netstat(8) - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships



  • NETSTAT(8)            Linux Programmer's Manual                NETSTAT(8)
    
    
    
    NAME
           netstat - Print network connections, routing tables, interface
           statistics, masquerade connections, and multicast memberships
    
    
    SYNOPSIS
           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]
           [--continuous|-c]
    
           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}
    
           address_family_options:
    
           [-4] [-6] [--protocol={inet,unix,ipx,ax25,netrom,ddp}[,...]]
           [--unix|-x] [--inet|--ip] [--ax25] [--ipx] [--netrom] [--ddp]
    
    
    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, -i
           Display a table of all network interfaces.
    
       --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, 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
           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 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
       Active Internet connections (TCP, UDP, raw)
       Proto
           The protocol (tcp, udp, raw) used by the socket.
    
       Recv-Q
           The count of bytes not copied by the user program connected to this
           socket.
    
       Send-Q
           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."
    
       State
           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:
    
           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
           (this needs to be written)
    
       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)
    
    NOTES
           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.
    
    
    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/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
    
    SEE ALSO
           route(8), ifconfig(8), ipchains(8), iptables(8), proc(5)
    
    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]> but could do with a bit more work.  It was updated
           again by Tuan Hoang <[email protected]>.
           The man page and the command included in the net-tools package is
           totally rewritten by Bernd Eckenfels <[email protected]>.
    
    
    
    net-tools                         2008-11-16                        NETSTAT(8)
    

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