• 1 Post
  • 33 Comments
Joined 10 months ago
cake
Cake day: September 7th, 2024

help-circle



  • Take this shape as an example. The “square” in question consists of AC, BD, the outer AB, and the inner CD.

    Point (5) means that, since the lines AC and BD are radii of the concentric circles, the arcs AB and CD should have the same inner angle. That’s because the angle COD is equal to AOB.

    Since, the inner angle is the same, then the outer AOB should, by definition, be 2π - (the inner AOB), because that’s how radiants work; a circle is 2π rads.



  • Solution:

    Explanation:

    1. in order for the straight lines to be 90 deg with the circles, they must be radii of circles with same central point

    2. the length of an arc is defined as c = r * θ (where r is the radius, and θ is the angle)

    3. we define the inner circle with radius r₁ and its arc L₁ = r₁ * θ₁

    4. we define the outer circle with radius r₂ and its arc L₂ = r₂ * θ₂

    5. Because of (1), θ₁ + θ₂ = 2π

    6. To create the shape, L₁ = L₂ = r₂ - r₁

    If you start replacing and solving, you will get a 2nd grade quadratic, which has a positive and a negative solution. The positive solution is that magic number.






  • Just like you can change your Windows PC to Linux, or install a custom ROM on Android, to have better control over your devices, it is also possible to change the firmware on most routers.

    OpenWRT is the most popular option for that. It’s a Linux based firmware, that has a package manager allowing you to install additional things on your router.

    For example, I have a TP-Link TL-WR902AC v3. Out of the box it is just a USB-powered 5GHz extender. After installing OpenWRT to it, I added:

    • WireGuard: to route all the traffic over my VPN
    • DNS-over-HTTPS: to encrypt all DNS requests
    • USBIP: this is because I sometimes use it to connect a webcam for my cat, and I forward the camera to my server in another room

    By adding WG and DoH to the “repeater”, I can connect this little guy to any public WiFi, and securely connect my devices to it.






  • TL;DR: Do not sell the app, sell the service

    After reading all the comments, I am a bit confused.

    Based on my understanding, this a self-hostable, privacy friendly app, that does not contain a libre license, as you plan on monetizing it.

    First of all, the primary reasons of opting for libre software are privacy and freedom. So, the lack of such license can be considered a red flag.

    Second, a lot of privacy conscious Android users download their apps from services like F-Droid, that have strict rules against closed-source. So, trying to sell a privacy solution on Play Store does not sound like a good business model.

    Tips for monetizing a libre service:

    1. The client should have a libre license. You code running on the user’s device should be verifiable.
    2. Charge for your STUN/TURN server.
    3. Sell the server blob. Sandboxing apps on a Linux system is far easier (to prevent them from accessing the internet and potentially leak data).

    There are apps that are even available on F-Droid, and are similarly monetized. Some examples, that I use, are: Bitwarden, Mullvad, Telegram and Tailscale.