Simple Network Management Protocol (SNMP)

Versions commonly used;
- SNMPv1 – RFC 1157 - SNMPv2c (an extension to SNMPv2 to allow for communities) – RFC 1901, RFC 1905, and RFC 1906 - SNMPv3 (provides mechnism to encrypt and authenticate) –  RFCs 3413 to 3415
SNMP Framework is made up of
- SNMP manager - SNMP agent - Management Information Base (MIB)
Two ways to collect data;
- Trapping – Managed device reports events to NMS (UDP 162) - Polling – NMS interigates managed device to report on a variable (UDP 161)
Message types
- GetRequest - GetResponce - GetNextRequest - Trap - GetBulk - Inform
Useful SNMP commands
- snmp-server communiity [ro|rw] [ACL] - snmp-server system-shutdown
  • show snmp
  • show snmp community
  • show snmp mib ifmib ifindex
RFC 1213 and definitions of SNMP traps described in RFC 1215
All snmp-server commands use v2c by default
ILMI is a hidden SNMP community string and used by ATM.
Table 1 SNMP Security Models and Levels
[]()
Model
[]()
Level
[]()
Authentication
[]()
Encryption
[]()
What Happens
[]()v1[]()noAuthNoPriv[]()Community String[]()No[]()Uses a community string match for authentication.
[]()v2c[]()noAuthNoPriv[]()Community String[]()No[]()Uses a community string match for authentication.
[]()v3[]()noAuthNoPriv[]()Username[]()No[]()Uses a username match for authentication.
[]()v3[]()authNoPriv[]()Message Digest 5 (MD5) or Secure Hash Algorithm (SHA)[]()No[]()Provides authentication based on the HMAC-MD5 or HMAC-SHA algorithms.
[]()v3[]()authPriv[]()MD5 or SHA[]()Data Encryption Standard (DES)[]()Provides authentication based on the HMAC-MD5 or HMAC-SHA algorithms. Provides DES 56-bit encryption in addition to authentication based on the CBC-DES (DES-56) standard.
Support>configure>products>Cisco IOS 12.4T>Configuration Guides>Network Management>Cisco IOS Network Management Configuration Guide
[http://www.cisco.com/en/US/customer/docs/ios/netmgmt/configuration/guide/12_4/nm_12_4_book.html](http://www.cisco.com/en/US/customer/docs/ios/netmgmt/configuration/guide/12_4/nm_12_4_book.html)
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