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Networking and IP Addressing

Networking is the communication between computer systems or devices. A computer network is any set of computers or devices connected to each other with the ability to exchange data. The three types of networks are: 

• the Internet: The network formed by the co-operative interconnection of millions of computers, linked together is called Internet

• intranet: Internal private networks built within an organization using Internet and World Wide Web standards and products that allows employees of an organization to gain access to corporate information

• extranet:It is the type of network that allows users from outside to access the Intranet of an organization

The main difference between extranets and intranets is that intranets are internal networks that are accessible only to employees, while extranets are extended networks that allow external parties to access certain parts of an organization's intranet. Intranets are used for internal communication, collaboration, and operations management, while extranets are used for external communication and collaboration with customers, suppliers, and partners. Having an extranet makes an organization vulnerable

• Examples of different network methods are:

• Personal area network (PAN): short range small networks. Typically wireless and allows transfer of data between devices (e.g. cellphone to tablet)

• Local area network (LAN), which is usually a small network constrained to a small geographic area. An example of a LAN would be a computer network within a building. The group of computers and devices are connected together by a switch, or stack of switches, using a private addressing scheme as defined by the TCP/IP protocol

• Wireless LANs and WANs (WLAN & WWAN) are the wireless equivalent of the LAN and WAN.

• Metropolitan area network (MAN), which is used for medium size area. examples for a city or a state. ISP-level networks

• Wide area network (WAN) that is usually a larger network that covers a large geographic area.

All networks are interconnected to allow communication with a variety of different kinds of media, including twisted-pair copper wire cable, coaxial cable, optical fiber, power lines and various wireless technologies. The devices can be separated by a few meters (e.g. via Bluetooth) or nearly unlimited distances (e.g. via the interconnections of the Internet). Networking, routers, routing protocols, and networking over the public Internet have their specifications defined in documents called RFCs.

source

So how does this networking thing work?

All computers on a network have to know how to talk to each other. This requires a 'protocol' (which is a set of rules that dictate how computers can talk to each other). Think of a protocol being like a language. Both computers have to speak the same language. The model used in networking is known as the OSI model which will be discussed in a future topic in the course.

Essentially the way your computer (phone/console/computer/'smart refrigerator' etc...) talks to another computer is that packets of information are created by the computer. They move to the network interface, then across a medium (copper/glass/air) to a receiving network interface that then hands the information 'up' to the relevant application on the next computer.

Model for computer networking

 ADDRESSING (IPv4)

Implemented in 1998, Internet Protocol version 4 addressing was/is a connectionless protocol (a message can be sent from one location to another without a prior connection being formed) for use on packet-switched networks (e.g., Ethernet). It operates on a best effort delivery model, in that it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol (e.g., Transmission Control Protocol). All that to say, 'Information A' goes from one address to another by being broken down into packets, which make their way to the end-address the best they can, then get reassembled into 'Information A' once more.

Interestingly enough, the backbone of the internet, IPv4 is currently being replaced by IPv6 as a default protocol (e.g. Windows 10 by defaults assigns IPv4 and IPv6 address). The top-level IPv4 'exhaustion' occurred in 2011. Reserve addresses were exhausted between 2011 and 2019 depending on the area of the world you were in. Individual ISPs still have pools of unassigned IP addresses, and reclaim them as they are no longer needed by subscribers. Switching equipment to enable IPv6 was no easy task since there was cost associated with it.

An understanding of the way that IPv4 addressing works will help us to understand IPv6 addressing, so let's start there. In IPv4 addressing (let's just refer to it as IP addressing), an IP address is a 32 bit, 4 octet address which is assigned (by who?) to every computer on an IP (ethernet protocol) network.

For example, the host address 192.168.1.1 (which is a very common router address for most home networks) resolves to:

There are major IP Address classes used in the wild:

Network and host addresses are like a real-world analogy: street address (ie I live on River Road) vs. street number (I'm at 1633 River Road)

1) Class A: Used by countries or VERY large companies (e.g. Cisco, Microsoft, Dell etc...). These are unique 1st octet ranges (1-> 127). They take the form of:

• network.host.host.host

• 255^3 bits so about 16.5million host addresses

• the default subnet mask (which creates subnets, or private addresses within the host network) for these is 255.0.0.0

2) Class B: Used by somewhat large companies. The first octet is in the range of 128-191 and has the pattern:

• network.network.host.host

• 63*255 class B networks which about 16k addresses 

• subnet mask is 255.255.0.0 so about (255x255) 65k host addresses inside

3) Class C: Used by small companies and individuals. The first octet is in the range 192-223 and has the pattern:

• network.network.network.host

• 254 hosts per network

• subnet mask is 255.255.255.0

4) Class D/E: are experimental networks used to multicast

Tools we use in IP networking are:

• ipconfig: which gives information about the host computer's network adapters as well as the details of the connection to the ethernet network.

• ping: which is a way in which to test the reachability of a host or IP address on a network.

• traceroute: is a diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol (IP) network.

There are several network IP addresses that reserved, they are:

• 10.host.host.host

• 127.host.host.host

• 169.host.host.host

• 192.host.host.host (chances are your home network is something like 192.168.X.X where the subnet IP addresses are likely 192.168.1.X or 192.168.2.X)

Network addresses, bits & masks

Let's use a home network (in IPV4):
Network: 192.168.2.0

Computer 1: 192.168.2.40

Computer 2: 192.168.2.55

Printer 1: 192.168.2.100

In this case, we’re using 24 bits (or three octets) for the network. Notice that every host device in the network has the same first three octets? That’s the network portion of the IP address with a /24 mask.

1. Network Address: The network bits stay the same. Host bits all resolve to 0

2. Broadcast Address: Network bits stay the same, host bits all are 1s

3. Subnet Mask: Network bits binary 1's, Host bits binary 0's

4. First available address: the first host bit will be 1

e.g. 172.168.14.11

1. 172.168.0.0

2. 172.168.255.255

3. 255.255.0.0

4. 172.168.0.1

e.g. 203.200.0.42

1. 203.200.0.0

2. 203.200.0.255

3. 255.255.255.0

4. 203.200.0.1

Quiz #4 - Networking & IP addressing

Network Topology

Describes the physical and logical layout of a network

1. Physical Topology: the actual (scaled) network

2. Logical Topology: how the various computers are organized from a communications perspective (star topology being common)

Activity: How to make a network cable

Materials:

• length of cat6 UTP (unshielded twisted pair): has 4 pairs of copper wires which have colour coding

• RJ45 jack

Tools:

• scissors

• crimper

• tester

Steps:

1. measure cable and add 15% length and cut it

2. cut away outer coating to expose the twisted pairs. Don't nick the copper cables as you cut away the protective sheath

3. Put the cable colors in order (what is a straightthrough vs. crossover):

StraightThrough (A-A or B-B)

• WG/G/WO/Bl/WBl/O/WBr/Br

Crossover (A-B or B-A)

• WO/O/WG/Bl/WBl/G/WBr/Br

4. Flatten out the wires and trip them so about 2cm of wire are exposed

5. Slide the RJ45 jack onto the wires (gold side up). The jack should JUST slide down to the cable sheath

6. Check with your teacher

7. Crimp and test the cable

Cryptography and CyberSecurity

Cryptography is the study and practice of techniques for secure communication in the presence of third parties called adversaries. It deals with developing and analyzing protocols that prevents malicious third parties from retrieving information being shared between two entities thereby following the various aspects of information security. Secure Communication refers to the scenario where the message or data shared between two parties can’t be accessed by an adversary. In Cryptography, an Adversary is a malicious entity, which aims to retrieve precious information or data thereby undermining the principles of information security. Data Confidentiality, Data Integrity, Authentication and Non-repudiation are core principles of modern-day cryptography.

Network security on the other hand are activities designed to protect the integrity of your network and data. They include both hardware and software technologies. The aim is to stops threats from entering or spreading on your network. 

Asymmetric Encryption:

Key Usage: Uses a pair of keys: a public key for encryption and a private key for decryption. 

Speed: Slower than symmetric encryption due to more complex algorithms and longer keys. 

Security: Enhanced security as the private key never needs to be shared, and the public key can be distributed widely. 

Examples: RSA, Diffie-Hellman. 

Use Cases: Ideal for secure key exchange and digital signatures

CyberSecurity

while a bit beyond the scope of grade 10, if you'd like to learn about cyber security you can check out this free online course