举荐浏览：每天学一个 Linux 命令（64）：ifconfig
命令简介
netstat（network statistics） 是一个命令行工具，它用来显示网络连接（传入和传出），路由表和许多网络接口（网络接口控制器或软件定义的网络接口）和网络协议统计信息。也可用于查找网络中的问题，打印 Linux 中网络系统的状态信息，查看整个 Linux 零碎的网络状况。
netstat 的应用平很广，包含 OS X、Linux、Solaris 和 BSD，以及基于 Windows NT 的操作系统，包含 Windows XP、Windows Vista、Windows 7/8/10。
语法格局
netstat { xxx } [ OPTIONS ]选项阐明
-a或--all #显示所有的网络连接信息-A<网络类型> #显示该网络类型连线中的相干地址-c或--continuous #继续列出网络状态信息-C或--cache #显示路由器配置的快取信息-e或--extend #显示网络其余相干信息-g或--groups #显示多播性能群组信息-h或--help #打印在线帮忙信息-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 #显示假装的网络连线-n或--numeric #间接应用ip地址-N或--netlink #显示网络硬件外围设备的符号连贯名称-o或--timers #显示计时器-r或--route #显示Routing Table-s或--statistice #显示所有端口的状态统计信息-t或--tcp #显示TCP传输协定的连贯状态-u或--udp #显示UDP传输协定的连贯状态-v或--verbose #显示指令执行过程信息-V或--version #显示版本信息-w或--raw #显示RAW传输协定的连线情况-x或--unix #此参数与"-A unix"参数后果雷同--ip或--inet #此参数与"-A inet"参数后果 雷同利用举例
列出端口
##列出所有端口[root@CentOS7-1 ~]# netstat -aActive Internet connections (servers and established)Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN tcp 0 0 localhost:smtp 0.0.0.0:* LISTEN tcp 0 0 localhost:8125 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:dnp-sec 0.0.0.0:* LISTEN tcp 0 52 CentOS7-1:ssh 192.168.1.93:58049 ESTABLISHEDtcp6 0 0 [::]:ssh [::]:* LISTEN tcp6 0 0 localhost:smtp [::]:* LISTEN tcp6 0 0 localhost:8125 [::]:* LISTEN tcp6 0 0 [::]:dnp-sec [::]:* LISTEN udp 0 0 localhost:8125 0.0.0.0:* udp 0 0 localhost:323 0.0.0.0:* udp6 0 0 localhost:8125 [::]:* udp6 0 0 localhost:323 [::]:* raw6 0 0 [::]:ipv6-icmp [::]:* 7 #列出所有tcp端口[root@CentOS7-1 ~]# netstat -atActive Internet connections (servers and established)Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN tcp 0 0 localhost:smtp 0.0.0.0:* LISTEN tcp 0 0 localhost:8125 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:dnp-sec 0.0.0.0:* LISTEN tcp 0 52 CentOS7-1:ssh 192.168.1.93:58049 ESTABLISHEDtcp6 0 0 [::]:ssh [::]:* LISTEN tcp6 0 0 localhost:smtp [::]:* LISTEN tcp6 0 0 localhost:8125 [::]:* LISTEN tcp6 0 0 [::]:dnp-sec [::]:* LISTEN #列出所有UDP端口[root@CentOS7-1 ~]# netstat -auActive Internet connections (servers and established)Proto Recv-Q Send-Q Local Address Foreign Address State udp 0 0 localhost:8125 0.0.0.0:* udp 0 0 localhost:323 0.0.0.0:* udp6 0 0 localhost:8125 [::]:* udp6 0 0 localhost:323 [::]:* #列出所有处于监听状态的 Socketsnetstat -l #只显示监听端口netstat -lt #只列出所有监听 tcp 端口netstat -lu #只列出所有监听 udp 端口netstat -lx #只列出所有监听 UNIX 端口 #显示每个协定的统计信息netstat -s #显示所有端口的统计信息netstat -st #显示TCP端口的统计信息netstat -su #显示UDP端口的统计信息显示路由表信息
[root@CentOS7-1 ~]# netstat -rKernel IP routing tableDestination Gateway Genmask Flags MSS Window irtt Ifacedefault gateway 0.0.0.0 UG 0 0 0 ens33192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 ens33[root@CentOS7-1 ~]# netstat -rnKernel IP routing tableDestination Gateway Genmask Flags MSS Window irtt Iface0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 ens33192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 ens33显示接口列表
[root@CentOS7-1 ~]# netstat -iKernel Interface tableIface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flgens33 1500 48619 0 5 0 7246 0 0 0 BMRUlo 65536 1730 0 0 0 1730 0 0 0 LRU分组查看各种连贯状态
[root@CentOS7-1 ~]# netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'LAST_ACK 5 (正在期待解决的申请数) SYN_RECV 3 ESTABLISHED 10 (失常数据传输状态) FIN_WAIT2 5TIME_WAIT 313 (处理完毕，期待超时完结的申请数)显示连接数
[root@CentOS7-1 ~]# netstat -an |grep :22tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp 0 52 192.168.1.100:22 192.168.1.93:58049 ESTABLISHEDtcp6 0 0 :::22 [root@CentOS7-1 ~]# netstat -an |grep :22 |wc -l3通过端口找过程ID
[root@CentOS7-1 ~]# netstat -anp | grep 58049tcp 0 52 192.168.1.100:22 192.168.1.93:58049 ESTABLISHED 1350/sshd: root@pts [root@CentOS7-1 ~]# netstat -anp | grep 58049 |grep ESTABLISHEDtcp 0 52 192.168.1.100:22 192.168.1.93:58049 ESTABLISHED 1350/sshd: root@pts [root@CentOS7-1 ~]# netstat -anp | grep 58049 |grep ESTABLISHED |awk '{print $7}'1350/sshd:[root@CentOS7-1 ~]# netstat -anp | grep 58049 |grep ESTABLISHED |awk '{print $7}' |cut -d/ -f11350查看连贯某个端口最多的IP地址
[root@CentOS7-1 ~]# netstat -ntu | grep :58049 | awk '{print $5}' | cut -d: -f1 | awk '{++ip[$1]} END {for(i in ip) print ip[i],"t",i}' | sort -nr1 192.168.1.93[root@CentOS7-1 ~]# netstat -ntu | grep :22 | awk '{print $5}' | cut -d: -f1 | awk '{++ip[$1]} END {for(i in ip) print ip[i],"t",i}' | sort -nr1 192.168.1.93显示所有端口的状态统计信息
[root@CentOS7-1 ~]# netstat -sIp: 15146 total packets received 0 forwarded 0 incoming packets discarded 15146 incoming packets delivered 3885 requests sent out 8 dropped because of missing routeIcmp: 4 ICMP messages received 0 input ICMP message failed. ICMP input histogram: destination unreachable: 4 44 ICMP messages sent 0 ICMP messages failed ICMP output histogram: destination unreachable: 44IcmpMsg: InType3: 4 OutType3: 44Tcp: 863 active connections openings 1 passive connection openings 858 failed connection attempts 0 connection resets received 1 connections established 5021 segments received 3772 segments send out 0 segments retransmited 0 bad segments received. 858 resets sentUdp: 200 packets received 44 packets to unknown port received. 0 packet receive errors 246 packets sent 0 receive buffer errors 0 send buffer errorsUdpLite:TcpExt: 1 TCP sockets finished time wait in fast timer 35 delayed acks sent 1 packets directly queued to recvmsg prequeue. 1362 packet headers predicted 438 acknowledgments not containing data payload received 1160 predicted acknowledgments TCPRcvCoalesce: 9 TCPOrigDataSent: 1719IpExt: InBcastPkts: 10042 InOctets: 4159848 OutOctets: 329931 InBcastOctets: 3778680 InNoECTPkts: 15150显示多播组信息
[root@CentOS7-1 ~]# netstat -gIPv6/IPv4 Group MembershipsInterface RefCnt Group--------------- ------ ---------------------lo 1 all-systems.mcast.netens33 1 all-systems.mcast.netlo 1 ff02::1lo 1 ff01::1ens33 1 ff02::1:ff4e:26b0ens33 1 ff02::1:ff01:b5bbens33 1 ff02::1ens33 1 ff01::1每天学一个 Linux 命令（62）：ping
每天学一个 Linux 命令（63）：route