Courses AQA GCSE Computer Science Networks & the internet IP v4, IPv6 & MAC Addresses

IP v4, IPv6 & MAC Addresses

Introduction to IPv4

Example: 192.168.0.1

Internet Protocol Version 4 is the underlying technology that allows devices to communicate with each other over the internet and other IP-based networks. It was originally designed in the early 1980s and has been widely used since the early days of the internet.

The purpose of IPv4 is route data to it's final address through the internet.

IP Addresses are logical addresses that reflect their logical location within the network they are connected to and are used by routers to route traffic between networks.

IPv4 Address Structure

192.168.0.1

IPv4 addresses are 32 bits in length, which allows for a total of approximately 4.3 billion unique addresses. Each IPv4 address is typically represented as four decimal numbers separated by periods.

Split into four parts ( 8 bits per subaddress)
Separated by periods (full stops)
Written in denary
Each sub address has values of 0 - 255

IP v4 addresses are made up of [[32]] bits.

{"cloze_text": "IP v4 addresses are made up of [[32]] bits."}

The maximum number of IPv4 addresses that can be assigned is 4.3 [[billion]].

{"cloze_text": "The maximum number of IPv4 addresses that can be assigned is 4.3 [[billion]]."}

An IPv4 address is divided into [[network]] and host portions.

{"cloze_text": "An IPv4 address is divided into [[network]] and host portions."}

Public IP Addresses

Public IP addresses are unique identifiers that are used for communication between devices on the internet and are crucial for identifying and routing data to specific devices or servers worldwide.

Internet Service Providers (ISPs) allocate public IP addresses to their customers, allowing them to access websites, online services, and resources on the internet.

Public IP addresses can be either static (unchanging) or dynamic (changing periodically) depending on the type of internet connection.

Examples: 8.8.8.8, 142.250.0.0

Characteristics:

Globally unique.
Can be accessed directly from anywhere on the Internet (unless blocked by firewalls).

An organization can obtain a block of [[public]] IP addresses from an Internet Service Provider (ISP).

{"cloze_text": "An organization can obtain a block of [[public]] IP addresses from an Internet Service Provider (ISP)."}

Private IP Addresses

Private IP addresses are used to identify devices within local or private networks, such as home networks, business intranets, or corporate LANs. Unlike public IP addresses, private IP addresses are not globally routable and cannot be used to directly access devices on the internet.

Private IP addresses provide a level of security by keeping internal network devices hidden from direct exposure to the internet, which can help protect against external threats and unauthorized access.

In order for data to be routed across the internet from a private IP address, the address must be replaced with a public IP address, using Network Address Translation (NAT).

Characteristics:

Not unique globally; the same private address can exist in multiple networks.
Requires NAT (Network Address Translation) to communicate with the Internet.

The use of [[private]] IP addresses helps conserve IPv4 address space.

{"cloze_text": "The use of [[private]] IP addresses helps conserve IPv4 address space."}

When a device communicates with the internet, its private IP address is translated to a [[public]] IP address through a process called Network Address Translation (NAT).

{"cloze_text": "When a device communicates with the internet, its private IP address is translated to a [[public]] IP address through a process called Network Address Translation (NAT)."}

IP Address Exhaustion

The limited number of IP addresses available (4.3 billion in total) means that eventually the number of addresses is insufficient, resulting in IP address exhaustion.

Temporary fixes have been put in place, such as IP pooling, however a long term solution was still needed. This was the reason for the development and rollout of IPv6

Internet Protocol Version 6

Example:2001:0db8:85a3:0000:0000:8a2e:0370:7334

IPv6, short for Internet Protocol version 6, is the successor to IPv4 (Internet Protocol version 4) and is designed to overcome the limitations of IPv4, primarily the exhaustion of available IP addresses.

The key new features of IPv6 are:

Expanded address space
Hexadecimal notation

IPv6 uses 128-bit addresses which means there are 2^128 (about 340 undecillion) possible unique IPv6 addresses.

IPv6 Address Structure

2001:0db8:85a3:0000:0000:8a2e:0370:7334

Addresses are 128 Bits Long
Written in Hexadecimal
Split Intro 8 sections of 4 bits
Separated by Colons

IP v6 addresses are made up of [[128]] bits.

{"cloze_text": "IP v6 addresses are made up of [[128]] bits."}

Which of the following is a valid IPv6 address?

{"answers": {"A": "fe80::1", "B": "1234:5678:9abc:defg::1", "C": "2001:0db8:85a3::8a2e:0370:7334", "D": "192.168.0.1"}, "question_text": "Which of the following is a valid IPv6 address?", "correct_answer": "C"}

IPv6 Address Compression

To simplify addresses, IPv6 allows for certain abbreviations, such as omitting leading zeros and using double colons (::) to represent consecutive groups of zeros. This is known is address compression.

Example

Full IPv6 Address: 2001:0db8:0000:0000:0000:0000:0000:0042

Compressed IPv6 Address: 2001:db8::42

Full details on how to compress addresses can be found here.

Introduction to MAC Addresses

Example : 00:1A:2B:3C:4D:5E

Media Access Control addresses are physical addresses that uniquely identify network interfaces, such as network interface cards (NICs) in computers and other devices that connect to a network. They are used by switches to send frames within networks.

They function at the:

The data link layer of the TCP/IP Model
The link layer (layer 2) of the OSI Model

What is the primary purpose of a MAC address in networking?

{"answers": {"A": "To uniquely identify a device on a local network segment", "B": "To route data between different networks", "C": "To assign IP addresses dynamically", "D": "To encrypt data packets during transmission"}, "question_text": "What is the primary purpose of a MAC address in networking?", "correct_answer": "A"}

MAC Address structure

Example : 00:1A:2B:3C:4D:5E

Usuallly 48 bits
Written in hexadecimal
6 sections of 2 digits
Separated by a semicolon or hypen.

Which of the following formats correctly represents a MAC address?

{"answers": {"A": "00-11-AA-BB-CC-DD", "B": "0011.AABB.CCDD", "C": "0011-AABB-CCDD", "D": "00:11:AA:BB:CC:DD"}, "question_text": "Which of the following formats correctly represents a MAC address?", "correct_answer": "D"}

MAC Address Assignment

MAC addresses are assigned by the manufacturer of the network interface card.

The first half of the MAC address (24 bits) is known as the OUI (Organizationally Unique Identifier), which is assigned to the manufacturer by the IEEE (Institute of Electrical and Electronics Engineers).

The second half is assigned by the manufacturer to uniquely identify each NIC they produce.

The first three groups in a MAC address represent the [[manufacturer]] of the device.

{"cloze_text": "The first three groups in a MAC address represent the [[manufacturer]] of the device."}

MAC address spoofing

MAC address spoofing is a technique used to change or falsify the Media Access Control (MAC) address of a network interface. This process involves modifying the MAC address of a network adapter, such as a network card or a wireless interface, to impersonate another MAC address.

This can be used for legitimate & malicious purposes:

Increased privacy
Bypassing network controls (such as 15 minute free internet access in airports)
Performing Man In The Middle (MITM) attacks on routers or other devices.

[[Spoofing]] the mac address of a device can make it difficult to track the origin of a network attack.

{"cloze_text": "[[Spoofing]] the mac address of a device can make it difficult to track the origin of a network attack."}

Is it possible to change the MAC address of a network device?

{"answers": {"A": "Yes, it can be changed using software tools", "B": "No, the MAC address is permanently assigned by the manufacturer", "C": "Only network administrators can change it through hardware modification", "D": "Yes, but only by replacing the network interface card"}, "question_text": "Is it possible to change the MAC address of a network device?", "correct_answer": "A"}

{"keyword": "MAC Addresses", "definition": "A unique identifier assigned to network interfaces for communications on the physical network segment."}

Review: Fill in the Blanks

Internet Protocol Version 4, or IPv4, is the technology that allows devices to communicate with each other over the and other IP-based networks. Its primary purpose is to route data to its through the internet, using logical addresses that reflect their within the network.

Each IPv4 address consists of 32 bits, which enables approximately 4.3 billion unique addresses. These addresses are typically represented as four decimal numbers, separated by , and each part is 8 bits long with values ranging from 0 to . Public IP addresses are unique identifiers that are crucial for routing data between devices on the internet and can be either or .

Private IP addresses, in contrast, are used within local networks like home or business intranets and are not globally routable. They provide security by keeping internal devices hidden from the , and communication with the internet requires the use of (NAT). Due to the limited number of available addresses, IPv4 faces , prompting the development of IPv6 to accommodate the growing need for more unique addresses.

Click the keywords below to fill in the blanks:

Dynamic Address Exhaustion Final Address Internet Periods 255 Network Address Translation Static Logical Location Internet

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