This presentation gives you a general overview of Simple Network Management Protocol covering different SNMP versions, simple commands, MIBs, OIDs and Traps.

1. IT Management, Simplified
Real-time IT management solutions for the new speed of business

2. SNMP Demystified
KARTHIK ANANDARAO
Sr. Product Consultant/Evangelist
ManageEngine

3. About ME
• Senior Product Consultant and Evangelist for
ManageEngine. With Engineering and MBA degrees from
reputed Indian institutions,
• With over 17 years of IT Experience, serving in different
capacities including System and Network Administration,
IT Management, and Consulting.
• Have travelled across the globe for implementation,
consultation and training of ManageEngine products and
solutions.

4. Agenda
• SNMP
• What is it?
• Components and their functionality
• Ports and Firewall
• SNMP Versions and Security
• MIBs and OIDs
• Basic Commands
• How does a SNMP Communication happen?
• Traps
• SNMP Tools

5. SNMP
• Simple Network Management Protocol
• Internet Standard Protocol to manage devices on IP Networks
• More precisely, the standard way of monitoring hardware and
software from any manufacturer from Cisco to Juniper, from
Microsoft to Unix.
• Part of Transmission Control Protocol / Internet Protocol (TCP /
IP) suite
• Uses UDP as the Transport Protocol

6. SNMP Components
• Components
• SNMP Manager
• SNMP Agent
• Managed Devices
SNMP
Manager
SNMP
Agent
Managed
Devices

7. SNMP Components
• Managed Device
• Could be any network device – router, switch, firewall, printer,
ups, load balancer, temperature sensor
• Could be any server – physical or virtual – be it any OS – linux,
solaris, windows, HP-UX
• Could be any device with an IP and a SNMP agent

8. SNMP Components
• SNMP Agent
• Windows – SNMP
• *UX – net-snmp
• Cisco – Cisco SNMP
Every device manufacturer configures SNMP agent on the
managed device.
Collects Management Information about its local environment
Stores and retrieves information as defined in the MIB
Signals an event to the manager

9. SNMP Components
• SNMP Manager
• NMS
• EMS
• Monitoring solutions like OpManager, Solarwinds

10. Ports and Firewall
• Open ports through firewall
• SNMP – 161 UDP
• SNMP Trap – 162 UDP (to be covered later)

11. SNMP Versions and Security
• SNMP Versions
• SNMPv1
Widely used, de-facto Network Management Protocol
Available since 1988
Authentication through Community String
• SNMPv2c
Revises Version 1
Improvements in performance, security, and manager-to-manager
communications
Introduced GetBulkRequest
Poor Security
Community String passed in Clear Text

12. SNMP Versions and Security
• SNMP Versions
• SNMPv3
• Adds security and remote configuration enhancements
o Each SNMP entity has an identifier – SNMPEngineID
o Communication possible only if the SNMP entity knows the identity of its peer
o Specification for USM – User based Security Model
o NoAuthNoPriv
o AuthNoPriv
o AuthPriv
o Authentication Protocols – MD5, SHA
o Privacy Protocols – CBC_DES, CFB_AES_128

13. SNMP Versions and Security
• SNMPv3
• Provides a secure environment for systems management covering
Discovery Procedure
Time synchronization procedure
SNMP Framework MIB
USM MIBs
VACM MIBs
Security goals - protection against Modification of Information, Masquerade,
Message Stream Modification, Disclosure
Address issues related to large-scale deployment of SNMP, accounting, and
fault management.
Focuses on Security and Administration

14. SNMP Versions and Security
• SNMPv3 Security
USM – User-based Security Model – provides authentication and
encryption functions – operates at message level
VACM – View-based Access Control Model – determines whether a
node is allowed access to a particular MIB object to perform specific
functions – operates at PDU level
TSM – Transport Security Mode – provides a method for authenticating
and encrypting messages over external security channels through SSH
and TLS/DTLS
Confidentiality – prevents snooping from unauthorized source
Integrity – ensure that a packet is not tampered
Authentication – verify message is from a valid source

15. MIBs and OIDs
• OID – Object Identifier
• Something that can gather information about on a SNMP enabled device
• Identified by a Name – Object Name
• Data-Type Definition – counter, string, gauge, integer
• Level of access – read/write
• Range Information
• Examples:
 Interface – Up-Down Status / Rx-Tx Traffic / Errors / Discards
 Process – Path / ID / CPU / Memory / Instances
 CPU – Speed / Utilization
 Memory – Total / Used / Free
 Disk – Total / Used / Free
OIDs defined in MIBs
OIDs Unique – specific to device
OIDs – Scalar or Tabular
OID – Typically a dotted list of integers

16. MIBs and OIDs
• How to locate ‘sysUpTime’ from RFC-1213 MIB?
sysUpTime - .1.3.6.1.2.1.3
• iso
• dod
• internet
• mgmt-2
• mib-2
• system
• sysDescr
• sysObjectID
• sysUpTime
• sysContact
• sysName
• sysLocation
• sysServices

17. MIBs and OIDs
• OID Example – Let us look at sysUpTime

18. MIBs and OIDs
• MIB – Management Information Base
Collection of OIDs
SNMP Agent maintains an information database describing
managed device parameters
SNMP Agent retrieves the value of the requested information
from the MIB when the SNMP Manager requests
Defines Managed Objects that an SNMP Manager requests from
the SNMP Agent
In short, MIB files are the set of questions that a SNMP Manager
can ask the agent.

19. MIBs and OIDs
• MIB – Management Information Base
• Comprises of Managed Objects identified by OID
• MIBs can be
• Standard – RFCs
• Custom / Private – provided by device manufacturers – Example : Cisco,
Huawei, Nortel

20. MIBs and OIDs
• MIB Tree Diagram

21. Basic SNMP Commands
• SNMP Commands
GET – Retrieve one value from the managed device
Example – sysName, sysUptime
GET NEXT – Retrieve the value of next OID
Used mostly by monitoring tools
GET BULK – Retrieve voluminous data
Example - ifTable
SET – Modify or assign value to a parameter
Example – Temperature Threshold on a server
TRAPS – Initiated by the agent to the SNMP Manager on occurrence of
an event
Example – linkUp, Fan Status
INFORM – Like TRAP, also includes confirmation from SNMP Manager
RESPONSE – Command used to carry back the value(s) or signal of
actions directed by the SNMP Manager

22. SNMP Communication
• SNMP Communication Diagram

23. SNMP Trap
• Trap
• Asynchronous notification from agent to Manager
• Includes
• Current sysUpTime
• An OID identifying the type of trap
• Optional Variable bindings
• Destination address for traps to be collected
• MIB contains Trap Configuration Variables
• Traps listen on 162 – UDP
• Trap Versions – SNMPv1, SNMPv2c, SNMPv3
• Example :
• 1999-11-13 08:31:33 localhost [127.0.0.1]: SNMPv2-MIB::sysUpTime.0 = Timeticks: (13917129) 1 day, 14:39:31.29
SNMPv2-MIB::snmpTrapOID.0 = OID: NOTIFICATION-TEST-MIB::demo-notif SNMPv2-MIB::sysLocation.0 = "just here"

24. SNMP Tools
• SNMP Tools
• Tools aplenty to retrieve/set SNMP messages / Traps
• Tool from ManageEngine
• ManageEngine SNMP MIB Browser
Available for Free
Trap Viewer
Get / Get Next / Get Bulk Operations
Set SNMP Variable Value
Load MIBs
Easy to Use

25. ManageEngine SNMP MIB Browser

26. ManageEngine SNMP MIB Browser
• Website
 http://www.manageengine.com/products/mibbrowser-free-tool/
• Download
 http://www.manageengine.com/products/mibbrowser-free-
tool/download.html
• Features
 http://www.manageengine.com/products/mibbrowser-free-
tool/features.html
• FAQ
 http://www.manageengine.com/products/mibbrowser-free-
tool/faq.html
• Feedback
 http://www.manageengine.com/products/mibbrowser-free-
tool/feedback.html

27. ManageEngine SNMP Community
• Join us @ SNMP Nuts & Bolts
• https://connect.manageengine.com/groups/snmp-nuts-and-
bolts
• An online community
• Share SNMP MIBs
• Upload MIBs to the community to fix errors
• Share your thoughts on SNMP
• Accept the group invite
• ManageEngine’s MIB Database
• Short URL - http://bit.ly/1mgRTb9

28. Q&A

29. Thank You