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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)            9  TCP/IP Network Management Framework and Protocols (SNMP and RMON)                 9  TCP/IP Simple Network Management Protocol (SNMP) Protocol                      9  SNMP Protocol Operations

SNMP Protocol Information Notification Using Trap(v2) and InformRequest Messages 1 2 3 SNMP Protocol Messaging and Message Formats

In my description of the various SNMP versions, it's possible that I may have been a bit harsh on those who worked on SNMP during the 1990s. The proliferation of many SNMP version 2 variants really was unfortunate, and not something we often see in the world of TCP/IP. However, now that we've seen the sort of work that SNMP does, the need for security in the protocol would seem to be clear. Given that, and given the very low level of security in the initial SNMPv1 protocol, it's understandable to some extent why a conflict over security issues arose.

The need for security in SNMP is obvious because the MIB objects being communicated contain critical information about network devices. We don't want just anyone “snooping” into our network to find out our IP addresses, or how long our machines have been running, or whether our links are down, or pretty much anything else. When it comes to object write operations using SetRequest-PDU, the concerned are magnified even more: we definitely don't want strangers being able to control or interfere with our managed devices by issuing bogus commands to change MIB objects that control device operation!

SNMP Protocol Information Notification Using Trap(v2) and InformRequest Messages 1 2 3 SNMP Protocol Messaging and Message Formats