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Monitor your network infrastructure with SNMP
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Routers, switches, servers, printers – data networks contain many complex components, and if you want to manage them with the least possible organizational and financial overhead, all you need is a Raspberry Pi and the Simple Network Management Protocol (SNMP). The latter can be used to query values such as data throughput and CPU load temperature of the device, or even to reconfigure the system.
SNMP is the successor to the Simple Gateway Management Protocol (SGMP). Its specification was approved by the Internet Engineering Task Force (IETF) in 1990, and it has seen several revisions since then. The current version is version 3. In contrast to its predecessors, SNMPv3 supports encrypted communication and secure authentication; however, many devices you can purchase today still only support SNMPv1 or SNMPv2.
Protocol Brief
SNMP uses UDP port 161 by default. Communications rely on agents and managers; the agents run on the individual devices and wait for queries or instructions from the managers. There are also SNMP traps, which cause the device to push a message to a manager when specific events occur. The message typically reaches the manager on port 162.
SNMP reads values from various network components known as managed objects. A managed object can be the status of a network interface, CPU, or device memory. To establish a standard here, the SNMP Management Information Base (MIB) was developed. The properties of many managed objects are described in the MIB tree structure. The descriptions contain the name, or OID (object identifier), and the permissible data types for an object. The OID can be numeric or humanly readable; for example, iso.org.dod.internet.mgmt and 1.3.6.1.2 refer to the same object, and they can be used as equivalents in queries.
SNMPv1 and SNMPv2 use what are known as "communities" to establish connections that are trusted by
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