# netstat

## NAME



           netstat - Print network connections, routing tables, interface
           statistics, 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**]
    
           **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



           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, -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



       **--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



       **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



           _/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
    


## BUGS



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


* * *