The earliest memory I have of ‘programming’ is in the early/mid 90s when my father brought home a computer from work. We could play games on it … so of course I took the spreadsheet program he used (LOTUS 123, did I date myself with that?) and tried to modify it to print out a helpful message for him. It … halfway worked? At least I could undo it so he could get back to work…

After that, I picked up programming for real in QBASIC (I still have a few of those programs lying around), got my own (junky) Linux desktop from my cousin, tried to learn VBasic (without a Windows machine), and eventually made it to high school… In college, I studied computer science and mathematics, mostly programming in Java/.NET, although with a bit of everything in the mix. A few of my oldest programming posts on this blog are from that time.

After that, on to grad school! Originally, I was going to study computational linguistics, but that fell through. Then programming languages (the school’s specialty). And finally I ended up studying censorship and computer security… before taking a hard turn into the private sector to follow my PhD advisor.

Since then, I’ve worked in the computer security space at a couple of different companies. Some don’t exist any more, some you’ve probably heard of. I still program for fun too, and not just in security.

But really, I still have a habit of doing a little bit of everything. Whatever seems interesting at the time!

Takuzu solver

2015-10-29

Based on a /r/dailyprogrammer puzzle: Takuzu solver.

Basically, Takuzu is a logic puzzle similar to Sudoku. You are given a grid partially filled with 0s and 1s. You have to fill in the rest of the grid according to three simple rules:

You cannot have more than three of the same number in a line
Each column must have an equal number of 0s and 1s¹
No two rows or no two columns can be identical

Thus, if you have a puzzle like this:

0.01.1
0....1
..00..
..00..
1....0
10.0.0

One valid solution (most puzzles should have only a single valid answer, but that doesn’t always seem to be the case):

Let’s do it!

Mandelbrot

2015-09-14

Perhaps the best known fractal of all: the Mandelbrot set.

Since I was already working on Python code that would render an image given a function (for a future post), I figured that I might as well render fractals with it.

Backing up GitHub repositories

2015-09-08

The newest chapter in my quest to collect entirely too much data / back up All The Things!: GitHub.

Basically, I want to back up all of my own personal GitHub repositories along with any from organizations that I am involved with. Strictly speaking, this is a little strange, since it’s unlikely that GitHub is going anywhere soon and, if it does, we are likely to have fair warning. But still, it’s nice to have a local copy just in case GitHub is down.

Adjacency Matrix Generator

2015-08-24

Been a while since I’ve actually tackled one of the Daily Programmer challenges, so let’s try one out. From a week and a half ago, we are challeneged to make an adjacency matrix generator, turning a graphical representation of a graph into an adjacency matrix.

Input:

a-----b
|\   / \
| \ /   \
|  /     e
| / \   /
|/   \ /
c-----d

Output:

Setting up Postfix and OpenDKIM

2015-08-10

Last week, I was presented with a fairly interesting challenge: add DKIM (via OpenDKIM) support to our mail servers (running Postfix). Given that I’ve never actually worked on a mail server before, it sounded fun. 😄

Finding AWS IAM users by access key

2015-07-22

Every once in a while¹, I find myself with an AWS access key and need to figure out who in the world it belongs to. Unfortunately, so far as I’ve been able to find, there’s no way to directly do this in either the AWS console or with the AWS api.

Configuring Websockets behind an AWS ELB

2015-07-20

Recently at work, we were trying to get an application that uses websockets working on an AWS instance behind an ELB (load balancer) and nginx on the instance.

If you’re either not using a secure connection or handling the cryptography on the instance (either in nginx or Flask), it works right out of the box. But if you want the ELB to handle TLS termination it doesn’t work nearly as well… Luckily, after a bit of fiddling, I got it working.

Update 2018-05-31: A much easier solution, [https://aws.amazon.com/blogs/aws/new-aws-application-load-balancer/](just use an ALB):

WebSocket allows you to set up long-standing TCP connections between your client and your server. This is a more efficient alternative to the old-school method which involved HTTP connections that were held open with a “heartbeat” for very long periods of time. WebSocket is great for mobile devices and can be used to deliver stock quotes, sports scores, and other dynamic data while minimizing power consumption. ALB provides native support for WebSocket via the ws:// and wss:// protocols.

Automagically storing Python objects in Redis

2015-07-16

When you’re starting out on a simple web application, eventually¹ you will reach the point where you need to store some form of persistant data. Basically, you have three options²:

Store the information in flat files on the file system
Store the information in a database (MySQL, SQLite etc)
Store the information in a key/value store (mongoDB, reddis)

There are all manner of pros and cons to each, in particular how easy they are to get started in, how well they fit the data you are using, and how well they will scale horizontally (adding more machines rather than bigger ones).

Backing up Moves Data

2015-07-10

Another backup post, this time I’m going to back up my data from the Moves App (step counter + GPS tracker). Theoretically, it should be possible to get this same data from the app as part of my iOS Backup series, but the data there is in a strange binary format. Much easier to use their API.

Scraping Kindle Highlights

2015-07-02

Edit March 2020: It seems the page ‘your highlights’ page on Amazon no longer exists, so this script no longer works. I’ll probably see if I can pull them from Goodreads instead now that the integration is there or directly from my Kindle, but for the moment, this script does not work.

As part of an ongoing effort to backup all the things, combined with a rather agressive 2015 Reading List, I wanted to the ability to back up any sections that I’ve highlighted on my Kindle. Unfortunately, Amazon doesn’t seem to have an API to do that, but why should that stop me?

Using a combination of Python and the Python libraries Requests and BeautifulSoup¹, it’s entirely possible to write a Python script that will log into Amazon, get a list of all of the books on your account, and download the highlights for each.

Let’s do it!