用Bash脚本发送新用户帐户创建的邮件

出于某些原因，你可能需要跟踪 Linux 上的新用户创建信息。同时，你可能需要通过邮件发送详细信息。这或许是审计目标的一部分，或者安全团队出于跟踪目的可能希望对此进行监控。

我们可以通过其他方式进行此操作，正如我们在上一篇文章中已经描述的那样。

• 在系统中创建新用户帐户时发送邮件的 Bash 脚本

Linux 有许多开源监控工具可以使用。但我不认为他们有办法跟踪新用户创建过程，并在发生时提醒管理员。

那么我们怎样才能做到这一点？

我们可以编写自己的 Bash 脚本来实现这一目标。我们过去写过许多有用的 shell 脚本。如果你想了解，请进入下面的链接。

• 如何使用 shell 脚本自动化日常活动？

这个脚本做了什么？

这将每天两次（一天的开始和结束）备份 /etc/passwd 文件，这将使你能够获取指定日期的新用户创建详细信息。

我们需要添加以下两个 cron 任务来复制 /etc/passwd 文件。

1. <span class="com">#</span><span class="pln"> crontab </span><span class="pun">-</span><span class="pln">e</span>
2.  
3. <span class="lit">1</span><span class="pln"> </span><span class="lit">0</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="kwd">cp</span><span class="pln"> </span><span class="pun">/</span><span class="pln">etc</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="pln">start</span><span class="pun">-</span><span class="pln">$</span><span class="pun">(</span><span class="kwd">date</span><span class="pln"> </span><span class="pun">+</span><span class="str">"%Y-%m-%d"</span><span class="pun">)</span>
4. <span class="lit">59</span><span class="pln"> </span><span class="lit">23</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="kwd">cp</span><span class="pln"> </span><span class="pun">/</span><span class="pln">etc</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="kwd">end</span><span class="pun">-</span><span class="pln">$</span><span class="pun">(</span><span class="kwd">date</span><span class="pln"> </span><span class="pun">+</span><span class="str">"%Y-%m-%d"</span><span class="pun">)</span>

它使用 diff 命令来检测文件之间的差异，如果发现与昨日有任何差异，脚本将向指定 email 发送新用户详细信息。

我们不用经常运行此脚本，因为用户创建不经常发生。但是，我们计划每天运行一次此脚本。

这样，你可以获得有关新用户创建的综合报告。

注意：我们在脚本中使用了我们的电子邮件地址进行演示。因此，我们要求你用自己的电子邮件地址。

1. <span class="com">#</span><span class="pln"> </span><span class="kwd">vi</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">new</span><span class="pun">-</span><span class="pln">user</span><span class="pun">-</span><span class="pln">detail</span><span class="pun">.</span><span class="pln">sh</span>
2.  
3. <span class="com">#</span><span class="pun">!</span><span class="str">/bin/</span><span class="kwd">bash</span>
4. <span class="kwd">mv</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="pln">start</span><span class="pun">-</span><span class="pln">$</span><span class="pun">(</span><span class="kwd">date</span><span class="pln"> </span><span class="pun">--</span><span class="kwd">date</span><span class="pun">=</span><span class="str">'yesterday'</span><span class="pln"> </span><span class="str">'+%Y-%m-%d'</span><span class="pun">)</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="pln">start</span>
5. <span class="kwd">mv</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="kwd">end</span><span class="pun">-</span><span class="pln">$</span><span class="pun">(</span><span class="kwd">date</span><span class="pln"> </span><span class="pun">--</span><span class="kwd">date</span><span class="pun">=</span><span class="str">'yesterday'</span><span class="pln"> </span><span class="str">'+%Y-%m-%d'</span><span class="pun">)</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="kwd">end</span>
6. <span class="pln">ucount</span><span class="pun">=</span><span class="pln">$</span><span class="pun">(</span><span class="kwd">diff</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="pln">start </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="kwd">end</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">grep</span><span class="pln"> </span><span class="str">">"</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">cut</span><span class="pln"> </span><span class="pun">-</span><span class="pln">d</span><span class="str">":"</span><span class="pln"> </span><span class="pun">-</span><span class="pln">f6 </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">cut</span><span class="pln"> </span><span class="pun">-</span><span class="pln">d</span><span class="str">"/"</span><span class="pln"> </span><span class="pun">-</span><span class="pln">f3 </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">wc</span><span class="pln"> </span><span class="pun">-</span><span class="pln">l</span><span class="pun">)</span>
7. <span class="kwd">if</span><span class="pln"> </span><span class="pun">[</span><span class="pln"> $ucount </span><span class="pun">-</span><span class="pln">gt </span><span class="lit">0</span><span class="pln"> </span><span class="pun">]</span>
8. <span class="kwd">then</span>
9. <span class="pln"> SUBJECT</span><span class="pun">=</span><span class="str">"ATTENTION: New User Account is created on server : `date --date='yesterday' '+%b %e'`"</span>
10. <span class="pln"> MESSAGE</span><span class="pun">=</span><span class="str">"/tmp/new-user-logs.txt"</span>
11. <span class="pln"> TO</span><span class="pun">=</span><span class="str">"[email protected]"</span>
12. <span class="pln"> </span><span class="kwd">echo</span><span class="pln"> </span><span class="str">"Hostname: `hostname`"</span><span class="pln"> </span><span class="pun">>></span><span class="pln"> $MESSAGE</span>
13. <span class="pln"> </span><span class="kwd">echo</span><span class="pln"> </span><span class="pun">-</span><span class="pln">e </span><span class="str">"\n"</span><span class="pln"> </span><span class="pun">>></span><span class="pln"> $MESSAGE</span>
14. <span class="pln"> </span><span class="kwd">echo</span><span class="pln"> </span><span class="str">"The New User Details are below."</span><span class="pln"> </span><span class="pun">>></span><span class="pln"> $MESSAGE</span>
15. <span class="pln"> </span><span class="kwd">echo</span><span class="pln"> </span><span class="str">"+------------------------------+"</span><span class="pln"> </span><span class="pun">>></span><span class="pln"> $MESSAGE</span>
16. <span class="pln"> </span><span class="kwd">diff</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="pln">start </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">passwd</span><span class="pun">-</span><span class="kwd">end</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">grep</span><span class="pln"> </span><span class="str">">"</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">cut</span><span class="pln"> </span><span class="pun">-</span><span class="pln">d</span><span class="str">":"</span><span class="pln"> </span><span class="pun">-</span><span class="pln">f6 </span><span class="pun">|</span><span class="pln"> </span><span class="kwd">cut</span><span class="pln"> </span><span class="pun">-</span><span class="pln">d</span><span class="str">"/"</span><span class="pln"> </span><span class="pun">-</span><span class="pln">f3 </span><span class="pun">>></span><span class="pln"> $MESSAGE</span>
17. <span class="pln"> </span><span class="kwd">echo</span><span class="pln"> </span><span class="str">"+------------------------------+"</span><span class="pln"> </span><span class="pun">>></span><span class="pln"> $MESSAGE</span>
18. <span class="pln"> mail </span><span class="pun">-</span><span class="pln">s </span><span class="str">"$SUBJECT"</span><span class="pln"> </span><span class="str">"$TO"</span><span class="pln"> </span><span class="pun"><</span><span class="pln"> $MESSAGE</span>
19. <span class="pln"> </span><span class="kwd">rm</span><span class="pln"> $MESSAGE</span>
20. <span class="kwd">fi</span><span class="pln"> </span>

给 new-user-detail.sh 文件添加可执行权限。

1. <span class="pln">$ </span><span class="kwd">chmod</span><span class="pln"> </span><span class="pun">+</span><span class="pln">x </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">new</span><span class="pun">-</span><span class="pln">user</span><span class="pun">-</span><span class="pln">detail</span><span class="pun">.</span><span class="pln">sh</span>

最后添加一个 cron 任务来自动执行此操作。它在每天早上 7 点运行。

1. <span class="com">#</span><span class="pln"> crontab </span><span class="pun">-</span><span class="pln">e</span>
2.  
3. <span class="lit">0</span><span class="pln"> </span><span class="lit">7</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="pun">*</span><span class="pln"> </span><span class="str">/bin/</span><span class="kwd">bash</span><span class="pln"> </span><span class="pun">/</span><span class="pln">opt</span><span class="pun">/</span><span class="pln">scripts</span><span class="pun">/</span><span class="kwd">new</span><span class="pun">-</span><span class="pln">user</span><span class="pun">.</span><span class="pln">sh</span>

注意：你会在每天早上 7 点都会收到一封关于昨日详情的邮件提醒。