West mail Linux team free exam secrets West mail Linux team free exam-continue to challenge

Do you still remember the admission poster from the Department of Information Technology at the University of Tokyo? If you get the correct answer, you will be admitted. At that time, people and Weibo were crazy to repost.

Now, the Western Mail Linux team has made such a question. If you have the correct answer, you will be able to enter the Western Mail Linux team without a try! I feel pretty fun, so I have a challenge.

Here: http://www.xiyoubbs.com/thread-81454-1-1.html

Level 1

The question is a piece of ciphertext:

0011011101111010101111001010111100100111000111000000000000000011100110111011010111100011010100101111011000000000000000000000000000000000000000000000000000000000010011100000000000000000000000000000000000000000000000000000000001011110001100000101000101001101000000000001000110011001000010001010011010000010100110011011100011000101100001110010010001011010011100010011010111011001000011110111010110101101101110011100111111110101000010110111001110001001011101111011010010011000001110111001111100010100100100010010110101010101100001000101011001110010101111101100100100000101011100000011011001010101000110111101011001010101000001101001000111000011100101101111010001010001100011110110000011111010100101111100101010000111010111001110111011011110100100001001110001111010110100111001110000111111100100010011010001011110000101010000110101000111100101111100110101000100111101101100000110111111000111100001010111000101100010011111100111101110111110111111001111010010000100010100000101011101011010001010111011110111011001000001111100110100111101011011111001101110000110101101010011101010101001000011011110111111001111000010000110010110101100100010110110101000110110111001100011010011111001110110111101100000101001011101110011111101010110101100010001011001010000100100100000001010110111111101101111001000011010111001101110100110000101110110100110101100100011100011110100111011010001001010110110101011010111111001001110101001011110010010001011101000010001101010001110100001011000001110011000100001110110101001000101110001100001010000101100101101111100101110011001011000111011010111010000010101111110001100001110011110010011110110101100110011101101110001101110110001101101001001011110110101101010110111111100111110000111010010111111110001010111000010100000000001100110001101111011001010101001100100101101010011110000010000100111000011110111001001100110101101101110101100111001101000010010101000100101111010101000000100011000101100110011111010101111000110100010110011000000110000000000110110001111011110001110011101000100100010010111110000001001000100100011011100110001011111101101011110100101101000010011010100110101100110001010011101111011101101111010000110110100111101100101110001100010100111111101101011110001101001111110010000000000000000000000010000010000000110000000000000000100001001100000001111011000000000000001110000101100000001000000000000000100100011000000110000000100000001000001010101110100000000000000000000000100000000000011001000001000000010000000000000100000001010000000011000110001111011110010111100101100000000000000000000010100000001000100010000111100000000011000110000000001101111000000000110010000000000011001010000000000101110000000000110001100000000000000000000000000010100000010100000000100000000000000000011101100100000001000010110000100100000110011100000000100010101000001100000000100000000001000001000000010110100100000010000000000000000

Analysis

A large string 01CodeBinary is also 01 code, which may have some association. First, convert it to ASCII code.

Online tools are the most convenient! Http://home.paulschou.net/tools/xlate /. Paste the 01 code into the second box and click "decode" below. The code is instantly completed:

Observe the first text box. The first two letters are "7z" and what is 7z? Isn't 7z in the 7zip compression format? Is this a 7z compressed package? Possible! Find another 7z compressed package and open it,Vim-B + file nameOpen a compressed package in 7z format and enter: %! XxdView its hexadecimal code:

Then compare it with the encoding of the third frame of the above image. What did you find? Previous37 7A BC af 27 1C 00 03They are exactly the same! This is not a coincidence. This is enough to convince us that this is a 7z compressed package. The following task is to restore the compressed package and write a small one in Python.Program:

#! /Usr/bin/ENV Python# Coding = UTF-8Data = open ('Data.txt') Out = open ('Out','A')While True: D = data. Read (8)IfLen (d )! =8:BreakOut. Write (CHR (eval ("0b % s"% D) data. Close () Out. Close ()
 

Data.txtThe long code string 01 is put in it. After the program is executed, a name is obtained.OutFile,File outCommand to view the file type, display:Out: 7-ZIP archive data, version 0.3.. It's useless! Next, extract the file:7z e outThen, we will find that there is one moreCode. cFile, the content is as follows:

 # Define ____ puts  # DEFINE _ main # DEFINE _ int  # Define _______ char  # Define _____{  # Define ______}  _   Puts ( _______ *); _   __ () _____   ____ ( "\ 151 \ 156 \ 164 \ 040 \ 143 \ 157 \ 144 \ 145 \ 040 \ 133 \ 135 \ 040 \ 075 \ 040 \ 173188"  "66 \ 0700168 \ 054 \ 04020163 \ 0658202 \ 054 \ 04019702 \ 0639849 \ 054 \ 040"  "016533 \ 06464554 \ 054 \ 0402016 \ 06423544 \ 054 \ 04017179 \ 0706918 \ 054 \ 0401" "8653 \ 0611846 \ 054 \ 0400x6 \ 06772 \ 175 \ 073 \ 012 \ 143"  "\ 150 \ 141 \ 162 \ 040 \ 052"  "\ 141 \ 156 \ 163 \ 167 \ 145 \ 162 \ 040 \ 075 \ 040 \ 050 \ 143 \ 150 \ 141 \ 162 \ 040 \ 052"  "\ 051 \ 143 \ 157 \ 144 \ 145 \ 073" ); ______ 

Is this a magic code? A lot of macro definitions. Do we need translation codes? No, let the computer translate it. Compile and execute:GCC code. C-O Code, Compiled successfully, executed./CodeTo obtain the following results:

IntCode [] = {1886680168,2016358202,1970239849,016533464554,2016423544,1717986918,1865311846,Zero X 6772};Char* Answer = (Char*) Code;
 

What is this magic code? Why is it like C language? This should be the C language code. Write a small program and execute this Code:

# Include <stdio. h>IntMain (){IntCode [] = {1886680168,2016358202,1970239849,016533464554,2016423544,1717986918,1865311846,Zero X 6772}; Char* Answer= (Char*)Code; puts (answer );Return 0;}
 

Compile and execute. Guess what the result is? The result is:Http://xiyoulinux.0xffffff.org, A URL! Haha, click it and the page jumpsHttp://xiyoulinuxgroup.sinaapp.com/The page is as follows:

You can access this page through this link: Page Link, you can also view the source code.

I was lucky enough to pass the first level!

Where is the second question?

We can see that there is an input box on the above page. If you enter something casually, the system prompts "Wrong Password !", It seems that a correct password is required to pass the customs clearance. What is the password? Find it by yourself.

When you open the source code, you can see a lot of numbers first. Save these numbersNum.txtWrite a small program to analyze it:

 A = Open ( "Num.txt" ) Li = A . Read (). Split () Num = [ Int ( I ) For   I  In   Li ] Count = Len ( Num ) Max = Max ( Num ) Min = Min ( Num ) Print   Max , Min , Count 

On the statistical result surface, the maximum number is 99991, the minimum is 8053, and a total of 8582. What do these numbers mean? Start to guess.

I remember there was a sound in the University of Tokyo. Isn't that a sound? Which of the following is a digital representation of the voice tone? The range of voice is too large. The frequency range of human voice is64 ~ 523HzObviously, the number provided above is a little big.

Or is it an image or a pixel color? The maximum pixel color is(255,255,255),255*255*255 = 16581375, It seems that the gap is also relatively large. After half a day, I felt unreliable and began to review the page.

Two things on the page are suspicious:
Export src = "http://s16.cnzz.com/stat.php? Id = 5134185 & web_id = 5134185 & show = pic "Language =" JavaScript "> </SCRIPT> 
And<Link href = "question.css" rel = "stylesheet">.
The previous JS was a mess. If you didn't guess it was wrong, it should be a page access statistics item, because cnzz is the statistics of the Data Expert webmaster. The following CSS is shown as follows:

. Style1 {Font-size: 36Px;Font-family: "";}. Style2 {Font-family:Arial, Helvetica, sans-serif}/* % E8 % af % B7 % E5 % 9C % A8 % E5 % 8e % 9f % E9 % a1 % B5 % E9 % 9d % A2 % E6 % 95% B0 % E5 % ad % 97% E4 % B8 % ad % E6 % 89% be % E5 % 87% Ba % E5 % 94% af % E4 % B8 % 80% E7 % 9A % 84% E5 % 90% 88% E6 % 95% B0 */
 

The bottom comment is quite suspicious! A bit of experience can be seen as URL encoding. What does it mean? You can simply decode the program and try it online: http://tool.chinaz.com/tools/urlencode.aspx. import the program and clickUrldecode DecodingIn an instant, the question came out:"Please find the unique sum in the number on the original page".

Oh, my God, it turns out to be a combination of numbers. It's easy. There are more than 8000 numbers. You can use python to write a small program in an instant:

 #! /Usr/bin/ENV Python  # Coding = UTF-8  Import Matha = open ( "Num.txt" ) Li = A. Read (). Split () num = [int (I) For I In Li] a. Close () Def Test(Num):      For I In Range ( 2 , INT (math. SQRT (Num ))): If Num % I = 0 : Return   True      Return   False  For I In Num: If Test (I) = True : Print I

The result is 98201, and the result is decisively entered on the page, and then it will pass! Then a QR code is displayed:

The page content is as follows:

<H1 Align="Center">[3/5]</H1><Div Align="Center"><IMG SRC=Http://heylindayi.sinaapp.com/test/new.jpg"></Div><Script SRC="Http://s16.cnzz.com/stat.php? Id = 5134185 & web_id = 5134185 & show = pic" Language="JavaScript"></Script>
 

Level 3

When I see the QR code, the first reaction is to scan the QR code. I checked the scan and scanned the URL. It is estimated that it is. Then I scanned the QR code and added it.Xiyou Linux Interest GroupAnd then there are all kinds of playings, playings, and playings. After being transferred for half a day, I didn't bring up a project...

Go back to the page and look for the source code above. There's nothing. What's the problem? If you have problems, you can solve them. If you do not know the problems, you will be miserable.

Is there any tricky image? With the try attitude, I opened the image with vim, and the final answer came out. In the last line, I wrote:Password: linustorvalds1969

Okay, this is the password. Then, after entering this string of passwords, they returned the information: "Sorry, you haven't passed any interview yet .".

Well, it seems that my external school can only challenge this ..

Summary

The questions of Western Mail are still very technical and very challenging for beginners! The question is not awesome, and the question is awesome!

The question does not require a particularly profound programming Foundation. As long as it is a little basic, a little experience, dare to explore, be brave in discovering and innovating, like tossing, it is not difficult to make a question. This is a required skill or quality for Linux team members.

The question is very interesting. It may be explained that more people are interested in Linux and Linux technology.

To promote xiyou Linux interest group:

• Group Homepage
• Group Profile
• Group blog
• Group album
• Group Wiki

By the way, we will promote the Linux team of Shandong University of Technology:

• Group Forum
• Group blog
• Group poster

The next article is even more exciting. Click to view:Western Mail Linux Group free exam-continue to challenge