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17/02/2018 - 8th Lecture

Test #1 - Networking Fundamentals

We've had our first test. You'll your grade next lesson.

Linux Command Line (bash)

We've learned and used the following commands:

chmod +x <filename>
chmod <number - e.g. 755>  <filename>
./<executable file>
ls -l
ls -a - list hidden files and directories (start with a ".")
pwd - print working directory
cd - change directory
cd ~ - go to home directory
cd .. - go one directory back
cat <file> - print the file content to stdout
mkdir - make a new directory
touch <filename>  - create a new empty file
rm <filename> - remove a file
mv <f1> <dir / f2> - move f1 to f2 / dir
ln -s <target> <link_name>
whoami - which user is logged in
file <file>  - determine file type
sudo <command> run command from a high privilege context
alias <cmd>="cmd arg1 arg2"

DAC - Discretionary Access Control

We've described Linux's DAC model and played with it.

We also explained MAC (Mandatory Access Control) and described how it hardens process / file permissions every further.

Magic Numbers

We've seen that most binary file format starts with their own magic number which allows operating systems to know the actual type of a file - regardless of its extension.

We've used the file command to check the types of files.

Pastebin and Sprunge

We've explained the value of services such as Pastebin and Sprunge.

We also tried to add an alias for Sprunge. We'll finish it next lesson :)

Homework

  1. Do HTML Dog's Beginner, Intermediate and Advanced HTML tutorials: http://www.htmldog.com/guides/html/. You can also do the CSS ones: http://www.htmldog.com/guides/css/.

  2. Watch Mr. Robot.

  3. Practice with https://www.typingclub.com. Reach at least 55WPM.

  4. Research and public speaking; find a topic - either a technologoy (e.g. DNS, DHCP) or a security-related news article and prepare a 2-3 minute talk about it.

  5. FOLLOW YOUR FELLOW CLASS MATES: http://bit.ly/2B87gDw with your Twitter, Github and Linkedin.

  6. Find relevant job descriptions (e.g. SOC Analyst). Put them in Google Docs. Highlight the different technologies that are required.

  7. Add a new command with alias, the command should print your name. Put the alias in the ~/.bashrc file and do (in the same terminal) $ source ~/.bashrc

  8. Work on your CV. In English. Print it for me to review.

  9. Find the magic number of three file types, verify it with hexdump, then write them down for next lesson.

  10. What does $ chmod 755 mean? What does $ chmod 666 mean?

Copyright 2019 Sagi Kedmi