SNMP (Simple Network Management Protocol)
SNMP was defined by IETF (Internet Engineering Task Force). It is used to manage the network. It is an internet standard protocol that monitors devices in IP networks and collects and organizes the information (data) of these devices. SNMP is supported by most network devices such as the hub, switch, router, bridge, server, modem, and printer, etc.
The concept of SNMP is based on the manager and agent. A manager is like a host that controls a group of agents, such as routers.
SNMP Manager: It is a computer system that monitors network traffic by the SNMP agent, and it queries these agents, takes answers, and controls them.
SNMP Agent: It is a software program that is located in a network element. It collects real-time information from the device and passes this information to the SNMP manager.
Management components
It has two components
- SMI
- MIB
SNMP:It defines the structure of packets that is shared between a manager and an agent.
SMI (Structure of Management Information): SMI is a network management component that defines the standard rules for the naming object and object type (including range and length) and also shows how to encode objects and values.
MIB (Management Information Base): MIB is the second component of the network management. It is virtual information storage where management information is stored.
SNMP basic operation
- GetRequest: The GetRequest operation is used by the SNMP manager to derive one or more values from the SNMP agent.
- GetNextRequest: The GetNextRequest is similar to the GetRequest operation, but it is used to get the next value from the SNMP agent.
- SetRequest: It is used by the manager to set the value of the agent device.
- Trap: This command is used by the SNMP agent to send acknowledgment messages to the SNMP manager.
- GetBulkRequest: It is used by the SNMP manager to retrieve the large data from the SNMP agent.
Difference between all versions of the SNMP?
| Feature | SNMP Version 1 | SNMP Version 2 | SNMP Version 3 |
|---|---|---|---|
| Developed Year | 1988 | 1993 | 2002 |
| Access Control | It is based on the SNMP community and MIB view. | It is based on the SNMP community and MIB view. | It is based on the SNMP user, group, and MIB view. |
| Authentication and privacy | SNMP v1 is not secure because anyone can access the network. | SNMPv2 failed to improve on security. | Its primary feature is enhanced security. |
| Standards | RFC-1155.1157.1212 | RFC-1441,1452 RFC-1909.1910 RFC- 1901 to 1908 | RFC-1902 to 1908,2271 to 2275 |
| Message Format | There are five messages format in the SNMP version 1 (GetRequest, GetNextRequest, SetRequest, Trap, Response). | Seven messages instead of five (inform-request, get-bulk-request) | Implements SNMP v1 and v2 specifications along with proposed new features |
| Default/known passwords | Yes | Yes | No |
| Susceptible to replay attacks | Yes | No | No |
| Susceptible to injection attacks | Yes | No | No |
| Susceptible to brute- force attacks | Yes | Yes | No |
| Susceptible to buffer-overflow attacks | Yes | Yes | No |
| Susceptible to sniffing of session keys | Yes | No | No |
SNMP Port
The SNMP sends instructions and messages using both port 161 and port 162. The SNMP agent uses the port 161, and the SNMP manager uses the port 162.