Kacang Bawang

E3372 stick + OpenWrt + USSD

This post is about setting up a LTE/4G/3G (cellular) modem to work with OpenWrt. But not just work, to also be able to use USSD codes and read SMS in order to check account balance and refill the data quota (data plan).

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Wavelength Calibration on a Spectronic 20

I have recently acquired a used Spectronic 20+. Great instrument in great condition! There was only one problem. It was dropped on its way to me. Read on for a story of restoration and the wavelength alignment procedure.

spectronic 20 plus

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Autossh for Synology Diskstation

This article is about compiling autossh for Synology Diskstation devices. The resulting pre-built binary for aarch64 will also be provided for download at the end of the post.

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Expanding your OpenWRT router

network diagram

network diagram

This post is about how to add a second router to your existing OpenWRT setup.

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RaspberryPi Kiosk Mode Explained

Just some notes on getting the raspberrypi kiosk mode going at the time of this writing (Jun 2017).

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My First 5 Minutes on a RaspberryPi

Greetings and salutations. It has been a really long time since my last post. IRL job has been sucking the life out of me. Someday I will tell you all about it…

Anyhow, I’ve been carving out some time for playing with a raspberrypi display and wanted to save some notes for posterity. This more a note to self than anything, but if someone ends up here via googling, I hope it will be of help.

Without further ado, here are the first things I do after booting up a new RaspberryPi installation.

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My First 5 Minutes on an OpenWRT Router

This article talks about the changes that I like to make away from default configuration on a new OpenWRT installation.

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Best New Router for OpenWRT ;)

A small note of triumph 🙂

For some time now I’ve been looking for a modern router. Yes, that WRT54G isn’t getting any younger 🙁 But few people are willing to “school” one on what’s the one to get these days (these days = May 2016). So after a long string of “google it” responses, I finally buckled down and did my own research. You wanna know the conclusion? 😉

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DSL provider blocks 3rd-party modems via MAC filter

About one week ago my internet provider started blocking 3rd-party/user-provided/own DSL modems. The symptom is that the router does not get an IP from the DSL modem, yet all the proper lights on the modem are on. I even called the main office and asked if the were blocking. They said no. But if you run OpenWRT, you can examine the PPPoE negotiation logs and will see that solicitations from the DSL modem are never answered.

One the other hand, if you plug in the provider’s router/DSL combo the connection is quickly established. Here it would be nice to get a wireshark dump of the negotiation, but let’s just check something first. What if we change the MAC address of our WAN interface to match that of the provider’s router? This can be easily done via

Let’s try connecting again. Sure enough, we’re in.

EEPROM for ESP8266

This article describes a small EEPROM emulation library that I wrote for ESP8266. It implements a very simple EEPROM emulation scheme that allows storing 16bit values. Each such 16bit value is found by its 16bit index.

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