Salamander

  • 380 Posts
  • 855 Comments
Joined 4 years ago
cake
Cake day: December 19th, 2021

help-circle



  • Don’t worry, I wouldn’t ban you for this.

    Yes, the physical modulation implemented by LoRa transceivers is proprietary.

    It is not entirely correct to say that the “mesh” itself is proprietary. Meshtastic is open source, even if it relies on proprietary radio hardware. In principle, one could take the Meshtastic codebase and adapt it to a different physical layer.

    It is perfectly reasonable to reject a technology because the full stack is not open. That said, once you look closely at most modern digital and RF hardware, you are extremely likely to encounter proprietary ICs, firmware, or physical layer implementations somewhere in the stack.



  • Yes, you have many options. It depends on how much “from scratch” you want to go.

    The simplest method is to purchase a module with the radio transceiver + microcontroller, flash it, and assemble it. If you don’t want any sensors, you can for example purchase from RAK the kit a kit with a ‘RAK19003’ base board + ‘RAK4631’ module (nRF52840 micro-controller + SX1262 transciever) . For Canada, you would pick the 900 MHz version that operates in the 915 MHz band. (https://store.rakwireless.com/products/wisblock-meshtastic-starter-kit?variant=43884035113158)

    For an enclosure, you can look up ‘Project box’ or 3D print a case.

    If you want to go even more “from scratch”, you can buy a module without a micro-controller (Waveshare core1262, Ra-01SH, Wio-SX1262), and interface with these using a micro-controller via SPI. At this layer it starts to become more of a hassle if you want to implement Meshtastic, because you will need to either copy an existing configuration, or modify the firmware so that it matches the way that your electronics are connected.

    Then, if you do not want to purchase a module, you would buy the transciever directly (for example, the SX1262), and assemble your own module. You can look up the schematic of the basic modules to get an idea of what this looks like. For example, you can see the Waveshare Core1262 schematic here: https://files.waveshare.com/upload/c/c1/CoreSX1262_Sch.pdf

    If you do not want to rely on an already existing LoRa transciever, but instead use a more general radio transciever, that is also possible. But, more expensive, and is unlikely to match performance. This is something that one might want to do if you already have an SDR transciever connected to raspberry pi and want to use it to interface with LoRa (still, it is much easier to connect a LoRa device over USB). I would not recommend building a meshtastic device from more general transcievers.






  • Thanks a lot for the examples! I have been looking through these, and, as far as I can tell:

    1. In SSL stripping, the site would appear to your client as HTTP, not HTTPS. If that’s the case, I think SSL stripping is blocked when using ‘HTTPS-Only’ mode
    2. For DNS spoofing, the visited site would show up as insecure because they would not be able to generate a valid certificate for the target website

    I still have not had the chance to look into leaky metadata. But, generally, I think metadata issues can in part be addressed by not generating much metadata.

    Probably the biggest vulnerability is the captive portal. There is no way to verify you’re connecting to an official Starbucks router. I think that when connecting to a public router it is wise to assume that it is malicious.






  • It depends. In my experience: in an academic laboratory I have been able to use common sense.

    For example, gloves go on when working with strong acids/bases. The statement:

    gloves apparently only give researchers a false sense of security that can dull the sense of touch and prevent you from recognizing chemical exposure

    Does not apply as much when you are working with such corrosive agents, because you really should never be in a position where spilling 4 M HCl into your hands would go unnoticed.

    When working with large quantitites of oils, even if non-hazardous, gloves go on and they will probably get oil in them.

    When working with cell cultures, the goal is often to not contaminate the cultures. Some people prefer to wash their hands thoroughly and not use gloves, and they have been working at it for many years and they seem to do just fine. It’s a risk mitigation strategy - if the cultures have antibiotics and fungicides, risk is already not too high.

    In an industry setting it is different. Companies often comply with specific standards and health and safety regulations. While the individual can use common sense, the people in charge of ascertaining compliance (sometimes ‘EHS’, Environment, health and safety personnel) aren’t necessarily chemists themselves, nor should they need to be aware of the identity of the transparent liquid in the flask that you are holding. So, generic rules are often set in place not only because of their practical utility but also to simplify enforcement. In some cases external auditors can come in (announced or not) and verify compliance - this, again is much simpler when the rule is ‘lab coat behind yellow line, gloves always on when touching a container with a liquid’ than having to interview each person to understand what they were touching without gloves and to understand their philosophy of why they chose to do so.


  • By hand. We are only two people, and we usually clean after we cook/eat. When one is cleaning only 2 plates + a pot/pan at a time, it is easy to use little water. Spray of soap, metal scrub, sponge scrub, and then turn the tap on to rinse for a few seconds. Utensils get individually scrubbed and then all rinsed together for a few seconds.

    Maybe when we have kids a dish washer will make sense.








  • I do have a wall with similar boxes. From the image, I am not sure if they are the same size. I just measured one of my small drawers and it is 14 cm x 5.5 cm x 5 cm. Since I have many different tiny components, I quickly ran out of space when I tried to give each component its own drawer.

    But I think that I might be able to do a better job with these if I take everything out and start organizing again. I set the rules for how to place things before I started buying SMD components, and many of the through-hole components I can combine without problem. An improvement would be if I can find something like this but with many more and much smaller boxes.