Lesson on IP addresses for Bill
Mar 14, 2006 01:35 PM
Bill - Here's something that'll keep you busy for a while. It
includes some information on how IP addresses can be faked with
proxies, and that sort of thing. This may be right up your alley.
In computer networking, an IP address (internet protocol address) is
a unique number that devices use in order to identify and
communicate with each other on a network utilizing the Internet
Protocol standard. (Sometimes this is shortened to just "IP" as
in "My IP is A.B.C.D".) Any participating device — including
routers, computers, time-servers, printers, internet fax machines,
and some telephones — must have its own globally unique communicable
IP is a network layer protocol in the internet protocol suite and is
an upper layer protocol that also provides globally unique addresses
(e.g., MAC address for ethernet) but two of these addresses will not
necessarily be able to communicate to each other. IP adds a service
on top of these data link layer protocols — through the use of an IP
address — that provides the ability to uniquely identify with and
communicate with any other device on the network.
In other words, an IP address is like a full address for postal mail
while a MAC address is just the house number. For example, there are
many addresses with a house number of 123 but there is only one
address for 123 Main Street, Anytown, California, United States.
Simply mailing something to "123" will not get it there but "123
Main Street, Anytown, California, United States" is a globally
The unique nature of IP addresses makes it possible in many
situations to track which computer — and by extension, which person —
has sent a message or engaged in some other activity on the
Internet. This information has been used by law enforcement
authorities to identify criminal suspects; however, dynamically-
assigned IP addresses can make this difficult.
Since IP addresses are not easy to remember, the Domain Name System
provides the ability to map domain names (e.g. www.wikipedia.org) to
an IP address (220.127.116.11).
1 Dynamic vs. static IP addresses
2 IP version 4
3 IP version 5
4 IP version 6
5 See also
6 External links
Dynamic vs. static IP addresses
There are two methods to assigning IP addresses to computers:
dynamic and static.
Static IP addresses are used primarily for servers so that they
don't appear to "move" while non-servers are usually assigned
dynamic IP addresses. Most dynamic IP address users are users of
internet service providers (ISPs) since not all the users of an ISP
are online at one time and the ISPs can "get away" with not having
enough IP addresses for each user.
In order to use a dynamic IP address, a service such as Dynamic Host
Configuration Protocol (DHCP) is used to assign addresses
dynamically to devices as they request them. If a static address is
used, it must be manually programmed into parameters of the device's
network interface. (It is also possible to "fake" static IP address
assignments through DHCP by assigning the same IP address to a
computer — and no other — each time it is requested.)
IP version 4
Main article: IPv4#Addressing
IPv4 uses 32-bit (4 byte) addresses which limits the address space
to 4,294,967,295 possible unique addresses. However, many are
reserved for special purposes such as private networks (~18 million
addresses) or multicast addresses (~1 million addresses). This
reduces the number of addresses that can be allocated as public
Internet addresses and as the number of addresses available is
consumed, an IPv4 address shortage appears to be inevitable in the
This limitation has helped stimulate the push towards IPv6, which is
currently in the early stages of deployment and is currently the
only contender to replace IPv4. It is also sometimes impossible to
track someone's real IP because they can use Internet proxies, in
which they can fake that they are from a different country
IP version 5
What would be considered IPv5 existed only as an experimental non-IP
real time streaming protocol called ST2, described in RFC 1819. In
keeping with standard UNIX release conventions, all odd-numbered
versions are considered experimental, and this version was never
intended to be implemented; the protocol was not abandoned. RSVP has
replaced it to some degree.
IP version 6
In IPv6, the new (but not yet widely deployed) standard protocol for
the Internet, addresses are 128 bits wide, which, even with generous
assignment of netblocks, should suffice for the foreseeable future.
In theory, there would be exactly 2128, or about 3.403 × 1038 unique
host interface addresses. If the earth were made entirely out of 1
cubic millimeter grains of sand, then you could give a unique
address to each grain in 300 million planets the size of the earth.
This large address space will be sparsely populated, which makes it
possible to again encode more routing information into the addresses
A version 6 address is written as eight 4-digit hexadecimal numbers
separated by colons. For readability, addresses may be shortened in
two ways. Within each colon-delimited section, leading zeroes may be
truncated. Secondly, one string of zeroes (and only one) may be
replaced with two colons (::). For example, all of the following
addresses are equivalent:
Global unicast IPv6 addresses are constructed as two parts: a 64-bit
routing part followed by a 64-bit host identifier.
Netblocks are specified as in the modern alternative for IPv4:
network number, followed by a slash, and the number of relevant bits
of the network number (in decimal). Example: 12AB::CD30:0:0:0:0/60
includes all addresses starting with 12AB00000000CD3.
IPv6 has many improvements over IPv4 other than just bigger address
space, including autorenumbering and mandatory support for IPsec.
Further reading: Internet RFCs including RFC 791, RFC 1519 (IPv4
addresses), and RFC 2373 (IPv6 addresses).
Regional Internet Registry
African Network Information Center
American Registry for Internet Numbers
RIPE Network Coordination Centre
Asia-Pacific Network Information Centre
Latin American and Caribbean Internet Addresses Registry
Introduction to geolocation by IP address
Articles on CircleID about IP addressing
IP Spoofing: An Introduction
IP-Address Management on LANs - article in Byte magazine
Introduction to IP Address Allocation
Community project to geotarget IP addresses
Retrieved from "http://en.wikipedia.org/wiki/IP_address"
Categories: Computer networks | Information technology | Internet
architecture | Identifiers
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