ntp NTP server frequency stability Stratum 2+ NTP servers have multiple potential sources of error, let's experiment with lowering them.
battery Battery backup for fridge, part 2 Continuing from part 1, I run my fridge on battery. Setup To start, I connected the inverter to the battery, first using the 1ohm resister to allow the capacitors to pre-charge then connecting
battery Battery backup for fridge With the instability with the power grid in the past few years, I wanted to have a plan for how to handle power being out for 24+ hours at a time. For this
ssh U2F/Fido2 based SSH keys on Windows When trying to figure out why ssh-agent forwarding wasn't working from Windows to an Ubuntu 22 server [https://stackoverflow.com/questions/71399334/ssh-fails-to-use-private-key-from-ssh-agent-communication-with-agent-failed] , I saw that build V8.9.0.0p1-Beta of Microsoft's
TCXO TCXO RTC Raspberry Pi Hat, part 2 The motivation for this project is NTP servers in datacenters - it can be expensive to get a GPS antenna on top of other people's buildings with a wire running down into your
ntp TCXO RTC Raspberry Pi Hat History I'm bringing my RTC Hats [https://blog.dan.drown.org/tag/stratum2/] back online (source code [https://github.com/ddrown/stm32-input-capture-f031] and hardware design [https://github.com/ddrown/stm32-input-capture-f031/tree/master/hardware]
Adding IPv6 to teensy-ntp I ported my NTP server [https://blog.dan.drown.org/embedded-ntp-server/] from the stm32f407 to the Teensy 4.1 [https://forum.pjrc.com/threads/61581-Teensy-4-1-NTP-server]. Because I recently switched from a cable modem
Event Loop Software The simple description of an event loop is a program waits for an external event from many different sources, does some processing on that event, and then waits for the next event. It
AWS Cognito error message "Invalid base64 SAMLResponse" While debugging why AWS Cognito was giving the error "Invalid base64 SAMLResponse", I didn't see many good answers on the internet. TL;DR - double check your SAML attributes Configuration * My SAML Identity
crypto Cryptanalysis of the Oceantoo cipher I saw this video of creating an encryption algorithm on the channel Gary Explains: Gary's video goes through creating a new symmetric crypto algorithm. He says multiple times that this is just an
2.5 Gigabit ethernet I've been wanting to upgrade my home network for a few years now. My home server/NAS can easily fill 1 gigabit, but I also didn't want to spend a lot of money
database Database substring indexes Goals Imagine you have an application that keeps track of domain names. And this application has millions of entries in a MySQL database. How do you efficiently find all domain names that have
kerberos Kerberos for Windows, without AD Continuing from the previous post [https://blog.dan.drown.org/kerberos-configuration/], let's see what Windows can do with a MIT Kerberos based realm. Windows normally uses Kerberos as part of Active Directory, but
kerberos SSH single-sign on I was looking for a way to deal with ssh/sudo authentication between multiple clients and multiple devices. I wanted something with a balance between convenience and security.
wsl Mounting a dedicated disk in WSL2 In WSL2, the default disks are virtual. Microsoft has recently added support for mapping physical disks to your WSL2 VM. I was running low on space my C: drive, so I wanted to move some of my WSL2 data to a dedicated Linux drive.
bluetooth Bluetooth Low Energy sensor, part 2 To continue from part 1 [https://blog.dan.drown.org/bluetooth-low-energy-sensor/]: I want a wireless sensor that will last more than a month on 2x rechargeable AA or AAA batteries. Some ideas I
arduino Bluetooth Low Energy sensor I have some ideas for a low power wireless sensor. I want something that will last more than a month on 2x rechargeable AA or AAA batteries. I first tried an esp8266 and
wsl Replacing the WSL Kernel Backstory I had a dual boot Windows/Fedora machine, and I wanted to be able to run the Fedora install as a VM inside WSL. To do this, I needed the physical disk
teensy Teensy 4.1 ethernet I'm a fan of the Teensy [https://www.pjrc.com/teensy/] line of microcontrollers. I have a whole pile of them for various projects. When I saw that 4.1 was combining a
ntp Embedded NTP Server Now that I got the results I wanted from my embedded NTP client [https://blog.dan.drown.org/embedded-ntp-client-ntp-interleaved-mode-part-5/], I wanted to convert it to an NTP server. I also wanted it to
ntp Embedded NTP client/NTP interleaved mode, part 5 I'll test what happens when I plug my embedded NTP client directly into my NTP servers, bypassing the Ethernet switch. This ends my long running embedded NTP client series. The systems involved Embedded
stm32 Embedded NTP client/NTP interleaved mode, part 4 Part 3 [https://blog.dan.drown.org/embedded-ntp-client-ntp-interleaved-mode-part-3/] ended with an unexplained 3us offset, this post will reduce that. Verifying PTP clock sync I wanted to measure the NTP client's PTP clock sync
ntp STM32MP1 NTP server, part 3 Previous posts: part 1 [https://blog.dan.drown.org/stm32mp1-ntp-server/], part 2 [https://blog.dan.drown.org/stm32mp1-ntp-server-part-2/], NTP client [https://blog.dan.drown.org/embedded-ntp-client-ntp-interleaved-mode-part-3/] The NTP client confirmed that there was
ntp Embedded NTP client/NTP interleaved mode, part 3 Previous posts: part 1 [https://blog.dan.drown.org/archmax-ntp-client/], part 2 [https://blog.dan.drown.org/embedded-ntp-client-ntp-interleaved-mode-part-2/] In this post, I wrap up my embedded NTP client and use it to measure