database Database substring indexes GoalsImagine 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 part
kerberos Kerberos for Windows, without AD Continuing from the previous post, let's see what Windows can do with a MIT Kerberos based realm. Windows normally uses Kerberos as part of Active Directory, but it does have some basic support
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: I want a wireless sensor that will last more than a month on 2x rechargeable AA or AAA batteries. Some ideas I have for what I could do
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 BackstoryI 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 accessible
teensy Teensy 4.1 ethernet I'm a fan of the Teensy line of microcontrollers. I have a whole pile of them for various projects. When I saw that 4.1 was combining a 600MHz processor, 1MB ram, 8MB
ntp Embedded NTP Server Now that I got the results I wanted from my embedded NTP client, I wanted to convert it to an NTP server. I also wanted it to support interleaved NTP mode, so it
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 involvedEmbedded NTP
stm32 Embedded NTP client/NTP interleaved mode, part 4 Part 3 ended with an unexplained 3us offset, this post will reduce that. Verifying PTP clock syncI wanted to measure the NTP client's PTP clock sync externally. The PTP peripheral has the option
ntp STM32MP1 NTP server, part 3 Previous posts: part 1, part 2, NTP client The NTP client confirmed that there was a 943ns difference between my two NTP servers. Now, to investigate where it is coming from. ChangesI'll start
ntp Embedded NTP client/NTP interleaved mode, part 3 Previous posts: part 1, part 2 In this post, I wrap up my embedded NTP client and use it to measure the difference between my other two NTP servers with hardware timestamps. Goal
stm32mp1 STM32MP1 NTP server, part 2 Previous post: https://blog.dan.drown.org/stm32mp1-ntp-server/ I figured out my offset problem, which was not a PLL problem like I thought. Connman has a NTP client enabled by default:(The distro
ntp STM32MP1 NTP server Previous post: Debian for STM32MP1 NIC Hardware TimestampsFirst step: enable hardware timestamps in chrony.conf: chrony configuration for hardware timestampsNext, enable chrony's measurements log, and verify it's using hardware timestamps (H) not kernel
arduino Wifi NTP server I saw a thread about someone who wanted a low power NTP stratum 1 server that could run off of batteries and could be put somewhere without an internet connection. That had me
glibc glibc/Linux DNS Round Robin A friend was trying to figure out what glibc is doing with DNS round robin, and information about it is somewhat scarce. He was expecting it to randomly chose an address out of
stm32 Debian for STM32MP1 I bought a STM32MP1 dev board because it has a gigabit NIC with 1588 PTP timestamps as well as hardware timers that can timestamp PPS events without interrupt latency and jitter. I am
arduino 2 button keyboard I wanted a simple keyboard with play and pause media keys to make it convenient to control my music. To handle the USB, I used a STM32F103 based "blue pill" board because they're
ntp NTS part 2 Part 1: Packet format of Network Time Security I wanted to measure the overhead that NTS adds to NTP. To give a rough estimate, I modified the benchmark program included in libaes_siv
ntp NTP security (NTS) I've been hearing about Network Time Security (NTS) being in development for awhile now. With Cloudflare's release of a public NTS service, I wanted to take a closer look at the protocol and
ntp Embedded NTP client/NTP interleaved mode, part 2 Hardware transmit timestamps added to NTP client.
ntp APU2 NTP server I bought an apu2c0. I believe it will make a better NTP server than my other NTP servers.
ntp RK3328 based NTP server I got a ROC-RK3328-CC SBC because it has true gigabit ethernet, emmc, and USB3. These are all better I/O options than the latest Raspberry Pi 3 B+. I put a SATA hard
