Terms 11
Definitions and Questions
TCP/IP
Abbreviation of Transmission Control Protocol, and
pronounced as separate letters. TCP is one of the main
protocols in TCP/IP networks. Whereas the IP protocol
deals only with packets, TCP enables two hosts to
establish a connection and exchange streams of data.
TCP guarantees delivery of data and also guarantees
that packets will be delivered in the same order in which
they were sent.
Internet Protocol - The network layer for the TCP/IP
protocol suite widely used on Ethernet networks. IP is a
connectionless, best-effort packet switching protocol. It
provides packet routing, fragmentation and re-assembly
throughthe data link layer.
IP Address
An identifier for a computer or device on a TCP/IP network.
Networks using the TCP/IP protocol route messages based on the
IP address of the destination. The format of an IP address is a 32-bit
numeric address written as four numbers separated by periods.
Each number can be zero to 255. For example, 1.160.10.240 could
be an IP address.
Within an isolated network, you can assign IP addresses at random
as long as each one is unique. However, connecting a private
network to the Internet requires using registered IP addresses
(called Internet addresses) to avoid duplicates.
The four numbers in an IP address are used in different ways to
identify a particular network and a host on that network.
UDP
(User Datagram Protocol)
A protocol within the TCP/IP protocol suite that is
used in place of TCP when a reliable delivery is
not required. There is less processing of UDP
packets than there is for TCP.
UDP is widely used for streaming audio and
video, voice over IP (VoIP) and
videoconferencing, because there is no time to
retransmit erroneous or dropped packets.
TCP/IP Q/A
Q: What does the address 127.0.0.1
mean?
A: 127.0.0.1 is a loopback network
connection. If you telnet, ftp, etc... to it you
are connected to your own machine. This
is commonly used as a practical joke with
people who are new to TCP/IP. It’s also
called the “home” address.
127.0.0.1
Think Geek
http://www.thinkgeek.com/tshirts/coder/5d6a/
Dynamic IP
A term used to describe how IP addresses
are dynamically assigned to computers as
and when needed.
Unlike Static IP addresses, the IP address
is temporary e.g. when you connect to
your ISP using a dial-up connection , you
PC or router will be dynamically assigned
an IP address while you are on-line.
Static IP
Referred to as fixed IP address.
A static IP address is a number that is
assigned to a computer by an Internet
service provider (ISP) to be its permanent
address on the internet.
Dynamic / Static IP Q/A
Q: Who would typically have a static IP
address? Why?
A: Large corporations tend to have static
IPs for their servers. This allows their
clients to consistently access these
servers.
DHCP
-Short for Dynamic Host Configuration Protocol, a protocol for assigning
dynamic IP addresses to devices on a network. With dynamic addressing, a
device can have a different IP address every time it connects to the
network. In some systems, the device's IP address can even change while it
is still connected. DHCP also supports a mix of static and dynamic IP
addresses.
A method of automatically assigning a TCP/IP address to a client. A DHCP
server is used to dole out a TCP/IP address from a pool of TCP/IP
addresses to a client that supports DHCP. When you connect to your ISP
over a modem or broadband you are typically assigned a dynamic (nonstatic) TCP/IP address via DHCP. The big advantage to DHCP is that you
don't need to manually assign a TCP/IP address to a client--the DHCP
server takes care of that. After an amount of time passes where the client
does not contact the server, the server puts the TCP/IP address of the client
back into the pool to be assigned to that client or any other client hat
requests a TCP/IP address. The disadvantage of DHCP for the DHCP client
is that the client is not guaranteed to have a particular TCP/IP address at
any given time. For that you want a static IP address.
DNS
Domain name servers, or DNS, are an incredibly important but
completely hidden part of the Internet. The DNS system forms one
of the largest and most active distributed databases on the planet.
Without DNS, the Internet would shut down very quickly.
This service maps TCP/IP numbers, such as 123.12.4.245, to a
more easily remembered name, such as www.geek.com. Thus,
when you type www.geek.com into your browser, it goes out to the
DNS server specified by your ISP and asks for a matching TCP/IP
address. If the browser finds a DNS entry for the name you typed in,
you see the appropriate website. If not, it lets you know. Every
domain name that is actually being used for a website has a
corresponding TCP/IP address. When you set up a site you have
your ISP add a DNS entry to its DNS servers (or manage it
yourself). This entry gets replicated across the Internet in a matter of
hours, and, once fully replicated, you can reach your website from
any Internet connection.
DHCP / DNS Q/A
Q: Does IU use DHCP for dorm
connections?
A: Yes. If they didn’t, you would have to
call UITS up and request an IP address.
Plus, if you took your computer off of the
network for a while and they accidentally
gave ‘your’ IP address to someone else,
you would have an IP conflict if you
plugged your machine back in.
Denial of Service
An attack that is specifically designed to prevent the normal
functioning of a system, and thereby to prevent lawful access to that
system and its data by its authorized users.
On the Internet, a denial of service (DoS) attack is an incident in
which a user or organization is deprived of the services of a
resource they would normally expect to have. Typically, the loss of
service is the inability of a particular network service, such as e-mail,
to be available or the temporary loss of all network connectivity and
services. In the worst cases, for example, a Web site accessed by
millions of people can occasionally be forced to temporarily cease
operation.
Although usually intentional and malicious, a denial of service attack
can sometimes happen accidentally. A denial of service attack is a
type of security breach to a computer system that does not usually
result in the theft of information or other security loss. However,
these attacks can cost the target person or company a great deal of
time and money.
Honey Pot
A honey pot is a computer system on the Internet that is
expressly set up to attract and "trap" people who attempt
to penetrate other people's computer systems. To set up
a honey pot, it is recommended that you:



Install the operating system without patches installed and using
typical defaults and options
Make sure that there is no data on the system that cannot safely
be destroyed
Add an application that is designed to record the activities of the
invader
Maintaining a honey pot is said to require a considerable
amount of attention and may offer as its highest value
nothing more than a learning experience (that is, you
may not catch any crackers).
War Dialing
A war dialer is a computer program used to identify the
phone numbers that can successfully make a connection
with a computer modem. The program automatically
dials a defined range of phone numbers and logs and
enters in a database those numbers that successfully
connect to the modem. Some programs can also identify
the particular operating system running in the computer
and may also conduct automated penetration testing. In
such cases, the war dialer runs through a predetermined
list of common user names and passwords in an attempt
to gain access to the system.
An identical technique was sometimes used to get the
first call for prizes in radio "call-in" shows, thus leading to
the adoption of random "fifth caller," "secenteenth caller"
etc. by radio stations to circumvent this practice.
WiFi
Short for ‘wireless fidelity’. A term for certain
types of wireless local area networks (WLAN)
that use specifications conforming to IEEE
802.11.
WiFi has gained acceptance in many
environments as an alternative to a wired LAN.
Many airports, hotels, and other services offer
public access to WiFi networks so people can
log onto the Internet and receive emails on the
move.
These locations are known as hotspots.
War Chalking
Warchalking is the practice of marking a series of symbols on
sidewalks and walls to indicate nearby wireless access. That way,
other computer users can pop open their laptops and connect to the
Internet wirelessly.
As the Warchalking web site states, this kind of language was first
utilized by hobos during the Great Depression to communicate with
each other for various purposes, mostly to find safe harbor.
Warchalking itself capitalizes on this idea. Wireless users help other
wireless users by communicating about nearby access points
Creator Matt Jones began by posting three possible war chalking
symbols on his blog. Two semi-circles back-to-back would indicate
an open node, a circle would indicate the presence of a closed node,
and a circle with the letter "W" inside it would indicate a WEP node.
Ideally, each symbol would be chalked with a corresponding SSID
next to it which would act as a password to the node.
War Chalking
War Driving
A computer cracking technique that
involves driving through a neighborhood
with a wireless-enabled notebook
computer and mapping houses and
businesses that have wireless access
points.
War Q/A
Q: Other than people trying to break into
computers, who might use a wardialer or
wardialer-like system?
A: Telemarketers use wardialer-like
systems to call hundreds of numbers at
once, and then transfer numbers that
picked up to salesmen. In this case,
they’re actually looking for numbers –notconnected to modems or faxes.
Short Quiz
Please get out a blank sheet of paper and
put your name and the date on it.
Short Quiz
1. Define “HTML”.
2. Define “DRM”.
3. Analog signals are composed of discrete
1s and 0s – T/F?
4. Your intranet and extranet are often
separated by a _______ designed to
keep out intruders.
5. How many signals are needed for GPS
to precisely pinpoint your location?
Short Quiz
1.
2.
3.
4.
5.
Hyper Text Markup Language
Digital Rights Management
F
Firewall
3