Exercise: Listing Building Blocks of Your Computing Devices

Before moving on further, take some time to look at your own Local Area Network (LAN), whether it’s the one in your place of residence, the LAN of a family or friend, or that of your workplace, library, community center, etc. To the extent possible, do this at a physical location where you can see the various network building blocks, and maybe do it with the person who took the lead in setting things up if you weren’t the one who did that.

Download the Excel spreadsheet template.

1. Begin with the information regarding the Internet Service Provider connecting the premises to the Internet. What type of communication technology and media is used to connect the premises to the Internet? What are the specified upload and download speeds for the service being provided? Are there any monthly data caps limiting use? As other things come to mind, also include notes on this information.
2. Next, explore the gateway router that provides the first hop between the WAN and the LAN you are documenting. To the extent possible, document the MAC and IP addresses of the router’s WAN Network Interface Controller, and also that of the router’s LAN NIC (remember, many devices have multiple network interface controllers, and therefore multiple node identifiers). Are there additional devices between the outdoor media and the router, such as a modem or optical network terminal? Does the router provide one or more LAN ports? Does it serve as a wireless access point? What are the settings for these? Does it provide a DHCP server giving IP addresses to other LAN nodes, and if so, what are the settings for this service? Are any IP addresses reserved for specific devices? Does it forward port requests that come to its WAN IP address to specific LAN node IP addresses? Are there any security access controls, block sites, and block services being used?
3. Finally, do all you can to document every node connected on this LAN, noting the type of device, the media being used, the assigned MAC and IP address, and any notes you think would be helpful to keep on record. Remember to that your laptop, printer, Raspberry Pi, and other devices might be connected through multiple means such as via WiFi and also wired Ethernet. You might also document devices that are connected to multiple different networks, for instance a smartphone that is connected to the LAN using WiFi and also to a cell network. And there may be devices like that smartphone that also serve as hotspot routers, connecting some devices to the Internet via the cell network instead of the LAN’s ISP.

More on IP Addresses and IP Names

When we type in a URL, or Uniform Resource Locator, in a web browser, we’re almost always typing in an Internet Protocol name. Consider for instance the URL to this book:

https://iopn.library.illinois.edu/pressbooks/demystifyingtechnology/

Hypertext Transfer Protocol (HTTP) is the ever-present client-server protocol we have used for the last several decades to move information across the Internet. In this case, the first part, https, indicates the resource we’re searching for is the secured HTTP protocol (HTTPS). The second part indicates the providing resource is the web server with name iopn.library.illinois.edu. The last two parts indicate the directory and subdirectory in which the specific resources being requested are located. Not specified is the specific file, which in this case probably defaults to index.html, index.php, or something similar.

But as with our phone system, the name doesn’t truly get you in. Rather, the IP name needs to be associated with an IP address to pull up a web page, just as a person’s or organization’s name needs to be associated with a phone number to make a phone call. As of this writing, to get to the website, iopn.libary.illinois.edu is actually first converted to the IP address 130.126.162.192 in order to access the server. We can do this ourselves by typing in:

https://130.126.162.192/pressbooks/demystifyingtechnology/

Only IP names are converted to IP addresses. The directory and subdirectory listings use whatever characters were used to create those directories.

Exercise: Internet Detective

When the Internet is working at expected levels, we generally don’t think about the extensive collection of sociotechnical artifacts needed for one node to communicate with another node on a local network, let alone the many more that allow us to connect when the end-points cross the globe. When things are less than optimal, our responses vary from stepping out for coffee in passive acceptance, to pangs of guilt that we must be doing something wrong, to anger that nothing can be done when essential services are being lost.

This exercise equips us with sleuthing tools as we work to demystify the Internet further.

As explored in the extension chapter on Network Troubleshooting, there is a range of network troubleshooting tools such as ping, traceroute, and speedtest. And there are a couple of tools that are especially helpful when sleuthing IP names: whois and dig. These tools are often installed or available to be installed on different operating systems. They are also integrated into various webpage tool sets.

Before beginning, we must update and upgrade the Raspberry Pi operating system. This is necessary for The General Purpose Raspberry Pi Web Server exercise later, so let’s get a head start. At the same time, we can install whois and dig in the operating system. The advantage to this is ensures the following exercises are completed in a consistent manner.

Enter these commands to update the Raspberry Pi and install the following packages. Note that each of these commands start with the word “sudo.” This indicates the command that follows (such as apt) is issued as a superuser: a user with administrative privileges. As you go, you may periodically be required to enter “y” for yes, or hit “q” after reading upgrade information, before you can proceed with the upgrade.

pi@raspberrypi:~ $ sudo apt update

pi@raspberrypi:~ $ sudo apt upgrade

pi@raspberrypi:~ $ sudo apt install dnsutils

pi@raspberrypi:~ $ sudo apt install whois

Take a few minutes to test the strategies for tracking down problems and identifying if there’s something we might do about them in Network Troubleshooting. Take a close look especially at traceroute. What can the following tools tell you about a network?

• link lights
• ifconfig/ipconfig
• ping
• traceroute
• speedtest

Let’s do a quick initial exploration with the traceroute command to see where the Adafruit.com website might be located physically:

pi@raspberrypi:~ $ traceroute adafruit.com

For those running the traceroute command in a Windows PowerShell terminal, you’ll type in tracert adafruit.com instead.

I see a first hop that takes me to my gateway router on my LAN, and then the first router of my ISP. A few lines down, I see I’ve reached ntt.net. A quick search on my web browser, typing in ntt.com in the search bar, takes me to NTT Communications, a Global IP network. In my search, it actually defaulted to Japanese which I had my browser translate, indicating this is likely a Japanese-owned corporation providing backbone service in the United States. The 5th hop also includes “chcgil09.us” within the IP name, which suggests the router is probably in Chicago, Illinois, United States. This would make sense as I live and am doing this traceroute just a couple hours south in Champaign, Illinois. Hop seven takes me to an IP address that includes the name “cloudflare” before finally reaching 104.20.38.240, the IP address associated with the IP name adafruit.com as listed at the top of the traceroute.

One thing that isn’t fully clear is the details regarding the second hop of the traceroute, the one that leaves my premises and takes the packets of data to my ISP. This is a place where the ‘dig’ command can sometimes prove very helpful. Before moving on to explore the use of that command, here’s a snapshot of a search I did indicating that second hop was to iTV-3.com, the leaser of the fiber optics municipal area backbone network owned by the cities of Champaign and Urbana in collaboration with the University of Illinois Urbana-Champaign.

Once installation for dnsutils (which include the dig command) and whois is complete, proceed. Let’s learn more about the dig command, starting with a search of the manual command within Linux before moving on to do a couple of searches specific to the Adafruit.com IP name and IP address.

From the Raspberry Pi command line, type:

pi@raspberrypi:~ $ man dig

Dig (domain information groper) performs Domain Name System (DNS) lookups. It’s a flexible tool which can take some time to understand fully. After skimming through the manual entry, let’s do a couple of quick tests of the command.

pi@raspberrypi:~ $ dig adafruit.com

Here, we see within the “QUESTION SECTION” that we’re looking for type ‘A’ information. In DNS, ‘A’ records store the 32-bit IPv4 address(es) associated with a hostname. Here, we see the IP name adafruit.com actually has been assigned two, 104.20.38.240 and 104.20.39.240.

In a web browser, type in first one, then the other, of these IP addresses. What do you get as a webpage? What does this tell you?

Let’s do a reverse lookup to get the ‘PTR’, a pointer from an IP address to the associated canonical name.

pi@raspberrypi:~ $ dig -x 104.20.38.240

Here we see in the “AUTHORITY SECTION” that ARPA provided ‘SOA’, that is, the start of a zone of authority record, in which this IP address is associated with dns.cloudflare.com, the authoritative Domain Name Server for cloudflare.com. According to their “About” page, Cloudflare is a “service that protects websites from all manner of attacks, while simultaneously optimizing performance.”^[5] While we don’t know specifically how, we do know that Adafruit Industry is associated with, or makes use of in some way, Cloudflare.

Let’s now use the whois command to see if we can learn more about Adafruit and Cloudflare. From the command line, type:

pi@raspberrypi:~ $ whois adafruit.com | less

(NOTE: the pipe symbol, found on the upper right between the “enter” and “backspace” keys on US keyboards, takes the output from one command and passes it to the next command, in the case “less” which allows us to view the contents one page at a time, moving back and forth within the text.)

Here, we see that the domain “adafruit.com” is registered through NameCheap, Inc. The name was created in May 2005, was last updated July 2018, and will expire May 2026 — IP names are not owned, but only leased.

We then find that the Domain Name Server for the domain name “adafruit.com” is hosted by Cloudflare.com. Adafruit, Inc. may still host the website in-house, or may use another service to do the hosting using an Infrastructure-as-a-Service or Platform-as-a-Service “cloud” web server. From this, the only thing we do know is that Cloudflare is performing as a Domain Name Server for Adafruit. The DNS system actually has quite a range of record types that can be effectively used to support a wide mix of IaaS, PaaS, and in-house infrastructures simultaneously in support of one domain name. As a result, Adafruit.com can actually be making use of a number of different in-house and remote-located services.

Use the up and down arrows to explore further the Registrant, Admin, Tech, and Name Server information records for the Adafruit.com domain name. Then let’s do the same for Cloudflare.com by typing:

pi@raspberrypi:~ $ whois cloudflare.com | less

We do see some information regarding creation, updated, and expiry dates, and also the Name Sever for the domain. But we also see that while early in the establishment of the Internet Protocol all records were kept open, today many items can be held private from the public. So we see far less in whois for Cloudflare than we did for Adafruit.

Before moving on, let’s take a quick look at the whois manual:

pi@raspberrypi:~ $ man whois

This description specifies this application searches for an object in the Request for Comments (RFC) 3912 database. Towards the bottom of the manual, NOTES are listed clarifying the search process and some of the underlying official resources searched depending on context.

Cloud Computing

When discussing Internet-based applications today, the term cloud or cloud computing is often used. Indeed, sometimes the word cloud is used synonymously with the word Internet. Cloud computing, like the Internet of Things, is an evolving paradigm. For this reason, in 2011 the National Institute for Standards and Technology, as part of its statutory responsibilities under the Federal Information Security Management Act of 2002, developed a short document highlighting important aspects of cloud computing. The goal was to provide a baseline for further discussion regarding cloud computing and as a means for comparison of cloud services and deployment strategies. Essential characteristics include on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. Together, these provide a means by which multiple organizational, community, or public consumers to which these services are deployed can each have great individual flexibility and freedom to unilaterally adjust services to fit current and anticipated demands across a range of devices. These essential characteristics and deployment models are associated with one of three service models:

Others have noted that the distinction between higher-level Platform and lower-level Infrastructure as a Service found within a large data center is not a crisp line and should be considered together as utility computing.^[6]

What is not generally recognized in relation to Cloud Computing is that, as part of the Internet with its foundational concepts of the end-to-end protocol creating a federation of the locals, data centers themselves are housed within their own Local Area Networks (LANs), some of which may be located within broader corporate Campus Area Networks (CANs). As part of a federation of the locals, these data centers should not be seen as centralized servers with overriding authority control, but rather local nodes internetworked with other local nodes to provision hardware and software services, a concept that was underlined within the Essential Characteristics section of the NIST Definition of Cloud Computing.

Wouldn’t it therefore be accurate to consider the research servers (e.g., Prairienet Community Network server computers), the University library servers, and University campus infrastructure servers that serve on- and off-campus associates a Cloud service?

Exercise: The General Purpose Raspberry Pi Web Server

In session one of the Rainbow Unit, we did a few different exercises exploring some of the underlying concepts behind the Internet of Things, also highlighted in Limor Fried’s segments “All the Internet of Things.” Of special note now, reflect back on the Hyptertext Transport Protocol (HTTP), an example of a client/server protocol that works at layers 6 and 7 of the OSI model.

Let’s finish this chapter by testing out a more general-purpose installation of HTTP on the Raspberry Pi, setting it up as web server that can be used on the world wide web. While we did create an HTTP-based web server in session 1, the Python library code used created a special-purpose web server. This time we’ll install the Apache web server, a widely used general purpose web server.^[7] Before starting the installation of Apache, take a few minutes to follow though Carrie Anne Philbin’s Crash Course Computer Science episode #30 on the World Wide Web.

pi@raspberrypi:~ $ ls -al /etc/apache2

pi@raspberrypi:~ $ cd /var/www/html
pi@raspberrypi:/var/www/html $ ls -al

pi@raspberrypi:/var/www/html $ sudo chown pi: index.html

pi@raspberrypi:/var/www/html $ nano index.html

sudo nano mypage.html

http://10.0.0.30/mypage.html

pi@raspberrypi:/var/www $ sudo nano iot.html

<html>

<head><title>IoT Gathering Page</title></head>

 <body>

      <h1>Internet of Things Gathering Page</h1>

      <p>This page is used to gather datasets from various

            local Internet of Things devices

      </p>

      <iframe width="1024" height="768"

                 src="http://10.0.0.30:8401"

                 frameborder="0" allowfullscreen>

      </iframe>

 </body>

</html>

http://10.0.0.30:8401/
http://10.0.0.30/iot.html

pi@raspberrypi:/var/www/html $ sudo apt install php libapache2-mod-php -y

pi@raspberrypi:/var/www/html $ sudo mv index.html index-orig.html

pi@raspberrypi:/var/www/html $ sudo nano index.php

<?php echo "hello world"; ?>

<?php echo date('Y-m-d H:i:s'); ?>

<?php phpinfo(); ?>

Wrap Up

As noted earlier in this session, internetworking can happen in many shapes and forms which regularly incorporate the Internet suite of protocols and applications. The key is the level to which we enter into use of an Internet-based tool from a ‘thing-oriented’ compared to a ‘person-oriented’ framing. Through the exercises within this part of the session, we’ve made use of different research methods to explore key social and technical aspects of the Internet suite, seeking to decodify key terms and concepts related to networked information systems. The infrastructure of the Internet provides an amazing opening for us to build from ‘person-centered’ digital internets past and present, and to also open new critical lenses to further challenge the dominant ‘thing-oriented’ framings through new pathways as we move forward within the information sciences.