• ping

  通過ping命令向網絡主機發送一個回應請求，進而驗證可否進行通信：

  $ ping baidu.com
  

  可使用Control+C停止發送請求。

• 診斷路由節點

  $ traceroute baidu.com
  
  traceroute: Warning: baidu.com has multiple addresses; using 220.181.57.216
  traceroute to baidu.com (220.181.57.216), 64 hops max, 52 byte packets
   1  172.24.50.1 (172.24.50.1)  0.728 ms  0.416 ms  0.377 ms
   2  10.74.0.53 (10.74.0.53)  1.131 ms  0.886 ms  0.924 ms
   3  10.74.0.29 (10.74.0.29)  1.252 ms  1.051 ms  1.023 ms
   4  10.74.253.10 (10.74.253.10)  1.624 ms  1.182 ms  1.206 ms
   5  10.74.253.46 (10.74.253.46)  0.276 ms  0.255 ms  0.238 ms
   6  123.59.170.193 (123.59.170.193)  0.711 ms  0.532 ms  0.495 ms
   7  10.74.253.42 (10.74.253.42)  1.153 ms  0.974 ms  0.909 ms
   8  172.16.31.77 (172.16.31.77)  4.341 ms  3.549 ms  3.402 ms
   9  * * *
  10  123.59.201.209 (123.59.201.209)  2.599 ms
      123.59.201.201 (123.59.201.201)  2.947 ms  2.453 ms
  11  * * *
  12  220.181.16.213 (220.181.16.213)  3.099 ms  3.071 ms
      220.181.177.185 (220.181.177.185)  3.558 ms
  13  * * *  
  14  220.181.17.150 (220.181.17.150)  3.202 ms
      220.181.17.18 (220.181.17.18)  3.058 ms
      220.181.17.22 (220.181.17.22)  2.770 ms
  15  * * *
  16  * * *
  17  * * *
  18  * * *
  

• 檢查某個主機是否運行 HTTP 服務，或者檢查某網站是否可用

$ curl -I www.oschina.net | head

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0   277    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
HTTP/1.1 200 OK
Server: bfe/1.0.8.18
Date: Wed, 12 Dec 2018 10:39:50 GMT
Content-Type: text/html
Content-Length: 277
Last-Modified: Mon, 13 Jun 2016 02:50:08 GMT
Connection: Keep-Alive
ETag: "575e1f60-115"
Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform
Pragma: no-cache

//不通
$ curl -I www.oschddfina.net | head
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0curl: (6) Could not resolve host: www.oschddfina.net

• 來診斷域名信息

$ dig www.oschina.net A
$ dig www.oschina.net MX

• 查看誰正在登錄到你的 Mac 機器

$ w

顯示系統路由表

$ netstat -r

顯示活動網絡連接

$ netstat -an

顯示網絡統計

$ netstat -s