SnapGear 2.0.1 user manual Idb, Appendix B Terminology

Extranet	A private network that uses the public Internet to securely share
	business information and operations with suppliers, vendors, partners,
	customers, or other businesses. Extranets add external parties to a
	company's intranet.
Failover	A method for detecting that the main Internet connection (usually a
	broadband connection) has failed and the CyberGuard SG apliance
	cannot communicate with the Internet. If this occurs, the CyberGuard
	SG appliance automatically moves to a lower speed, secondary
	Internet connection.
Fall-forward	A method for shutting down the failover connection when the main
	Internet connection can be re-established.
Firewall	A network gateway device that protects a private network from users on
	other networks. A firewall is usually installed to allow users on an
	intranet access to the public Internet without allowing public Internet
	users access to the intranet.
Gateway	A machine that provides a route (or pathway) to the outside world.
Hashes	A code, calculated based on the contents of a message. This code
	should have the property that it is extremely difficult to construct a
	message so that its Hash comes to a specific value.Hashes are useful
	because they can be attached to a message, and demonstrate that it
	has not been modified. If a message were to be modified, then its hash
	would have changed, and would no longer match the original hash
	value.
Hub	A network device that allows more than one computer to be connected
	as a LAN, usually using UTP cabling.
IDB	Intruder Detection and Blocking. A feature of your CyberGuard SG
	appliance that detects connection attempts from intruders and can also
	optionally block all further connection attempts from the intruder's
	machine.
Internet	A worldwide system of computer networks - a public, cooperative, and
	self-sustaining network of networks accessible to hundreds of millions
	of people worldwide. The Internet is technically distinguished because
	it uses the TCP/IP set of protocols.
Intranet	A private TCP/IP network within an enterprise.
IP Compression	A good encryption algorithm produces ciphertext that is evenly
	distributed. This makes it difficult to compress. If one wishes to
	compress the data it must be done prior to encrypting. The IPcomp
	header provides for this. One of the problems of tunnel mode is that it
	adds 20 bytes of IP header, plus 28 bytes of ESP overhead to each
	packet. This can cause large packets to be fragmented. Compressing
	the packet first may make it small enough to avoid this fragmentation.
IPSec	Internet Protocol Security. IPSec provides interoperable, high quality,
	cryptographically-based security at the IP layer and offers protection for
	network communications.

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Appendix B – Terminology