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Reserve Your Seat TodaySimple Network Management Protocol (SNMP) is a standard protocol language that computers use to send commands to each other and report important information.
SNMP's purpose in monitoring and management systems is to provide network devices with a common language for exchanging data. Today, many computer devices support it, enabling them to work together.
The SNMP model is based on the manager/agent network management architecture. The managers collect and process data about devices on the network. The agents are any type of device component connected to the managed devices in the network (in remote monitoring systems, SNMP agents are usually the RTUs).
There are three versions of SNMP: v1, v2c, and v3.
To truly grasp the differences between these versions, it's essential to look at the security features each one offers.
SNMPv1:
The first version, SNMPv1, is known for its limited security capabilities. Authentication occurs without encryption, making it susceptible to unauthorized access. This version often relies on default credentials, which, if not updated by administrators, can lead to unauthorized network access. Despite these vulnerabilities, SNMPv1 remains in use across some networks due to lack of updates.
SNMPv2:
Introduced in 1993, SNMPv2 brought some improvements in security. However, its enhancements were not substantial enough to withstand the test of time. By 1998, SNMPv2 was overshadowed by the more secure and robust SNMPv3, but it marked a pivotal step in evolving SNMP's security framework.
SNMPv3:
SNMPv3 is a significant leap forward, featuring robust security measures such as data encryption and customizable authentication requirements. This version allows administrators to set specific security parameters, ensuring that unauthorized access is significantly minimized and data transfers can be encrypted for added protection.
In summary, while SNMPv1 and SNMPv2 laid the groundwork, it is SNMPv3 that truly addresses the security challenges, providing a modern and secure way to monitor networks.
SNMP "agents" are remote devices out in the network. They can be printers, managed switches, alarm remotes, generators, servers, and lots of other things. These agents report problems and receive commands from a central "manager". This is known as the "manager-agent model".
The SNMP agent listens to requests coming from the SNMP manager on the User Datagram Protocol (UDP) port 161.
The manager side of the model describes the device, computer or program that builds reports based on status reports sent by the agents. It ensures that devices are still active, because you may not know if a quiet device is offline or simply doesn't have any alarms to report.
A manager may wait for the agent to send data at a regular, pre-set interval, or it may proactively ask for data using a series of five basic messages: TRAP, GET, GET-NEXT, GET-RESPONSE, and SET.
For example, a manager may ask an agent for data with a "get" message, the agent will send back a "get-response". The manager might only need that one piece of data, or it can then send a "get-next" message (and then another, and then another) to request a full status update.
The SNMP manager listens to Trap messages coming from the agent on port UDP 162.
Seeing real devices in real-world examples is incredibly helpful when learning a new protocol like SNMP. Here is a small collection of examples of typical SNMP deployments including legacy integration. The managers and RTUs and specific, but the concepts are universal:
A SNMP Trap is one of the 5 basic message types used in SNMP protocol (although more types have been added since version 1 of SNMP). What makes an SNMP trap unique from all other message types is the fact that it is the only method that can be directly initiated by an SNMP agent in the field.
All other core SNMP message types are either initiated by the SNMP manager or issued in response to an SNMP manager's message. This is what makes a trap so important and the most common SNMP message in most networks. A trap is an SNMP agent's way of notifying the manager that there is a problem.
The Management Information Base, or MIB, is an ASCII text file that catalogs SNMP network elements as a list of data objects, similar to a dictionary of the SNMP language. Every object that is referred to in an SNMP message must be listed in the MIB.
When an SNMP device sends a Trap or other message, it identifies each data object in the message with a number string called an object identifier, or OID. The MIB provides a text label called for each OID. The SNMP manager then uses the MIB to decode the OID numbers into a human-readable display.
Solve MIB problems in 5 easy steps.
