Python Challenge level 15

http://www.pythonchallenge.com/pc/return/uzi.html (login: huge/file)

- A calendar. January 26. Don't know which year it is. "he ain't the youngest, he is the second". "todo: buy flowers for tomorrow".

- I have to buy flowers on January 27 for a man who is the second and not the youngest one. What?

Python Challenge level 14

http://www.pythonchallenge.com/pc/return/italy.html (login: huge/file)

- "Walk around" is the title. A spiral bread. A 10000*1 picture named "wire.png" presented as a 100*100 one. An equation: 100*100 = (100+99+99+98) + (...
- What we should do is rearrange the pixels in wire.png in a spiral manner like that bread and make it a 100*100 picture!

Python Challenge level 13

http://www.pythonchallenge.com/pc/return/disproportional.html (logon:huge/file)

- "call him"... click number 5 on the phone, and then a xml error page shows up!
- Google the fault code (105) and knowing that it is a XMLRPC module error. According to http://stackoverflow.com/questions/7950297/faultcode-105-faultstring-xml-error-invalid-document-end-at-line-1-column-1, I should send some "xml request" to this page rather than just browsing the page.

Python Challenge level 12

http://www.pythonchallenge.com/pc/return/evil.html (login:huge/file)

- I downloaded evil1.jpg and checked this picture over and over again, but I still don't know how to deal with the EVIL here.
- After searching for some tips on Google, there is a person said, "The picture is evil1.jpg, so not surprisingly there will be evil2.jpg." Well, for me, at least, it has little sense.

Python Challenge level 11

http://www.pythonchallenge.com/pc/return/5808.html (login:huge/file)

- No much tips, just "odd even" in the title and a very vague picture. Seems like this picture is processed for a certain purpose.
- Divide the picture into 4 parts according to the pixel coordinate. (00, 01, 10, 11)

Python Challenge level 10

http://www.pythonchallenge.com/pc/return/bull.html (login:huge/file)

- Click the bull in the picture, you will see "a = [1, 11, 21, 1211, 111221, "
- This is so called "look and say sequence", please refer to https://en.wikipedia.org/wiki/Look-and-say_sequence

Python Challenge level 9

http://www.pythonchallenge.com/pc/return/good.html (login:huge/file)

- "connect the dots", remember me a little game i played when i was young...
- See also: http://pillow.readthedocs.org/en/3.1.x/reference/ImageDraw.html
- Draw a picture according to two lists: "first" and "second"

Python Challenge level 8

http://www.pythonchallenge.com/pc/def/integrity.html

- "Where is the missing link?" If you click the bee in the picture, you will be asked to input a pair of username and password.
- Find the 'un' and 'pw' data streams in the source page.

Python Challenge level 7

http://www.pythonchallenge.com/pc/def/channel.html

- To do this challenge, please make sure you have already installed PILLOW.
https://pypi.python.org/pypi/Pillow
- This is such a huge task. First of all, the code is hidden in the picture. See the grayscale bar across the picture?

Python Challenge level 6

http://www.pythonchallenge.com/pc/def/channel.html

- Visit the source page, and just see "zip" is useful
- http://www.pythonchallenge.com/pc/def/channel.zip -> get a zip file
- Unzip the file, you will know that it is just like challenge level 4. According the readme.txt, you should start from 90052

Python Challenge level 5

http://www.pythonchallenge.com/pc/def/peak.html

- Pronounce "peak hell". What?? I pronounced it in my room, and nothing happened...
- Google "peak hell", it turns out to be "pickle."
- See also: https://docs.python.org/2/library/pickle.html
- The target that should be pickled is banner.p (showed in the source page)

Python Challenge level 4

http://www.pythonchallenge.com/pc/def/linkedlist.php

- click the picture, you will know that it will be an exhausted work
- knowing from source page, we should keep modifying the nothing value for at most 400 times

Python Challenge level 3

http://www.pythonchallenge.com/pc/def/equality.html

- See also: https://docs.python.org/2/library/re.html
- As the previous level, copy the mess message in the page source
- Try to find " 3 uppercase + 1 lowercase + 3 uppercase" pattern
  - For example, "AAAaAAA"
  - They emphasize "EXACTLY 3 bodyguards," so string like "AAAAaAAA" is not acceptable
- Finally, concat all lowercase letters

Python Challenge level 2

http://www.pythonchallenge.com/pc/def/ocr.html

- find the mess message in the page source (commend), copy the content and save it as a file

- "find rare characters in the mess below", so find the letter frequency of this message

Python Challenge level 1

http://www.pythonchallenge.com/pc/def/map.html

- observe the picture, there are all 2 lexicographical difference between each pairs of letters
- not sure what the tip means is
  1. k should be changed to m
  2. in the cipher text, k is changed to m

Python Challenge level 0

http://www.pythonchallenge.com/pc/def/0.html

- just calculate 2^38

g = lambda x, y:x**y
print g(2, 38)

Vocabulary

vulnerability 易受攻擊的
wreak havoc 造成破壞

forensic 法庭的, 辯論的, 鑑識
falsification 竄改；偽造；曲解
depletion 消耗；用盡
repudiation 否認
countermeasures 對策
ossification 僵化；鈣化
convolution 迴旋；盤繞

delegate 授權；委託
anomalous 不規則的；異常的
unprecedented 史無前例的
impasse 僵局
unorthodox 非正統的
susceptible 易受影響的

rudimentary 早期的；未成熟的
albeit 雖然
vantage points 有利的位置

Integer Linear Programing - Using Binary Vaviables

Some tips about ILP transformaion using binary variables.

- Logic
  - Conjunction, A and B, A∩B => a+b = 2
  - Disjunction, A or B, A∪B => a+b ≥ 1
  - if A then B, A→B, ~A∪B => a ≤ b
  - A if only if B, A↔B => a = b
  - A = ~B => a+b = 1
  - C = A∩B => c ≤ a, c ≤ b, c ≥ a+b-1
  - C = A∪B => c ≥ a, c ≥ b, c ≤ a+b

Integer Linear Programming - Duality

Main Resource: Applied Mathematical Programming by Bradley, Hax, and Magnanti (Addison-Wesley, 1977), provided by MIT

A canonical form of duality of an Integer Linear Programming problem:

IP address, Subnet, Netmask

- Classes of IP address:

- There are also class D and E, and the leading bits are 1110 and 1111 respectively.
- IP address is divided into two parts, net id and host id.
- Hosts with the same net id are within the same subnet.

L2/L3 Switching

See https://en.wikipedia.org/wiki/LAN_switching

L2 switching - see MAC address only
L3 switching - see IP address

Comparison between L2/L3 switching, see also:
 - Cisco Meraki documentation
 - IThome
 - http://www.networkpcworld.com/differences-between-layer-2-3-4-switching-multilayer-switching-layer-3-routing/

Virtual Machine setup

Got a new homework as below:

1. 從官方網站下載"Oracle VM VirtualBox" 或 "VMware Workstation Player"
2. 從官方網站下載linux作業系統，可選 ubuntu、centos 或其他你熟悉的
3. 新增一個虛擬機器，至少要有兩張虛擬網卡，第一張使用nat功能，第二張指定成內部網路。接著設定一台虛擬光碟機，並將光碟檔案指定為在第二步下載的光碟映像檔。