A network management system contains: several (potentially many) nodes, each with a processing entity, termed an agent, which has access to management instrumentation; at least one management station; and, a management protocol, used to convey management information between the agents and management stations. Operations of the protocol are carried out under an administrative framework which defines both authentication and authorization policies.
Network management stations execute management applications which monitor and control network elements. Network elements are devices such as hosts, routers, terminal servers, etc., which are monitored and controlled through access to their management information.
In the Administrative Model for SNMPv2 document [1], each SNMPv2 party is, by definition, associated with a single authentication protocol and a single privacy protocol. It is the purpose of this document, Security Protocols for SNMPv2, to define one such authentication and one such privacy protocol.
The authentication protocol provides a mechanism by which SNMPv2 management communications transmitted by the party may be reliably identified as having originated from that party. The authentication protocol defined in this memo also reliably determines that the message received is the message that was sent.
The privacy protocol provides a mechanism by which SNMPv2 management communications transmitted to said party are protected from disclosure. The privacy protocol in this memo specifies that only authenticated messages may be protected from disclosure.
These protocols are secure alternatives to the so-called "trivial" protocol defined in [2].
The Digest Authentication Protocol is described in Section 3. It provides a data integrity service by transmitting a message digest - computed by the originator and verified by the recipient - with each SNMPv2 message. The data origin authentication service is provided by prefixing the message with a secret value known only to the originator and recipient, prior to computing the digest. Thus, data integrity is supported explicitly while data origin authentication is supported implicitly in the verification of the digest.
The Symmetric Privacy Protocol is described in Section 4. It protects messages from disclosure by encrypting their contents according to a secret cryptographic key known only to the originator and recipient. The additional functionality afforded by this protocol is assumed to justify its additional computational cost.
The Digest Authentication Protocol depends on the existence of loosely synchronized clocks between the originator and recipient of a message. The protocol specification makes no assumptions about the strategy by which such clocks are synchronized. Section 5.3 presents one strategy that is particularly suited to the demands of SNMP network management.
Both protocols described here require the sharing of secret information between the originator of a message and its recipient. The protocol specifications assume the existence of the necessary secrets. The selection of such secrets and their secure distribution to appropriate parties may be accomplished by a variety of strategies. Section 5.4 presents one such strategy that is particularly suited to the demands of SNMP network management.