13 限制 agent 检查

概述

可以通过创建监控项来限制agent端的检查 黑名单、白名单或白名单/黑名单的组合。

为此，使用两个agent的组合 configuration 参数:

• AllowKey=<pattern> - 允许执行哪些检查；<pattern>是 使用通配符(*)表达式指定

• DenyKey=<pattern> - 哪些检查被拒绝; <pattern>是

  specified using a wildcard (*) expression

请注意：

• 所有 system.run[*] 监控项（远程命令、脚本）默认被禁用 默认情况下，即使未指定任何拒绝密钥；

• 自Zabbix 5.0.2起，EnableRemoteCommands agent参数为：

  • deprecated by Zabbix agent
  • unsupported by Zabbix agent2

因此，要允许远程命令，需指定 AllowKey=system.run[<command>,*] 对于每个允许的命令，* 代表等待和非等待模式。也可以指定 AllowKey=system.run[*] 参数用于允许所有带有wait和nowait模式的命令。要禁止特定的远程命令，需添加带有system.run[]的DenyKey参数 在AllowKey=system.run[*]参数之前的命令。

重要规则

• 不带拒绝规则的白名单仅允许用于系统.run[*] 监控项. 对于所有其他监控项, 不允许使用AllowKey参数 没有DenyKey参数的情况下；此时Zabbix agent 将不会 start 仅使用 AllowKey 参数。
• 顺序很重要。指定的参数会逐一进行检查 根据它们在配置中的出现顺序file:
  • 一旦监控项键匹配到允许/拒绝规则，该监控项即被 允许或拒绝；规则检查随即停止。因此，如果某个监控项 既匹配允许规则又匹配拒绝规则时，结果将是 取决于哪条规则先出现。
  • 该顺序还会影响EnableRemoteCommands参数（如果使用）。
• 支持无限数量的AllowKey/DenyKey参数
• AllowKey、DenyKey规则不影响HostnameItem HostMetadataItem, HostInterfaceItem 配置参数。
• 键模式是一个包含通配符(*)的通配符表达式 字符匹配在特定位置上的任意数量的任意字符。 它可能同时用于键名和参数中。
• 如果在agent配置中禁止使用特定的监控项键 监控项 将被报告为不受支持（未提供任何提示说明原因） 原因);
• 使用--print (-p)命令行选项的Zabbix agent将不会显示 配置不允许的键
• 使用--test (-t)命令行选项的Zabbix agent将返回 "不支持 监控项 键。" 对于不允许的键的状态 配置
• 被拒绝的远程命令将不会记录在agent日志中（如果 LogRemoteCommands=1).
  远程日志命令=1).

Allow/deny rule order

You can specify an unlimited number of AllowKey or DenyKey rules, though their order matters.

• Rules are evaluated one by one, from top to bottom.
• When an item key matches a rule, it is either allowed or denied, and rule evaluation stops.

For example, when evaluating vfs.file.contents[/etc/passwd], the rules are processed as follows:

AllowKey=vfs.file.contents[/tmp/app.log]    # Item key pattern does not match, agent proceeds to the next rule.
       AllowKey=vfs.file.contents[/etc/passwd]     # Item key pattern matches; agent allows the item check and stops rule evaluation.
       DenyKey=vfs.file.*[*]                       # Agent ignores the rule, as the evaluation has stopped.

The following rule order will deny the item check:

DenyKey=vfs.file.*[*]                       # Item key pattern matches; agent denies the item check and stops rule evaluation.
       AllowKey=vfs.file.contents[/etc/passwd]     # Agent ignores the rule, as the evaluation has stopped.
       AllowKey=vfs.file.contents[/tmp/app.log]    # Agent ignores the rule, as the evaluation has stopped.

使用场景

Allowing specific checks and commands

Allow only two vfs.file item checks and two system.run commands:

AllowKey=vfs.file.contents[/tmp/app.log]
       AllowKey=vfs.file.size[/tmp/app.log]
       AllowKey=system.run[/usr/bin/uptime]
       AllowKey=system.run[/usr/bin/df -h /]
       DenyKey=vfs.file.*[*]

Allowing scripts

Allow Zabbix agent to execute scripts on hosts via all available methods:

• Global scripts that can be executed in the frontend or via API (this method always uses the system.run[myscript.sh] key)
• Remote commands from action operations (this method always uses the system.run[myscript.sh,nowait] key)
• system.run Zabbix agent items with the script, for example:
  • system.run[myscript.sh]
  • system.run[myscript.sh,wait]
  • system.run[myscript.sh,nowait]

AllowKey=system.run[myscript.sh,*]

To control the wait/nowait parameter, you must set a different rule. For example, you can allow only system.run[myscript.sh,wait] items, thus excluding other methods:

AllowKey=system.run[myscript.sh,wait]

Securing allow/deny rules

This example shows how to secure overly permissive AllowKey or DenyKey rules.

Consider the following rules:

AllowKey=system.run["C:\Program^ Files\Zabbix^ Agent^ 2\scripts\test.bat*"]
       DenyKey=vfs.file.*
       DenyKey=system.cpu.load[*]

These rules contain a wildcard (*), which can be misused:

• The test.bat script can be executed with any arguments, including unintended ones.
• The vfs.file.* pattern matches only item keys without parameters; however, all vfs.file items require parameters.
• The system.cpu.load[*] pattern matches only item keys with parameters; however system.cpu.load items do not require parameters.

To secure these rules, explicitly allow executing test.bat only with specific arguments, and deny correct item key patterns; for example:

AllowKey=system.run["C:\Program^ Files\Zabbix^ Agent^ 2\scripts\test.bat status"]
       AllowKey=system.run["C:\Program^ Files\Zabbix^ Agent^ 2\scripts\test.bat version"]
       DenyKey=vfs.file.*[*]
       DenyKey=system.cpu.load
       DenyKey=system.cpu.load[*]

You can test the rules by running the following commands, which will return ZBX_NOTSUPPORTED.

cd "C:\Program Files\Zabbix Agent 2"
       zabbix_agent2.exe -t system.run["C:\Program^ Files\Zabbix^ Agent^ 2\scripts\test.bat debug"]
       zabbix_agent2.exe -t vfs.file.size["C:\ProgramData\MyApp\config.ini"]
       zabbix_agent2.exe -t vfs.file.contents["C:\Windows\System32\drivers\etc\hosts"]
       zabbix_agent2.exe -t system.cpu.load
       zabbix_agent2.exe -t system.cpu.load[all,avg1]

模式示例