Dan Drown

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] is on github). I originally designed it for frequency synchronization without phase alignment [https://blog.

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 to fiber, I wanted to use my home stratum 1 NTP servers with my public servers in

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 is a common architecture in many different types of software. This blog post will go into the

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 Provider (IdP) is AWS SSO, and I'm using IdP initiated SAML

NFS Readonly Root Filesystem

Setting up a Fedora Readonly Root filesystem via NFS

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 experiment and not to be used with anything important. This is because crypto is challenging,

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 on the upgrade. $ sudo hdparm -t /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/

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 part of a word inside of them? This article assumes some understanding of how SQL queries work.

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 it does have some basic support for a non-AD version of Kerberos. I'll

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.