功能说明：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。

[root@SM155 proc]# netstat -sIp:    8530928 total packets received    0 forwarded    0 incoming packets discarded    6972819 incoming packets delivered    8521573 requests sent out    1 fragments dropped after timeout    39629 reassemblies required    19667 packets reassembled ok    1 packet reassembles failedIcmp:    16023 ICMP messages received    175 input ICMP message failed.    ICMP input histogram:        destination unreachable: 4362        echo requests: 11661    19476 ICMP messages sent    0 ICMP messages failed    ICMP output histogram:        destination unreachable: 7815        echo replies: 11661Tcp:    1651264 active connections openings    159526 passive connection openings    197 failed connection attempts    150104 connection resets received    31 connections established    6439010 segments received    6739834 segments send out    423 segments retransmited    0 bad segments received.    1649444 resets sentUdp:    135397 packets received    7341 packets to unknown port received.    0 packet receive errors    1762263 packets sentTcpExt:    ArpFilter: 0    800 TCP sockets finished time wait in fast timer    300 time wait sockets recycled by time stamp    8850 delayed acks sent    1 delayed acks further delayed because of locked socket    Quick ack mode was activated 12 times    552580 packets directly queued to recvmsg prequeue.    296789 packets directly received from prequeue    724223 packets header predicted    11117 packets header predicted and directly queued to user    TCPPureAcks: 249691    TCPHPAcks: 1235152    TCPRenoRecovery: 0    TCPSackRecovery: 1    TCPSACKReneging: 0    TCPFACKReorder: 0    TCPSACKReorder: 0

 

   

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）。

[root@SM155 proc]# netstat -eActive Internet connections (w/o servers)Proto Recv-Q Send-Q Local Address               Foreign Address             State       User       Inode     tcp        0      0 10.90.243.155:49182         10.90.243.27:32931          ESTABLISHED root       382858     tcp        0      0 localhost.localdomain:49176 localhost.localdomain:39918 ESTABLISHED root       24542      tcp        1      0 10.90.243.155:64766         10.90.243.27:951            CLOSE_WAIT  root       3239351    tcp        0      0 localhost.localdomain:39015 localhost.localdomain:49178 ESTABLISHED root       24546      tcp        0      0 localhost.localdomain:39016 localhost.localdomain:49179 ESTABLISHED root       24548      tcp        0      0 10.90.243.155:ssh           10.88.22.243:3672           ESTABLISHED root       6062002

 

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。

[root@SM155 proc]# netstat -rKernel IP routing tableDestination     Gateway         Genmask         Flags   MSS Window  irtt Iface10.90.243.0     *               255.255.255.0   U         0 0          0 eth010.10.10.0      *               255.255.255.0   U         0 0          0 eth1169.254.0.0     *               255.255.0.0     U         0 0          0 eth1default         10.90.243.1     0.0.0.0         UG        0 0          0 eth0[root@SM155 proc]#

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。

[root@SM155 proc]# netstat -aActive Internet connections (servers and established)Proto Recv-Q Send-Q Local Address               Foreign Address             State      tcp        0      0 10.90.243.155:39010         *:*                         LISTEN      tcp        0      0 *:shell                     *:*                         LISTEN      tcp        0      0 10.90.243.155:39011         *:*                         LISTEN      tcp        0      0 *:39012                     *:*                         LISTEN      tcp        0      0 *:39015                     *:*                         LISTEN      tcp        0      0 *:49159                     *:*                         LISTEN      tcp        0      0 localhost.localdomain:39016 *:*                         LISTEN      tcp        0      0 *:49166                     *:*                         LISTEN      tcp        0      0 *:39918                     *:*                         LISTEN      tcp        0      0 *:sunrpc                    *:*                         LISTEN      tcp        0      0 *:49173                     *:*                         LISTEN      tcp        0      0 *:ftp                       *:*                         LISTEN      tcp        0      0 *:ssh                       *:*                         LISTEN      tcp        0      0 *:13819                     *:*                         LISTEN      tcp        0      0 *:2812                      *:*                         LISTEN      tcp        0      0 10.90.243.155:49182         *:*                         LISTEN      tcp        0      0 10.90.243.155:49182         10.90.243.27:32931          ESTABLISHED tcp        0      0 localhost.localdomain:49176 localhost.localdomain:39918 ESTABLISHED tcp        1      0 10.90.243.155:64766         10.90.243.27:951            CLOSE_WAIT  tcp        0      0 localhost.localdomain:39015 localhost.localdomain:49178 ESTABLISHED tcp        0      0 localhost.localdomain:39016 localhost.localdomain:49179 ESTABLISHED

 

netstat -n

显示所有已建立的有效连接。

[root@SM155 proc]# netstat -nActive Internet connections (w/o servers)Proto Recv-Q Send-Q Local Address               Foreign Address             State      tcp        0      0 10.90.243.155:49182         10.90.243.27:32931          ESTABLISHED tcp        0      0 127.0.0.1:49176             127.0.0.1:39918             ESTABLISHED tcp        1      0 10.90.243.155:64766         10.90.243.27:951            CLOSE_WAIT  tcp        0      0 127.0.0.1:39015             127.0.0.1:49178             ESTABLISHED tcp        0      0 127.0.0.1:39016             127.0.0.1:49179             ESTABLISHED tcp        0      0 127.0.0.1:39918             127.0.0.1:49176             ESTABLISHED tcp        0      0 10.90.243.155:58692         10.90.243.155:39010         ESTABLISHED tcp        0      0 10.90.243.155:39012         10.90.243.155:49168         ESTABLISHED tcp        0      0 127.0.0.1:39012             127.0.0.1:49174             ESTABLISHED tcp        0      0 10.90.243.155:39012         10.90.243.155:49175         ESTABLISHED tcp        0      0 127.0.0.1:39012             127.0.0.1:49160             ESTABLISHED tcp        0      0 10.90.243.155:39012         10.90.243.155:49161         ESTABLISHED tcp        0      0 127.0.0.1:39012             127.0.0.1:49167             ESTABLISHED tcp        0      0 10.90.243.155:49185         10.90.243.155:39011         ESTABLISHED tcp        0      0 127.0.0.1:49174             127.0.0.1:39012             ESTABLISHED tcp        0      0 10.90.243.155:49175         10.90.243.155:39012         ESTABLISHED tcp        0      0 10.90.243.155:49168         10.90.243.155:39012         ESTABLISHED tcp        0      0 127.0.0.1:49167             127.0.0.1:39012             ESTABLISHED tcp        0      0 127.0.0.1:49160             127.0.0.1:39012             ESTABLISHED tcp        0      0 10.90.243.155:49161         10.90.243.155:39012         ESTABLISHED tcp        0      0 10.90.243.155:49159         10.90.243.155:58726         ESTABLISHED tcp        0      0 127.0.0.1:49178             127.0.0.1:39015             ESTABLISHED