SNMP in Network Management: A Powerful Tool for Keeping Your Network Running Smoothly

Published on: November 20, 2023

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9 min read

The last ten years have seen a tremendous expansion of computer networks due to the emergence of wireless networking. In the meantime, this expansion has led to considerably more sophisticated network administration difficulties, such as maintaining intricate networks of switches, servers, or routers. This is the situation when SNMP is useful.

In computer networks, SNMP was created in response to the growing demand for a common method of tracking and managing IP-based devices. The "simple" set of operations that SNMP offers its clients makes remote administration of these devices possible. This article will mainly cover the SNMP protocol, including the following topics related to it:

• What is SNMP?
• What are the SNMP components?
• What is the purpose of SNMP in network management?
• What are the different versions of SNMP?
• What are the advantages of SNMP?
• What are common issues or considerations with SNMP?
• How does SNMP work?
• How is SNMP used for monitoring network devices?
• What are the SNMP commands?
• What are SNMP ports and port numbers?
• Is SNMP TCP or UDP?
• What are the best practices for SNMP monitoring?
• What are open-source SNMP tools?

What is SNMP?

A Simple Network Management Protocol is referred to as SNMP. SNMP is a commonly used and defined application layer protocol that is intended to facilitate the sharing of device management data between network devices connected to a TCP/IP network. The main purpose of the SNMP protocol is to collect configuration and statistical information about different network devices, such as hubs, switches, routers, computers, and network printers. Metrics like the number of frames or packets sent or received in a second, the frequency of errors per second, and so forth are included in the statistical data. It is essential to remember that network managers may keep an eye on the functionality and availability of SNMP network devices by using the statistics and configuration data that SNMP provides. With the appropriate SNMP monitoring tool, administrators can view the whole network and track the status of various SNMP versions.

What are the SNMP Components?

There are four primary components to the SNMP architecture. The SNMP components are as follows:

1. SNMP Manager

2. SNMP Agent

3. Managed Devices

4. MIB

Figure 1. SNMP Architecture

1. SNMP Manager

The SNMP Manager serves as both the central system and a client for SNMP network monitoring. The job of communicating with network devices that have installed SNMP agents falls to the SNMP manager, often known as a network management station (NMS). The host on which the system runs is part of the network.

The manager asks questions of the agents, gets answers in return, configures variables for them, and accepts information that they share about occurrences. When the SNMP manager sends a request, the SNMP agent uses the Management Information Base (MIB) to transmit the appropriate response.

2. SNMP Agent

A server is acted upon via an SNMP agent. It describes a software procedure that answers SNMP queries and provides details about a network node's status and statistics. The most important management task is carried out via SNMP agents. They carry out tasks including gathering, storing, and sending monitoring data while being locally connected to networked equipment.

The selected SNMP manager receives transmitted data upon query. To communicate configuration changes and status information, SNMP software agents installed on network devices and services connect to a network management system.

3. Managed Devices

A network node that supports the SNMP and offers read-only or read/write access to device data in both directions is referred to as a managed device.

4. MIB (Management Information Base)

MIB serves as a repository. A MIB structure controls the information exchange of an SNMP system. The parameters of the devices that each SNMP agent manages are described in its own information database. A software program that collects data related to capacity planning, performance management, and fault management using SNMP is called an SNMP manager.

Between the agent and the management, the MIB acts as a shared database. The names assigned to the managed objects included inside an MIB are called object identifiers, sometimes referred to as object IDs or OIDs. An MIB, which functions as a shared database for the agent and the manager, houses the gathered data in SNMP managers.

Every item handled inside an MIB hierarchy has a unique identification known as the item identification (OID). Due to its architecture, a great deal of flexibility is possible, including support for proprietary needs.

What is the Purpose of SNMP in Network Management?

What uses does SNMP serve? Network managers keep an eye on the devices connected to the network and allocate, decommission, and free up ports and interfaces to guarantee continuous availability and effective utilization of bandwidth throughout network operations. Vigilantly watching SNMP devices is a major part of this approach.

An administrator must configure the SNMP agent to send monitoring data to an SNMP manager in order to use SNMP monitoring. The network management tool takes care of the monitoring, freeing up administrators to focus on making necessary corrections. Administrators would find it difficult to manage and keep an eye on the devices connected to their networks without SNMP monitoring, though.

Using the data provided by SNMP, administrators can monitor the performance and availability of SNMP network devices and identify problems to maintain the health of their network. With the right SNMP monitoring solution, IT professionals therefore obtain a comprehensive image of their whole network environment. Furthermore, SNMP monitoring software provides presentations on how to enhance network performance, together with data presented in easily comprehensible ways. The collection and organization of device data would take too long without SNMP monitoring solutions, wasting the time of IT team members.

What are the SNMP Versions?

SNMPv1, SNMPv2c, and SNMPv3 are the three versions of SNMP that have been produced. User Datagram Protocol (UDP) is used to carry all SNMP messages, and it supports the GET, GetNext, and Set SNMP actions in all versions. SNMP versions are outlined below:

1. SNMPv1: There are significant security and performance issues with SNMPv1, the initial version of the protocol. Authentication is provided using SNMPv1, and it is password-based (community string). The NMS management and the agents exchange the community string in plain text. Therefore, if IP access control lists (ACLs) are not in place, the controlled device is susceptible to unauthorized users who can quickly modify the device.

   There is no encryption used in the data transfers between the NMS manager and the agents for SNMPv1 and 2c.

   The list of protocol transactions for SNMPv1 protocol performance is restricted to the Gets, Sets, and Traps of certain MIB objects. As a result, retrieving a row of information from enormous collections of data requires many transactions.

2. SNMPv2c: The replacement for the original SNMPv1 is SNMPv2c. For SNMPv1, the normal MIB2 integer has a length of 32 bits; however, SNMPv2 introduces a new kind of integer that has a length of 64 bits. Because 32-bit counters have limited capacity and must wrap fast, 64-bit counters are better suited to handle high-speed connections. This results in higher network traffic and lower CPU usage for the NMS management and the agent.

   Moreover, SNMPv2c enhances SNMPv1's speed by adding the Get Bulk Requests function. The NMS management sends a GetBulk message to the agent rather than a Get request if it has to retrieve a lot of data. Compared to repeatedly issuing GetNext instructions, the GetBulk operation is far more efficient and returns values for every variable in the list.

   SNMPv2c introduces a brand-new type of SNMP communication known as an SNMP Inform request. Managers often communicate with one another over an SNMP Inform to confirm receipt of notifications. Until an SNMP acknowledgment is received by the sender SNMP manager, the SNMP Inform request packet will be transmitted continuously.

   The basic authentication method used by the SNMPv1 and SNMPv2c protocols depends on community names.

3. SNMPv3: The most recent version of the SNMP protocol, known as SNMPv3, fixes the security flaws in previous SNMP versions. SNMpv3 implements SNMP View, SNMP Group, and SNMP User to enable message integrity, authentication, and encryption.

   What a certain SNMPv3 user may see is defined by SNMP View. One way to set this up is so that, for instance, a user can only see the interface index, OID 1.3.6.1.2.1.2, and everything below that.

   You need to specify the name iso in order to establish an all-access view. Because of the tree structure of the MIB, everything below the iso is accessible.

   • noauth: nor authentication or encryption
   • auth: only authentication, no encryption
   • priv: authentication and encryption

The SNMP Group specifies the kind of access, read-only or read/write, and is linked to the SNMP View. Additionally, it specifies the kind of security that is in effect while using the gadget.

With the appropriate degree of encryption and authentication, an SNMP user is added to the group. The group, such as priv, the password, the encryption technique, such as AES, the shared secret for generating encryption keys, and the kind of password hash, such as SHA, must all meet the security model.

What are the Advantages of SNMP?

There are several benefits to SNMP use. The visibility that SNMP provides is its greatest feature. To keep an eye on your whole network, you may utilize SNMP monitoring tools. This will assist you in resolving difficulties with performance. The principal advantages of SNMP use are as follows:

• Open Source: The SNMP protocol is fully open source. The main advantage of utilizing SNMP is that it is open-source software. The fact that SNMP is an independent protocol guarantees this. As a result, a lot of suppliers support this standard. In the event that you employ a proprietary protocol, your reliance on the vendor will never end. There are several SNMP suppliers on the market. You may thus select the optimal technology for your network.
• SNMP Traps: You can receive warnings about your network devices using SNMP traps. Your device will notify the SNMP manager if there is a problem. By doing this, you can be certain that you are aware of all network problems. You may utilize a wide range of parameters with SNMP traps. As such, you may alter it to suit your requirements.
• Fault Management: Using SNMP to manage your network is ideal. For network management, the majority of network administrators already use it. You will always be current if you use SNMP traps. It will help you keep an eye on the condition of your gadgets. SNMP traps will transmit your crucial information. You can get assistance from your SNMP manager on troubleshooting network issues.

What are the Drawbacks of SNMP?

The use of SNMP still has several drawbacks. The key areas where SNMP falls short are security and scalability. With heavier workloads, it is less effective. You are open to several types of assault if you are still using outdated versions. The following are some major drawbacks to utilizing SNMP:

• Scalability: The primary issue with utilizing SNMP is scalability. Devices cannot send massive amounts of data to SNMP. When it comes to translating the data it gets, SNMP excels. It isn't effective with a lot of data, though. It is thus incompatible with your routing table. SNMP is ideal if total visibility is what you're after.

• Security: Security is yet another major SNMP problem. SNMP V3 makes use of reliable encryption techniques. SNMP V2 and V1 are still open to a lot of assaults, though. There are no security features in these versions. They don't employ any encryption techniques. As such, attacking these versions is rather simple. You must set up SNMP V3 correctly if you're utilizing it. Otherwise, breaking into SNMP devices is rather simple. An attacker will be able to access your whole network if they manage to breach your SNMP management.

  By utilizing V3, the security threats may be reduced. It's crucial to modify your tools' default settings. You ought to set your SNMP to read-only mode as well. Upgrade to the most recent SNMP version if you're still using the older one. This will assist you in lowering the dangers.

• SNMP-Enabled Devices: You require devices that are SNMP-enabled in order to utilize SNMP. The SNMP manager is not compatible with monitoring other kinds of devices. As a result, network monitoring tools are using a variety of network protocols to address the visibility issue. Make sure the devices you're utilizing are SNMP-enabled if you're using an SNMP monitoring tool.

How does SNMP Work?

Sending protocol data units, or SNMP GET requests, to network devices that reply to SNMP is how SNMP operates. Network monitoring tools use GET requests to retrieve data from SNMP, and they monitor every connection. Your network receives traffic from a variety of sources. The Simple Network Management Protocol is what connects the devices and the network as a whole.

Devices are preconfigured with SNMP, as previously indicated, and will record performance statistics once the protocol is enabled. There will be several management information base (MIB) files on each network server. The monitoring data is retrieved by querying the device MIB files. The components of SNMP are what make it function, and each one helps with resource management.

How is SNMP used for Monitoring Network Devices?

The best way to describe SNMP monitoring is as a collaboration between agents on managed devices and one or more managers who gather and examine the information the agents send in. The SNMP-retrievable data is appropriate for network device status information retrieval, making it perfect for network monitoring. The network monitoring solution receives event messages and functions as a central processor, retrieving data from the SNMP agents on the devices that need to be watched in a targeted manner.

What are the SNMP Commands?

Using a combination of push and pull connections between network devices and the management system, SNMP carries out a wide range of tasks. It is capable of issuing read-only or write-only instructions, like password resets and configuration changes. Additionally, many SNMP managers automatically send the administrator an email or text message alert if a specified threshold is surpassed. It can report back on the amount of bandwidth, CPU, and memory that is being used.

The majority of the time, SNMP operates in a synchronous manner, where the agent responds to an initial message from the SNMP management. Protocol data units (PDUs) are these commands and messages that are usually sent over Transmission Control Protocol/IP (TCP/IP) or UDP.

Common SNMP commands are listed below:

• GET Request: A request created by the SNMP manager and routed to an agent in order to get the value of a variable in an MIB that is identifiable by its OID.
• GETBULK Request: This is a request that the SNMP manager sends to the agent in order to effectively get a sizable quantity of data, particularly huge tables.
• GETNEXT Request: The SNMP manager sends the agent a GETNEXT request to obtain the values of the next OID in the MIB hierarchy.
• INFORM Request: Similar to a TRAP, an asynchronous alert that needs the SNMP manager to acknowledge receipt is called an INFORM Request.
• RESPONSE: The agent responded to a GET request, GETNEXT request, GETBULK request, and SET request by sending this letter to the SNMP manager. includes the specified variables' values.
• SET Request: A request for configurations or commands sent to the agent by the SNMP management.
• TRAP: An asynchronous alarm that the agent sends to the SNMP management to let them know something important has happened, such as a failure or error.

What are SNMP Ports and Port Numbers?

An SNMP communication endpoint that designates SNMP data transfers is called an SNMP port. For transmitting instructions and messages, SNMP utilizes ports 161 and 162. SNMP ports are used by SNMP managers and SNMP agents to interact.

The port numbers that each protocol utilizes for certain processes are listed below:

Process	Protocol	Port number
Request receipt by the agent	UDP	161
The manager's communication with the agent	UDP	161
Notification receipt by the manager	UDP	162
Agent's notification generation	UDP	Any available port
Request receipt	TLS/DTLS	10161
Notification receipt	TLS/DTLS	10162

Table 1. Port Numbers used for SNMP Processes

Is SNMP TCP or UDP?

User Datagram Protocol (UDP) is used for SNMP message transmissions. Sometimes, the protocols known as Transport Layer Security (TLS) or Datagram Transport Layer Security (DTLS) are employed.

The IP layer's Transport Layer uses two different kinds of protocols: User Datagram Protocol (UDP) and Transmission Control Protocol (TCP). Through LAN, SNMP may be deployed over both protocols. SNMP packets are normally sent over UDP, although they can also be sent via TCP ports.

What are Best Practices for SNMP Monitoring?

You may monitor and get alerts about the hardware component condition of your device by using SNMP. The following are some best practices for SNMP usage in your network:

• While extended polling intervals cause you to miss an event as values average out over time, setting a polling period that is too short will increase the load on your network device and generate a barrage of notifications. Select a polling interval that works for your network, taking into account the devices that are being polled as well as the kind of data you are gathering. Select a lower polling interval for vital data that sheds light on network uptime; non-critical statistics can tolerate less frequent polling.
• Make sure you give each device the proper "read-only" or "read/write" rights, depending on how important the device is. For your devices, create robust community strings and don't accept inbound SNMP requests over the WAN. By doing this, you can strengthen security and keep unwanted people off of your network.
• Choose an NMS system that supports SNMP v3 in order to mitigate the security threats related to SNMP v1 and v2. With the addition of user and message authentication as well as encryption to guard against data eavesdropping, SNMPv3 closes the security gaps left by earlier iterations. To put it briefly, SNMP offers an application-layer protocol that makes it easier for network devices to share management data and alerts the NMS when this happens. It gives network managers the ability to easily identify and fix issues with their networks before they cause outages, control network performance, and offer data for network expansion planning.

What are Open-Source SNMP Tools?

Below, you can find information about the top open-source SNMP tools:

1. LibreNMS: One of the greatest open-source network monitoring programs is LibreNMS. Its API gathers, organizes, and produces data visualizations. With SNMP, it automatically scans the whole network, and it can be scaled horizontally to increase the scope of its monitoring. Its alerting mechanism may be adjusted to connect with the network in an efficient manner. It provides iOS and Android solutions as well.
2. NetXMS: NetXMS offers visual graphs, reports, and procedures for each layer of an IT system. It has full support for SMNPv3 and offers automated Layer 2 and Layer 3 discovery functionalities. This network monitoring tool uses scanning probes and information capabilities to allow both passive and active findings.
3. Pandora FMS: An open-source monitoring tool is Pandora FMS. It helps businesses monitor their whole IT infrastructure. One of the open-source programs that supports SNMP for servers, networks, and virtual interfaces is Pandora FMS. It enables the installation of agents to monitor the temperature and record events in the log file on the device.
4. Mibble: One of the Java SNMP MIB's open-source library utilities is called Mibble. It decodes MIB files and grants the API access to data like types, descriptions, OIDs, and so on. It is one of the open-source programs that provides both thorough MIBs and a basic SNMP manager.
5. Cacti: Cacti is a provider of open-source SNMP tools built on the data recording and graphing architecture of RRDTool. It supports SNMP polling and allows customized designs for data collection. It retrieves device information for networks of various sizes using functions like data collection and network polling.
6. SNMP Collector: One of the fully functional and open-source programs is SNMPcollector. The SnmpCollector is an open-source program that serves as a comprehensive and versatile Generic SNMP data collector. Its primary objective is to streamline the setup process for obtaining data from any device that supports the SNMP protocol. Additionally, it facilitates the transmission of the collected data to an influxdb backend. The utility also has a user-friendly web administration interface.
7. SNMPsim: One of the pure Python, open-source tools for running the SNMP agent simulator is called SNMP Simulator. It is licensed under the BSD License and is distributed. Data is gathered from network traffic and tcdump snoops by the open-source SNMP utility. Additionally, it keeps agent snapshots for use in simulations down the road. It is a highly portable, simple-to-deploy, pure Python solution.
8. Collectd: A small daemon called Collectd collects data from a system. It makes it possible for mechanisms to gather and examine values using various methods.
9. Reconnoitre: Reconnoitre and other open-source SNMP tools are reliable security solutions. It gathers multithreaded data and counts the number of services. It creates IT structures and directories to hold data from several sources. It uses recommended commands and directory structures to automate the information collection process.
10. Sharpsnmplib: The Sharp SNMP Library is a Mono and .NET open-source utility. It serves as SNMP's source code repository. One open-source utility that may be included in Windows is the Sharp SNMP Library. For compilation, Visual Studio 2019 and the.NET Core SDK are needed.
11. Thola: One of the open-source network monitoring programs that primarily makes use of SNMP is called Thola. It is the perfect tool for network device management and monitoring. Using development guidelines and monitoring plugins, it activates a "check mode" function. It works with Icinga, Zabbix, Nagios, and other programs.
12. Observium Community: The open-source version of Observium's network monitoring tools for controlling SNMP-enabled devices is called Observium Community. It provides network mapping tools and aids in multi-device monitoring. The network monitoring system refreshes the map on a regular basis and enables automated device detection. This open-source network monitoring application allows you to select IPv4 settings and modify the automatic (DHCP) static settings for SNMP.
13. Snimpy: One of the most engaging Python-based SNMP utilities is Snimpy. It constructs SNMP queries and offers a straightforward interface. It is an open-source SNMP utility that functions as a library-based MIB parser. It offers scalars according to the session characteristics. Similar to the Python dictionary, which is a feature, it permits columns. It has functions like the SET and GET methods as well as the GETNEXT table iteration.
14. ntopng: One of the greatest web-based, open-source tools for traffic network monitoring on SNMP devices is ntopng. It permits access to trigger inquiries and offers real-time device examination. Performance, usability, and functionality have all improved in the most recent version. Users can view past SNMP data for many devices and interfaces thanks to it.