Network devices such as servers, routers, switches, printers, firewalls, and more are essential for the smooth operation of any network. However, managing and monitoring these devices can be challenging, especially when they come from different vendors and have different features and functions.

That’s where SNMP comes in. SNMP stands for Simple Network Management Protocol, and it is a standard protocol for network management. It enables you to communicate with various devices on your network and collect information about their status, configuration, performance, and errors. You can also use SNMP to change some settings on the devices remotely.

In this article, you will learn what an SNMP server is, how it works, why you need it, and how to set it up and configure it. By the end of this article, you will have a better understanding of SNMP and how it can help you manage and monitor your network devices more easily and effectively.

What Is SNMP Server?

An SNMP server is any device that runs an SNMP agent and can be monitored and managed by an SNMP manager using the SNMP protocol. An SNMP server can be any type of network device, such as a router, switch, printer, firewall, load balancer, workstation, server, camera, etc.

An SNMP server can provide various information about its status and performance, such as CPU usage, memory usage, disk space, network traffic, temperature, fan speed, etc. It can also receive commands from an SNMP manager to change certain settings or perform certain actions, such as rebooting, updating, or shutting down.

Why You Need SNMP Server Monitoring

SNMP server monitoring is a process of using an SNMP manager to collect and analyze data from SNMP agents on your network devices. It helps you to:

• Identify your network devices and their characteristics
• Monitor their performance metrics such as CPU usage, memory usage, disk space usage, bandwidth usage, etc.
• Detect any problems or errors that may affect their availability or functionality
• Troubleshoot any issues or resolve any incidents quickly
• Optimize your network resources and improve your network efficiency
• Maintain your network security and compliance

SNMP server monitoring can be used for various purposes, such as:

• Inventory management: You can use SNMP to discover and document your network devices and their configuration details. You can also use SNMP to track any changes or updates on your devices.
• Fault management: You can use SNMP to monitor the status and health of your network devices and receive alerts when something goes wrong. You can also use SNMP to diagnose and fix any problems remotely.
• Performance management: You can use SNMP to measure and analyze the performance of your network devices and identify any bottlenecks or issues. You can also use SNMP to tune and optimize your network settings and parameters.
• Security management: You can use SNMP to enforce your network policies and rules and prevent any unauthorized access or modification. You can also use SNMP to detect and respond to any threats or attacks.

How SNMP Server Works And Configure It

SNMP Architecture

SNMP has a simple architecture based on a client-server model. The servers, called managers, collect and process information about devices on the network. The clients, called agents, are any type of device or device component connected to the network. They can include not just computers, but also network switches, phones, printers, and so on.

The managers and agents communicate using messages called protocol data units (PDUs). There are different types of PDUs for different purposes. For example, there are PDUs for requesting information (GET), sending information (RESPONSE), setting values (SET), sending notifications (TRAP), and acknowledging notifications (INFORM).

The managers can send PDUs to the agents to request information or to modify some settings. The agents can send PDUs to the managers to respond to requests or to notify them of events or errors. The communication can be initiated by either side.

SNMP operations and data types

SNMP operations are the actions that can be performed by an SNMP manager or an agent using the SNMP protocol. The most common operations are:

• GET : This operation is used by a manager to retrieve the value of one or more OIDs from an agent. The manager sends a GET request with a list of OIDs to the agent, and the agent responds with a GETRESPONSE message containing the values of those OIDs.
• SET : This operation is used by a manager to modify the value of one or more OIDs on an agent. The manager sends a SET request with a list of OIDs and their new values to the agent, and the agent responds with a SETRESPONSE message indicating whether the operation was successful or not.
• GETNEXT : This operation is used by a manager to retrieve the value of the next OID in a MIB from an agent. The manager sends a GETNEXT request with an OID to the agent, and the agent responds with a GETNEXTRESPONSE message containing the value of the next OID in the MIB.
• GETBULK : This operation is used by a manager to retrieve the values of multiple OIDs in a MIB from an agent in one request. The manager sends a GETBULK request with an OID and a number of repetitions to the agent, and the agent responds with a GETBULKRESPONSE message containing the values of those OIDs.
• TRAP : This operation is used by an agent to send unsolicited notifications to one or more managers about certain events or conditions that occur on the device. The agent sends a TRAP message with an OID and a variable binding list to the managers, and does not expect any response from them.
• INFORM : This operation is used by an agent or a manager to send confirmed notifications to another manager about certain events or conditions that occur on the device. The sender sends an INFORM message with an OID and a variable binding list to the receiver, and expects an INFORMRESPONSE message from them.
• REPORT : This operation is used by an agent to send error messages to a manager about certain problems that occur during SNMP communication. The agent sends a REPORT message with an OID and a variable binding list to the manager, and expects a REPORTRESPONSE message from them.

SNMP data types are the formats that can be used to represent the values of OIDs in SNMP messages. The most common data types are:

• Integer : This data type represents a signed 32-bit integer value ranging from -2147483648 to 2147483647.
• Unsigned Integer : This data type represents an unsigned 32-bit integer value ranging from 0 to 4294967295.
• Counter : This data type represents an unsigned 32-bit integer value that can only increase or wrap around to zero when it reaches its maximum value. It is used to count events or occurrences on a device.
• Gauge : This data type represents an unsigned 32-bit integer value that can increase or decrease, but cannot exceed its maximum or minimum value. It is used to measure values such as speed, temperature, or voltage on a device.
• TimeTicks : This data type represents an unsigned 32-bit integer value that counts time in hundredths of seconds since some epoch. It is used to measure durations or intervals on a device.
• Octet String : This data type represents a sequence of octets (bytes) that can have any length. It is used to store text, binary, or hexadecimal data on a device.
• Object Identifier : This data type represents an OID that uniquely identifies an object in a MIB. It is used to refer to other OIDs or values on a device.
• IPAddress : This data type represents an IPv4 address in dotted decimal notation (for example, 192.168.1.1). It is used to store network addresses on a device.

SNMP Components

SNMP relies on three main components: management information base (MIB), object identifiers (OIDs), and data types.

• MIB is a hierarchical database that stores information about the devices on the network. It defines what kind of information can be accessed and modified using SNMP. Each device has its own MIB that describes its characteristics and capabilities.
• OIDs are uniIPAddressque identifiers that refer to specific entries in the MIB. They are composed of numbers separated by dots that follow a tree-like structure. For example, 1.3.6.1.2.1.1.1 is an OID that refers to the system description entry in the MIB.
• Data types are the formats of the values that can be exchanged using SNMP. They include integers, strings, booleans, counters, gauges, timestamps, and more.

SNMP protocol versions and features

There are three main versions of the SNMP protocol: SNMPv1, SNMPv2c, and SNMPv3. Each version has its own advantages and disadvantages in terms of security, functionality, and compatibility.

• SNMPv1 : This is the original version of the protocol that was released in 1988. It supports basic operations such as GET (to retrieve data from an agent), SET (to modify data on an agent), GETNEXT (to retrieve the next OID in a MIB), GETRESPONSE (to acknowledge a request), TRAP (to send unsolicited notifications from an agent to a manager), and INFORM (to send confirmed notifications from one manager to another). It uses community strings as passwords to authenticate managers and agents. However, this method is insecure because community strings are sent in plain text over the network.
• SNMPv2c : This is an extension of SNMPv1 that was released in 1996. It adds new operations such as GETBULK (to retrieve multiple OIDs in one request), REPORT (to send error messages from an agent to a manager), and NOTIFICATION (to replace TRAP and INFORM). It also improves the performance and efficiency of the protocol by using 64-bit counters and reducing the size of the messages. It still uses community strings as passwords, which makes it vulnerable to snooping and spoofing attacks.
• SNMPv3 : This is the latest and most secure version of the protocol that was released in 1998. It adds new features such as user-based security model (USM), which allows for authentication and encryption of SNMP messages using various algorithms. It also supports view-based access control model (VACM), which allows for fine-grained authorization of managers and agents based on their roles and privileges. It also supports remote configuration and administration of SNMP entities using SNMP commands.

Enabling SNMP on Windows Server

If you are using a Windows server as your SNMP manager, you need to enable the SNMP service on it. To do that, follow these steps:

• Open the Control Panel and click on Programs.
• Click on Turn Windows features on or off.
• Expand the SNMP feature and check the box next to Simple Network Management Protocol (SNMP).
• Click OK and wait for the installation to complete.
• Open the Services app and locate the SNMP Service.
• Right-click on it and select Properties.
• On the General tab, set the Startup type to Automatic and click Start.
• On the Security tab, enter the community names and permissions for your SNMP agents. A community name is a password that allows access to the SNMP data. You can use public as the default read-only community name and private as the default read-write community name. However, for security reasons, you should change them to something more secure and unique.
• On the Traps tab, enter the IP addresses of your SNMP managers that will receive trap notifications from your SNMP agents. A trap is a message that an agent sends to a manager when an event or error occurs.
• On the Agent tab, enter the contact information and location of your server. You can also select the services that you want to monitor using SNMP, such as physical, applications, end-to-end, etc.
• Click OK to save the changes.

Configuring SNMP on Other Devices

If you want to monitor other devices on your network using SNMP, you need to enable and configure the SNMP agent on them. The exact steps may vary depending on the device type and manufacturer, but in general, you need to do the following:

• Log in to the device’s web interface or command-line interface using an administrator account.
• Navigate to the SNMP settings or options.
• Enable the SNMP agent and set its status to active or enabled.
• Enter the community names and permissions for your SNMP managers. Make sure they match with those on your SNMP server.
• Enter the IP addresses of your SNMP managers that will receive trap notifications from your device.
• Enter the contact information and location of your device.
• Select the MIBs that you want to expose or monitor using SNMP. A MIB is a collection of OIDs that define the information that can be accessed or modified using SNMP.
• Save the changes and restart the device if necessary.

How to monitor SNMP servers using PRTG Network Monitor

PRTG Network Monitor is a network monitoring software that can monitor and manage SNMP servers using a graphical user interface (GUI) or a web browser. It can also send alerts and notifications when certain events or thresholds are met.

To monitor SNMP servers using PRTG Network Monitor, follow these steps:

• Download and install PRTG Network Monitor from here.
• Run PRTG Network Monitor and log in with your credentials.
• Click on Devices in the main menu and then click on Add Device.
• In the Add Device dialog box, enter a name for your device (for example, My Server) and select an IP version (for example, IPv4).
• Enter the IP address or hostname of your server (for example, 192.168.1.101) and click Next.
• In the Device Settings dialog box, select an icon for your device (for example, Server) and click Next.
• In the Credentials for Windows Systems dialog box, enter your Windows username and password for your server and click Next.
• In the Credentials for Linux/Solaris/Mac OS (SSH/WBEM) Systems dialog box, enter your Linux username and password for your server if applicable and click Next.
• In the Credentials for VMware/XenServer Systems dialog box, enter your VMware username and password for your server if applicable and click Next.
• In the Credentials for SNMP Devices dialog box, enter your community name for your server (for example, public) and select an SNMP version (for example, v2c). Click Next.
• In the Sensor Management dialog box, select the sensors that you want to add to your device. Sensors are the components that monitor specific aspects of your device, such as CPU, memory, disk, network, etc. You can select from a list of recommended sensors or choose from a list of all sensors. Click Next.
• In the Summary dialog box, review the settings for your device and click Finish.

You have now added your SNMP server to PRTG Network Monitor. You can see the status and performance of your server in the device overview page. You can also customize the sensors, alerts, notifications, reports, and dashboards for your server according to your needs.

Conclusion

SNMP is a simple yet powerful protocol for network management. It allows you to communicate with various devices on your network and collect information about their status, configuration, performance, and errors. You can also use SNMP to change some settings on the devices remotely. To use SNMP effectively, you need an SNMP server that can collect and process data from your network devices. You also need an SNMP monitoring tool that can display and analyze the data in a user-friendly way. In this article, we have explained what an SNMP server is, how it works, why you need it, and how to set it up and configure it. We hope this article has helped you understand SNMP better and how it can help you manage and monitor your network devices more easily and effectively.