netstat

NETSTAT(8)     Linux Programmer’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]   [--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 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, 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  --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
       (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 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)

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.

       If the sctp module is not added to the kernel, running netstat with the
       -A inet or -A inet6 option abnormally  terminates  with the  following
       message:

       netstat: no support for ‘AF INET (sctp)’ on this system.

       To avoid this, install the sctp kernel module.

 

 

其他帮助

Netstat用于显示与IP、TCP、UDP和ICMP协议相关的统计数据，一般用于检验本机各端口的网络连接情况。

　　语　　法：netstat [-acCeFghilMnNoprstuvVwx][-A<网络类型>][--ip]

　　补充说明：利用netstat指令可让你得知整个Linux系统的网络情况。

　　参　　数：

　　-a或–all 显示所有连线中的Socket。

　　-A<网络类型>或–<网络类型> 列出该网络类型连线中的相关地址。

　　-c或–continuous 持续列出网络状态。

　　-C或–cache 显示路由器配置的快取信息。

　　-e或–extend 显示网络其他相关信息。

　　-F或–fib 显示FIB。

　　-g或–groups 显示多重广播功能群组组员名单。

　　-h或–help 在线帮助。

　　-i或–interfaces 显示网络界面信息表单。

　　-l或–listening 显示监控中的服务器的Socket。

　　-M或–masquerade 显示伪装的网络连线。

　　-n或–numeric 直接使用IP地址，而不通过域名服务器。

　　-N或–netlink或–symbolic 显示网络硬件外围设备的符号连接名称。

　　-o或–timers 显示计时器。

　　-p或–programs 显示正在使用Socket的程序识别码和程序名称。

　　-r或–route 显示Routing Table。

　　-s或–statistice 显示网络工作信息统计表。

　　-t或–tcp 显示TCP传输协议的连线状况。

　　-u或–udp 显示UDP传输协议的连线状况。

　　-v或–verbose 显示指令执行过程。

　　-V或–version 显示版本信息。

　　-w或–raw 显示RAW传输协议的连线状况。

　　-x或–unix 此参数的效果和指定”-A unix”参数相同。

　　–ip或–inet 此参数的效果和指定”-A inet”参数相同

　　netstat 的一些常用选项

　　·netstat –s

　　本选项能够按照各个协议分别显示其统计数据。如果我们的应用程序（如Web浏览器）运行速度比较慢，或者不能显示Web页之类的数据，那么我们就可以用本选项来查看一下所显示的信息。我们需要仔细查看统计数据的各行，找到出错的关键字，进而确定问题所在。

　　·netstat –e

　　本选项用于显示关于以太网的统计数据。它列出的项目包括传送的数据报的总字节数、错误数、删除数、数据报的数量和广播的数量。这些统计数据既有发送的数据报数量，也有接收的数据报数量。这个选项可以用来统计一些基本的网络流量）。

　　·netstat –r

　　本选项可以显示关于路由表的信息，类似于后面所讲使用route print命令时看到的 信息。除了显示有效路由外，还显示当前有效的连接。

　　·netstat –a

　　本选项显示一个所有的有效连接信息列表，包括已建立的连接（ESTABLISHED），也包括监听连接请（LISTENING）的那些连接。

　　·netstat –n

　　显示所有已建立的有效连接