Skip to content

Latest commit

 

History

History
121 lines (77 loc) · 3.34 KB

lecture6.md

File metadata and controls

121 lines (77 loc) · 3.34 KB
Raw

10/02/2018 - 6th Lecture

NETCAT

We used netcat to create a lasting tcp server on port 1234 with:

$ netcat -l 1234 -k

We then browsed to http://localhost:1234/ and saw the HTTP request that our browser sent inside netcat's terminal.

Pipes

We used cat <file> to print a file's content to stdout. We then used pipe to channel the stdout one program to another.

For instance,

$ cat baba.html | hexdump

Would show us the hexdump of the file baba.html.

We also learned about CRLF (Carriage Return / Line Feed) and their ascii representations.

We noted that Linux uses only LF (0x0a) for newines while Windows uses CRLF (0x0d 0x0a).

VLANs

We understood why and how VLANs are used within a network topology.

VLANs use 802.1q Ethernet tagging in order to "paint" a packet with a specific VLAN. VLANs can spread over different switches. Each VLAN has it's own default gateway.

We understood that Broadcast Storms may happen with some network topologies and that the solution is employing a protocol that is called "Spanning Tree" (STP).

HTTP

We understood what are HTTP methods (e.g. GET / POST), HTTP paths (e.g. "/index.html", "/images/baba.png"), and HTTP headers

Web Servers

We understood the basics of HTTP. We understood the role of a Web server, such as apache or nginx.

We installed apache on a Ubuntu machine with:

$ sudo apt install apache2

We verified with netstat that there is program with the name "apache" that listens on TCP/80:

$ netstat -ltnp

Then we used cd to change our current directory to /var/www/html, and created a new file there: gedit baba.html.

We then wrote simple HTML in baba.html and opened Chrome with "http://localhost/baba.html"

We saw how we can use CSS to create better looking web sites.

APIs

We understood what are APIs, how they're used by different companies to consume the services of other companies.

We also noted that many companies use internal APIs in the form of "Microservices".

We also noted that APIs can be used to describe the interface between different components in an operating system.

We understood the difference between Monoliths and Microservices.

Linux Commands

  • cd - change directory, e.g. cd /var/www/html.
  • ls - list files in current directory.
  • pwd - print working directory.
  • cat <flie> - print file content to stdout.

Terms

Cryptojacking, stdout, hexdump, Markdown.

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. Review all previous lecture notes, make sure you understand what's going on - if you aren't - Google it. If it doesn't help - make a list of questions for me to answer :).

Copyright 2019 Sagi Kedmi