Man Linux: Main Page and Category List


       netstat   -   Print  network  connections,  routing  tables,  interface
       statistics, 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-users]           [--symbolic|-N]
       [--extend|-e[--extend|-e]]  [--timers|-o] [--program|-p] [--verbose|-v]

       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] [--raw|-w]

       netstat {--version|-V}

       netstat {--help|-h}


       [-4]      [-6]       [--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 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.

   --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.

       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 up

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

       Print routing information from the route cache.


   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

       CLOSE  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
              --listening (-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
       information  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 <>.