What Is SNMP Port And How Does It Work?

Numerous networking devices aid in the correct operation of a network, such as routers, switches, gateways, etc. Large corporations typically have private networks that allow computers to communicate with one another.

A specific protocol is put in place to manage the operations of these network devices and ensure they function properly, The Simple Network Management Protocol (SNMP). SNMP keeps track of any network or network device faults and alerts the user to any fault in the network by detecting network malfunctions. 

In this article, you will learn about the SNMP protocol, ports, uses, and how it works. 

What Is Simple Network Management Protocol (SNMP)?

SNMP is a management protocol used on TCP/IP networks. It is a network protocol that manages and monitors network devices in an internet-connected network.

Furthermore, SNMP messages are sent in User Datagram Protocol (UDP) packets, which most network devices support.

Its primary function, however, is to detect faults in connected network devices. Imagine a large company with over 1000 connected network devices. It would be difficult to check each device for faults manually. 

This is where the SNMP protocol comes into play. It monitors all faulty devices and informs the network administrator. Not only that, but it also enables network administrators to remotely modify network device settings and configurations.

Key Components of SNMP

An SNMP system comprises four main components: the network management station (NMS), the agent, the managed object, and the Management Information Base (MIB).

Network Management Station (NMS):

The NMS is a network manager that monitors and controls network objects via SNMP. Its essential functions are to:

• Send requests to agents on managed devices to query or modify variables.
• Receive traps from agents on managed devices to learn the device status.

Agent:

The agent is a program that runs on a managed device. The agent keeps track of data on the managed device, reacts to NMS requests, and reports management data to the NMS.

• When the agent receives a request from the NMS, it conducts the necessary operation on the MIB and sends the operation result to the NMS.
• When a fault or an event happens on a managed device, the agent sends a notification to the NMS with the current state the device is in.

Managed object:

A managed object is an object to be managed on a network device. A managed device may contain multiple managed objects, for example, a hardware component and parameters configured for the hardware or software (such as a routing protocol).

Management Information Base (MIB):

The MIB specifies the managed device’s attributes, such as its name, status, access rights, and data type. The MIB can be used by an agent to:

• Learn the current device status.
• Set the device status.

SNMP Versions

There are three versions of the SNMP protocol. They are:

SNMPv1

The first version of SNMP, SNMPv1, offers a method for monitoring and managing computer networks. It uses community names for authentication, has a low-security level, and can only send a few error codes.

Additionally, since admins don’t regularly update the default credentials used by SNMPv1, unauthorized parties can easily access essential network data.

SNMPv2

Unlike SNMPv1, SNMPv2 offers advancements to standard error codes, data types, and operations such as GetBulk and Inform.

SNMPv3

Data protection is made possible by SNMPv3 through sophisticated encryption. It allows admins to precisely specify different authentication standards for managers and agents.

This prevents unauthorized authentication and can be used to encrypt data transfers. SNMPv3 is the most secure version of SNMP so far.

What Is An SNMP Port?

Basically, SNMP ports are SNMP communication endpoints. SNMP uses UDP as its transport protocol to transmit messages. Most frequently, UDP ports 161 and 162 are used. 

SNMP Managers use UDP 161 to poll SNMP Agents, and Agents use UDP 162 to send unauthorized SNMP traps to the SNMP Manager.

Some other protocols that support SNMP are Ethernet, Transport Layer Security (TLS), Datagram Transport Layer Security (DTLS), and Transmission Control Protocol (TCP) IPX. However, most SNMP packets are delivered over UDP.

How does the SNMP port work?

All SNMP messages are exchanged between two entities: managers or servers and agents or clients. SNMP managers are used to communicate with network devices’ SNMP agents. 

An SNMP agent is usually any network-connected device such as phones, printers, laptops, and network switches. The SNMP manager is typically installed on the network’s managing entity. SNMP agents are normally installed on managed devices. 

As stated earlier, SNMP Managers use UDP 161 to poll SNMP Agents, and Agents use UDP 162 to send unauthorized SNMP traps to the SNMP Manager.

The process is as follows:

• The SNMP manager at the top of your system provides instructions to a network device or SNMP agent via destination port 161.
• If the agent needs to report something or respond to an instruction, it will send an SNMP trap to the SNMP manager on port 162.

The SNMP Manager can communicate with the SNMP Agent in two ways:

Polling

In this method, an SNMP server sends messages to the network devices it manages using UDP port 161 with a single SNMP command (GET, GETNEXT, GETBULK, SET, etc.).

SNMP Traps

This method does not involve the server frequently sending commands to the network devices. 

The SNMP agent initiates this conversation by sending events as SNMP commands to the SNMP manager’s port 162 (TRAPS or INFORM). The SNMP agent must first be configured before it can recognize the SNMP manager. 

Conclusion

SNMP is a helpful network protocol that manages and monitors network devices in an internet-connected network, while the SNMP ports are SNMP communication endpoints. This article explored all you need to know about the SNMP protocol, SNMP ports, and how they function.