![Example of a Class in C++ class Employee { public: char firstname[25]; char lastname[25]; char PlaceOfBirth[30]; [code continues] }; void GetEmp() { // Perform tasks to get employee info [program code goes here] }](https://image.slidesharecdn.com/ch07-090816002703-phpapp01/85/Ch07-Programming-for-Security-Professionals-45-320.jpg)
Ch07 Programming for Security Professionals
- 1. Hands-On Ethical Hacking and Network Defense Chapter 7 Programming for Security Professionals
- 2. Objectives Explain basic programming concepts Write a simple C program Explain how Web pages are created with HTML Describe and create basic Perl programs Explain basic object-oriented programming concepts
- 3. Introduction to Computer Programming Computer programmers must understand the rules of programming languages Programmers deal with syntax errors One minor mistake and the program will not run Or worse, it will produce unpredictable results Being a good programmer takes time and patience
- 4. Computer Programming Fundamentals Fundamental concepts Branching, Looping, and Testing (BLT) Documentation Function Mini program within a main program that carries out a task
- 5. Branching, Looping, and Testing (BLT) Branching Takes you from one area of the program to another area Looping Act of performing a task over and over Testing Verifies some condition and returns true or false
- 6. A C Program Filename ends in .c It's hard to read at first A single missing semicolon can ruin a program
- 7. Comments Comments make code easier to read
- 8. Branching and Testing Diagram of branches See links Ch 7b, 7c main() printf() scanf()
- 9. Looping
- 10. Branching, Looping, and Testing (BLT) Algorithm Defines steps for performing a task Keep it as simple as possible Bug An error that causes unpredictable results Pseudocode English-like language used to create the structure of a program
- 11. Pseudocode For Shopping PurchaseIngredients Function Call GetCar Function Call DriveToStore Function Purchase Bacon, Bread, Tomatoes, Lettuce, and Mayonnaise End PurchaseIngredients Function
- 12. Documentation Documenting your work is essential Add comments to your programs Comments should explain what you are doing Many programmers find it time consuming and tedious Helps others understand your work
- 13. Bugs Industry standard 20 to 30 bugs for every 1000 lines of code (link Ch 7f) Textbook claims a much smaller number without a source Windows 2000 contains almost 50 million lines And fewer than 60,000 bugs (about 1 per 1000 lines) See link Ch 7e for comments in the leaked Win 2000 source code Linux has 0.17 bugs per 1000 lines of code (Link Ch 7f)
- 14. Learning the C Language Developed by Dennis Ritchie at Bell Laboratories in 1972 Powerful and concise language UNIX was first written in assembly language and later rewritten in C C++ is an enhancement of the C language C is powerful but dangerous Bugs can crash computers, and it's easy to leave security holes in the code
- 15. Assembly Language The binary language hard-wired into the processor is machine language Assembly Language uses a combination of hexadecimal numbers and expressions Very powerful but hard to use (Link Ch 7g)
- 16. Compiling C in Ubuntu Linux Compiler Converts a text-based program (source code) into executable or binary code To prepare Ubuntu Linux for C programming, use this command: sudo apt-get install build-essential Then you compile a file named "program.c" with this command: gcc program.c –o program.exe
- 17. Anatomy of a C Program The first computer program a C student learns "Hello, World!"
- 18. Comments Use /* and */ to comment large portions of text Use // for one-line comments
- 19. Include #include statement Loads libraries that hold the commands and functions used in your program
- 20. Functions A Function Name is always followed by parentheses ( ) Curly Braces { } shows where a function begins and ends main() function Every C program requires a main() function main() is where processing starts
- 21. Functions Functions can call other functions Parameters or arguments are optional \n represents a line feed
- 22. Declaring Variables A variable represents a numeric or string value You must declare a variable before using it
- 23. Variable Types in C
- 24. Mathematical Operators The i++ in the example below adds one to the variable i
- 26. Logical Operators The i<11 in the example below compares the variable i to 11
- 29. Understanding HTML Basics HTML is a language used to create Web pages HTML files are text files Security professionals often need to examine Web pages Be able to recognize when something looks suspicious
- 30. Creating a Web Page Using HTML Create HTML Web page in Notepad View HTML Web page in a Web browser HTML does not use branching, looping, or testing HTML is a static formatting language Rather than a programming language < and > symbols denote HTML tags Each tag has a matching closing tag <HTML> and </HTML>
- 34. Understanding Practical Extraction and Report Language (Perl) PERL Powerful scripting language Used to write scripts and programs for security professionals
- 35. Background on Perl Developed by Larry Wall in 1987 Can run on almost any platform *NIX-base OSs already have Perl installed Perl syntax is similar to C Hackers use Perl to write malware Security professionals use Perl to perform repetitive tasks and conduct security monitoring
- 37. Understanding the Basics of Perl perl –h command Gives you a list of parameters used with perl
- 39. Understanding the BLT of Perl Some syntax rules Keyword “sub” is used in front of function names Variables begin with the $ character Comment lines begin with the # character The & character is used when calling a function
- 40. Branching in Perl &speak; Calls the subroutine sub speak Defines the subroutine
- 41. For Loop in Perl For loop
- 42. Testing Conditions in Perl
- 43. Understanding Object-Oriented Programming Concepts New programming paradigm There are several languages that support object-oriented programming C++ C# Java Perl 6.0 Object Cobol
- 44. Components of Object-Oriented Programming Classes Structures that hold pieces of data and functions The :: symbol Used to separate the name of a class from a member function Example: Employee::GetEmp()
- 45. Example of a Class in C++ class Employee { public: char firstname[25]; char lastname[25]; char PlaceOfBirth[30]; [code continues] }; void GetEmp() { // Perform tasks to get employee info [program code goes here] }
- 46. Error in textbook C example on page 138 should be this instead