netstat命令用于显示与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。netstat是在内核中访问网络及相关信息的程序，它能提供TCP连接，TCP和UDP监听，进程内存管理的相关报告。
如果计算机有时候接收到的数据报导致出错数据或故障，不必感到奇怪，TCP/IP可以容许这些类型的错误，并能够自动重发数据报。但如果累计的出错情况数目占到所接收的IP数据报相当大的百分比，或者它的数目正迅速增加，那么就应该使用netstat查一查为什么会出现这些情况了。
1．命令格式
netstat [-acCeFghilMnNoprstuvVwx][-A<网络类型>][--ip]
2．命令功能
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。
3．命令参数
-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。
4．使用实例
实例1：无参数使用
命令：
netstat
输出：
[zaixian@localhost ~]$ netstat
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 localhost.localdoma:ssh 192.168.0.5:54835 ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ] DGRAM 13100 /run/systemd/shutdownd
unix 2 [ ] DGRAM 8385 /run/systemd/notify
unix 2 [ ] DGRAM 8387 /run/systemd/cgroups-agent
unix 5 [ ] DGRAM 8398 /run/systemd/journal/socket
unix 13 [ ] DGRAM 8400 /dev/log
unix 3 [ ] STREAM CONNECTED 19870
unix 3 [ ] STREAM CONNECTED 19850
unix 3 [ ] STREAM CONNECTED 19871
unix 3 [ ] STREAM CONNECTED 19830
unix 3 [ ] STREAM CONNECTED 16422
unix 3 [ ] STREAM CONNECTED 19852
unix 3 [ ] STREAM CONNECTED 16423 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19873
unix 3 [ ] STREAM CONNECTED 19874
unix 3 [ ] STREAM CONNECTED 15501
unix 3 [ ] STREAM CONNECTED 19847
unix 3 [ ] STREAM CONNECTED 19821
unix 3 [ ] STREAM CONNECTED 19849
unix 3 [ ] STREAM CONNECTED 19844
unix 3 [ ] STREAM CONNECTED 19820
unix 3 [ ] STREAM CONNECTED 19876
unix 3 [ ] STREAM CONNECTED 19833
unix 3 [ ] STREAM CONNECTED 19877
unix 2 [ ] DGRAM 16501
unix 3 [ ] STREAM CONNECTED 16576
unix 3 [ ] STREAM CONNECTED 19879
unix 3 [ ] STREAM CONNECTED 19829
unix 2 [ ] DGRAM 80277
unix 3 [ ] STREAM CONNECTED 19880
unix 3 [ ] STREAM CONNECTED 15803 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 19882
unix 3 [ ] STREAM CONNECTED 19263
unix 3 [ ] STREAM CONNECTED 19883
unix 3 [ ] STREAM CONNECTED 19853
unix 2 [ ] DGRAM 16412
unix 3 [ ] STREAM CONNECTED 19855
unix 3 [ ] STREAM CONNECTED 15802
unix 3 [ ] STREAM CONNECTED 19856
unix 3 [ ] STREAM CONNECTED 15502 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 80280
unix 3 [ ] STREAM CONNECTED 19858
unix 3 [ ] STREAM CONNECTED 19859
unix 3 [ ] STREAM CONNECTED 80281
unix 3 [ ] STREAM CONNECTED 19861
unix 3 [ ] STREAM CONNECTED 19843
unix 3 [ ] STREAM CONNECTED 19862
unix 3 [ ] STREAM CONNECTED 15457
unix 3 [ ] STREAM CONNECTED 19864
unix 3 [ ] STREAM CONNECTED 15613 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19865
unix 3 [ ] STREAM CONNECTED 19846
unix 2 [ ] DGRAM 80112
unix 3 [ ] STREAM CONNECTED 19867
unix 3 [ ] STREAM CONNECTED 16577 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19868
unix 2 [ ] DGRAM 15509
unix 3 [ ] STREAM CONNECTED 19264 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 16129 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 13393
unix 3 [ ] STREAM CONNECTED 19837
unix 2 [ ] DGRAM 13285
unix 3 [ ] STREAM CONNECTED 13530 /run/systemd/journal/stdout
unix 2 [ ] DGRAM 19784
unix 3 [ ] STREAM CONNECTED 16379 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 16160
unix 3 [ ] STREAM CONNECTED 13796 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 15732 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 15611
unix 3 [ ] STREAM CONNECTED 13777
unix 2 [ ] DGRAM 20011
unix 3 [ ] STREAM CONNECTED 16106 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 19840
......
说明：
从整体上看，netstat的输出结果可以分为两个部分：
一个是Active Internet connections，称为有源TCP连接，其中”Recv-Q”和”Send-Q”指的是接收队列和发送队列。这些数字一般都应该是0。如果不是则表示软件包正在队列中堆积。这种情况只能在非常少的情况见到。
另一个是Active UNIX domain sockets，称为有源Unix域套接口(和网络套接字一样，但是只能用于本机通信，性能可以提高一倍)。
Proto显示连接使用的协议,RefCnt表示连接到本套接口上的进程号,Types显示套接口的类型,State显示套接口当前的状态,Path表示连接到套接口的其它进程使用的路径名。
套接口类型：
-t：TCP-u：UDP-raw：RAW类型--unix：UNIX域类型--ax25：AX25类型--ipx：ipx类型--netrom：netrom类型
状态说明：
LISTEN：侦听来自远方的TCP端口的连接请求SYN-SENT：再发送连接请求后等待匹配的连接请求(如果有大量这样的状态包，检查是否中招了)SYN-RECEIVED：再收到和发送一个连接请求后等待对方对连接请求的确认(如有大量此状态，估计被flood攻击了)ESTABLISHED：代表一个打开的连接FIN-WAIT-1：等待远程TCP连接中断请求，或先前的连接中断请求的确认FIN-WAIT-2：从远程TCP等待连接中断请求CLOSE-WAIT：等待从本地用户发来的连接中断请求CLOSING：等待远程TCP对连接中断的确认LAST-ACK：等待原来的发向远程TCP的连接中断请求的确认(不是什么好东西，此项出现，检查是否被攻击)TIME-WAIT：等待足够的时间以确保远程TCP接收到连接中断请求的确认CLOSED：没有任何连接状态
实例2：列出所有端口
命令：
netstat -a
输出：
[zaixian@localhost ~]$ netstat -a
Active 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 52 localhost.localdoma:ssh 192.168.0.5:54835 ESTABLISHED
tcp6 0 0 [::]:ssh [::]:* LISTEN
tcp6 0 0 localhost:smtp [::]:* LISTEN
udp 0 0 0.0.0.0:trnsprntproxy 0.0.0.0:*
udp 0 0 localhost:323 0.0.0.0:*
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp6 0 0 [::]:rnm [::]:*
udp6 0 0 localhost:323 [::]:*
raw6 0 0 [::]:ipv6-icmp [::]:* 7
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ACC ] STREAM LISTENING 12805 /run/lvm/lvmpolld.socket
unix 2 [ ACC ] SEQPACKET LISTENING 12811 /run/udev/control
unix 2 [ ACC ] STREAM LISTENING 12827 /run/lvm/lvmetad.socket
unix 2 [ ] DGRAM 13100 /run/systemd/shutdownd
unix 2 [ ACC ] STREAM LISTENING 19872 public/showq
unix 2 [ ACC ] STREAM LISTENING 19842 private/rewrite
unix 2 [ ACC ] STREAM LISTENING 15231 /var/run/dbus/system_bus_socket
unix 2 [ ACC ] STREAM LISTENING 19845 private/bounce
unix 2 [ ACC ] STREAM LISTENING 19848 private/defer
unix 2 [ ACC ] STREAM LISTENING 19851 private/trace
unix 2 [ ACC ] STREAM LISTENING 19854 private/verify
unix 2 [ ACC ] STREAM LISTENING 19860 private/proxymap
unix 2 [ ACC ] STREAM LISTENING 19863 private/proxywrite
unix 2 [ ACC ] STREAM LISTENING 19866 private/smtp
unix 2 [ ACC ] STREAM LISTENING 19869 private/relay
unix 2 [ ACC ] STREAM LISTENING 19875 private/error
unix 2 [ ACC ] STREAM LISTENING 19878 private/retry
unix 2 [ ACC ] STREAM LISTENING 19881 private/discard
unix 2 [ ACC ] STREAM LISTENING 19884 private/local
unix 2 [ ACC ] STREAM LISTENING 19887 private/virtual
unix 2 [ ACC ] STREAM LISTENING 19890 private/lmtp
unix 2 [ ACC ] STREAM LISTENING 19893 private/anvil
unix 2 [ ACC ] STREAM LISTENING 19896 private/scache
unix 2 [ ACC ] STREAM LISTENING 19822 public/pickup
unix 2 [ ACC ] STREAM LISTENING 19832 public/cleanup
unix 2 [ ACC ] STREAM LISTENING 19835 public/qmgr
unix 2 [ ACC ] STREAM LISTENING 19857 public/flush
unix 2 [ ACC ] STREAM LISTENING 17836 /var/run/NetworkManager/private-dhcp
unix 2 [ ] DGRAM 8385 /run/systemd/notify
unix 2 [ ] DGRAM 8387 /run/systemd/cgroups-agent
unix 2 [ ACC ] STREAM LISTENING 19839 private/tlsmgr
......
说明：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。
实例3：显示当前UDP连接状况
命令：
netstat -nu
输出：
[zaixian@localhost ~]$ netstat -nu
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
[zaixian@localhost ~]$
实例4：显示UDP端口号的使用情况
命令：
netstat -apu
输出：
[zaixian@localhost ~]$ netstat -apu
(No info could be read for "-p": geteuid()=1000 but you should be root.)
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
udp 0 0 0.0.0.0:trnsprntproxy 0.0.0.0:* -
udp 0 0 localhost:323 0.0.0.0:* -
udp 0 0 0.0.0.0:bootpc 0.0.0.0:* -
udp6 0 0 [::]:rnm [::]:* -
udp6 0 0 localhost:323 [::]:* -
[zaixian@localhost ~]$
实例5：显示网卡列表
命令：
netstat -i
输出：
[zaixian@localhost ~]$ netstat -i
Kernel Interface table
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
ens33 1500 63831 0 0 0 6313 0 0 0 BMRU
lo 65536 19 0 0 0 19 0 0 0 LRU
[zaixian@localhost ~]$
实例6：显示组播组的关系
命令：
netstat -g
输出：
[zaixian@localhost ~]$ netstat -g
IPv6/IPv4 Group Memberships
Interface RefCnt Group
--------------- ------ ---------------------
lo 1 all-systems.mcast.net
ens33 1 all-systems.mcast.net
lo 1 ff02::1
lo 1 ff01::1
ens33 1 ff02::1:ff35:dd8c
ens33 1 ff02::1
ens33 1 ff01::1
[zaixian@localhost ~]$
实例7：显示网络统计信息
命令：
netstat -s
输出：
[zaixian@localhost ~]$ netstat -s
Ip:
28607 total packets received
0 forwarded
0 incoming packets discarded
4123 incoming packets delivered
4143 requests sent out
50 dropped because of missing route
Icmp:
767 ICMP messages received
402 input ICMP message failed.
ICMP input histogram:
destination unreachable: 152
timeout in transit: 164
echo requests: 402
echo replies: 49
467 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 9
echo request: 458
IcmpMsg:
InType0: 49
InType3: 152
InType8: 402
InType11: 164
OutType3: 9
OutType8: 458
Tcp:
3 active connections openings
3 passive connection openings
0 failed connection attempts
0 connection resets received
1 connections established
2880 segments received
2548 segments send out
0 segments retransmited
0 bad segments received.
0 resets sent
Udp:
474 packets received
2 packets to unknown port received.
0 packet receive errors
1160 packets sent
0 receive buffer errors
0 send buffer errors
UdpLite:
TcpExt:
3 TCP sockets finished time wait in fast timer
11 delayed acks sent
1 delayed acks further delayed because of locked socket
1 packets directly queued to recvmsg prequeue.
1139 packet headers predicted
441 acknowledgments not containing data payload received
1356 predicted acknowledgments
IPReversePathFilter: 1
TCPRcvCoalesce: 69
TCPOrigDataSent: 2427
IpExt:
InNoRoutes: 5
InMcastPkts: 435
InBcastPkts: 24444
OutBcastPkts: 402
InOctets: 2452235
OutOctets: 539407
InMcastOctets: 13920
InBcastOctets: 2027384
OutBcastOctets: 33768
InNoECTPkts: 28642
[zaixian@localhost ~]$
说明：
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。
实例8：显示监听的套接口
命令：
netstat -l
输出：
[zaixian@localhost ~]$ netstat -l
Active Internet connections (only servers)
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
tcp6 0 0 [::]:ssh [::]:* LISTEN
tcp6 0 0 localhost:smtp [::]:* LISTEN
udp 0 0 0.0.0.0:trnsprntproxy 0.0.0.0:*
udp 0 0 localhost:323 0.0.0.0:*
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp6 0 0 [::]:rnm [::]:*
udp6 0 0 localhost:323 [::]:*
raw6 0 0 [::]:ipv6-icmp [::]:* 7
Active UNIX domain sockets (only servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ACC ] STREAM LISTENING 12805 /run/lvm/lvmpolld.socket
unix 2 [ ACC ] SEQPACKET LISTENING 12811 /run/udev/control
unix 2 [ ACC ] STREAM LISTENING 12827 /run/lvm/lvmetad.socket
unix 2 [ ACC ] STREAM LISTENING 19872 public/showq
unix 2 [ ACC ] STREAM LISTENING 19842 private/rewrite
unix 2 [ ACC ] STREAM LISTENING 15231 /var/run/dbus/system_bus_socket
unix 2 [ ACC ] STREAM LISTENING 19845 private/bounce
unix 2 [ ACC ] STREAM LISTENING 19848 private/defer
unix 2 [ ACC ] STREAM LISTENING 19851 private/trace
unix 2 [ ACC ] STREAM LISTENING 19854 private/verify
unix 2 [ ACC ] STREAM LISTENING 19860 private/proxymap
unix 2 [ ACC ] STREAM LISTENING 19863 private/proxywrite
unix 2 [ ACC ] STREAM LISTENING 19866 private/smtp
unix 2 [ ACC ] STREAM LISTENING 19869 private/relay
unix 2 [ ACC ] STREAM LISTENING 19875 private/error
unix 2 [ ACC ] STREAM LISTENING 19878 private/retry
unix 2 [ ACC ] STREAM LISTENING 19881 private/discard
unix 2 [ ACC ] STREAM LISTENING 19884 private/local
unix 2 [ ACC ] STREAM LISTENING 19887 private/virtual
unix 2 [ ACC ] STREAM LISTENING 19890 private/lmtp
unix 2 [ ACC ] STREAM LISTENING 19893 private/anvil
unix 2 [ ACC ] STREAM LISTENING 19896 private/scache
unix 2 [ ACC ] STREAM LISTENING 19822 public/pickup
unix 2 [ ACC ] STREAM LISTENING 19832 public/cleanup
unix 2 [ ACC ] STREAM LISTENING 19835 public/qmgr
unix 2 [ ACC ] STREAM LISTENING 19857 public/flush
unix 2 [ ACC ] STREAM LISTENING 17836 /var/run/NetworkManager/private-dhcp
unix 2 [ ACC ] STREAM LISTENING 19839 private/tlsmgr
unix 2 [ ACC ] STREAM LISTENING 8395 /run/systemd/journal/stdout
unix 2 [ ACC ] STREAM LISTENING 12794 /run/systemd/private
[zaixian@localhost ~]$
实例9：显示所有已建立的有效连接
命令：
netstat -n
输出：
[zaixian@localhost ~]$ netstat -n
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 52 192.168.0.197:22 192.168.0.5:54835 ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ] DGRAM 13100 /run/systemd/shutdownd
unix 2 [ ] DGRAM 8385 /run/systemd/notify
unix 2 [ ] DGRAM 8387 /run/systemd/cgroups-agent
unix 5 [ ] DGRAM 8398 /run/systemd/journal/socket
unix 13 [ ] DGRAM 8400 /dev/log
unix 3 [ ] STREAM CONNECTED 19870
unix 3 [ ] STREAM CONNECTED 19850
unix 3 [ ] STREAM CONNECTED 19871
unix 3 [ ] STREAM CONNECTED 19830
unix 3 [ ] STREAM CONNECTED 16422
unix 3 [ ] STREAM CONNECTED 19852
unix 3 [ ] STREAM CONNECTED 16423 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19873
unix 3 [ ] STREAM CONNECTED 19874
unix 3 [ ] STREAM CONNECTED 15501
unix 3 [ ] STREAM CONNECTED 19847
unix 3 [ ] STREAM CONNECTED 19821
unix 3 [ ] STREAM CONNECTED 19849
unix 3 [ ] STREAM CONNECTED 19844
unix 3 [ ] STREAM CONNECTED 19820
unix 3 [ ] STREAM CONNECTED 19876
unix 3 [ ] STREAM CONNECTED 19833
unix 3 [ ] STREAM CONNECTED 19877
unix 2 [ ] DGRAM 16501
unix 3 [ ] STREAM CONNECTED 16576
unix 3 [ ] STREAM CONNECTED 19879
unix 3 [ ] STREAM CONNECTED 19829
unix 2 [ ] DGRAM 80277
unix 3 [ ] STREAM CONNECTED 19880
unix 3 [ ] STREAM CONNECTED 15803 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 19882
unix 3 [ ] STREAM CONNECTED 19263
unix 3 [ ] STREAM CONNECTED 19883
unix 3 [ ] STREAM CONNECTED 19853
unix 2 [ ] DGRAM 16412
unix 3 [ ] STREAM CONNECTED 19855
unix 3 [ ] STREAM CONNECTED 15802
unix 3 [ ] STREAM CONNECTED 19856
unix 3 [ ] STREAM CONNECTED 15502 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 80280
unix 3 [ ] STREAM CONNECTED 19858
unix 3 [ ] STREAM CONNECTED 19859
unix 3 [ ] STREAM CONNECTED 80281
unix 3 [ ] STREAM CONNECTED 19861
unix 3 [ ] STREAM CONNECTED 19843
unix 3 [ ] STREAM CONNECTED 19862
unix 3 [ ] STREAM CONNECTED 15457
unix 3 [ ] STREAM CONNECTED 19864
unix 3 [ ] STREAM CONNECTED 15613 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19865
unix 3 [ ] STREAM CONNECTED 19846
unix 2 [ ] DGRAM 80112
unix 3 [ ] STREAM CONNECTED 19867
unix 3 [ ] STREAM CONNECTED 16577 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19868
unix 2 [ ] DGRAM 15509
unix 3 [ ] STREAM CONNECTED 19264 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 16129 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 13393
unix 3 [ ] STREAM CONNECTED 19837
unix 2 [ ] DGRAM 13285
unix 3 [ ] STREAM CONNECTED 13530 /run/systemd/journal/stdout
unix 2 [ ] DGRAM 19784
unix 3 [ ] STREAM CONNECTED 16379 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 16160
unix 3 [ ] STREAM CONNECTED 13796 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 15732 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 15611
unix 3 [ ] STREAM CONNECTED 13777
unix 2 [ ] DGRAM 20011
unix 3 [ ] STREAM CONNECTED 16106 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 19840
unix 2 [ ] DGRAM 16231
unix 3 [ ] STREAM CONNECTED 16105
unix 3 [ ] STREAM CONNECTED 16320
unix 3 [ ] STREAM CONNECTED 19885
unix 3 [ ] DGRAM 13816
unix 3 [ ] STREAM CONNECTED 18433 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 16321 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19886
unix 3 [ ] STREAM CONNECTED 16161 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 16378
unix 3 [ ] STREAM CONNECTED 19888
unix 3 [ ] STREAM CONNECTED 15612
unix 3 [ ] STREAM CONNECTED 18432
unix 3 [ ] STREAM CONNECTED 19889
unix 2 [ ] DGRAM 16204
unix 3 [ ] STREAM CONNECTED 15731
unix 3 [ ] STREAM CONNECTED 19834
unix 3 [ ] STREAM CONNECTED 19891
unix 3 [ ] STREAM CONNECTED 19841
unix 3 [ ] STREAM CONNECTED 19836
unix 2 [ ] DGRAM 79889
unix 3 [ ] STREAM CONNECTED 19892
unix 2 [ ] DGRAM 16133
unix 3 [ ] STREAM CONNECTED 15152
unix 3 [ ] STREAM CONNECTED 16128
unix 3 [ ] STREAM CONNECTED 19894
unix 3 [ ] STREAM CONNECTED 19895
unix 3 [ ] STREAM CONNECTED 15153
unix 3 [ ] STREAM CONNECTED 19897
unix 3 [ ] STREAM CONNECTED 19898
unix 3 [ ] DGRAM 13817
unix 2 [ ] DGRAM 13797
unix 2 [ ] DGRAM 15143
[zaixian@localhost ~]$
实例10：显示关于以太网的统计数据
命令：
netstat -e
输出：
[zaixian@localhost ~]$ netstat -e
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode
tcp 0 52 localhost.localdoma:ssh 192.168.0.5:54835 ESTABLISHED root 80161
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ] DGRAM 13100 /run/systemd/shutdownd
unix 2 [ ] DGRAM 8385 /run/systemd/notify
unix 2 [ ] DGRAM 8387 /run/systemd/cgroups-agent
unix 5 [ ] DGRAM 8398 /run/systemd/journal/socket
unix 13 [ ] DGRAM 8400 /dev/log
unix 3 [ ] STREAM CONNECTED 19870
unix 3 [ ] STREAM CONNECTED 19850
unix 3 [ ] STREAM CONNECTED 19871
unix 3 [ ] STREAM CONNECTED 19830
unix 3 [ ] STREAM CONNECTED 16422
unix 3 [ ] STREAM CONNECTED 19852
unix 3 [ ] STREAM CONNECTED 16423 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19873
unix 3 [ ] STREAM CONNECTED 19874
unix 3 [ ] STREAM CONNECTED 15501
unix 3 [ ] STREAM CONNECTED 19847
unix 3 [ ] STREAM CONNECTED 19821
unix 3 [ ] STREAM CONNECTED 19849
unix 3 [ ] STREAM CONNECTED 19844
unix 3 [ ] STREAM CONNECTED 19820
unix 3 [ ] STREAM CONNECTED 19876
unix 3 [ ] STREAM CONNECTED 19833
unix 3 [ ] STREAM CONNECTED 19877
unix 2 [ ] DGRAM 16501
unix 3 [ ] STREAM CONNECTED 16576
unix 3 [ ] STREAM CONNECTED 19879
unix 3 [ ] STREAM CONNECTED 19829
unix 2 [ ] DGRAM 80277
unix 3 [ ] STREAM CONNECTED 19880
unix 3 [ ] STREAM CONNECTED 15803 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 19882
unix 3 [ ] STREAM CONNECTED 19263
unix 3 [ ] STREAM CONNECTED 19883
unix 3 [ ] STREAM CONNECTED 19853
unix 2 [ ] DGRAM 16412
unix 3 [ ] STREAM CONNECTED 19855
unix 3 [ ] STREAM CONNECTED 15802
unix 3 [ ] STREAM CONNECTED 19856
unix 3 [ ] STREAM CONNECTED 15502 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 80280
unix 3 [ ] STREAM CONNECTED 19858
unix 3 [ ] STREAM CONNECTED 19859
unix 3 [ ] STREAM CONNECTED 80281
unix 3 [ ] STREAM CONNECTED 19861
unix 3 [ ] STREAM CONNECTED 19843
unix 3 [ ] STREAM CONNECTED 19862
unix 3 [ ] STREAM CONNECTED 15457
unix 3 [ ] STREAM CONNECTED 19864
unix 3 [ ] STREAM CONNECTED 15613 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19865
unix 3 [ ] STREAM CONNECTED 19846
unix 2 [ ] DGRAM 80112
unix 3 [ ] STREAM CONNECTED 19867
unix 3 [ ] STREAM CONNECTED 16577 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19868
unix 2 [ ] DGRAM 15509
unix 3 [ ] STREAM CONNECTED 19264 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 16129 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 13393
unix 3 [ ] STREAM CONNECTED 19837
unix 2 [ ] DGRAM 13285
unix 3 [ ] STREAM CONNECTED 13530 /run/systemd/journal/stdout
unix 2 [ ] DGRAM 19784
unix 3 [ ] STREAM CONNECTED 16379 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 16160
unix 3 [ ] STREAM CONNECTED 13796 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 15732 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 15611
unix 3 [ ] STREAM CONNECTED 13777
unix 2 [ ] DGRAM 20011
unix 3 [ ] STREAM CONNECTED 16106 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 19840
unix 2 [ ] DGRAM 16231
unix 3 [ ] STREAM CONNECTED 16105
unix 3 [ ] STREAM CONNECTED 16320
unix 3 [ ] STREAM CONNECTED 19885
unix 3 [ ] DGRAM 13816
unix 3 [ ] STREAM CONNECTED 18433 /run/systemd/journal/stdout
unix 3 [ ] STREAM CONNECTED 16321 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 19886
unix 3 [ ] STREAM CONNECTED 16161 /var/run/dbus/system_bus_socket
unix 3 [ ] STREAM CONNECTED 16378
unix 3 [ ] STREAM CONNECTED 19888
unix 3 [ ] STREAM CONNECTED 15612
unix 3 [ ] STREAM CONNECTED 18432
unix 3 [ ] STREAM CONNECTED 19889
unix 2 [ ] DGRAM 16204
unix 3 [ ] STREAM CONNECTED 15731
unix 3 [ ] STREAM CONNECTED 19834
unix 3 [ ] STREAM CONNECTED 19891
unix 3 [ ] STREAM CONNECTED 19841
unix 3 [ ] STREAM CONNECTED 19836
unix 2 [ ] DGRAM 79889
unix 3 [ ] STREAM CONNECTED 19892
unix 2 [ ] DGRAM 16133
unix 3 [ ] STREAM CONNECTED 15152
unix 3 [ ] STREAM CONNECTED 16128
unix 3 [ ] STREAM CONNECTED 19894
unix 3 [ ] STREAM CONNECTED 19895
unix 3 [ ] STREAM CONNECTED 15153
unix 3 [ ] STREAM CONNECTED 19897
unix 3 [ ] STREAM CONNECTED 19898
unix 3 [ ] DGRAM 13817
unix 2 [ ] DGRAM 13797
unix 2 [ ] DGRAM 15143
[zaixian@localhost ~]$
说明：
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)
实例11：显示关于路由表的信息
命令：
netstat -r
输出：
[zaixian@localhost ~]$ netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
default gateway 0.0.0.0 UG 0 0 0 ens33
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 ens33
[zaixian@localhost ~]$
实例12：列出所有 tcp 端口
命令：
netstat -at
输出：
[zaixian@localhost ~]$ netstat -at
Active 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 52 localhost.localdoma:ssh 192.168.0.5:54835 ESTABLISHED
tcp6 0 0 [::]:ssh [::]:* LISTEN
tcp6 0 0 localhost:smtp [::]:* LISTEN
[zaixian@localhost ~]$
实例13：统计机器中网络连接各个状态个数
命令：
netstat -a | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
输出：
[zaixian@localhost ~]$ netstat -a | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
LISTEN 4
ESTABLISHED 1
[zaixian@localhost ~]$
实例14：把状态全都取出来后使用uniq -c统计后再进行排序
命令：
netstat -nat |awk '{print $6}'|sort|uniq -c
输出：
实例15：查看连接某服务端口最多的的IP地址
命令：
netstat -nat | grep "192.168.120.20:16067" |awk '{print $5}'|awk -F: '{print $4}'|sort|uniq -c|sort -nr|head -20
输出：
[zaixian@localhost ~]$ netstat -nat |awk '{print $6}'|sort|uniq -c
1 established)
1 ESTABLISHED
1 Foreign
4 LISTEN
[zaixian@localhost ~]$
实例16：找出程序运行的端口
命令：
netstat -ap | grep ssh
输出：
[zaixian@localhost ~]$ netstat -ap | grep ssh
(No info could be read for "-p": geteuid()=1000 but you should be root.)
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN -
tcp 0 52 localhost.localdoma:ssh 192.168.0.5:54835 ESTABLISHED -
tcp6 0 0 [::]:ssh [::]:* LISTEN -
[zaixian@localhost ~]$
实例17：在 netstat 输出中显示 PID 和进程名称
命令：
netstat -pt
输出：
[zaixian@localhost ~]$ netstat -pt
(No info could be read for "-p": geteuid()=1000 but you should be root.)
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 52 localhost.localdoma:ssh 192.168.0.5:54835 ESTABLISHED -
[zaixian@localhost ~]$
说明：netstat -p可以与其它开关一起使用，就可以添加 “PID/进程名称” 到 netstat 输出中，这样 debugging 的时候可以很方便的发现特定端口运行的程序。
实例18：找出运行在指定端口的进程
命令：
netstat -anpt | grep ':16160'
输出：
[root@localhost zaixian]# netstat -anpt | grep ':16160'
[root@localhost zaixian]# netstat -anpt | grep ':22'
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1032/sshd
tcp 0 52 192.168.0.197:22 192.168.0.5:54835 ESTABLISHED 4039/sshd: zaixian [
tcp6 0 0 :::22 :::* LISTEN 1032/sshd
[root@localhost zaixian]#
说明：
运行在端口22的进程id为1032，再通过ps命令就可以找到具体的应用程序了。
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traceroute命令
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ss命令