在Android下利用Shell命令管理网络接口

为啥要使用shell命令操纵本地网络？因为这样就可以绕过上层connectService来干一些事情，至于具体要干点什么事情，容我先卖个关子在以后的blog里说明。

首先进入adb shell，然后去Ping一个服务器的ip地址

<code style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;"><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">ping </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
PING </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">(</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">)</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">56</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">(</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">84</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">)</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes of data</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">64</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">from</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> icmp_seq</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">1</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ttl</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">46</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">356</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ms
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">64</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">from</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> icmp_seq</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">2</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ttl</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">46</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">294</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ms
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">64</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">from</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> icmp_seq</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">5</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ttl</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">46</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">342</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ms
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">64</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">from</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> icmp_seq</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">6</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ttl</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">46</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">341</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ms
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">64</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">from</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> icmp_seq</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">8</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ttl</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">46</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">342</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ms
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">64</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> bytes </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">from</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> icmp_seq</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">9</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ttl</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">46</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">330</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ms
</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">^</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">C
</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">---</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">211.69</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">198.222</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ping statistics </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">---</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">9</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> packets transmitted</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">,</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">6</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> received</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">,</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">33</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">%</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> packet loss</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">,</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> time </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">8025ms</span></code>

接着我们通过ifconfig命令（虽然是阉割版）来将我的3g网络接口关闭，随后再打开，然后再去尝试ping刚才的网络地址。

<code style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;"><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ifconfig rmnet0</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
rmnet0</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ip </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">172.22</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">39.243</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> mask </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">255.255</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">255.248</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> flags </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">[</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">up broadcast running multicast</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">]</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
</span><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ifconfig rmnet0 down</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
</span><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ping 211.69.198.222</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
connect</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(43, 145, 175); background-color: transparent;">Network</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">is</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> unreachable
</span><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ifconfig rmnet0 up</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
</span><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ping 211.69.198.222</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
connect</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(43, 145, 175); background-color: transparent;">Network</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">is</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> unreachable
</span><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ping 211.69.198.222</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
connect</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(43, 145, 175); background-color: transparent;">Network</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(0, 0, 139); background-color: transparent;">is</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> unreachable
</span><span class="com" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: gray; background-color: transparent;"># ifconfig rmnet0</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">
rmnet0</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> ip </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">172.22</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">39.243</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> mask </span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">255.255</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="lit" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; color: rgb(128, 0, 0); background-color: transparent;">255.248</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;"> flags </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">[</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">up broadcast running multicast</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent;">]</span></code>

经过仔细的思考，我猜测是因为当你把网络接口down掉之后，你的ip在路由器（基站？）上被释放了，虽然显示网络是可用的，但是这时候的网络是没有配置有效IP的。

这时候通过netcfg rmnet0 dhcp 重新申请一个ip ，然后继续Ping，不出所料，果然成功。

# netcfg rmnet0 dhcp
# ping 211.69.198.222
PING 211.69.198.222 (211.69.198.222) 56(84) bytes of data.
64 bytes from 211.69.198.222: icmp_seq=1 ttl=46 time=2743 ms
64 bytes from 211.69.198.222: icmp_seq=2 ttl=46 time=1747 ms
64 bytes from 211.69.198.222: icmp_seq=3 ttl=46 time=739 ms
64 bytes from 211.69.198.222: icmp_seq=4 ttl=46 time=98.9 ms
64 bytes from 211.69.198.222: icmp_seq=5 ttl=46 time=97.1 ms
^C
--- 211.69.198.222 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4015ms

结论：

通过Android Shell命令，完全可以绕开上层的网络管理机制来控制网络接口的状态。