What Is SNMP?

SNMP (Simple Network Management Protocol) is a network protocol used over User Datagram Protocol (UDP) that allows network administrators to monitor the status of the Dell SonicWALL security appliance and receive notification of critical events as they occur on the network. The Dell SonicWALL security appliance supports SNMP v1/v2c/v3 and all relevant Management Information Base II (MIBII) groups except egp and at.

SNMPv3 expands on earlier versions of SNMP and provides secure access to network devices by means of a combination of authenticating and encrypting packets.

Packet security is provided through:

•	Message Integrity: ensures a packet has not been tampered with in transit

•	Authentication: verifies a message comes from a valid source

•	Encryption: encodes packet contents to prevent its being viewed by an unauthorized source.

SNMPv3 provides for both security models and security levels. A security model is an authentication strategy set up between a user and the group in which the user resides. The security level is the permitted level of security within a given security model. The security model and associated security level determine how an SNMP packet will be handled. SNMPv3 provides extra levels of authentication and privacy, as well as additional authorization and access control.

The following table shows how security levels, authentication, and encryption are handled by the different versions of SNMP.

 

Table 21. Security level, authentication and encryption based on SNMP version

Model	Level	Authentication Type	Encryption	Means of Authentication
v1	noAuthNoPriv	Community String	No	Community string match
v2c	noAuthNoPriv	Community String	No	Community string match
v3	noAuthNoPriv	Username	No	Username match
v3	authNoPriv	MD5 or SHA	No	Authentication is based on the HMAC-MD5 or HMSC-SRA algorithms.
v3	authPriv	MD5 or SHA	DES or AES	Provides authentication is based on the HMAC-MD5 or HMSC-SRA algorithms. Provides DES 56-bit encryption in addition to authentication based on the CBC-DES (DES-56) standard, or AES 128-bit encryption, as well.

The Dell SonicWALL security appliance replies to SNMP Get commands for MIBII, using any interface, and supports a custom Dell SonicWALL MIB for generating trap messages. The custom Dell SonicWALL MIB is available for download from the Dell SonicWALL Web site and can be loaded into third-party SNMP management software such as HP Openview, Tivoli, or SNMPC.

SNMP settings can be viewed and configured by the administrator. Settings cannot be viewed or modified by the user. SNMPv3 can be modified at the User or Group level. Access Views can be read, write, or both, and can be assigned to users or groups. A single View can have multiple Object IDs (OIDs) associated with it.

SNMPv3 settings for the SNMPv3 Engine ID are configurable Under the General Settings menu. The Engine ID is used to authorize a received SNMP packet. Only matching packet EngineIDs will be processed.