netstat命令详解

netstat命令详解

NAME       netstat  -  Print network connections, routing tables, interface statistics, masquerade connections, and multi-       cast memberships

SYNOPSIS       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}

address_family_options:

[--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.

--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.

OPTIONS   --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.

--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       marked

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

-C       Print routing information from the route cache.

-Z --context       If SELinux enabled print SELinux context.

-T --notrim       Stop trimming long addresses.

delay       Netstat will cycle printing through statistics every delay seconds.  UP.

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 corre-       sponding 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.

CLOSED 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)

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