FTP vs PSFTP

 

FTP vs PSFTP

These are two different things — one is a protocol, the other is a specific program — so the comparison works a bit like comparing "email" to "Outlook."

FTP (File Transfer Protocol)

• A protocol (a set of rules) for transferring files between a client and a server over a network.
• Sends data, usernames, and passwords in plain text — unencrypted. Anyone intercepting the traffic can read your credentials and file contents.
• Uses two separate connections: one for commands, one for data.
• Accessed via a client program — on Windows/Linux/Mac, often just the built-in ftp command, or graphical tools like FileZilla.
• Still used in some legacy systems, but considered insecure for anything sensitive over the open internet.

PSFTP (PuTTY SFTP client)

• Not a protocol — it's a specific program, part of the PuTTY suite of tools (alongside PuTTY itself, PSCP, Plink, etc.), built by Simon Tatham for Windows (and available on Unix-like systems too).
• PSFTP implements SFTP (SSH File Transfer Protocol), which is a completely different protocol from FTP, despite the similar name.
• SFTP runs over SSH (Secure Shell), so everything — commands, filenames, file contents, login credentials — is encrypted.
• Uses a single secure connection (unlike FTP's two-connection setup).
• Typically used to connect to Unix/Linux servers that accept SSH connections.

Quick comparison

	FTP	PSFTP (SFTP)
Type	Protocol	Program (implements the SFTP protocol)
Security	Unencrypted	Encrypted (via SSH)
Port	21 (commands), 20 (data)	22 (same as SSH)
Typical client	ftp command, FileZilla	psftp command (PuTTY suite)
Risk	Passwords/data visible if intercepted	Protected by SSH encryption

Why this matters for your lab

If your Unix server only accepts SSH connections (common for university lab servers), the plain ftp command from your earlier steps may simply fail to connect, because the server isn't running an FTP service at all — it's running SSH/SFTP instead. In that case, PSFTP (or an SFTP-capable client like WinSCP or FileZilla's SFTP mode) is the one that will actually work.

If ftp <server_address> connected successfully in your earlier task, the server does support plain FTP, so you're fine as-is. If it timed out or refused the connection, try psftp <server_address> instead — the commands inside (cd, ls, get, mget, bye) are almost identical to what you already used.

 

📘 Introduction to C#

✅ What is C#?

C# (C-Sharp) is a modern, object-oriented programming language developed by Microsoft.

👉 It is mainly used to build:

• Desktop applications
• Web applications
• APIs
• Enterprise software

---

✅ Why use C#?

• ✔ Simple and easy to learn
• ✔ Strongly typed (reduces errors)
• ✔ Supports Object-Oriented Programming (OOP)
• ✔ Works well with .NET ecosystem
• ✔ Widely used in industry

---

❌ Why NOT use C#?

• ❌ Not ideal for low-level system programming (like OS/kernel)
• ❌ Requires .NET runtime
• ❌ Less popular than JavaScript for frontend

---

✅ How C# Works (Basic Flow)

1. Write code in .cs file
2. Compile using .NET compiler
3. Run → Output shown in console/app

---

📘 Core Concepts Explained

---

1️⃣ namespace

✅ What

A namespace is a container for classes.

✅ Why

• Avoids naming conflicts
• Organizes code

✅ Example

namespace MyApp
{
}

---

2️⃣ internal

✅ What

An access modifier.

✅ Why

• Restricts access within the same project only

❌ Why not public?

• public exposes it everywhere (less secure)

---

3️⃣ class

✅ What

A blueprint for creating objects.

✅ Why

• Groups data and methods together

---

4️⃣ object

✅ What

Instance of a class.

✅ Why

• Used to access class properties and methods

---

5️⃣ static

✅ What

Belongs to class, not object.

✅ Why

• No need to create object to access it

---

6️⃣ void

✅ What

Method returns nothing.

✅ Why

• Used when no return value is needed

---

7️⃣ string[]

✅ What

Array of strings.

✅ Why

• Used to store multiple values
• In Main, it stores command-line arguments

---

8️⃣ Console.WriteLine()

✅ What

Prints output to console.

✅ Why

• Used for displaying messages

---

9️⃣ Console.ReadKey()

✅ What

Waits for a key press.

✅ Why

• Prevents console from closing immediately

---

💡 Real-Time Example (Beginner Friendly)

👉 Scenario: Display employee details in console

---

✅ Full Program with Comments

// Namespace: groups related classes
namespace CompanyApp
{
    // internal: accessible only within this project
    internal class Employee
    {
        // Member variables
        string _name;
        int _age;

        // Method to set values
        public void SetDetails(string name, int age)
        {
            _name = name;
            _age = age;
        }

        // Method to display values
        public void Display()
        {
            Console.WriteLine("Employee Name: " + _name);
            Console.WriteLine("Employee Age: " + _age);
        }
    }

    internal class Program
    {
        // Entry point of program
        static void Main(string[] args) // string[] stores command-line inputs
        {
            // Creating object of Employee class
            Employee emp = new Employee();

            // Setting values
            emp.SetDetails("Rahul", 25);

            // Displaying output
            emp.Display();

            // Static method call (no object needed)
            Console.WriteLine("Press any key to exit...");

            // Wait for user input
            Console.ReadKey();
        }
    }
}

---

🔄 Flow of Above Program

1. Program starts → Main()
2. Object emp is created
3. Data is assigned using method
4. Data is displayed
5. Message printed
6. Program waits for key press

---

🎯 Key Takeaways

• namespace → organizes code
• internal → restricts access
• class → blueprint
• object → real instance
• static → no object required
• void → no return
• string[] args → input arguments
• Console.WriteLine() → output
• Console.ReadKey() → pause

---

✅ One-Line Summary

👉 C# is an object-oriented language where programs are built using classes, objects, and methods, and executed starting from the Main() method.

PYTHON

 

PART 1: PYTHON FUNDAMENTALS

1. INTRODUCTION TO PYTHON

📖 What is Python?

Python is a high-level, interpreted programming language created by Guido van Rossum and first released in 1991 . It is designed with a philosophy that emphasizes code readability through significant whitespace and a straightforward syntax that resembles natural English.

python

# This is Python - clean and readable
print("Hello, World!")  # Simple, right?

🎯 Why Learn Python?

Reason	Explanation
Readable Syntax	Code looks almost like natural English, making it easier to learn and maintain
Versatile Applications	Web development, data science, automation, AI/ML, and more
Rich Ecosystem	Extensive standard library and thousands of third-party packages
Cross-platform	Runs on Windows, macOS, Linux, and many other platforms
Strong Community	Excellent documentation, tutorials, and community support
Rapid Development	Faster to write and maintain than many other languages

🛠️ How to Set Up Python

Windows Installation

bash

# 1. Download from python.org
# 2. Run installer - IMPORTANT: Check "Add Python to PATH"
# 3. Verify installation
python --version

macOS Installation

bash

# Using Homebrew (recommended)
brew install python

# Verify
python3 --version

Linux Installation (Ubuntu/Debian)

bash

sudo apt update
sudo apt install python3 python3-pip python3-venv
python3 --version

📝 Your First Python Program

Create a file called hello.py:

python

#!/usr/bin/env python3
"""
My First Python Program
This demonstrates basic Python syntax and structure
"""

# This is a comment - it's ignored by Python

# Get user input
name = input("What is your name? ")

# Create a greeting
greeting = f"Hello, {name}! Welcome to Python programming."

# Display the greeting
print(greeting)

# Show current year
year = 2026
print(f"The year is {year}")

Run it:

bash

python3 hello.py


PRACTICE QUESTIONS

 To find the solution in Python

16 – System life cycle

 Questions and Answers

1.  Identify five stages in the system life cycle. 

Ans: Feasibility; analysis; design; implementation/ development/coding/programming; testing; installation/implementation; maintenance; documentation; evaluation.

2. Explain why interviews are better than questionnaires for smaller groups of users. 

Ans: The analyst can expand upon questions that have been asked during the interview to gain further information from the user; questionnaires take time to create and so it is unnecessary when a small group of users can all be interviewed.

3. State the purpose of the system specification.

Ans: To identify the hardware and software required to operate the developed system.

4. Identify the purpose of a data flow diagram (DFD).

Ans: To show the data flows within a system

5. Identify one rule for data flows within a level 1 DFD.

Ans: Each data flow must have a process attached to it. A data flow cannot move directly from one external entity to another or from one data store to another or between an external entity and a data store

6. Describe the difference between a tick box and an option button

Ans: A tick box allows more than one response where as an option button only allows one response.

7. Describe the purpose of using extreme test data

Ans: To test that a validation rule accepts data that is within the acceptable range.

8.Describe two differences between alpha and beta testing

Ans:  Alpha testing is carried out by the development team whereas beta testing is carried out by users; alpha testing is planned and structured whereas beta testing is ordinary everyday use; alpha testing uses test data whereas beta testing uses real data.

9. Explain black box testing

 Ans:  Tester will use input data to test part of a system or a whole system and check the expected results against actual results without knowing or understanding the code inside the black box

10. Explain the importance of having a test plan

Ans: A test plan will identify all the tests that are needed for every input, every button, every link, every report, every screen and all other elements of a system. The test plan will include different types of test data including valid, invalid and extreme so that inputs are tested to their limits. Without this planning, important parts of testing would be missed out and errors could be left untested. The plan will also cover all the user’s requirements and ensure that they are tested.

11. Identify four methods of changeover

Ans:  Parallel; direct; phased; pilot

12. Describe one situation when direct changeover would be more appropriate than parallel changeover

Ans:  If it would be too costly or take too long to input data into both systems, then direct would be more appropriate.

13. Describe one situation when pilot changeover would be more appropriate than phased changeover 

Ans:  If there are a lot of users then pilot changeover will enable training to take place in stages rather than all at once; If the new system is not very big and doesn’t have features that can be separated then pilot could be used instead of trying to phase something that can’t be broken into parts.

14. Give three sections you would expect to find in user documentation

Ans:  Cover, contents, introduction, hardware/ software requirements, instructions, glossary, troubleshooting, index.

15.  Describe the purpose of a glossary in user documentation

Ans:  To give definitions of any technical terms used in the user documentation.

16. Give a situation when technical documentation would be needed.

Ans:  When a system requires maintenance

17. State three elements that might be evaluated after a system has been installed

Ans:  Working relationship; efficiency of system; bugs or errors in the system; ease of use of the system; possible improvements to the system.

18. Give a situation when corrective maintenance would be required.

Ans:  If a bug or error is found within a system.

19. Compare and contrast evolutionary and throw away prototyping.

Ans:  Evolutionary prototyping develops each prototype further whereas throw-away prototyping involves disposing of the prototype. Evolutionary prototyping involves refining user requirements after each evolution of the prototype and throw-away prototyping also involves refining requirements after the prototype is developed. Both methods involve producing a basic version of what the user interface will look like. Both methods involve getting feedback from the user early during the project.

20. Describe the differences between incremental and iterative methods of development.

Ans:  With incremental development, a part of the software is fully developed before moving on to the next part of the software whereas with iterative development, the phase of a system (e.g. design) is completed before feedback is sought and improvements made.

21. Describe joint application development.

Ans:  JAD involves both users and developers working together to develop a working prototype with the user being able to refine the design and layout as the development progresses. Software application frameworks will be used to develop the prototype and end-solution.

EXAM-STYLE QUESTIONS

1- 

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2-

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5-

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6- 

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14 - COMMUNICATIONs TECHNOLOGY

 1- Identify two examples where an infrared wireless connection could be used.

Ans: 

2. What do you think would happen if a buffer were not used when streaming data?

Ans: 

3. A  company creates websites using style sheets.

Describe another scenario that would allow an organisation to take advantage of the ability to scale up resources using cloud computing.

Ans: 

EXAM-STYLE QUESTIONS 

 1 Explain the function of the presentation layer in the OSI model. [2] 

Ans: 

 2 Explain the function of the network layer in the TCP/IP model. [2] 

Ans: 

 3 William wants to create a network in his home that will connect three computers, a printer, a mobile tablet device and a mobile telephone. He wants to minimise the costs in setting up his network. 

 a Identify the network structure that would be suitable for William to use. 

Ans: 

Justify your choice. b Identify the components William will need to build the network and describe the role of each. [4] 

Ans: 

 c William wants to use the network to stream videos and music. Explain the importance of bandwidth and bit rate for this purpose. [2] [Total 7] 

Ans: 

 4 Identify two protocols that are used in the transmission of emails. Describe the role of each protocol in the process. [4] 

Ans: 

 5 Describe how the sound required to make a telephone call is sent from one mobile device to another, using a mobile network. [4] 

Ans: 

 6 Emily stores data about her customers on a server in a server room in her office building. Emily wants to keep the data more secure, so she installs a biometric device required to gain access to the server room. She also installs a firewall. 

 a Explain one advantage and one disadvantage of using a biometric device to secure access to the server room. [2]

Ans: 

 b Describe how the firewall will help keep the data safe. [4] [Total 6] 

Ans: 

 7 Discuss the impact of implementing a disaster recovery plan for an organisation. [6]

Ans: