Dan's notes
  • Home
  • NTP
  • router
  • android

Dan Drown

100 posts •
ntp

NTP server frequency stability

Stratum 2+ NTP servers have multiple potential sources of error, let's experiment with lowering them.

  • Dan Drown
6 min read
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

  • Dan Drown
2 min read
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

  • Dan Drown
5 min read
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

  • Dan Drown
3 min read
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

  • Dan Drown
4 min read
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]

  • Dan Drown
3 min read

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

  • Dan Drown
4 min read

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

  • Dan Drown
3 min read

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

  • Dan Drown
2 min read
kerberos

NFS Readonly Root Filesystem

Setting up a Fedora Readonly Root filesystem via NFS

  • Dan Drown
10 min read
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

  • Dan Drown
4 min read

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

  • Dan Drown
3 min read
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

  • Dan Drown
4 min read
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

  • Dan Drown
5 min read
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.

  • Dan Drown
8 min read
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.

  • Dan Drown
2 min read
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

  • Dan Drown
1 min read
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

  • Dan Drown
4 min read
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

  • Dan Drown
1 min read
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

  • Dan Drown
3 min read
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

  • Dan Drown
3 min read
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

  • Dan Drown
3 min read
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

  • Dan Drown
4 min read
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

  • Dan Drown
3 min read
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

  • Dan Drown
5 min read
Dan's notes © 2023
Latest Posts Ghost