What is SNMP?

Not all devices support SNMP. The typical devices that use SNMP are hardware like printers, routers, switches, servers, and workstations, and more recently, devices connected via the Internet of Things (IoT). SNMP is a very common protocol, and used extremely widely in business environments. Most network devices will therefore come with SNMP agents ready to go on the device. All admins or technicians have to do is configure and manage the settings so that the agents can communicate directly with the management system of the network.

What is SNMP used for?

SNMP helps maintain efficient, secure, and well-functioning networks. It is primarily used for:

• Monitoring network performance: SNMP helps detect network faults and identify patterns that might indicate potential issues.
• Managing devices: Admins can manage a wide range of network devices like routers, switches, servers, and printers, assisting in inventory management.
• Maintaining network security and compliance: SNMP can detect unusual activity aiding in the prevention of security breaches.
• Optimizing network performance: By analyzing the data collected with SNMP, admins can make informed decisions to optimize network performance, like upgrading hardware or modifying network configurations.

How does SNMP work?

SNMP is a key network management tool that works by exchanging important information between network devices and the central management system, making sure that all transmissions are consistent for all devices, regardless of device type or manufacturer. It works like a conversation; the central system gives a command or asks for information (this is the ‘request’), and the network devices reply with data or confirm that they’ve made the requested changes (this is the ‘response’). SNMP allows technicians to monitor, adjust, and manage these devices from a distance using back-and-forth communication, and ensures everything on the network runs smoothly.

The 3 elements of SNMP networking

SNMP uses a client-server architecture, where the SNMP manager is the client, and the SNMP agent is the server. Here are the three components that you’ll have in a network that is managed by SNMP.

• SNMP agent: The agent works continuously to collect all the information that is necessary and might be queried by the client. This is usually network performance metrics. At any point, the SNMP manager may send a query, and the agent needs to be ready to send the relevant information. In some cases, an agent will act without a query – for example if there is an error or a performance issue
• SNMP devices: These are the devices and the services that have the agents installed on them, the SNMP-managed network nodes. While these devices usually come pre-loaded with SNMP enabled, they will need to be configured on your own network to work as intended. You can use various SNMP test tools that are created for specific devices to test and debug SNMP devices and to monitor configurations and check for any errors.
• SNMP manager: What software will you use to manage your SNMP devices, and make requests? This system will practically monitor and control the behavior and communications of managed devices, and allow technicians to send batch updates or commands to devices. This is where most of the processing will happen, and networks might even use more than one software solution – usually called a network management station, or an NMS. You can configure your SNMP manager to send regular queries to get feedback on status and performance, or you can set up rules to trigger queries based on events.
• Management Information Base (MIB: MIB, or Management Information Base, is a hierarchical database crucial to SNMP. It stores vital information and configurations of monitored devices as data objects. Each piece of data, identified by an OID (Object Identifier), reveals a device’s status, helping network admins understand managed device capabilities.

Understanding MIB for SNMP-enabled devices

When the SNMP manager, (which functions in this case as the client) asks the server a question, the SNMP agent will need to use a database to find the answer. For SNMP, this is called the Management Information Base, more commonly known as an MIB. The MIB organizes all of the information, and will formally describe all of the components of a network device, plus its current status.

The MIB is a text file, and each item within the database will have its own unique OID, or Object Identifier.

Why do MIB items need OIDs?

When we talk about objects in relation to the MIB, we need to remember that any device can have multiple objects, which can be items like the CPU or hard drive space. An OID is a name, a string of numbers which is associated with specific information, such as the memory status of a single workstation.

Unique numbers are completely unambiguous and easy to track, and in SNMP devices, a tree-like hierarchy is used within the MIB so that you can easily see how information is being communicated.

Types of SNMP Configurations

SNMP can be configured in different ways, depending on the network needs. Common configurations include read-only (monitor data without changes), read-write (enabling full control over device settings), and trap-directed (devices automatically alert the system about significant issues or events). Each configuration offers a tailored approach to network management and security.

What are fundamental SNMP commands?

SNMP commands are essential tools for interacting with network devices and enable technicians to control a network efficiently. Some fundamental SNMP commands include:

• Get: The get command is used to request specific information from a network device, like its status or performance metrics. For example, a technician might use the get command to verify the status of a server or check the current usage of a router’s bandwidth.
• GetNext: The getNext command retrieves the next item in a sequence of data from a device and is useful for browsing through a list of items and navigating through a series of data points or settings. If a technician wants to review a list of all devices on a network, the getNext command could be used to move from the information of one device to the next in the sequence.
• Set: The set command modifies the settings or value on a network device, such as configuration parameters. This command is vital for keeping networks aligned with changing requirements and maintaining optimal performance.
• GetResponse: When a get or getNext command is requested, the network device responds with a getResponse. This command contains the requested information or data.
• Trap: The trap command is unique because it is requested by the network device itself, rather than the technician. It is an automatic alert or notification about important events or errors like a system failure, security breach or other critical incidents.

SNMP Protocol Version

There are three versions of SNMP:

• SNMP v1 is the most basic form, created back in 1988 for monitoring devices over TCP/IP networks. As it’s the most basic, it has the most lax security measures, and no encryption algorithms. The main reason why it’s still in use is because it is so low-maintenance and requires very few resources. However, many people believe it is not safe enough to be used.
• SNMP v2 has 64-bit counters, (SNMP v1 only supports 32-bit) and has a lot more functionality than SNMP v1. It offers simpler MIB discovery, more protocol packet types, and it’s become widely popular for internal networks. However, it doesn’t do much to address the security concerns of SNMP v1.
• Enter SNMP v3. This has been around since 1998, and is a lot more secure, offering role-based access control functionality. It uses SNMP view so that admins can define exactly what information users can access, SNMP groups, to make it easier to create categories for bulk actions, and also SNMP users – who can be added to groups with a pre-defined level of security and access. So, working from the ground up, if you onboard a new member of staff, you can make them an SNMP user, giving them a username and a password, add them to an SNMP group which has pre-customized policies for the SNMP view this group is allowed to have. On top of this, data leakage or tampering is a lot harder because encryption is used for authenticated devices.
• Watch out! In SNMP v3, you won’t see the terminology of SNMP manager and SNMP agent. Instead, there will be SNMP entities. These are an engine, which takes the place of the agent – and then one or more SNMP applications, which work the same way as the manager.

What is a SNMP trap?

An SNMP trap is like an automatic alert sent from a network device (the SNMP agent) to a monitoring system (the SNMP manager) to notify about specific events or changes. The traps are initiated and sent by the devices themselves, not manually by technicians. For example, if there is a configuration change or a system error within a network device, it automatically sends a trap message containing details of the event to alert the technicians without the need for manual intervention. Because these alerts are automatic, they enable quick and proactive responses to network issues.

How is SNMP connected to UDP?

In the majority of cases, SNMP works in a single direction – the SNMP manager sends a request, and then the SNMP agent replies with the information. That’s how it got its reputation as being as simple as its name suggests! This is usually done using UDP, User Datagram Protocol as the transport protocol. For this, there are specific ports used as defaults, which will be the same no matter what versions of SNMP are in use.

For standard synchronous traffic where the manager is sending a read command to access performance data, or a write command to reset a password or change a setting, the port used will be port 161, and when there is an error to report, this will be 162 – also known as SNMPTRAP. When 162 is used, this will be for the agent to report something back to the manager, in an asynchronous way.

What SNMP use cases are there?

The main functionality of the SNMP protocol is to push and pull information to and from devices. It’s not just about monitoring for information – it’s about actively making changes, like changing or rotating passwords, or organizing reboots and updates. This is great for MSPs and other IT professionals who might not be physically in front of the devices that they want to configure or maintain.

However, monitoring is also a use case in and of itself. Staying on top of elements of the network like bandwidth utilization, uptime, CPU or hard-disk space is really important, and it’s powerful to be able to make this happen on a granular level per network device. This helps you to educate specific teams or users if they have poor tech hygiene, encouraging them to restart assets, or make smarter decisions about data usage.

Because of the way that SNMP allows devices to report back to the SNMP manager, you can also use auto SNMP reporting to collect error messages and find issues before they become an issue for the end user. Over time, you can establish baselines and troubleshoot using this data. These messages from the SNMP devices can be sent by email, text message, or any other communication method that works for your network environment.

Why is SNMP monitoring curial?

SNMP is crucial for efficient network management. It offers real-time insights into network performance, allowing for quick identification and resolution of issues. This proactive approach helps in maintaining consistent network reliability and performance. SNMP’s ability to automatically send alerts ensures that potential problems are addressed immediately, avoiding issues before they even arise. Its automated data collection from various devices reduces the risk of manual errors, enhancing accuracy in network monitoring. SNMP’s compatibility with a wide range of devices simplifies the management process, making it easier to oversee and maintain a diverse network infrastructure. This combination of real-time monitoring, automation, and broad compatibility makes SNMP an essential tool in network management.

How does Atera help with SNMP monitoring?

Atera incorporates a built-in SNMP module that assists in device monitoring, providing notifications for any abnormalities or issues detected. It simplifies the process of monitoring network devices by using SNMP to gather critical information. This information includes device performance data, such as bandwidth usage, system health, and other vital metrics. Atera then presents this data in an easily understandable format, allowing IT professionals to quickly identify and address network issues. Additionally, Atera automates alert notifications when it detects irregularities, ensuring prompt responses to potential problems. Any device that supports Simple Network Management Protocol (SNMP) can be monitored using Atera. This streamlined approach with an SNMP monitoring software not only saves time but also improves the overall efficiency and reliability of network management.