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% List of Common Abbreviations. Feel free to add more.          %
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\postchapter{Glossary}
\label{glossary}

{\bf [Meta: This could use more entries, and a little polishing.
Feel free to make suggestions.]}

An enormous difficulty in networking is to remember what all the
abbreviations and terms one encounters really mean. Here's a list of
those used frequently throughout the guide, along with a short
explanation. 

\begin{dispitems}
\ditem[ACU]
        Automatic Call Unit. A modem.\footnote{
         Alternatively: A teenager with a telephone.
        }

\ditem[ARP]
        Address Resolution Protocol. Used to map IP~addresses
        to Ethernet addresses.

\ditem[ARPA]
	Advanced Research Project Agency, later DARPA. Founder
	of the Internet.

\ditem[ARPANET]
	The ancestor of today's Internet; an experimental network
	funded by the U.S. Defense Advanced Research Project Agency
	(DARPA).

\ditem[Assigned Numbers]
	The title of an \emph{RFC} published regularly that lists
	the publicly allocated numbers used for various things in
	TCP/IP networking. For example, it contains the list of all
	port numbers of well-known services like \prog{rlogin}, 
	\prog{telnet}, etc. The most recent release of this
	document is RFC~1340.

\ditem[bang path]
	In UUCP networks, a special notation for the path from
	one UUCP site to another. The name derives from the
	use of exclamation marks (`bangs') to separate the
	host names. Example: \email{foo!bar!ernie!bert} denotes
	a path to host \user{bert}, travelling (in this order)
	\host{foo}, \host{bar}, and \host{ernie}.

\ditem[BBS]
	Bulletin Board System. A dial-up mailbox system.

\ditem[BGP]
	Border Gateway Protocol. A protocol for exchanging
	routing information between autonomous systems.

\ditem[BIND]
        The Berkeley Internet Name Domain server. An implementation
        of a DNS server.

\ditem[BNU]
	Basic Networking Utilities. This is the most common UUCP
	variety at the moment.  It is also known as HoneyDanBer UUCP.
	This name is derived from the authors' names: P.~Honeyman,
	D.A.~Novitz, and B.E.~Redman.

\ditem[broadcast network]
	A network that allows one station to address a datagram
	to all other stations on the network simultaneously.

\ditem[BSD]
	Berkeley Software Distribution. A \unix{} flavor.

\ditem[canonical hostname]
	A host's primary name within the Domain Name System. This
	is the host's only name that has an A record 
	associated with it, and which is returned when performing
	a reverse lookup.

\ditem[CCITT]
        Comite\'e Consultatif International de  T\'el\'egraphique
        et T\'el\'ephonique. An International organization of
        telephone services, etc.

\ditem[CSLIP]
	Compressed Serial Line IP. A protocol for exchanging IP
	packets over a serial line, using header compression of
	most TCP/IP datagrams.

\ditem[DNS]
        Domain name system. This is a distributed database used on the
        Internet for mapping of host names to IP~addresses.

\ditem[EGP]
	External Gateway Protocol. A protocol for exchanging
	routing information between autonomous systems.

\ditem[Ethernet]
	In colloquial terms, the name of a sort of network equipment.
	Technically, Ethernet is part of a set of standards set forth by
	the IEEE. The Ethernet hardware uses a single piece of cable,
	frequently coax cable, to connect a number of hosts, and
	allows transfer rates of up to 10Mbps. The Ethernet protocol
	defines the manner in which hosts may communicate over
	this cable.\footnote{
	 As an aside, the Ethernet \emph{protocol} commonly used by TCP/IP
	 is \emph{not} exactly the same as IEEE~802.3. Ethernet frames
	 have a type field where IEEE~802.3 frames have a length field.
	}

\ditem[FQDN]
	Fully Qualified Domain Name. A hostname with a domain name
	tacked onto it, so that it is a valid index into the Domain Name
	database.

\ditem[FTP]
        File Transfer Protocol. The protocol one of the best-known
        file transfer service is based on and named after.

\ditem[FYI]
        ``For Your Information.'' Series of documents with informal
        information on Internet topics.

\ditem[GMU]
	Groucho Marx University. Fictitious University used as an example
	throughout this book.

\ditem[GNU]
	GNU's not Unix~-- this recursive acronym is the name of a project
	by the Free Software Association to provide a coherent set of
	\unix{}-tools that may be used and copied free of charge. All
	GNU software is covered by a special Copyright notice, also
	called the GNU General Public License (GPL), or Copyleft.
	The GPL is reproduced in section~\ref{appendix.gpl}.

\ditem[HoneyDanBer]
	The name of a UUCP variety. See also BNU.

\ditem[host]
	Generally, a network node: something that is able to receive and
	transmit network messages. This will usually be a computer, but
	you can also think of X-Terminals, or smart printers.

\ditem[ICMP]
        Internet Control Message Protocol. A networking protocol used
        by IP to return error information to the sending host, etc.

\ditem[IEEE]
	Institute of Electrical and Eletronics Engineers. Another standards
	organization. From a UNIX user's point of view, their most
	important achievement are probably the POSIX standards which
	define aspects of a UNIX systems, ranging from system call
	interfaces and semantics to administration tools.

	Apart from this, the IEEE developed the specifications for
	Ethernet, Token Ring, and Token Bus networks. A widely-used
	standard for binary representation of real numbers is also due to
	the IEEE.

\ditem[IETF]
        Internet Engineering Task Force.

\ditem[internet]
	A computer network formed of a collection of individual smaller
	networks.

\ditem[Internet]
	A particular world-wide internet.

\ditem[IP]
        Internet Protocol. A networking protocol.

\ditem[ISO]
	International Standards Organization.

\ditem[ISDN]
	Integrated Services Digital Network. New telecommunications
	technology using digital instead of analogue circuitry.

\ditem[LAN]
	Local Area Network. A small computer network.

\ditem[MX]
        Mail Exchanger. A DNS resource record type used for marking
        a host as mail gateway for a domain.

\ditem[network, packet-switched]
	A variety of networks that provide instantaneous forwarding
	of data by all data up in small packets, which are tramsported
	to their destination individually. Packet-switched networks
	rely on permanent or semi-permanent connections.

\ditem[network, store-and-forward]
	They are pretty much the opposite of packet-switched networks.
	These networks transfer data as entire files, and don't
	use permanent connections. Instead, hosts conect to each other
	at certain intervals only, and transfer all data at once.
	This requires that data be stored intermediately until a
	connection is established.

\ditem[NFS]
        Network File System. A standard networking protocol and
        software suite for accessing data on remote disks
        transparently.

\ditem[NIS]
        Network Information System. An RPC-based application that
        allows to share configuration files such as the password file
        between several hosts. See also the entry under YP.

\ditem[NNTP]
        Network News Transfer Protocol. Used to transfer news over
        TCP network connections.

\ditem[octet]
	On the Internet, the technical term referring to a quantity of
	eight bits. It is used rather than \emph{byte}, because there
	are machines on the Internet that have byte sizes other than eight
	bits.

\ditem[OSI]
	Open Systems Interconnection. An ISO standard on network software.

\ditem[path]
	Often used in UUCP networks as a synonym for \emph{route}. Also
	see \emph{bang path}.

\ditem[PLIP]
	Parallel Line IP. A protocol for exchanging IP packets over
	a parallel line such as a printer port.

\ditem[port, TCP or UDP]
	Ports are TCP's and UDP's abstraction of a service endpoint.
	Before a process can provide or access some networking service,
	it must claim (bind) a port. Together with the hosts' IP
	addresses, ports uniquely identify the two peers of a TCP connection.

\ditem[portmapper]
	The portmapper is the mediator between the program numbers used
	by RPC as an identification of individual RPC servers, and the
	TCP and UDP port numbers those services are listening to.

\ditem[PPP]
	The point-to-point protocol. PPP is a flexible and
	fast link-layer protocol to send various network protocols
	such as IP or IPX across a point-to-point connection.  Apart
	from being used on serial (modem) links, PPP can also be
	employed as the link-level protocol on top of ISDN.

\ditem[RARP]
        Reverse Address Resolution Protocol. It permits hosts to
        find out their IP~address at boot time.

\ditem[resolver]
	This is a library responsible for mapping hostnames to
	IP~addresses and vice versa.

\ditem[resource record]
	This is the basic unit of information in the DNS database, 
	commonly abbreviated as RR.
	Each record has a certain type and class associated with it,
	for instance a record mapping a host name to an IP~address
	has a type of A (for address), and a class of IN
	(for the Internet Protocol).

\ditem[reverse lookup]
	The act of looking up a host's name based on a given IP~address.
	Within DNS, this is done by looking up the host's IP~address
	in the \host{in-addr.arpa} domain.

\ditem[RFC]
        Request For Comments. Series of documents describing
        Internet standards.

\ditem[RIP]
        Routing Information Protocol. This is a routing protocol used
        dynamically adjust routes inside a (small) network.

\ditem[route]
	The sequence of hosts a piece of information has to travel
	from the originating host to the destination host. Finding
	an appropriate route is also called \emph{routing}.

\ditem[routing daemon]
	In larger networks, network topology changes are hard to adapt
	to manually, so facilities are used to distribute current
	routing information to the network's member hosts. This is
	called dynamic routing; the routing information is exchanged
	by \emph{routing daemons} running on central hosts in the network.
	The protocols they employ are called \emph{routing protocols}.

\ditem[RPC]
        Remote Procedure Call. Protocol for executing procdures inside
        a process on a remote host.

\ditem[RR]
	Short for \emph{resource record}.

\ditem[RS-232]
	This is a very common standard for serial interfaces.

\ditem[RTS/CTS]
	A colloquial name for the hardware handshake performed by
	two devices communicating over RS-232. The name derives from
	the two cicuits involved, RTS (``Ready To Send''), and
	CTS (``Clear To Send'').

\ditem[RTM Internet Worm]
	A Virus-like program that used several flaws in VMS and
	BSD~4.3 Unix to spread through the Internet. Several ``mistakes''
	in the program caused it to multiply without bound, and so
	effectively bringing down large parts of the Internet.
	RTM are the author's initials (Robert T.~Morris), which he left
	in the program.

\ditem[site]
	An agglomeration of hosts which, to the outside, behave almost
	like a single network node. For example, when speaking from an
	Internet point of view, one would call a Groucho Marx University
	a site, regardless of the complexity of its interior network.

\ditem[SLIP]
	Serial Line IP. This is a protocol for exchanging IP packets over
	a serial line, see also CSLIP.

\ditem[SMTP]
        Simple Mail Transfer Protocol. Used for mail transport
        over TCP connections, but also for mail batches transported
        over UUCP links (batched SMTP).

\ditem[SOA]
        Start of Authority. A DNS resource record type.

\ditem[System V]
	A \unix{} flavor.

\ditem[TCP]
        Transmission Control Protocol. A networking protocol.

\ditem[TCP/IP]
        Sloppy description of the Internet protocol suite
        as a whole.

\ditem[UDP]
        User Datagram Protocol. A networking protocol.

\ditem[UUCP]
        Unix to Unix Copy.
        A suite of network transport commands for dial-up
        networks.

\ditem[Version 2 UUCP]
	An aging UUCP variety.

\ditem[virtual beer]
	Every Linuxer's favorite drink. The first mention of virtual
	beer I remember was in the release note of the \linux{} 0.98.X kernel,
	where Linus listed the ``Oxford Beer Trolls'' in his credits section
	for sending along some virtual beer.

\ditem[well-known services]
	This term is frequently used to refer to common networking
	services such as \prog{telnet} and \prog{rlogin}.  In a more
	technical sense, it describes all services that have been
	assigned an official port number in the ``Assigned Numbers''
	RFC.

\ditem[YP]
	Yellow Pages. An older name for NIS which is no longer used,
	because Yellow Pages is a trademark of British Telecom.
	Nevertheless, most NIS utilities have retained names with
	a prefix of \prog{yp}.

\end{dispitems}
