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\chapter{A Tour of TFW}
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\chapter{A Tour of TFW}\label{atouroftfw}
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The bulk of the functionality provided by the Tutorial Framework
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is implemented in pre-made components that are built upon the architecture
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described in Chapter~\ref{architecture}.
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To create tutorials, developers generally rely on and use TFW provided components to
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implement most of the common functionality and then build more exercise-specific logic
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based on the TFW architecture themselves.
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A \emph{very important} point to keep in mind is that most of this
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exercise-specific logic will be implemented in \textbf{FSM callbacks} and
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custom \textbf{event handlers}.
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The whole framework is built in a way to faciliate this process and developers
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who understand this mindset are almost always guaranteed to create great
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content using TFW.
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The purpose of this chapter is to further detail the built-in components
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provided by the framework.
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@ -191,6 +204,28 @@ certain command are executed by the user.
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\pic{figures/terminal.png}{The Frontend Terminal of TFW Running top}
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The implementation of reading command history is quite an exotic one.
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The framework need to be able to detect if the user has executed any command in the
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container.
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This is not an easy thing to accomplish without relying some sort of heavyweight
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monitoring solution such as Sysdig%
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\footnote{\href{https://sysdig.comq}{https://sysdig.com}}.
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I deemed most simiar systems a huge overkill to implement this functionality, and their
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memory footprints are not something we can really afford here.
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Another way would be to use \texttt{pam_tty_audit.so} in the PAM%
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\footnote{Linux Pluggable Authentication Modules:
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\href{http://man7.org/linux/man-pages/man3/pam.3.html}
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{http://man7.org/linux/man-pages/man3/pam.3.html}}
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configurations responsible for logins, as this allows various TTY auditing, but
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I have found an ever simpler approach to the problem in the end.
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By using the inotify system built into TFW, I can set up the user's environment in
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such a way, that I can enforce or determine the location of the bash \texttt{HISTFILE}%
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\footnote{This environment variable contains the path to the file bash writes command
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history to}
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of the user.
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This way I can monitor changes made to this file and read the commands executed
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by the user from it.
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\section{Console Component}
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This component is a simple textbox that can be used to display anything to the user,
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@ -253,3 +288,25 @@ in a spectacular fashion until the whole thing managed to crash.
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It was an event of such chaotic beauty, that I often fondly recall it to this day.
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Of course it would take me several hours to identify the exact causes behind this
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fascinating phenomenon, but those were \emph{very} fun hours.
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\section{FSM Management}
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I have already mentioned the event handler called \texttt{FSMManagingEventHandler},
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which is responsible for managing the framework FSM.
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For completeness I chose to include it on this chapter as well.
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The API it exposes through TFW messages allows client code to attempt stepping the
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state machine.
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As previously explained this is something that is considered to be a \emph{privileged}
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operation in case authentication is enabled, causing the event handler to accept
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digitally signed messages only.
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In the event of a successful FSM step, this component is going to broadcast
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a message showcased as an example in the beginning of Chapter~\ref{atouroftfw}.
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\section{Additional Frontend Features}
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The frontend of the framework exposes some additional APIs through
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TFW messages.
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These include the changing of layouts, selecting the terminal or console
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component to be displayed, the possibility of dynamically modifying other
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frontend configuration (such as the frequency of autosaving the files in the editor)
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and more.
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\chapter{Framework Architecture}
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\chapter{Framework Architecture}\label{architecture}
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\section{Core Technology}
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It is important to understand that the Tutorial Framework is currently implemented as
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@ -331,6 +331,12 @@ users, which many solutions for distance education lack so often.
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Developers can use a YAML file or write Python code to implement finite
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state machines.
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In state machine implementations it is possbile to subscribe callbacks to be
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invoked on certain events regarding the machine, such as before and after
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state transitions, or onentering and exiting a state.
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It is \emph{very} important to be aware of these callbacks, as much of the
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actual tutorial logic is often going to be implemented in these.
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Architecturally a built-in event handler called \texttt{FSMManagingEventHandler}
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is capable of managing the FSM defined by clients.
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The responsibilities of said event handler include:
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\chapter{Using the Framework}
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In this section I am going to dive into further detail on how client code is supposed
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to use the framework, some of the design decisions behind this and how all all of this
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to use the framework, some of the design decisions behind this and how everything is
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is integrated into the \texttt{solvable} Docker image.
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To use the framework one has to do several things to get started.
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@ -15,14 +15,31 @@ The main poins include:
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\item set up reverse proxying for any user-facing network applications such as webservers,
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SSH and friends
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\end{itemize}
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At first all these tasks are quite overwhelming.
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At first all these tasks can seem quite overwhelming.
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Remember that witchcraft is what we practice here after all.
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To overcome the high initial learning curve of getting familiar with the framework
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I have created a repository called \emph{test-tutorial-framework} with the purpose of
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providing a project template for developers looking to create challenges using the
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framework.
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This repository is a really simple client codebase that is suitable for
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developing TFW itself as well (a good place to tests for the framework).
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Let us take a look at this to acquire a greater understanding of how the framework operates.
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developing TFW itself as well (a good place for the tests of the framework).
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I also provides an ``industry standard'' \texttt{hack} directory
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containing bash scripts that make the development of challenges and TFW itself very convenient.
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These scripts span from bootstrapping a complete development environment in one command,
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to building and running challenges based on the framework.
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Let us take a quick look at the \emph{test-tutorial-framework} project to acquire a greater
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understanding of how the framework operates.
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\section{Project Structure}
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\section{Project Structure}
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\section{Implementing a Finite State Machine}
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\section{Defining Processes to Run}
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\section{Exposing Front-facing Networking Applications}
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\section{How This Works}
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\section{Developer Tooling}
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\section{Framework Release Management}
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