|
Bill
Winslow
1154 E. Kenosha
Fresno, California 93720
559-438-1005
bill@winslownet.com
Glossary Of Terms
10-21-06
Glossary
BPS
(Bits-Per-Second) The speed at which data is transmitted in
bits-per-second. A 28.8 modem can move 28,800 bits per second.
Browser
A program that is used to look at various kinds of Internet
resources.
Country Codes
In the course of tracing intrusion attempts you will sooner or later
encounter a country code. The country code is a two-letter tag at the
end of a site URL which identifies the country where the site is
located. See the on-line help for a detailed list of country codes.
Domain Name System/Server (DNS)
The Domain Name System simplifies Internet navigation. Computers on
the Internet can only be found at their numerical IP address (e.g.,
206.216.115.4). An address like "
www.Fish-On-Guide.com
" makes sense to a human but a DNS server must match it up to its
IP address. The DNS server databases are updated regularly as new domain
names are registered.
Domain Name
An Internet site's unique name, which can consist of two or more
parts separated by dots (
www.winslownet.com).
Back
DSL
DSL or Digital Subscriber Line is an increasingly popular method of
connecting to the Internet over regular phone lines. DSL offers the
advantage of a relatively high speed connection at prices substantially
lower than ISDN connections. In theory DSN has a download speed limit of
9 megabits per second and an upload limit of 640 kilobits per second. In
reality, and dependent of your provider's equipment as well as your
system equipment, you can expect anything from about 1.5 megabit
download/128 kilobit upload (Asymmetric DSL) to 384 kilobits in both
directions (Symmetric DSL).
E-mail
Electronic Mail, messages sent via the Internet or within a company LAN
or WAN. E-mail attachments in the form of EXE (executable) files or VBS
(Visual Basic script) files have become increasingly popular as a means
of transmitting viruses and Trojans.
Firewall
Hardware and/or software designed to keep unauthorized outsiders
from tampering with a computer system. That system may be a standalone
computer, a small LAN or a company-wide network or WAN with thousands of
users.
HTTP
HyperText Transfer Protocol moves hypertext (HTML) files on the
Internet from the server you are visiting to the browser you are viewing
with.
Internet
The Internet consists of a huge number of inter-connected networks
that use the TCP/IP protocols for the location and transfer of data. The
Internet evolved from a linking of university and college computers (in
the late 1960s and early 1970s) funded by the U.S. Department of Defense
and called the ARPANET. The Internet today is a global network of almost
100,000 independent networks.
Intranet
A private network, usually inside an organization, that functions
very much like the Internet. It has become common practice to permit
access to such Intranets from standalone computers used by students or
employees off-campus or off-site. Firewalls, login procedures and
passwords are designed to provide security.
IP Number
The Internet Protocol Number or IP address is a unique number
consisting of four parts separated by dots (e.g. 63.227.89.66). Every
computer of the Internet from the largest server to a laptop
communicating through a cell phone has a unique IP number. Not every
computer has a domain name but every computer uses an IP.
ISP
Internet Service Provider. This is the service you subscribe to in
order to connect with the Internet. It may be a small local company with
a few thousand subscribers, a regional company (e.g. uswest.net) or a
nationwide mega-provider like AOL or AT&T WorldNet. Most ISPs sell a
connection, nothing more.
LAN
Local Area Network. Two or more computers that are linked together
and able to share programs, data and/or peripherals
Modem
MOdulator/DEModulator. Your modem takes data you are sending and
modulates it so that it can be transmitted over an analog voice phone
line. Your modem accepts incoming modulated data and demodulates it so
that it is usable by your computer. The earliest modems required the
user to place the telephone handset into a cradle with padded apertures
for the two ends of the handset. Speeds were in the range of 300 to
1,200 BPS. With improvements in error correction, modems today under
ideal conditions can transmit data at over 50,000 BPS. over a single
phone line. DSL and ISDN connections offer even higher speeds. These
days the term modem is frequently used to describe external network
connection devices that don't actually perform any modulation or
demodulation, such as DSL and Cable modems which are actually digital
end-to-end.
NAT (Network Address Translator)
A NAT is logically similar to both a proxy and a gateway. The NAT hides
the private addresses of the local network from the public address side
attached to the Internet. The NAT takes packets from the private network
and re-writes them using one of its public IP addresses and sends it
onto the public network (Internet). When the response to the packet
comes back the NAT takes this inbound packet and redirects it to the
private address that originated the traffic. NATs allow large groups of
computers to access the Internet through a very small number of IP
addresses. Without NAT technology the supply of IP addresses would have
run dry in the late 1990's. The Internet Connection Sharing built into
Windows 98SE and later is a NAT.
Network
When you connect two or more computers, you create a network. When
you connect two or more networks you create an internet (lower case
"i").
Node
A single computer connected to a network. Nodes simply serve as
connection points in passing along data.
Non-Routable IP
See 'Private IP Space'
Packet Switching
This is the method used to move data on the Internet. The data you
are sending or receiving is broken up into pieces, each piece carrying
the IP address of where it is going and where it is coming from.
Billions of these pieces are passing through the Internet at any given
time and the major node servers are sorting these pieces and routing
them at incredible speeds. The E-mail you are reading or the web page
you are looking at has been reassembled and delivered to your monitor
after traveling across town or around the world and, best of all, you
don't have to give it a moments thought.
PING
Packet Internet Groper is a program used to determine whether a
specific IP address is accessible. A packet is sent to the specified
address and the program waits for a reply. Programs use PING to identify
and/or troubleshoot Internet connections. In addition to identifying the
target site, these programs also note all of the nodes the data passed
through between the two ends of the connection.
Private IP Space
Also known as non-routable IP address space. There are three block of IP
addresses which are reserved for private networks. These IP addresses
are used only on private networks, and cannot be connected directly to
the public Internet. If a non-routable IP address is used on a computer
connected to the Internet it must gateway through a NAT. The private IP
blocks are:
10.0.0.0 through
10.255.255.255 (Any IP Address starting with 10.)
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255
Proxy Server
Proxies are used as intermediaries in connections to the Internet. They
are generally only useful for common application uses such as web
browsing. Proxies offer several benefits. They are able to cache page
content locally; reducing Internet bound traffic as well as local
response time. They offer some security benefits by isolating the local
network from direct contact with the Internet. They also offer local
ability to restrict access to the Internet in general. Proxies do have
many limitations, one of which is that they cannot handle ICMP traffic.
For small networks a NAT is a superior solution to a proxy.
Server
A computer or software that provides specific services to software
running on other computers. The "mail server" at your ISP is
software that handles all of the incoming and outgoing mail for all of
your ISP's users. A server on a LAN is hardware that constitutes the
primary node on the network. It may also have software which provides
specific services, data or other capabilities to all of the client
computers attached to it.
TCP/IP
Transmission Control Protocol/Internet Protocol, the protocols that
make the Internet possible and that make it possible for your computer
to be part of the Internet.
URL
Uniform Resource Locator, the standard format for Internet
addresses.
WAN
Wide Area Network, a network of computers that covers an area larger
than a single building or campus. In the past WANs have been private
networks connecting geographically separated offices of the same
organization. WANs are rapidly being replaced by the Internet and the
wide use of VPNs.
WWW
The World Wide Web or just "The Web." Many people think of
this in terms of what is accessible to their browser but in reality the
web now encompasses all of the resources that make up the Internet
including such things as FTP sites, USENET, and much more.
Back
|
