Andrew Ferrier

Tip for anyone who blogs and uses Google Reader:  the new ‘Discover’ feature of Google Reader enables you to see how many people are subscribed to your blog. Select ‘Browse’ and search for your blog using keywords. When you’ve found it, it’ll show how many subscribers there are. Take the number with a pinch of salt: it is, of course, only one of many blog readers, albeit a popular one.

Thinkpad problems mean that I’m currently borrowing a T42 from work. It took me a while to get WPA working with Knoppix 5.1.1. Here are the magic incantations required:

wpa_passphrase YOURSSID YourWPAPassPhrase > /etc/wpa_supplicant/wpa_supplicant.conf
wpa_supplicant -ieth1 -c /etc/wpa_supplicant/wpa_supplicant.conf &
ifup eth1
pump -i eth1

Replace eth1 in the list above with whatever network interface name Knoppix has assigned to your wireless card (reading through the output of dmesg should help you with this). Don’t forget to double-check that your router has the MAC address of the card (use ifconfig to find this) if you’re using MAC address filtering.

Just spent a little while consolidating all my photos: moving the remainder from my Gallery installation on andrewferrier.com to their new and preferred home on Flickr. My Flickr account is now vastly more populated with photos (and more variable in quality). This script basically did all the work. It doesn’t support nested albums, so I had to move all sub-albums to the top level, as well as removing the few ‘symlinks’ I had on photos (later versions of Gallery support this). But apart from that, it was plain (if a little slow) sailing. A recommended approach.

As part of my cunning plan to move my data online, I decided to move away from using my Palm for managing my diary – and towards Google Calendar instead. I’ve already stopped using the Palm to-do list; all I really need to do now is find a decent online addressbook; Plaxo being one possibility that Chris suggested.

It took me a while to figure out how to get my data out of the Palm. Palm don’t provide a decent export to anything other than Palm formats for the datebook, so a third-party exporter was called for. The web is seemingly full of dodgy Windows shareware to do the job, but jpilot (which I already, but rarely, use on my Linux machine) turned up trumps. It exports directly to the modern iCalendar standard, fully supported by Google Calendar. Hurrah! Since this solution doesn’t seem to be well-documented, I thought I’d write it down.

I recently installed the Subscribe to Comments plugin on this blog. However, it seems to have attracted far too much spam. I’ve therefore disabled it again until a version is developed that’s a bit more hardy against spammers. You can always subscribe to an RSS feed for the comments on any post (as you can with any WordPress-powered blog) by appending /feed to the permalink URL for that post.

Fun chemistry fact of the day: Acidity regulators regulate pH in general, not just acidity. Hence (presumably) why this smoothie bottle contains Citric Acid as an acidity regulator (my first thought was: shouldn’t it be an alkali?).

This is when I wish I’d done Chemistry A-Level rather than Further Maths.

This blog has now moved to my new domain andrewferrier.com. You shouldn’t notice any change if you are using a web browser or a well-designed feedreader to read it, as all parts of the old blog (including permalinks, RSS feed, etc.) should permanently redirect to the new one. You might just want to check that your RSS reader is pointing to the new blog though, or alter your browser bookmarks. The redirection will disappear in a few months. I’d appreciate it if you can let me know if you see any problems with the new blog.

Update 2007-01-13: I should add that some feedreaders will treat all the items in the feed as new, because the GUID will have changed. Just mark them all as read. Apologies for the inconvenience.

For users of Exim only:

It’s normally recommended to include the line if error_message then finish endif in your .forward filter file, to make sure error messages don’t cause recursive problems in your mail system. I have found that this doesn’t work in practice if you normally receive a lot of spam, because spammers are increasingly using your email address to spam other people. This causes bounces back to you, which bypass your spam filter because of that line (at least in my setup, using sa-exim). Removing that line greatly reduced the amount of spam reaching my inbox.

It’s strange how the same techniques can be used to attack both sides of a problem. For some time now, some of the more sophisticated web spammers have been using OCR techniques to circumvent CAPTCHAs on websites in order to hijack free email accounts, submit comment spam on blogs, and similar forms of mischievousness.

As the more capable e-mail spammers seem to be figuring out that anti-spam technologies are getting pretty good at filtering out the crap they send, normally using rule-based detection, Bayesian learning, or a combination of the two, a lot of spam now being sent out is image-based – and anti-spammers are now using OCR to fight back against this new tide.

As I’ve mentioned before, I have a huge spam problem on my personal e-mail account (~4,000/week) – due to a combination of bad luck and some foolish naivety at a few points – and so I have a fairly highly-tuned SpamAssassin installation running at home, with plenty of custom rules and plugins. I’ve seen a rising amount of image spam on it, so I decided to give FuzzyOcr, a plugin for SpamAssassin, a try. So far, the results are pretty impressive. FuzzyOcr uses the open-source gocr program as the engine, and ties it to with SpamAssassin and some logic. The OCR is fairly CPU-intensive, so unlike most SpamAssassin plugins, it only kicks in if the message is otherwise going to be below a certain scoring threshold. So far it has roughly halved the volume of spam that slips through into my inbox (previously ~40-50/day), which is a welcome improvement.

However, fun though they are as a technical challenge, technical approaches such as these always feel like fighting a losing battle. I might write a lengthier article on this at a later date, but I’d like to see ISPs take a far more hardline attitude with their peers that host spammers. There are also compelling economic solutions to the problem, mostly related to micro-payments for sending email. There are problems with those too (how do you roll them out gradually?), but you rarely see graphs of spam that have a downward trend – a solution to the spam problem would be most welcome.

A pint is yours if you can solve this conundrum for me (a theoretical explanation you can convince me of will do; I have a practical workaround).

A few weeks ago I replaced some of the bulbs in my house with energy-saving ones. However, the ceiling light in my hall behaves in a very odd manner. Occasionally, after I switch it off at the wall, it flickers on very briefly (for about 1/10 second) about once every minute – even though the power is (allegedly) off. The flicker is fairly dim, so I only notice it at night. If I take the bulb out of the socket, the flicker stops. If I put it back, it starts again. This behaviour happily continues for hours – to the extent that I remove the bulb when it happens because it’s too distracting when trying to sleep.

Perhaps it’s some kind of residual charge in the bulb. But this doesn’t really seem to explain why it only flickers when the bulb is in the socket (even though the switch is off). It also doesn’t explain why it doesn’t happen in the rest of the house (they have the same brand of bulb). The only difference is that the hall has two switches – but they aren’t dimmer switches or anything special.

Any thoughts?