False Rejects are when an authentication system fails to recognize a valid user.
Protection method used by botnets consisting of a continuous and fast change of the DNS records for a domain name through different IP addresses.
Fault Line Attacks use weaknesses between interfaces of systems to exploit gaps in coverage.
A TCP/IP protocol specifying the transfer of text or binary files across the network.
A filter is used to specify which packets will or will not be used. It can be used in sniffers to determine which packets get displayed, or by firewalls to determine which packets get blocked.
An inter-network router that selectively prevents the passage of data packets according to a security policy. A filtering router may be used as a firewall or part of a firewall. A router usually receives a packet from a network and decides where to forward it on a second network. A filtering router does the same, but first decides whether the packet should be forwarded at all, according to some security policy. The policy is implemented by rules (packet filters) loaded into the router.
A protocol to lookup user information on a given host. A Unix program that takes an e-mail address as input and returns information about the user who owns that e-mail address. On some systems, finger only reports whether the user is currently logged on. Other systems return additional information, such as the user's full name, address, and telephone number. Of course, the user must first enter this information into the system. Many e-mail programs now have a finger utility built into them.
Sending strange packets to a system in order to gauge how it responds to determine the operating system.