World IPv6 Day is tomorrow, June 8 — which also happens to be my birthday. I took it as a personal challenge to see if I could get IPv6 working at home, and to report back on how difficult it was. The answer: Extraordinarily difficult and beyond the reach of the average consumer.

Neglecting the fact that no major ISP (aside from Comcast, perhaps) provides native IPv6 service to the home, one is forced to use a tunnel broker, like SiXXS or Hurricane Electric. These organizations will let you establish an IPv6 tunnel between two IPv4 endpoints (i.e. their server and your router), and they will also assign and route you an IPv6 /64 subnet. The rest — getting all the moving parts up and running — is up to you. Continue reading →

I used to read a magazine called 2600, which was billed as a “Hacker’s Quarterly”. The title refers to the audio frequency, in hertz, used as a control tone in early analog telephone systems. Enterprising hackers discovered that a free promotional whistle in boxes of Cap’n Crunch cereal could be used to generate this tone. A whole class of phone hacking — or “phreaking” — was born. (Trivia: Apple co-founders Steve Jobs and Steve Wozniak were phreakers; Woz’s "blue box" or DTMF frequency generator, is preserved at the Computer History Museum in Mountain View, CA.)

This is an example of a system using “in-band signalling”. Both the control and data signals (audio) on early phone systems were transmitted on the same channel, thereby making the system open to compromise. Today’s modern phone networks have a completely isolated signalling system known as SS7.

Twitter is also a system with in-band signalling. I’ve always been bothered by the fact that Twitter commands — DM, FOLLOW, LEAVE, etc. — are transmitted by the user as part of the data signal (your tweet). This leads to all kinds of mistakes. For example, users have publicly tweeted when they think they have DM‘d, because they forgot to prefix their DM with “DM “. Other users accidentally expose their intent to FOLLOW or LEAVE users, due to misspelling commands (e.g. “FOLOW”).

The “@” reply prefix is also problematic. Tweets beginning with “@[username]” are only seen by the receiver’s followers, and not the sender’s. If the sender wants a wider distribution, hacks like “.@[username]” are used.

In-band signalling on Twitter clearly originated from the fact that it was intended to be used via SMS. Traditional mobile devices have no way to send signalling data out-of-band. What you see in 140 characters is what you get. As Twitter migrates to the desktop (or at least to rich mobile devices like the iPhone), we begin to see Twitter addressing this long-standing flaw. For example, the retweet identifier (RT) is no longer considered as part of the actual tweet, as long as one is using the Twitter API. Other metadata like geolocation and user agent are already transmitted as signalling data through the API.

Eventually, I believe that even the remaining in-band commands will transition out of the data stream. It’s only a matter of time before a celebrity’s mistweet makes the news and forces Twitter to clearly separate control from data. (Could you imagine something like President Obama accidentally tweeting “DM tonyhayward You are a first-class douchebag”?) Fortunately, they already have an API on which to build the control system. Shall we call it Twittering System Seven?

Recently, I decided to experiment with Amazon Web Services‘ Simple Storage Service (S3) for online backups. This was predicated by my DLT7000 tape drive dying; when I discovered the repair cost is nearly $400, I decided to do a cost-benefit analysis using the S3 platform as a proof-of-concept before sending it off to the shop. Today’s post will review the results of that analysis. Continue reading →

I’ve long been an advocate of origin HTTP caching and acceleration for large websites, something I alluded to in the post Performance Tuning and Optimization of High-Traffic Websites, which I wrote almost eleven months ago. In the early, heady days of the World Wide Web, many vendors like CacheFlow (later BlueCoat) and Nortel made HTTP caching appliances, but there are almost no such vendors in the marketplace now. I still believe there is a sound technical reason for an origin website architecture with HTTP accelerators deployed in front of it, and I’m happy to see that one recent entrant into this space, the Varnish HTTP Accelerator, is nearing a stable 2.0 release. In this post, I’ll elaborate on why I think HTTP caching solutions went the way of the dodo, why I think they should come back, and use the feature set and stated goals of the Varnish project as evidence. Continue reading →

A while ago I wrote a post about how the Windows Media video experience is sub-optimal on non-Windows computers — in particular, Macintoshes — and why I think this will trigger a run towards Flash on-demand and eventually Flash live. Here’s a concrete example: over the last six months to a year, and perhaps longer, we’ve been dealing with a steady stream of user complaints that the nightly newscast of CBC’s The National (insert promotional tagline about “Canada’s most trusted news source, hosted by newly-announced Order of Canada member Peter Mansbridge”) is frequently “out of date”. While I haven’t totally nailed down why this might be the case, I do note that most complainants seem to be using Quicktime to play back the stream, with Flip4Mac (ugh) as the translation layer. I believe that with so many moving parts, something is inevitably going to go wrong. Continue reading →