Patent ID: 8190755

Claim:
A method of authenticating a host requesting access to a resource managed by a network access control (NAC) server on a network, comprising: identifying a network address asserted by the host; determining whether the network address is valid; if the network address is valid: determining unique indicium uniquely identifying the host, wherein the unique indicium is a hash value computed from the network address and at least one of an operating system version, an operating system serial number, or one or more serial numbers or versions of software present on the host; obtaining pre-computed indicium for the network address; comparing the unique indicium and the pre-computed indicium; generating an instruction to block traffic at the resource from the host if the unique indicium does not match the pre-computed indicium or allow traffic at the resource from the host if the unique indicium matches the pre-computed indicium; and caching the instruction to block traffic or allow traffic at the resource for the network address asserted by the host; wherein the step of determining whether the network address is valid comprises receiving a table with the network address at the resource from the NAC server.