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جلسه دوم پایتون برای هکر های قانونی دوره مقدماتی پاییز ۹۲

جلسه دوم پایتون برای هکر های قانونی دوره مقدماتی پاییز ۹۲

در این جلسه از کلاس به معرفی ساختار های داده ای در زبان پایتون و معرفی رشته ها و اعداد می‌پردازیم

Mohammad reza Kamalifard

November 18, 2013
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  1. Python language essentials Module 1: Introduction to Python and Setting

    up an Environment for Programing Part 2 : Variables and Data Types
  2. Variables, Objects and References • There are integers, floating point

    numbers, strings, and many more, but things are not the same as in C or C++. • Python variables do not have any types associate with them • Don’t need declaration before use • Variable name is a reference to an Object
  3. Variables • Something which can change • Way of referring

    to a memory location used by a computer program. Variable is a symbolic name for this physical location • Memory location contains values, like numbers, text or more complicated types
  4. Variables, Objects and References >>> name = 'reza' >>> print

    name reza >>> >>>name = 10 >>>name 10 Identifier Object
  5. Data Type >>> name = 10 >>> type(name) <type 'int'>

    >>> name = 'Reza' >>> type(name) <type 'str'> >>> name = 10.42 >>> type(name) <type 'float'> >>>
  6. Variables vs. Identifiers • Variables and identifiers are very often

    mistaken as synonyms • The name of a variable is an identifier, but a variable is "more than a name". • An identifier is not only used for variables. An identifier can denote various entities like variables, types, labels, subroutines or functions, packages and so on.
  7. Naming Identifiers of Variables A valid identifier is a non-empty

    sequence of characters of any length with: • the start character can be the underscore "_" or a capital or lower case letter • the letters following the start character can be anything which is permitted as a start character plus the digits. • Just a warning for Windows-spoilt users: Identifiers are case-sensitive • Python keywords are not allowed as identifier names and, as, assert, break, class, continue, def, del, elif, else, except, finally, for, from, global, if, import, in, is, lambda, nonlocal, not, or, pass, raise, return, try, while, with, yield
  8. Variables vs. Identifiers >>> name = 'reza' >>> id(name) 3072831328L

    >>> hex(id(name)) '0xb727af60L' >>> An other way to do that : >>> name.__repr__ <method-wrapper '__repr__' of str object at 0xb727af60> >>> 0xb727af60 is exact memory location where the object stored, name is just a reference to that object.
  9. Data Types Python offers 1. Numbers 2. Strings 3. List

    4. Dictionaries 5. Tuples 6. Boolean 7. …
  10. Numbers - Integer • Normal integers e.g. 4321 • Octal

    literals (base 8) A number prefixed by a 0 (zero) will be interpreted as an octal number >>> a = 010 >>> print a 8 • Hexadecimal literals (base 16) Hexadecimal literals have to be prefixed either by "0x" or "0X". >>> hex_number = 0xA0F >>> print hex_number 2575 • Long integers these numbers are of unlimeted size e.g.42000000000000000000L • Floating-point numbers for example: 42.11, 3.1415e-10
  11. Strings Strings are marked by quotes: – single quotes (')

    'This is a string with single quotes‘ – double quotes (") "Obama's dog is called Bo"" – triple quotes, both single (''') and (""") '''String in triple quotes can extend over multiple lines, like this on, and can contain 'single' and "double" quotes.'''
  12. Strings >>>name = 'reza' >>>name = "reza" >>>name = "rez'a"

    >>>name = 'Mohammd\nreza' >>>print name Mohammad reza
  13. Strings >>> name = ''' ... Hello Dear Students ...

    Welcome to PYSEC101 Course! ... Python Scripting Course for Ethical Hackers ... ''' >>> name '\nHello Dear Students\nWelcome to PYSEC101 Course!\nPython Scripting Course for Ethical Hackers\n' >>> print name Hello Dear Students Welcome to PYSEC101 Course! Python Scripting Course for Ethical Hackers
  14. String Index • A string in Python consists of a

    series or sequence of characters - letters, numbers, and special characters.
  15. Unicode • Used for internationalization • “Wide Characters” are they

    are called(code all languages) >>>name = u'Mohammad' >>> name u'Mohammad' >>> unicode to regular string conversion >>> str(name) 'Mohammad' >>> regular string to unicode conversion >>> unicode(name) u'Mohammad' >>>
  16. Concatenating Strings • Strings can be glued together (concatenated) with

    the + operator >>>s1 + s2 >>> s1 = 'Hamid' >>> s2 = 'rezaie' >>> s1 + s2 'Hamidrezaie' >>> s1 + ' ' + s2 'Hamid rezaie' >>>
  17. Repetition • String can be repeated or repeatedly concatenated with

    the asterisk operator "*“ >>> buffer = 'A' * 20 >>> buffer 'AAAAAAAAAAAAAAAAAAAA' >>>
  18. Int to string • >>> 'a' + 42 • Traceback

    (most recent call last): • File "<stdin>", line 1, in <module> • TypeError: cannot concatenate 'str' and 'int' objects • >>> • >>> str(42) • '42' • >>>>'a' + str(42)
  19. Slicing • Substrings can be created with the slice or

    slicing notation, i.e. two indices in square brackets separated by a colon: • "Python"[2:4] -> "th“ • >>>string[start:end:steps]
  20. >>> name = 'Mohammad reza' >>> name[5:10] 'mad r' >>>

    name[0:10] 'Mohammad r' >>> name[0:-1] 'Mohammad rez' >>> name[0:-5] 'Mohammad' >>> name[:] 'Mohammad reza' >>> name[::-1] 'azer dammahoM' >>> name[::2] 'Mhma ea' >>>
  21. Stirngs are immutable objects >>>name = 'reza' >>>name[0] r name

    [0] = 'a' TypeError: 'str' object does not support item assignment You can not change String Object directly in memory because they are immutable >>>name = 'reza' name = 'Mohammad' • 'reza' object still does exists now name is referenced to 'Mohammad' object
  22. >>> name = 'mohammad reza' >>> name.find('PYSEC101') -1 >>> name.find('mma')

    4 >>> >>> name.split() ['mohammad', 'reza'] by default split on white spaces and return list of strings. split on 'a' >>> name.split('a') ['moh', 'mm', 'd rez', ''] >>> >>> name.replace('m', 'H') 'HohaHHad reza' >>>
  23. String Formatting >>> ip = '192.168.1.252' >>> line = 'Crack

    this IP :%s' % ip >>> line 'Crack this IP :192.168.1.252' >>> >>> line = 'Crack this IP : %s and name %s ' % (ip, 'Reza-PC') >>> line 'Crack this IP : 192.168.1.252 and name Reza-PC '
  24. References SPSE securitytube training by Vivek Ramachandran SANS Python for

    Pentesters (SEC573) Violent python Security Power Tools python-course.eu ----------------------------- http://www.tutorialspoint.com/python/python_strings.htm http://www.tutorialspoint.com/python/python_numbers.htm http://www.python-course.eu/variables.php http://www.python-course.eu/sequential_data_types.php http://www.python-course.eu/sets_frozensets.php
  25. This work is licensed under the Creative Commons Attribution-NoDerivs 3.0

    Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nd/3.0/ Copyright 2013 Mohammad Reza Kamalifard All rights reserved. Go to Kamalifard.ir/pysec101 to Download Slides and Course martials .