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