SNMP(V1-2-3)

source: cisco.com

1- What is SNMP?

SNMP is an application-layer protocol that provides a message format for communication between managers and agents. The SNMP system consists of:

  • an SNMP manager,

  • an SNMP agent,

  • and a MIB.

The SNMP agent contains MIB variables whose values the SNMP manager can request or change. A manager can get a value from an agent or store a value into the agent. The agent gathers data from the MIB, the repository for information about device parameters and network data. The agent can also respond to a manager’s requests to get or set data.

An agent can send unsolicited traps to the manager. Traps are messages alerting the SNMP manager to a condition on the network. Traps can mean improper user authentication, restarts, link status (up or down), MAC address tracking, closing of a TCP connection, loss of connection to a neighbor, or other significant events.

SNMP Versions

Model

Level

Authentication

Encryption

Result

SNMPv1

noAuthNoPriv

Community string

No

Uses a community string match for authentication.

SNMPv2C

noAuthNoPriv

Community string

No

Uses a community string match for authentication.

SNMPv3

noAuthNoPriv

Username

No

Uses a username match for authentication.

SNMPv3

authNoPriv

Message Digest 5 (MD5) or Secure Hash Algorithm (SHA)

No

Provides authentication based on the HMAC-MD5 or HMAC-SHA algorithms.

SNMPv3

authPriv (requires the cryptographic software image)

MD5 or SHA

Data Encryption Standard (DES) or Advanced Encryption Standard (AES)

Provides authentication based on the HMAC-MD5 or HMAC-SHA algorithms. Allows specifying the User-based Security Model (USM) with these encryption algorithms: DES 56-bit encryption in addition to authentication based on the CBC-DES (DES-56) standard. 3DES 168-bit encryption AES 128-bit, 192-bit, or 256-bit encryption

configuring SNMPV2 is so simple, just write :

SW# conf t
SW(conf t)# snmp-server community HRT ro
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ro means read only and rw means read/write

configuring SNMPV3 needs three steps:

1- Defining View

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iso means everything in MIB.

2- Defining Group

3- Defining User

2- Connect your Device to PRTG

PRTG is really good tool for grabbing information from devices which are working with SNMP. You can download arrow-up-rightthis software and connecting around 100 sensors are free. In other word, you can use it for small business.

1-First, Add a New Device, and IPV4 address.

2- Second, Select SNMP version, type of Authentication(SHA-MD5) and enter your username and password.

3- Third, enter encryption type and Pre-shared key.

4- Add your desire sensor, there are alot of sensors for different devices, for example I add ping to this device.

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