Computer Networks and Programming Ethics

Introduction to Network Programming

• Network programming is covered in ITCE 320 and runs the 2019–2020 academic year.

Agenda

• The agenda includes discussion of basic concepts, terminologies related to computer networks, network layers, concepts, and models.
• Also features programming languages, implementation considerations, and programming ethics.

Definitions

• Computer networks involves the study of networks.
• Programming studies relevant computer languages.
• Protocols is a key area of focus.
• A network address involves another area of study.

Computer Networks

• A computer network is a group of computer systems and hardware devices linked via communication links to share resources and services.
• Computer networks include edge systems such as laptops, PCs, and handheld devices.
• Computer networks include core devices such as routers and switches.

Programming

• Programming is the process of writing a collection of executable instructions for computers to perform specific tasks.
• A program is an organized set of such executable instructions.
• Programming and networks involves writing programs that communicate with other programs over a network, including network, distributed, and socket programming.

Network Protocols

• Network Protocols constitutes a language and a set of rules that allow two or more network devices to communicate effectively over a network.
• Network Protocols help to know how to format, transmit and receive data, avoid conflict between devices, ensure each device knows their responsibilities and tasks, and define how to respond to messages and errors.

Network Addresses

• A network address is a physical or logical identifier for a node, host, or application over a network.
• A physical address includes MAC addresses which are 48-bit, located at the data link layer, represented by hexadecimal digits, are used at the Frame and an example being 07:A1:05:1F:13:9D.
• A logical address consists of IP addresses, which are 32 or 128 bit addresses, located at the network layer, and an example being 192.168.93.43.
• A port address is a 16-bit address found at the transport layer.
• A specific address is found at the application layer.

Reasons and Advantages of Reference Models

• Reference models offer easier and simpler to manage network processes, encouraging industry standardization plus independent processes throughout their designs.
• Changes at a certain layer does not impact the entire process while enabling multi-vendor internetworking and interconnection between different types of hardware and software.
• Reference models add greater flexibility and are easy to maintain.

OSI Model

• The Open System Interconnection (OSI) model was introduced by the International Organization for Standardization (ISO) in the late 1970s.
• The OSI model contains seven layers: application, presentation, session, network, datalink, physical.
• The OSI model is a blueprint of how hosts should communicate, defines services, interfaces, and protocols, divided into standards and protocols.

OSI Model Continued

• The top three layers define and manage process-to-process communication and interaction with the user.
• The lower four layers define and manage host-to-host connection and manage communication within a LAN or WAN.

TCP/IP Model

• TCP/IP Model is a suite of protocols and sub-protocols.
• TCP/IP predates the OSI model (late 1960s).
• TCP/IP was implemented by UNIX and Linux and now by all other network OSs.
• It matches modules according to the need of the system.
• Each protocol hinges on other protocols in lower layers.

TCP/IP Model Continued

• The TCP/IP Model originally had 4 layers: application, transport, internet, host-to-host (network interface).
• The Host-to-host layer was then divided into Data Link and Physical layers.
• The TCP/IP advantages: open to the public, runs on any platform, implements IP addressing used by routers, and is more practical than the ISO model.

Packet Encapsulation

• A packet is a small unit of data exchanged between two network devices.
• Most protocols encapsulate data adding protocol specific information to the data which facilitates packet transmission over the network.
• This encapsulation is multi-level.
• There is a protocol after protocol and layer after layer.
• For each protocol will be a header and a payload.

Connection Models

• There are connection models, including connection oriented, connectionless and TCP protocols to establish a reliable connection,
• A connectionless requires UDP protocol, and provides no such need for connection establishment offering an unreliable connection.

Network Architecture: Client-Server

• This architecture includes centralized management where a client or a server is utilized.
• Servers provide services upon request.
• Clients know where to go and whom to ask.
• Specialized servers exists for specialized servives.

Network Architecture: Peer-to-Peer

• P2P is decentralized with a set of peers (similar roles) providing direct communication between peers.
• P2P peers can provide a service or a resource, request a service or a resource, and help in forwarding requests to resources.
• P2P offers advantages such as simplicity to configure and low deployement expenses.
• P2P drawbacks include inflexibility and non-scalability.

Points of Failure

• Potential client-side errors include the client application crashing, hardware problems, or the client's network card failing.
• Potential network errors include network contention causing timeouts, network address conflicts, network routers failing, or transmission errors losing messages.
• Potential client-server version incompatiblity can exist.
• Sever errors can be a a faulty network card, hardware problems, software crashes or a corrupted database.
• These potential errors must be considered when designing and developing network applications.

Transparency

• Access Transparency: The user should not know (or need to know) if access to all or parts of the system are local or remote.
• Location Transparency: The location of a service should not matter.
• Migration Transparency: If part of the system moves to another location, it should make no difference to a user.
• Replication Transparency: It should not matter if one or multiple copies of the system are running.
• Concurrency Transparency: There should be no interference between parts of the system running concurrently.
• Scalability Transparency: It shouldn't matter if one or a million users are on the system.
• Performance Transparency: Performance should not be affected by any of the system or network characteristics.
• Failure Transparency: The system should not fail. If parts of it fail, the system should recover.

Security and Issues

• Network administrators protect the network using firewalls and proxy servers.
• Firewalls block inbound and oubound ports and traffic.
• Proper well-known protocols must get selected.
• The firewall(s) between the local and remote applications need to allow the traffic through.

Network Programming

• There are different programming languages such as Python, Perl, Bash and Java which require a compiler or interpreter.
• During network program design, a program must be created that can send data through the network layers.
• Selecting the proper network protocols in conjuction data encapsulation is crucial.
• Packets can be forwarded to the destination as intended.

Things to Consider

• Items to consider will involve available ready-made packages, potential points of failure, transparency, security, firewalls, Network Address Translation (NAT), IPv4 and IPv6 migration plans.

Programming Ethics

• Avoid desiging harmful applications.
• Honesty and trustworthiness is required.
• Do not hide any limitation or problems within the code to the appropropriate party.
• Do not use falsified data.
• Declare any conflict of interest.
• Credit the source of the idea.
• Be careful and respect the security of all data.
• Do not disclose any customer secret.

Ethics Case Study

• Ethical case studies involve the consideration of the ethical dimensions of sensitive customer data protection, integrity, and professionalism in following company guidelines.

Case Study: Options!

• Option A: A programmer can immediately report accidental access of data to the appropriate supervisor who takes the necessary information to resolve that problem.
• Option B: A programmer could secure the data to prevent unauthorized access and then report the inciden,
• Option C: A programmer may ignore the incident which represents a disregard for ethical responsibilities and could potentially lead to privacy and legal consequences for both the programmer and the company.

This quiz covers the fundamentals of computer networks, including their purpose and core devices. It also explores ethical responsibilities for programmers, especially concerning data privacy and security. Test your understanding of network protocols and ethical conduct.