Local Area Networks (LANs) in Aircraft - FTP Directory Listing - FAA

un as long as the operating system is up. Other daemons are started when needed and run only
as long as they are useful.
Error—An omission or incorrect action by a crew member or maintenance personnel, or a
mistake in requirements, design, or implementation.
Evaluation Assurance Level (EAL)—Part 3 of the CC [46] identifies seven EALs. The EALs
are predefined packages of assurance components that comprise the CC’s scale for rating
confidence in the security of IT products and systems. EAL levels 2-7 are generally equivalent
to the Trusted Computer System Evaluation Criteria (TCSEC) (see also TCSEC in this Glossary)
(i.e., the “Orange Book” [42]) C2 through A1 security ratings.
Event—An occurrence that has its origin distinct from the airplane, such as atmospheric
conditions, runway conditions, conditions of communication, navigation, and surveillance
services, bird-strike, cabin and baggage fires. The term is not intended to cover sabotage.
Exercise a threat—(1) a malicious attempt to gain unauthorized access to an IT system to
compromise system and data integrity, availability, or confidentiality or (2) a benign, but
nonetheless purposeful, attempt to circumvent system security. (NIST 800-30)
Exploit—A purposeful action (or actions) by a threat source to accidentally trigger or
intentionally cause, either directly or consequentially, a threat condition.
Failure—An occurrence that affects the operation of a component, part, or element such that it
can no longer function as intended.
Failure condition—A condition that has an effect on either the airplane or its occupants, or both,
either direct or consequential, which is caused or contributed to by one or more failures or errors,
considering flight phase and relevant adverse operational or environmental conditions or external
events.
Function—The lowest defined level of a specific action of a system, equipment, and flight crew
performance aboard the airplane that, by itself, provides a complete recognizable operational
capability.
ICMP—About a dozen types of Internet Control Message Protocol (ICMP) messages have been
defined. These messages are used to report IP protocol errors to the sender as well as to provide
IP-level services. The error messages most relevant to this report are: destination unreachable,
time exceeded, parameter problems, source quench, and redirect. The two IP services most
relevant to this report are (1) Echo request and Echo reply, which are used to see if a given
destination is reachable and alive. Upon receiving the Echo message, the destination is expected
to send an Echo reply message back. Another useful service is (2) the Timestamp request and
the Timestamp reply, which are like Echo except that the arrival time of the message and the
departure time of the reply are recorded in the reply.
Impact—Magnitude of harm that could be caused by a threat’s exercise of a vulnerability
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