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Notions

• /dev/cdc-wdm1: Linux device node for a Qualcomm-based 4G/5G modem. Used to send commands to modem (See QMI).
• wwan0: Network interface on Linux for a cellular modem that uses 4G/5G.

Configuration

$ # Connect the dongle with the pin code already disabled
$ mmcli -L  # List the connected modems. modem-code: number at the end

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Features

• Code not run on a VM (i.e. directly compiled to machine code).
• Automatic garbage collection.

Module

• Collection of packages versioned together (e.g. a simple go repo on Github).
• Defined by a go.mod file placed at its root directory.

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#!/usr/bin/env python3
"""
Python datetime: https://docs.python.org/3/library/datetime.html
Numpy datetime: https://numpy.org/doc/stable/reference/arrays.datetime.html
Pandas datetime: https://pandas.pydata.org/docs/user_guide/timeseries.html
"""
import argparse
from pathlib import Path
from datetime import datetime
import calendar

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set style fill solid 0.5;
set xtics rotate
set xlabel "Day";
set ylabel "MiB";

# data file passed as a command-line argument (variable ARG1)
# 0: pseudo-column for indexes starting from zero = x-axis
# 2: y-axis=2nd column in file
# xticklabels(1): ticks on x-axis from 1st column in file
plot ARG1 using 0:2:xticlabels(1) title "Daily data usage in MiB" with boxes;

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Batch processing

• Install batcher Gimp plugin by copying its extracted folder to ~/.config/GIMP/3.0/plug-ins.
• Multiple images can be easily resized from its gui in gimp.

Multiple images to pdf

• Gimp not used because the pdf produced is too large on the disk.
• convert (from imagemagick) and img2pdf without the --imgsize option, produce pages of different sizes in the same pdf document.
• Without sorting by number, wildcards would sort files in an alphabetical order.

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Minimal plasma installation

$ sudo pacman -Sy plasma-desktop

Plasma applet for managing audio volume

Visible in lower-right corner:

$ sudo pacman -Sy plasma-pa

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Linking order

The dependent executable should appear before the libraries it depends on, as order is important (See 1).

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Kotlin

• Statically typed language.
• Outputs bytecode that runs on the JVM (like Java).

Build Automation tools for JVM projects

All of them are similar to CMake but for Java/Kotlin:

• Gradle: Build system for Android used for compilation, packaging (APK), and for dependency management. Preferred for Kotlin projects.

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What is it

An instrumentation tool for x86, Android..., that targets binary applications.

Usage

• To debug live processes.
• To execute your script inside another process.

Applications

• Frida is used for dynamic reverse engineering (i.e. analyze a program while software is running).
• Static reverse engineering software in contrast take binaries to dissect them.

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#include <limits.h>
#include <string.h>
#include <stdbool.h>
#include <gd.h>

#include "utils.h"

/**
 * Print password written beforehand on image with steganography_write.c
 * - GD documentation: https://libgd.github.io/manuals/2.1.1/files/preamble-txt.html