Sneaking through the Analog Hole

I perhaps-foolishly recently agreed to perform a media-archiving task. A series of books-on-tape (yes, on physical audio cassettes), almost unplayable at this point in the century, needed to be moved onto a playable media. For this particular client, that meant onto Audio CDs (OK so we're moving forward, but not _too_ far!). I myself didn't have a suitable playback device, but quickly located a bargain-priced solution, second-hand on eBay (of course) - an **AWA _E-F34U_** that appears to be exclusively distributed by the [Big W](https://www.bigw.com.au) retail chain here in Australia:

This device purports to be a one-USB-cable solution to digitising the contents of analogue cassettes. Unfortunately, the example I just purchased had extremely severe issues with its USB implementation. The audio coming straight off the USB cable would jump between perfectly fine for a few seconds, to glitchy, stuttering and repeating short sections, to half-speed slooooow with the attendant drop in pitch. Unusable. I only hope that the problem is isolated to my unit (which was _cheap_ and described as "sold untested" so I have no-one to blame but myself) - if not, someone's done a really bad job at their USB Audio implementation. Luckily, the USB Power works absolutely fine, so I had to resort to the old "Analog Hole" solution via my existing (rather nice) USB Audio Interface, a **Native Instruments _Komplete Audio 1_** which I picked up after my previous interface, a [**TASCAM _FireOne_**, finally kicked the bucket](https://blog.themillhousegroup.com/2020/07/tascam-fireone-on-macos-high-sierra.html).

In the following picture, you can see my digitising solution. AWA tape transport (powered by USB) to 3.5mm headphone socket, through a 1/4" adaptor to a short guitar lead and into the _Komplete Audio 1_'s Line In. From there, it goes in via the _KA1_'s (fully-working!) USB connection to GarageBand on the Mac. A noise gate and a little compression are applied, and once each side of each tape has been captured, it gets exported directly to an MP3 file. I intend to present the client with not only the Audio CDs but also a data CD containing these MP3s so that future media formats can hopefully be more easily accommodated.

What if I _didn't_ already have a USB audio interface? Would the client have given up, with their media stuck in the analog era, never to be heard again? It amused me that analog technology was both the **cause of** this work - in that this medium and the ability to play it has gone from ubiquitous in the 1980s to virtually extinct - **and its solution**, using an analog interface to get around a deficient digital one.

Green Millhouse - Hacking WiFi Power Points

I recently discovered Mr Money Mustache and his delightfully-entertaining take on frugality. Turns out I had independently come to some very similar conclusions (live close to work, ride a bike to work, minimise car ownership/usage, avoid borrowing) but he still offers a ton of new perspectives on saving money that I'm really enjoying.

An area in particular is running an efficient home. My first toe-dip in this area is shutting down (not putting-into-standby, shutting down) as many things as possible for as much of the day as possible. Being a geek, controlling some power-points via WiFi seemed like a great way to get started. Hence:

These $20 devices can be found on eBay and are controlled by an app that is only ever named in the user manual. This smells of "security by obscurity" and after further investigation I can see why...

My particular one (which was identical to the photo) was called a "Small-K" but you'll probably get the most Google-joy by searching for "Kankun" devices. There are a whole pile of different iOS and Android apps, with various brandings and/or success at translation into English.

There is an extremely troubling suggestion that the various Android apps do some "calling home" via some Chinese servers - this, combined with the fact that you have to tell your device your SSID and WiFi password, made me sufficiently uneasy that even though I have uninstalled the Android app (it was junk anyway), I'll be putting my smart plugs into a dedicated subnet that is unable to "get out of" my network. How?

Putting network devices in jail

I use DNSmasq on my NAS which gives me much more control over my DHCP than the usual on/off switch in consumer routers. The setup to make sure a particular device doesn't go wandering off out onto the interwebs just needs two lines of configuration in dnsmasq.conf, namely:

# Always give the host with ethernet address 11:22:33:44:55:66
# the name smartplug1,
# IP address 10.200.240.1,
# lease time 45 minutes, and
# assign it to the "jailed" group
dhcp-host=11:22:33:44:55:66,smartplug1,10.200.240.1,45m,net:jailed

Why 10.200.240.1? Well:

• 10 because I like to have space ;-)
• 200d is 11001000 which in my bitwise-masking permissions scheme means:
  • Firewalled FROM internet
  • Trusted WITHIN home network; and
  • Prevented from going TO internet (I've added that last bit flag since writing that old post)
• 240d because it's 240-Volt mains power (geddit?); and
• 1 because it's my first device of this type

Now for the part where inhabitants of the 200 subnet get jailed:

# Members of the "jailed" group don't get 
# told about the default gateway 
#("router" in DHCP-speak) 
#- this sends a zero-length value:
dhcp-option = net:jailed, option:router

And we can check this after rebooting the plug; in the DNSmasq logs:

dnsmasq-dhcp: DHCPDISCOVER(eth0) 11:22:33:44:55:66 
dnsmasq-dhcp: DHCPOFFER(eth0) 10.200.240.1 11:22:33:44:55:66 
dnsmasq-dhcp: DHCPREQUEST(eth0) 10.200.240.1 11:22:33:44:55:66 
dnsmasq-dhcp: DHCPACK(eth0) 10.200.240.1 11:22:33:44:55:66 smartplug1

.. and after logging in to root@smartplug1:

root@koven:~# ping www.google.com
PING www.google.com (220.244.136.54): 56 data bytes
ping: sendto: Network is unreachable

Avoiding The Chinese Entirely :-)

Now that I've been through the pain of the Android-app-setup dance (which sucked, and never correctly registered the presence of the WiFi power point in its own app), I can heartily recommend just SSH'ing into the plug and doing it manually. It was at this point that I came across the awesome OpenHAB project, which is an open-source universe of "bindings" for devices such as these, with the nice UI required for a high WAF. Much more OpenHAB-hacking to follow!