johnk's blog

A Long Explanation of Character Encodings and UTF-8 and the IMC Software

This was posted as a correction to a note I made about some character encoding errors that appeared on the LA Indymedia website. It's poorly written. If you need me to edit and clarify, send an email to

It's ISO 8859, not 8890.

Note on Migrating from Qmail to Postfix

I got this done (i think):
- scanning old email addresses, forwards, and lists, and reconstructing the email and forwards and aliases for lists on a postfix instance

Migrating with Data...

It's one thing to upgrade software. It's an entirely different thing to migrate to new software. If you have a whole system of software, integrated in to a mega-app, it's even more difficult.

Script to Compile Videos from JPGs Uploaded from Low-End IP Camera DLINK DCS-932L

This script uses ImageMagick and AVConc (ffmpeg) to convert images uploaded by a low-end DLINK internet camera to an FTP server.

D-Link Switch Power Adapter Barrel Size

I had a couple of these, and lost the power adapters. (OK, someone else lost them, but whatever.) As always, the voltage and current matter, and these guys use 5V 1.2A or 2A.

Discover the IP Address of a Cisco Aironet 1200 Series on Linux without IPSU

I got an Aironet 1200 and didn't have the serial cable, so I tried to use IPSU to find the IP address. I ran it in a VM, bridged the ethernet interface, and it failed.

Lament about IT and Communication of Knowledge

Like a lot of people who work with computers, I have some communication problems. Sometimes, I'm too blunt; other times, too reticent.

Postfix Install Stuff

(argh, forgot to back up my postfix work. i have to start fresh, so this is an opportunity to document work.)

# first get a superuser shell with sudo
sudo -s

apt-get install mailutils

Install Java JDK into /usr/local/bin

There's a zillion ways to do it, and editing $PATH is probably the best, but I didn't want to do that, so I did this:

Learning Javascript via the Read Eval Print Loop (REPL)

All the tutorials out there teach JS by having the user write a file, and load it into the browser.

Javascript APIs and Libraries Change the Game

I was thinking a bit about the JS co-learning thing, and discovered that services, APIs and libraries really change the game, or have changed the game.

Horizontal Javascript Class

Sketching out a possible class for learning Javascript / learning to learn Javascript / learning to teach Javascript.


Bypass a Password with a Proxy

This is a one-line trick to serve images from a password-protected webcam to the world.

curl -i http://admin:@ | nc -lCt localhost 10203

NAS Backup Awesomeness

We have this old Terastation NAS, and it's been solid, but I just figured out that it has support for an external USB disk, and it's easy to set up to backup to the external USB disk. Right now, we're using around 1TB of the array, and it's being backed up to the external disk once a day. The backup is done with Rsync, and it takes around 10 minutes.

Cloud Computing Costs

I was checking out cloud services a year ago, and pricing them out. The general rule of thumb seemed to be that the up-front costs were lower, but the cost over time was higher.

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