Cloud-Enabling a Bathroom Scale

Last week as I was making my rounds at the supermarket, I came across this digital bathroom scale on sale. With some membership card, the discount was almost 50% and at S$16, I thought that was a pretty good deal. It is “wireless” in that it has a separate display unit that could be detached from the scale itself. This bathroom scale had “HACK ME” written all over it.

It turns out that this bathroom scale is the EB9121 made by a Chinese (OEM?) company called Zhongshan Camry Electronic Co. Ltd (or simply Camry). The box specifically mentions that it uses infrared for transmission, and given that I had some experience looking at IR signals, I thought it would be rather straightforward.

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Creating Minimal Throw-away CentOS 6 VMs

Whether you are using CentOS for a build server or simply testing out a new configuration, you can quickly create a VM (virtual machine) that is under 1GB. You can do this without downloading any special tools or ISO files — just the CentOS installation DVD and VirtualBox (or VMware if you prefer).

I like the text-based console, so you won’t be getting a GUI or fancy Linux desktop with this one. Given its small size, you could also archive the entire environment (or even several of them) for future use without having to waste gigabytes of free space. These environments also serve as a base which can be upgraded or added onto to provide more functionality later.

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Encrypt All the Drives

I have always been an advocate on storage security (all types of security, actually). I like how iOS devices keep all files encrypted, even if you do not set a passcode on the device. They do this to facilitate quick erasure of files on the device — to erase all the data, they simply wipe the master key.

Erasing magnetic storage media isn’t difficult, but it is time-consuming. For solid state media such as SSDs and flash drives, the wear-leveling makes it difficult to ensure that all flash blocks have been securely overwritten. The answer to this is to encrypt everything.

Encrypt all the drives!! (meme)

Recently I have been busy building a Linux-based NAS and I decided to put this to practice.

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Implementing EAP-SIM at Home

What is EAP-SIM?

EAP-SIM is one of the authentication methods that can be used in an 802.1x or WPA Enterprise network. Specifically, it relies on the user’s SIM card to process a presented challenge. This has been used by some telcos to provide WiFi service without having to maintain a separate set of credentials. However, not all phones support EAP-SIM.

Phone displaying EAP-SIM as a WiFi authentication method

Since I’m already using a RADIUS setup at home, the use of EAP-SIM will eliminate the need to install my CA certs onto each device. But of course, there is still a fair bit of work to do…

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