GeoDesy GD-3000 Series - Manual (Page 50)

50
verifies the digest. A secret value, known only to the sender and the receiver, is
prefixed to the message. After the digest is used to verify message integrity, the
secret value is used to verify the message's origin.
To help ensure message privacy, the Symmetric Privacy Protocol uses a secret
encryption key known only to the sender and the receiver. Before the message is
authenticated, this protocol uses the Data Encryption Standard (DES) algorithm to
effect privacy. DES is a documented National Institute of Standards and Technology
(NIST) and American National Standards Institute (ANSI) standard.
Originally, SNMPv1 specified that SNMP should operate over the User Datagram
Protocol (UDP) and IP. The SNMPv2 transport mapping document (RFC 1449)
defines implementations of SNMP over other transport protocols, including OSI
Connectionless Network Service (CLNS), AppleTalk's Datagram Delivery Protocol
(DDP), and Novell's Internet Packet Exchange (IPX). RFC 1449 also includes
instructions on how to provide a SNMPv1 proxy and use of the BER. UDP/IP is still
SNMPv2's preferred transport mapping because UDP is compatible with SNMPv1 at
both the transport and network layers.