User-Based Security Model (USM) for Version 3 of the Simple Network Management Protocol (SNMPv3). U. Blumenthal, B. Wijnen. January 1998. http://www.faqs.org/rfcs/rfc2274.html
Network Ingress Filtering: Defeating Denial of Service Attacks which Employ IP Source Address Spoofing. P. Ferguson, D. Senie. January 1998. http://www.faqs.org/rfcs/rfc2267.html