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"All Watched Over by Machines of Loving Grace"

How would you summarize the view that this documentary takes? What do you think of the view that this documentary takes? Is this view still the one that drives technological innovation? Is there any aspect you can think of in which this view is not fulfilled?

"Neither Confirm Nor Deny"

How does government conceal its secrets in this story? In the story told by the program they point to the fact that evasion techniques are often used by government to be apaque about certain subjects. Why would a government want to keep information away from the citizens it governs? Do you think they do it for our own good? Do you think that free access to information would harm citizens?

Julian Oliver at 30C3

Julian Oliver says in his presentation “right of access, is a financial transaction”, what do you think that means? Is there anything about Julian's work that called your attention? What was Julian Oliver's definition of the Internet? Would you agree with that?

Critical Engineering Manifesto

Have you seen in the CE website that you can download the PDF with the manifesto? What are those weird numbers at the bottom? What do you think they are for? What is a fingerprint?

On the 6th of June 2014 the CIA became an active Twitter user, follow them on: This is their first tweet:

Since then they have posted a great deal more about the “Glomar Response”.


The Internet is a very complex beast with a rather sophisticated yet simple design under it, when the network itself and most of its protocols where designed there were very few people connected and few would suspect that it became so central to our lives as it is today.

The Internet also happens to be broken.

It is the network of networks.

The Internet runs on the IP, short for Internet Protocol.

Let's look a bit deeper into the IP.

Going online requires that your computer be connected to the national internet infrastructure, normally this is done through an ISP or a telecommunications company. They themselves are connected to the internet via larger providers or through country backbones.

Different backbone are connected to each other through “peering agreements” this is interesting because it's the only link where the “common good” overrules the financial transaction.

When you connect to a particular address on the internet what is a large mesh of interconnected computers becomes a straight line. This line is called “the route”, each step in the route is called a Hop. The first hop in a route is normally the modem/router that connects you to the internet.

*The Internet is a packet-switching network*, this means that each piece of communication in it is broken down in tiny packets containing fractions of that information. For example when you send an email to a friend of yours in South Africa this email gets broken down into tiny fractions of just a few bytes each and are sent over the network to the next hop. This means that each little packet of information can actually take a different route to it's destination. At the destination hop all these packets are assembled together again and the content of the communication recomposed.

(!!!) This means that once you send a piece of information you have no control whatsoever about how that data will travel over the network. You can make certain informed assumptions and you can research the actual path. But before the fact happens you can never be 100% sure.

IP addresses

Internet routing is possible because each device connected to the internet is identified by an IP address. These addresses are composed of 4 numbers between 0 and 255. IP addresses are segmented and they are given to you by your ISP and your ISP gets them from the national RIR or Regional NIC (Network Information Center). Currently there are 5 RIRs:

  1. African Network Information Centre (AfriNIC)[1] for Africa
  2. American Registry for Internet Numbers (ARIN)[2] for the United States, Canada, several parts of the Caribbean region, and Antarctica.
  3. Asia-Pacific Network Information Centre (APNIC)[3] for Asia, Australia, New Zealand, and neighboring countries
  4. Latin America and Caribbean Network Information Centre (LACNIC)[4] for Latin America and parts of the Caribbean region
  5. Réseaux IP Européens Network Coordination Centre (RIPE NCC)[5] for Europe, Russia, the Middle East, and Central Asia

Whenever you open a website from your browser the transaction involves your IP address and the IP address of the computer that hosts the website you want to open, so that the connection can be made.

When you are behind a router in a home network or a cafe, your IP address (the one you see in your computer) might be different from the one reported by websites. This is because your computer can have multiple IP addresses.

(!!!) But from the point of view of the greater Internet only your EXTERNAL IP address will be visible.

NAT (network address translation)


IP addresses are cumbersome to use and difficult to remember. So instead we give these IPs a name, a domain name. DNS stands for Domain Name System and it is a system of linking up domain names to IP addresses.

DNS is quite complex so we will not go into so much detail, but there are a few things that are important to understand about DNS. DNS is a hierarchical system. When typing an address in your browser your computer will first look into your hosts file and try to find the IP address there. If it doesn't find it it will try to look in its cache of previously resolved addresses and try to find it there. If it doesn't find it it will ask the DNS server of your internet provider and so on untill it finds it, if it doesn't find it the address will not resolve. This doesn't mean that the resource doesn't exist, it just means that the address couldn't be resolved.

The Unix terminal

This is where hackers spend most of their day. It's a clunky interface but to this day it remains the most powerful interface between a power user and a computer. The terminal allows you to do things that it would be impractical to do over a graphical interface such as rebooting 3000 computers at the same time, resize every image in your harddisk.


  1. Open your hosts file.
  2. Add an entry at the end that reads:
  1. Save the hosts file.
  2. Open a browser and type the address What do you see?
  3. How did I know the IP address of that other search engine?


Some servers do not respond to pings but most edge servers will.

Exercise: Change the hosts file in your computer in a way that the domain “myhome” resolves to your personal website. Does it work?

Find out your IP.

What is an IP address? Why can IP addresses be geolocated? Get the data here:

Learning how to use whois and traceroute.

Download the Open Visual Traceroute software and install it. Make a list of the 20 websites that you visit more often and traceroute them.

Where do the routes normally end? Which ones surprised you the most? Why do you think they end where they end? What can you tell about each hop? What do these routes tell us about the nature of the internet? What does the term jurisdiction mean and how does it apply to the internet?

Add for good measure the following sites:

Why is this relevant?


On March 30th 2014 Recep Tayipp Erdogan, Turkey's prime minister, ordered a nation-wide blockade on Twitter to prevent people from spreading a recording of him telling his son to dispose of large sums of money that he had diverted from public funds.

The government agencies implemented the Twitter blockade in a peculiarly clumsy way, they blocked Twitter via DNS. This meant that if you changed your computers DNS for a DNS server outside of Turkey you could bypass the censorship.

This is how people in Turkey reacted.

course/catt/session_2.txt · Last modified: 24/11/2015 19:47 (external edit)