v]
       [--continuous|-c] [delay]

       netstat             {--route|-r}              [address_family_options]
       [--extend|-e[--extend|-e]]  [--verbose|-v]  [--numeric|-n] [--numeric-
       hosts][--numeric-ports][--numeric-ports] [--continuous|-c] [delay]

       netstat         {--interfaces|-i}          [iface]          [--all|-a]
       [--extend|-e[--extend|-e]]        [--verbose|-v]        [--program|-p]
       [--numeric|-n]     [--numeric-hosts][--numeric-ports][--numeric-ports]
       [--continuous|-c] [delay]

       netstat   {--groups|-g}   [--numeric|-n]  [--numeric-hosts][--numeric-
       ports][--numeric-ports] [--continuous|-c] [delay]

       netstat  {--masquerade|-M}  [--extend|-e]  [--numeric|-n]  [--numeric-
       hosts][--numeric-ports][--numeric-ports] [--continuous|-c] [delay]

       netstat {--statistics|-s} [--tcp|-t] [--udp|-u] [--raw|-w] [delay]

       netstat {--version|-V}

       netstat {--help|-h}


       [--protocol={inet,unix,ipx,ax25,netrom,ddp}[,...]]         [--unix|-x]
       [--inet|--ip] [--ax25] [--ipx] [--netrom] [--ddp]

       Netstat prints information about the Linux networking subsystem.   The
       type  of  information  printed is controlled by the first argument, as

       By default, netstat displays a list of open  sockets.   If  you  don't
       specify  any  address families, then the active sockets of all config-
       ured address families will be printed.

   --route , -r
       Display the kernel routing tables.

   --groups , -g
       Display multicast group membership information for IPv4 and IPv6.

   --interface=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.

   --numeric , -n
       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.

   --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, unix, ipx,
       ax25, netrom, and ddp.  This has the same effect as using the  --inet,
       --unix (-x), --ipx, --ax25, --netrom, and --ddp options.

       The address family inet includes raw, udp and tcp protocol sockets.

   -c, --continuous
       This will cause netstat to print the selected information every second

   -e, --extend
       Display additional information.  Use this  option  twice  for  maximum

   -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 sockets.  With the --interfaces
       option, show interfaces that are not marked

       Print routing information from the FIB.  (This is the default.)

       Print routing information from the route cache.

       Netstat will cycle printing through statistics  every  delay  seconds.

   Active Internet connections (TCP, UDP, raw)
       The protocol (tcp, udp, raw) used by the socket.

       The  count  of  bytes not copied by the user program connected to this

       The count of bytes not acknowledged by the remote host.

   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."

       The state of the socket. Since there are no states  in  raw  mode  and
       usually no states used in UDP, this column may be left blank. Normally
       this can be one of several values:

              The socket has an established connection.

              The socket is actively attempting to establish a connection.

              A connection request has been received from the network.

              The socket is closed, and the connection is shutting down.

              Connection is closed, and the socket is waiting for a  shutdown
              from the remote end.

              The  socket  is  waiting after close to handle packets still in
              the network.

       CLOSED The socket is not being used.

              The remote end has shut down, waiting for the socket to  close.

              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 --listen-
              ing (-l) or --all (-a) option.

              Both sockets are shut down but we still don't have all our data

              The state of the socket is unknown.

       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 infor-
       mation on sockets you don't own.  This identification  information  is
       not yet available for IPX sockets.

       (this needs to be written)

   Active UNIX domain Sockets
       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:

              The socket is used in Datagram (connectionless) mode.

              This is a stream (connection) socket.

              The socket is used as a raw socket.

              This one serves reliably-delivered messages.

              This is a sequential packet socket.

              Raw interface access socket.

              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

              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.

              The socket is about to establish a connection.

              The socket is connected.

              The socket is disconnecting.

              The socket is not connected to another one.

              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.

       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)

       Starting with Linux release 2.2 netstat -i  does  not  show  interface
       statistics  for  alias interfaces. To get per alias interface counters
       you need to setup explicit rules using the ipchains(8) command.

       /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/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), ipchains(8), iptables(8), proc(5)

       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
         the  man  page  basically by Matt
       Welsh   .   It   was   updated   by    Alan    Cox
         but  could  do  with  a  bit  more work.  It was
       updated again by Tuan Hoang .
       The man page and the command included  in  the  net-tools  package  is
       totally rewritten by Bernd Eckenfels .

net-tools                      19 December 2000                    NETSTAT(8)