internet basics: how it works

• how did the internet start and grow?
• how does packet switching work?
• what are IP, MAC, DNS?
• Example: What happens when I visit a website?
• what are protocols?
• Example: What happens when I encrypt an email?

one history of the internet

• communication for fun and freedom?
• developed by the US military as a cold war weapon
• ARPANET
• Advanced Research Projects Agency
• since 1972 DARPA (Defense ARPA)
• the basic idea:
• a packet-switched network (with automatic route selection and redundant routes):
• to remain intact nationwide even in the event of an atomic bomb attack on individual cities
• to be used for resource sharing for faster scientific progress

Hello operator?

Source: https://search.creativecommons.org/photos/73ca35f9-65f6-40d8-9da6-4dd936a1d91a

1969

Source: https://www.vox.com/a/internet-maps & http://mercury.lcs.mit.edu/~jnc/tech/arpageo.html

1970

Source: https://www.vox.com/a/internet-maps & http://mercury.lcs.mit.edu/~jnc/tech/arpageo.html

1973

Source: https://www.vox.com/a/internet-maps & http://mercury.lcs.mit.edu/~jnc/tech/arpageo.html

today

Source: https://tutorial.djangogirls.org/en/how_the_internet_works

under the sea

Source: https://www.vox.com/a/internet-maps

development before 2000

• 1973 first standards for the definition of e-mails as we know them today
• 1981 first SMTP standard (today's protocol for sending mails)
  • also: further research expansion in 1981 with CSNET and 1986 with NSFNET
• 1982 TCP/IP specified
• first commercial ISPs in the late 1980s and early 1990s
• 1990 ARPANET is decomissioned
• more on history and development since 2000:
  • Vox: 40 maps that explain the internet

the heavy stuff:

IP, MAC, DNS

• computers are locally addressed via their MAC address (e.g. in your LAN or WLAN):
  • an example MAC address: E3:F2:23:42:AC:AB
• computers are globally addressed via their IP address:
  • an example IP address: 176.9.22.182
• the DNS system maps domain-names to IP addresses:

What happens when I visit a website?

1. I enter https://diebin.at into my browser and hit return
2. My browser asks the DNS system "What's the IP address of diebin.at?" and waits for a response - "Hey there, it's: 176.9.22.182!".
3. My browser sends a first request packet through the internet to the IP address 176.9.22.182
4. The webserver, that's running on diebin.at (176.9.22.182), receives the request and sends the website of "diebin.at" as a response.
   (one or more response packets are sent, depending on the size of the webservers reply)
5. My computers receives all the packets, assembles them according to TCP/IP protocol, and hands them to my webbrowser
6. My browser shows me the response in the form of a website

Protocols

• different (text-)formats used for different applications
• examples: http, smtp, imap, ...

Speaking HTTP

Speaking SMTP

Speaking IMAP

How does my encrypted mail look like?

secure communication

• Transport encryption
• End-To-End encryption

Transport encryption

• it's the S in HTTPS if you are browsing websites
• it's the SSL/TLS setting if you are configuring your mail-account

http://

https://

Authenticity

• How to assure that the sender of a message can't be forged?
• A third trusted authority is needed to verify the sender
• Certificate Authorities, e.g. Let's Encrypt

http://       https://

End-To-End encryption

• Especially important when you're not communicating directly but via a third party:
• e.g. email, chat, messenger apps, ...

No Encryption

Transport Encryption

End-to-End Encryption

protect your data

Any secure software and any secure communication channel are of no use if I don't take care to handle information safely.

metadata

• Even without the content, it can be interesting to know who talks to whom and when.
• e.g.: SMS chains before demonstrations
• e.g.: After being on the phone with a medical laboratory I visit a website on how to do deal with Covid-19
• e.g.: Headers of encrypted E-mail

tracking

Source: https://www.geekculture.com/joyoftech/joyarchives/2066.html

tracking

Source: https://www.geekculture.com/joyoftech/joyarchives/2066.html

Tracking: How does it work?

What do I deliberatly post on the internet?

• private pictures ...
• blog entries ...
• using the same alias over and over again ...
• passwords in pictures ...

trust on the internet / secure software

• What organization is behind the software?
• Proprietary or open-source software?
• Who hosts the software? Who operates the server?

Messenger

• Whatsapp: since 2014 Facebook
• Telegram: Pavel Durov, one of the "VKontakte" founders, private company
• Signal: (Open) Whispersystems, primarily supported by the Open Technology Fund (US state department), developed as F/LOSS

Shared documents

• GoogleDocs: owned by Google, very usable, but problematic in terms of data protection
• Nextcloud: open-source file cloud with many other applications (e.g. LibreOffice online), fork of ownCloud, e.g. Systemli Cloud
• Etherpad: open-source, web-based collaborative text editor, e.g. https://pad.riseup.net
• CryptPad: open-source, zero-knowledge, web-based collaborative document editor, e.g. https://cryptpad.fr or https://pads.c3w.at

tips and advice

What to watch out for, what to use?

• Use password managers like KeePassXC!
• activate two-factor authentication!
• Tor and TAILS (the**amnesic**incognito**live**system)
• Use the following browser plugins/extensions:
• HTTPS Everywhere
• Privacy-Badger
• uBlock Origin ( & on Wikipedia)

more references

• code.org video library, with a section on "How the internet works", explaining IP, DNS, routing, HTTP, HTML and more in much more detail than we had time for here, also in nicely animated in short <10min videos.
• me and my shadow, a website by the Tactical Tech Collective explaining the digital traces we all leave when using the Internet as well as providing data detox tips
• Surveillance Self-Defense, a website by the Electronic Frontier Foundation with tips, tools and how-tos for safer online communications
• Command Line Heroes, a podcast by Saron Yitbarek and Red Hat, with background infos and history of our current IT landscapes
• [de]: So Many Tabs, awesome ~10 min videos where IT experts Sarah, Anne, Kathrin and Sarina explain all things digital (e.g. issues with popular messenger apps and their security and privacy approach) in hilariously amusing yet informative and succinct ways.