在 Ubuntu 16.04 下随机化你的 WiFi MAC 地址

你的设备的 MAC 地址可以在不同的 WiFi 网络中记录你的活动。这些信息能被共享后出售，用于识别特定的个体。但可以用随机生成的伪 MAC 地址来阻止这一行为。

每一个诸如 WiFi 或者以太网卡这样的网络设备，都有一个叫做 MAC 地址的唯一标识符，如：b4:b6:76:31:8c:ff。这就是你能上网的原因：每当你连上 WiFi，路由器就会用这一地址来向你接受和发送数据，并且用它来区别你和这一网络的其它设备。

这一设计的缺陷在于唯一性，不变的 MAC 地址正好可以用来追踪你。连上了星巴克的 WiFi? 好，注意到了。在伦敦的地铁上? 也记录下来。

如果你曾经在某一个 WiFi 验证页面上输入过你的真实姓名，你就已经把自己和这一 MAC 地址建立了联系。没有仔细阅读许可服务条款、你可以认为，机场的免费 WiFi 正通过出售所谓的 ‘顾客分析数据’（你的个人信息）获利。出售的对象包括酒店，餐饮业，和任何想要了解你的人。

我不想信息被记录，再出售给多家公司，所以我花了几个小时想出了一个解决方案。

MAC 地址不一定总是不变的

幸运的是，在不断开网络的情况下，是可以随机生成一个伪 MAC 地址的。

我想随机生成我的 MAC 地址，但是有三个要求：

1. MAC 地址在不同网络中是不相同的。这意味着，我在星巴克和在伦敦地铁网络中的 MAC 地址是不相同的，这样在不同的服务提供商中就无法将我的活动系起来。
2. MAC 地址需要经常更换，这样在网络上就没人知道我就是去年在这儿经过了 75 次的那个人。
3. MAC 地址一天之内应该保持不变。当 MAC 地址更改时，大多数网络都会与你断开连接，然后必须得进入验证页面再次登陆 - 这很烦人。

操作网络管理器NetworkManager

我第一次尝试用一个叫做 macchanger 的工具，但是失败了。因为网络管理器NetworkManager会根据它自己的设置恢复默认的 MAC 地址。

我了解到，网络管理器 1.4.1 以上版本可以自动生成随机的 MAC 地址。如果你在使用 Ubuntu 17.04 版本，你可以根据这一配置文件实现这一目的。但这并不能完全符合我的三个要求（你必须在随机random和稳定stable这两个选项之中选择一个，但没有一天之内保持不变这一选项）

因为我使用的是 Ubuntu 16.04，网络管理器版本为 1.2，不能直接使用高版本这一新功能。可能网络管理器有一些随机化方法支持，但我没能成功。所以我编了一个脚本来实现这一目标。

幸运的是，网络管理器 1.2 允许模拟 MAC 地址。你在已连接的网络中可以看见 ‘编辑连接’ 这一选项。

网络管理器也支持钩子处理 —— 任何位于 /etc/NetworkManager/dispatcher.d/pre-up.d/ 的脚本在建立网络连接之前都会被执行。

分配随机生成的伪 MAC 地址

我想根据网络 ID 和日期来生成新的随机 MAC 地址。 我们可以使用网络管理器的命令行工具 nmcli 来显示所有可用网络：

1. <span class="pun">></span><span class="pln"> nmcli connection</span>
2. <span class="pln">NAME UUID TYPE DEVICE</span>
3. <span class="typ">Gladstone</span><span class="typ">Guest</span><span class="lit">618545ca</span><span class="pun">-</span><span class="pln">d81a</span><span class="pun">-</span><span class="lit">11e7</span><span class="pun">-</span><span class="pln">a2a4</span><span class="pun">-</span><span class="lit">271245e11a45</span><span class="lit">802</span><span class="pun">-</span><span class="lit">11</span><span class="pun">-</span><span class="pln">wireless wlp1s0</span>
4. <span class="typ">DoESDinky</span><span class="lit">6e47c080</span><span class="pun">-</span><span class="pln">d81a</span><span class="pun">-</span><span class="lit">11e7</span><span class="pun">-</span><span class="lit">9921</span><span class="pun">-</span><span class="lit">87bc56777256</span><span class="lit">802</span><span class="pun">-</span><span class="lit">11</span><span class="pun">-</span><span class="pln">wireless </span><span class="pun">--</span>
5. <span class="typ">PublicWiFi</span><span class="lit">79282c10</span><span class="pun">-</span><span class="pln">d81a</span><span class="pun">-</span><span class="lit">11e7</span><span class="pun">-</span><span class="lit">87cb</span><span class="pun">-</span><span class="lit">6341829c2a54</span><span class="lit">802</span><span class="pun">-</span><span class="lit">11</span><span class="pun">-</span><span class="pln">wireless </span><span class="pun">--</span>
6. <span class="pln">virgintrainswifi </span><span class="lit">7d0c57de</span><span class="pun">-</span><span class="pln">d81a</span><span class="pun">-</span><span class="lit">11e7</span><span class="pun">-</span><span class="lit">9bae</span><span class="pun">-</span><span class="lit">5be89b161d22</span><span class="lit">802</span><span class="pun">-</span><span class="lit">11</span><span class="pun">-</span><span class="pln">wireless </span><span class="pun">--</span>

因为每个网络都有一个唯一标识符（UUID），为了实现我的计划，我将 UUID 和日期拼接在一起，然后使用 MD5 生成 hash 值：

1. <span class="com">#</span><span class="pln"> eg </span><span class="lit">618545ca</span><span class="pun">-</span><span class="pln">d81a</span><span class="pun">-</span><span class="lit">11e7</span><span class="pun">-</span><span class="pln">a2a4</span><span class="pun">-</span><span class="lit">271245e11a45</span><span class="pun">-</span><span class="lit">2017</span><span class="pun">-</span><span class="lit">12</span><span class="pun">-</span><span class="lit">03</span>
2. <span class="pun">></span><span class="kwd">echo</span><span class="pun">-</span><span class="pln">n </span><span class="str">"${UUID}-$(date +%F)"</span><span class="pun">|</span><span class="kwd">md5sum</span>
3. <span class="lit">53594de990e92f9b914a723208f22b3f</span><span class="pun">-</span>

生成的结果可以代替 MAC 地址的最后八个字节。

值得注意的是，最开始的字节 02 代表这个地址是自行指定的。实际上，真实 MAC 地址的前三个字节是由制造商决定的，例如 b4:b6:76 就代表 Intel。

有可能某些路由器会拒绝自己指定的 MAC 地址，但是我还没有遇到过这种情况。

每次连接到一个网络，这一脚本都会用 nmcli 来指定一个随机生成的伪 MAC 地址。

最后，我查看了 ifconfig 的输出结果，我发现 MAC 地址 HWaddr 已经变成了随机生成的地址（模拟 Intel 的），而不是我真实的 MAC 地址。

1. <span class="pun">></span><span class="kwd">ifconfig</span>
2. <span class="pln">wlp1s0 </span><span class="typ">Link</span><span class="pln"> encap</span><span class="pun">:</span><span class="typ">Ethernet</span><span class="typ">HWaddr</span><span class="pln"> b4</span><span class="pun">:</span><span class="pln">b6</span><span class="pun">:</span><span class="lit">76</span><span class="pun">:</span><span class="lit">45</span><span class="pun">:</span><span class="lit">64</span><span class="pun">:</span><span class="lit">4d</span>
3. <span class="pln">inet addr</span><span class="pun">:</span><span class="lit">192.168</span><span class="pun">.</span><span class="lit">0.86</span><span class="typ">Bcast</span><span class="pun">:</span><span class="lit">192.168</span><span class="pun">.</span><span class="lit">0.255</span><span class="typ">Mask</span><span class="pun">:</span><span class="lit">255.255</span><span class="pun">.</span><span class="lit">255.0</span>
4. <span class="pln">inet6 addr</span><span class="pun">:</span><span class="pln"> fe80</span><span class="pun">::</span><span class="lit">648c</span><span class="pun">:</span><span class="pln">aff2</span><span class="pun">:</span><span class="lit">9a9d</span><span class="pun">:</span><span class="lit">764</span><span class="pun">/</span><span class="lit">64</span><span class="typ">Scope</span><span class="pun">:</span><span class="typ">Link</span>
5. <span class="pln">UP BROADCAST RUNNING MULTICAST MTU</span><span class="pun">:</span><span class="lit">1500</span><span class="typ">Metric</span><span class="pun">:</span><span class="lit">1</span>
6. <span class="pln">RX packets</span><span class="pun">:</span><span class="lit">12107812</span><span class="pln"> errors</span><span class="pun">:</span><span class="lit">0</span><span class="pln"> dropped</span><span class="pun">:</span><span class="lit">2</span><span class="pln"> overruns</span><span class="pun">:</span><span class="lit">0</span><span class="pln"> frame</span><span class="pun">:</span><span class="lit">0</span>
7. <span class="pln">TX packets</span><span class="pun">:</span><span class="lit">18332141</span><span class="pln"> errors</span><span class="pun">:</span><span class="lit">0</span><span class="pln"> dropped</span><span class="pun">:</span><span class="lit">0</span><span class="pln"> overruns</span><span class="pun">:</span><span class="lit">0</span><span class="pln"> carrier</span><span class="pun">:</span><span class="lit">0</span>
8. <span class="pln">collisions</span><span class="pun">:</span><span class="lit">0</span><span class="pln"> txqueuelen</span><span class="pun">:</span><span class="lit">1000</span>
9. <span class="pln">RX bytes</span><span class="pun">:</span><span class="lit">11627977017</span><span class="pun">(</span><span class="lit">11.6</span><span class="pln"> GB</span><span class="pun">)</span><span class="pln"> TX bytes</span><span class="pun">:</span><span class="lit">20700627733</span><span class="pun">(</span><span class="lit">20.7</span><span class="pln"> GB</span><span class="pun">)</span>

脚本

完整的脚本也可以在 Github 上查看。

1. <span class="com">#</span><span class="pun">!</span><span class="str">/bin/</span><span class="pln">sh</span>
2. <span class="com"># /etc/</span><span class="typ">NetworkManager</span><span class="pun">/</span><span class="pln">dispatcher</span><span class="pun">.</span><span class="pln">d</span><span class="pun">/</span><span class="pln">pre</span><span class="pun">-</span><span class="pln">up</span><span class="pun">.</span><span class="pln">d</span><span class="pun">/</span><span class="pln">randomize</span><span class="pun">-</span><span class="pln">mac</span><span class="pun">-</span><span class="pln">addresses</span>
3. <span class="com">#</span><span class="typ">Configure</span><span class="pln"> every saved </span><span class="typ">WiFi</span><span class="pln"> connection </span><span class="kwd">in</span><span class="typ">NetworkManager</span><span class="kwd">with</span><span class="pln"> a spoofed MAC</span>
4. <span class="com">#</span><span class="pln"> address</span><span class="pun">,</span><span class="pln"> seeded </span><span class="kwd">from</span><span class="pln"> the UUID of the connection </span><span class="kwd">and</span><span class="pln"> the </span><span class="kwd">date</span><span class="pln"> eg</span><span class="pun">:</span>
5. <span class="com">#</span><span class="str">'c31bbcc4-d6ad-11e7-9a5a-e7e1491a7e20-2017-11-20'</span>
6. <span class="com">#</span><span class="typ">This</span><span class="pln"> makes your MAC impossible</span><span class="pun">(?)</span><span class="pln"> to track across </span><span class="typ">WiFi</span><span class="pln"> providers</span><span class="pun">,</span><span class="kwd">and</span>
7. <span class="com">#</span><span class="kwd">for</span><span class="pln"> one provider to track across days</span><span class="pun">.</span>
8. <span class="com">#</span><span class="typ">For</span><span class="pln"> craptive portals that authenticate based on MAC</span><span class="pun">,</span><span class="pln"> you might want to</span>
9. <span class="com">#</span><span class="pln"> automate logging </span><span class="kwd">in</span><span class="pun">:)</span>
10. <span class="com">#</span><span class="typ">Note</span><span class="pln"> that </span><span class="typ">NetworkManager</span><span class="pun">>=</span><span class="lit">1.4</span><span class="pun">.</span><span class="lit">1</span><span class="pun">(</span><span class="typ">Ubuntu</span><span class="lit">17.04</span><span class="pun">+)</span><span class="pln"> can </span><span class="kwd">do</span><span class="pln"> something similar</span>
11. <span class="com">#</span><span class="pln"> automatically</span><span class="pun">.</span>
12. <span class="kwd">export</span><span class="pln"> PATH</span><span class="pun">=</span><span class="pln">$PATH</span><span class="pun">:</span><span class="str">/usr/</span><span class="pln">bin</span><span class="pun">:/</span><span class="pln">bin</span>
13. <span class="pln">LOG_FILE</span><span class="pun">=</span><span class="str">/var/</span><span class="pln">log</span><span class="pun">/</span><span class="pln">randomize</span><span class="pun">-</span><span class="pln">mac</span><span class="pun">-</span><span class="pln">addresses</span>
14. <span class="kwd">echo</span><span class="str">"$(date): $*"</span><span class="pun">></span><span class="pln"> $</span><span class="pun">{</span><span class="pln">LOG_FILE</span><span class="pun">}</span>
15. <span class="pln">WIFI_UUIDS</span><span class="pun">=</span><span class="pln">$</span><span class="pun">(</span><span class="pln">nmcli </span><span class="pun">--</span><span class="pln">fields type</span><span class="pun">,</span><span class="pln">uuid connection show </span><span class="pun">|</span><span class="kwd">grep</span><span class="lit">802</span><span class="pun">-</span><span class="lit">11</span><span class="pun">-</span><span class="pln">wireless </span><span class="pun">|</span><span class="kwd">cut</span><span class="str">'-d '</span><span class="pun">-</span><span class="pln">f3</span><span class="pun">)</span>
16. <span class="kwd">for</span><span class="pln"> UUID </span><span class="kwd">in</span><span class="pln"> $</span><span class="pun">{</span><span class="pln">WIFI_UUIDS</span><span class="pun">}</span>
17. <span class="kwd">do</span>
18. <span class="pln">UUID_DAILY_HASH</span><span class="pun">=</span><span class="pln">$</span><span class="pun">(</span><span class="kwd">echo</span><span class="str">"${UUID}-$(date +F)"</span><span class="pun">|</span><span class="kwd">md5sum</span><span class="pun">)</span>
19. <span class="pln">RANDOM_MAC</span><span class="pun">=</span><span class="str">"02:$(echo -n ${UUID_DAILY_HASH} | sed 's/^\(..\)\(..\)\(..\)\(..\)\(..\).*$/\1:\2:\3:\4:\5/')"</span>
20. <span class="pln">CMD</span><span class="pun">=</span><span class="str">"nmcli connection modify ${UUID} wifi.cloned-mac-address ${RANDOM_MAC}"</span>
21. <span class="kwd">echo</span><span class="str">"$CMD"</span><span class="pun">>></span><span class="pln"> $</span><span class="pun">{</span><span class="pln">LOG_FILE</span><span class="pun">}</span>
22. <span class="pln">$CMD </span><span class="pun">&</span>
23. <span class="kwd">done</span>
24. <span class="pln">wait</span>

更新：使用自己指定的 MAC 地址可以避免和真正的 intel 地址冲突。感谢 @_fink

via: https://www.paulfurley.com/randomize-your-wifi-mac-address-on-ubuntu-1604-xenial/

作者：Paul M Furley 译者：wenwensnow 校对：wxy

本文由 LCTT 原创编译，Linux中国 荣誉推出