Machine A sends a packet with a SYN flag set to Machine B. B acknowledges A's SYN with a SYN/ACK. A acknowledges B's SYN/ACK with an ACK.
Access Control ensures that resources are only granted to those users who are entitled to them.
Access Control List (ACL)
A mechanism that implements access control for a system resource by listing the identities of the system entities that are permitted to access the resource.
Access Control Matrix
An Access Matrix uses rows to represent subjects and columns to represent objects with privileges listed in each cell.
Access Control Service
A security service that provides protection of system resources against unauthorized access. The two basic mechanisms for implementing this service are ACLs and tickets.
Management is the maintenance of access information which consists of four tasks: account administration, maintenance, monitoring, and revocation.
Account Harvesting is the process of collecting all the legitimate account names on a system.
ACK piggybacking is the practice of sending an ACK inside another packet going to the same destination.