使用 SNMP 和 Cacti 监控 Linux 服务器

SNMP（简单网络管理协议）用于收集设备内部发生的数据，如负载、磁盘状态、带宽之类。像Cacti这样的网络监控工具用这些数据来生成图标以达到监控的目的。

在一个典型的Cacti和SNMP部署中，会有一台或多台启用了SNMP的设备，以及一台独立的用来从那些设备收集SNMP回馈的监控服务器。请记住，所有需要监控的设备必须启用SNMP。在本教程中，出于演示目的，我们将在同一台Linux服务器上配置Cacti和SNMP。

在Debian或Ubuntu上配置SNMP

要在基于Debian的系统上安装SNMP代理（snmpd），请运行以下命令：

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> apt</span><span class="pun">-</span><span class="kwd">get</span><span class="pln"> install snmpd</span>

然后，如下编辑配置文件。

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> vim </span><span class="pun">/</span><span class="pln">etc</span><span class="pun">/</span><span class="pln">snmp</span><span class="pun">/</span><span class="pln">snmpd</span><span class="pun">.</span><span class="pln">conf</span>

1. <span class="com"># 使snmpd 监听再所有接口上</span>
2. <span class="pln">agentAddress udp</span><span class="pun">:</span><span class="lit">161</span>
3. <span class="com"># 定义一个只读的 community 'myCommunity' 和源网络</span>
4. <span class="pln">rocommunity myCommunity </span><span class="lit">172.17</span><span class="pun">.</span><span class="lit">1.0</span><span class="pun">/</span><span class="lit">24</span>
5. <span class="pln">sysLocation </span><span class="typ">Earth</span>
6. <span class="pln">sysContact email@domain</span><span class="pun">.</span><span class="pln">tld</span>

在编辑完配置文件后，重启snmpd。

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> service snmpd restart</span>

在CentOS或RHEL上配置SNMP

要安装SNMP工具和库，请运行以下命令。

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> sudo yum install net</span><span class="pun">-</span><span class="pln">snmp</span>

然后，如下编辑SNMP配置文件。

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> vim </span><span class="pun">/</span><span class="pln">etc</span><span class="pun">/</span><span class="pln">snmp</span><span class="pun">/</span><span class="pln">snmpd</span><span class="pun">.</span><span class="pln">conf</span>

1. <span class="com"># 定义一个使用 community 'myCommunity' 和源网络 172.17.1.0/24 的用户 'myUser'</span>
2. <span class="pln">com2sec myUser </span><span class="lit">172.17</span><span class="pun">.</span><span class="lit">1.0</span><span class="pun">/</span><span class="lit">24</span><span class="pln"> myCommunity</span>
3. <span class="com"># 将 myUser 加到 'myGroup' 组，定义组权限</span>
4. <span class="kwd">group</span><span class="pln"> myGroup v1 myUser</span>
5. <span class="kwd">group</span><span class="pln"> myGroup v2c myUser</span>
6. <span class="pln">view all included </span><span class="pun">.</span><span class="lit">1</span>
7. <span class="pln">access myGroup </span><span class="str">""</span><span class="pln"> any noauth exact all all none</span>

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> service snmpd restart</span>
2. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> chkconfig snmpd on</span>

重启snmpd服务，然后添加到启动服务列表。

测试SNMP

SNMP可以通过运行snmpwalk命令进行测试。如果SNMP已经配置成功，该命令会生成大量输出。

1. <span class="pln">root@server</span><span class="pun">:~#</span><span class="pln"> snmpwalk </span><span class="pun">-</span><span class="pln">c myCommunity </span><span class="lit">172.17</span><span class="pun">.</span><span class="lit">1.44</span><span class="pun">-</span><span class="pln">v1</span>

1. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.1</span><span class="pun">.</span><span class="lit">1.0</span><span class="pun">=</span><span class="pln"> STRING</span><span class="pun">:</span><span class="str">"Linux mrtg 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:31:23 UTC 2012 x86_64"</span>
2. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.1</span><span class="pun">.</span><span class="lit">2.0</span><span class="pun">=</span><span class="pln"> OID</span><span class="pun">:</span><span class="pln"> iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.4</span><span class="pun">.</span><span class="lit">1.8072</span><span class="pun">.</span><span class="lit">3.2</span><span class="pun">.</span><span class="lit">10</span>
3. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.1</span><span class="pun">.</span><span class="lit">3.0</span><span class="pun">=</span><span class="typ">Timeticks</span><span class="pun">:</span><span class="pun">(</span><span class="lit">2097</span><span class="pun">)</span><span class="lit">0</span><span class="pun">:</span><span class="lit">00</span><span class="pun">:</span><span class="lit">20.97</span>
4. <span class="pun">~~</span><span class="pun">输出截断</span><span class="pun">~~</span>
5. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.92</span><span class="pun">.</span><span class="lit">1.1</span><span class="pun">.</span><span class="lit">2.0</span><span class="pun">=</span><span class="typ">Gauge32</span><span class="pun">:</span><span class="lit">1440</span>
6. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.92</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.0</span><span class="pun">=</span><span class="typ">Counter32</span><span class="pun">:</span><span class="lit">1</span>
7. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.92</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">2.0</span><span class="pun">=</span><span class="typ">Counter32</span><span class="pun">:</span><span class="lit">0</span>
8. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.92</span><span class="pun">.</span><span class="lit">1.3</span><span class="pun">.</span><span class="lit">1.1</span><span class="pun">.</span><span class="lit">2.7</span><span class="pun">.</span><span class="lit">100.101</span><span class="pun">.</span><span class="lit">102.97</span><span class="pun">.</span><span class="lit">117.108</span><span class="pun">.</span><span class="lit">116.1</span><span class="pun">=</span><span class="typ">Timeticks</span><span class="pun">:</span><span class="pun">(</span><span class="lit">1</span><span class="pun">)</span><span class="lit">0</span><span class="pun">:</span><span class="lit">00</span><span class="pun">:</span><span class="lit">00.01</span>
9. <span class="pln">iso</span><span class="pun">.</span><span class="lit">3.6</span><span class="pun">.</span><span class="lit">1.2</span><span class="pun">.</span><span class="lit">1.92</span><span class="pun">.</span><span class="lit">1.3</span><span class="pun">.</span><span class="lit">1.1</span><span class="pun">.</span><span class="lit">3.7</span><span class="pun">.</span><span class="lit">100.101</span><span class="pun">.</span><span class="lit">102.97</span><span class="pun">.</span><span class="lit">117.108</span><span class="pun">.</span><span class="lit">116.1</span><span class="pun">=</span><span class="typ">Hex</span><span class="pun">-</span><span class="pln">STRING</span><span class="pun">:</span><span class="lit">07</span><span class="pln"> DD </span><span class="lit">0B</span><span class="lit">12</span><span class="lit">00</span><span class="lit">39</span><span class="lit">27</span><span class="lit">00</span><span class="lit">2B</span><span class="lit">06</span><span class="lit">00</span>

配置带有SNMP的Cacti

在本教程中，我们将在同一台Linux服务器上设置Cacti和SNMP。所以，到刚刚配置SNMP的Linux服务器上去[安装Cacti][2]吧。

安装完后，Cacti网页界面可以通过“http://172.17.1.44/cacti ”来访问，当然，在你的环境中，请将IP地址换成你的服务器的地址。

安装过程中Cacti的路径一般都是正确的，但是如有必要，请再次检查以下。

在首次安装过程中，Cacti默认的用户名和密码是“admin”和“admin”。在首次登录后会强制你修改密码。

添加设备到Cacti并管理

Cacti将���据先前配置的SNMP字符串注册设备。在本教程中，我们将只添加启用了SNMP的本地服务器。

要添加设备，我们必须以管理员登录，然后转到Cacti管理员面板中的控制台。点击 控制台 > 设备。

那里可能已经有一个名为‘localhost’的设备。我们不需要它，因为我们要创建全新的图表。我们可以将该设备从列表中删除，使用“添加”按钮来添加新设备。

接下来，我们设置设备参数。

现在设备已经添加，我们来指定想要创建的图表模板。你可以在该页面的最后部分中找到这块内容。

然后，我们继续来创建图表。

这里，我们创建用于平均负载、RAM和硬盘、处理器的图表。

接口的图表和64位计数器

默认情况下，Cacti在SNMP查询中使用32位计数器。32位计数器对于大多数带宽图表而言已经足够了，但是对于超过100Mbps的带宽，它就无能为力了。如果已经知道带宽会超过100Mbps，建议你使用64位计数器。使用64位计数器一点也不麻烦。

注意： Cacti会花费大约15分钟来产生新图表，除了耐心等待，你别无选择。

创建图表树

这些截图展示了如何创建图表树，以及如何添加图表到这些树中。

我们可以验证图表树中的图表。

用户管理

最后，我们创建一个只具有查看我们刚创建的图表权限的用户。Cacti内建了用户管理系统，而且是高度可定制的。

在完成这些步骤后，我们可以使用‘user1’来登录进去，并验证只有该用户可以查看该图表。

至此，我们在网络监控系统中部署了一台Cacti服务器。Cacti服务器比较稳定，可以处理大量图表而不会出问题。

希望本文对你有所帮助。

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Cacti 的详细介绍：请点这里
Cacti 的下载地址：请点这里

via: http://xmodulo.com/monitor-linux-servers-snmp-cacti.html

作者：Sarmed Rahman 译者：GOLinux 校对：wxy

本文由 LCTT 原创翻译，Linux中国 荣誉推出