netstat(8) - Print network connections, routing tables, interface...



  • NETSTAT(8)            Linux System Administrator's Manual           NETSTAT(8)
    
    NAME
           netstat  - Print network connections, routing tables, interface statis‐
           tics, masquerade connections, and multicast memberships
    
    SYNOPSIS
           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] [delay]
    
           netstat              {--route|-r}              [address_family_options]
           [--extend|-e[--extend|-e]]        [--verbose|-v]         [--numeric|-n]
           [--numeric-hosts] [--numeric-ports] [--numeric-users] [--continuous|-c]
           [delay]
    
           netstat {--interfaces|-I|-i}  [--all|-a]  [--extend|-e]  [--verbose|-v]
           [--program|-p]   [--numeric|-n]   [--numeric-hosts]   [--numeric-ports]
           [--numeric-users] [--continuous|-c] [delay]
    
           netstat      {--groups|-g}       [--numeric|-n]       [--numeric-hosts]
           [--numeric-ports] [--numeric-users] [--continuous|-c] [delay]
    
           netstat       {--masquerade|-M}       [--extend|-e]      [--numeric|-n]
           [--numeric-hosts] [--numeric-ports] [--numeric-users] [--continuous|-c]
           [delay]
    
           netstat    {--statistics|-s}   [--tcp|-t]   [--udp|-u]   [--udplite|-U]
           [--sctp|-S] [--raw|-w] [delay]
    
           netstat {--version|-V}
    
           netstat {--help|-h}
    
           address_family_options:
    
           [-4|--inet]                   [-6|--inet6]                    [--proto‐
           col={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
           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
           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=iface , -I=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.
    
    OPTIONS
       --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 proto‐
           col 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.
    
       -l, --listening
           Show only listening sockets.  (These are omitted by default.)
    
       -a, --all
           Show  both  listening and non-listening (for TCP this means established
           connections) 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.
    
       delay
           Netstat will cycle printing through statistics every delay seconds.
    
    OUTPUT
       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 con‐
           nected to this socket.  Listening: Since Kernel 2.6.18 this column con‐
           tains 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 usu‐
           ally 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 --listen‐
                  ing (-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 informa‐
           tion 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 writ‐
           ten 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
           /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
           route(8), ifconfig(8), iptables(8), proc(5) ss(8) ip(8)
    
    BUGS
           Occasionally  strange  information may appear if a socket changes as it
           is viewed. This is unlikely to occur.
    
    AUTHORS
           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]‐
           foot.com>. The man page and the command included in the net-tools pack‐
           age  is  totally rewritten by Bernd Eckenfels <[email protected]>.  UDPLite
           options were added by Brian Micek <[email protected]>
    
    net-tools                         2014-10-07                        NETSTAT(8)
    

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