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header from the physical layer, followed by a header from the datalink layer (e.g., Ethernet), followed by a
header from the network layer (IP), followed by a header from the transport layer (e.g. TCP), followed by the
application protocol data.
– A form of security wherein readable data is changed to a form that is unreadable to unauthorized
Encryption
users. Encryption involves the conversion of data into a secret code for transmission over a public network.
The original (plain) text is converted into coded form (called cipher text) using an encryption algorithm. The
cipher text is decoded (decrypted) at the receiving end, and is converted back into plain text.
ESP (Encapsulating Security Payload)
combination with AH. Security services can be provided between a pair of communicating hosts, between a
pair of communicating security gateways, or between a security gateway and a host. ESP may be used to
provide the same security services as AH, plus it provides an encryption service. The main difference between
the ESP authentication method and the AH authentication method is that ESP does not protect any IP header
fields unless those fields are encapsulated by ESP (tunnel mode). ESP is important for the integrity and
encryption of datagrams.
– Certificates and keys may have a limited lifetime, and expiration dates are used to monitor
Expiration Date
and control their useful life.
– A set of rules that define what packets may pass through a network. Filters can use source,
Filter
destination, or protocol to determine whether to pass or discard a packet transmission. Part of a packet (the
header) must contain information that matches the information in the defined rules or else the packet filter will
discard it.
– The act or process of defining which data traffic is to be allowed between the network and hosts,
Filtering
typically using packet filter rules. Filtering is the central part of firewall security. With packet filter rules, you
define which data traffic is allowed between the networks and hosts. You can also define particular packets to
be filtered and are not to be allowed to pass through the firewall. Several types of filtering exist (e.g., Protocol
filtering, port number filtering, URL address filtering, and IP address filtering).
– Windows NT and 2000 have a TCP/IP utility called Finger. This utility is an old TCP/IP tool (very
Finger
popular on UNIX systems) that matches an email address with the person who owns it and provides
information about that person. While the Finger utility is fairly old (there are more advanced tools available that
performs the same general function), it still works and can be a useful tool in certain situations.
The Finger utility was actually developed as the Finger Information Protocol. Finger was designed to provide
an interface to the Remote User Information Program (RUIP). RUIP provides information about users who have
accounts on UNIX-based computer networks. The Finger utility was created six years before the Internet was
born. The first documentation on the Finger utility was in IETF RFC742, dated December 1977. A popular
slogan promoting the phone book's yellow pages was "Let your fingers do the walking". The utility was
christened "Finger", since the utility was basically designed for tracking down people.
The Finger Information Protocol let UNIX users on college campuses create a profile, called a "Plan page",
which included personal and job-related information. A Plan page was similar to a personal home page on the
Internet today. So when someone "Fingered" your email address, they learned more about you. The Finger
utility is a command line tool, so in Windows NT or Windows 2000 you must first access a command-prompt
window to use it. You then type the command followed by an email address.
– A device that serves to shield and thus protect a (partial) network (e.g., MultiAccess) from another
Firewall
network (e.g. the Internet). The entire network traffic runs via the firewall where it can be controlled and
regulated. Technically this can be achieved in different ways. The use of special hardware firewalls is rare.
More frequent is the use of routers with firewall options. The most common is use of firewall software on a
specially dedicated computer.
– A combination of hardware and software that links two different types of networks. E.g., gateways
Gateway
between email systems allow users on different email systems to exchange messages.
– A person who tries to, and/or succeeds at defeating computer security measures.
Hacker
– The terms used by hackers; entire dictionaries exist to document hacking terms (e.g.,
Hacking Lexicon
http://www.robertgraham.com/pubs/hacking-dict.html). These documents clarify many of the terms used within
the context of information security (infosec).
– A one-way security function that takes an input message of arbitrary length and produces a fixed-
Hash
length digest. Used in SHA (Secure Hash Algorithm).
MultiAccess Communications Server MA30120 User Guide
– An authentication protocol much like AH. IP ESP may be applied in
Glossary
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