Say goodbye to your free time

I’m currently studying for my amateur radio Foundation license, and as part of this I’ve been playing about with electronics a bit – something which I never really learnt properly when I was younger.

There’s plenty of free electronics simulators (such as gEDA), and some not-so-free (Multisim), but the learning curve for them is perhaps a bit too steep for the absolute beginner.

A few weeks ago I stumbled across the personal site of Paul Falstad, and his amazing array of maths and physics Java applets. Covering acoustics, signals processing, electrodynamics and even quantum mechanics, there’s bound to be something there to keep your entertained for far longer than is probably appropriate.

The Analogue Circuit Simulator (warning: Java applet will start straight away) is the one that’s sucked up most of my time – it’s full of features and examples, and is easy to use. It allows you to see the voltages and currents at all parts of the circuit, and even has scopes so you can watch values change over time.

As well as that, I’ve also found the 2D Electrodynamics applet useful for visualising how electromagnetic waves propagate.

Give them a try, although I’m not responsible for the amount of time you’ll inevitably lose doing so…

Just a short one – and the first post in a while – but I’ve come across, which contains a guide to the syllabus for the exam for the Foundation license – as well as mock tests for the exam itself – which I’m hoping to do in the coming weeks. The site’s not quite finished – there’s some stuff missing for the Intermediate level, but it’s a really useful site.

A whole lot of nothing

Another repost, this time from last year when Peter Davies was elected Mayor of Doncaster. I’ve noticed this is being linked to a lot, so here it is

(Update (12.06.2009): I’ve had an email from Toby Foster’s brother, who’s pointed out that where I originally transcripted Toby as saying “About right”, he actually says “Well that’s bright”. I’ve updated the transcript to that effect)

Today is Doncaster’s brand-spanking-new Mayor‘s first day on the job, and his first engagement of the day was an interview with BBC Radio Sheffield‘s Toby Foster. I hope Mayor Davies didn’t think he was in for an easy ride for his first official interview, because that’s not what he got.

Over the course of seven and a half minutes, Toby Foster took Mr Davies’ election manifesto and pulled it apart, pointing out that he doesn’t know what ‘PC jobs’ there are in the council (Mr Davies’ reply being “the things that are usually advertised in the […] Guardian”), that he can’t cut translation services for non-English speakers (Toby Foster: “It’s more than likely illegal, isn’t it?”. Peter Davies: “I dunno”), and that he hasn’t even though of the possible benefits of funding minority events such as the Gay Pride march (when asked how much money went to funding it, he replies “Haven’t got a clue, I haven’t looked into… I haven’t got the details”). On top of this, he admits that his cuts will mean job losses – which I’m sure the electorate of Doncaster will be happy to hear.

Click here for BBC’s Listen Again (at about the 1hr 57min mark), or here for just the interview (which I hope the BBC won’t mind me putting here). For those who can’t listen to the interview, I’ve transcribed the whole thing below.

→ Continue reading ‘A whole lot of nothing’…

Up the proverbial creek, minus the paddle

Doncaster is my home town, and it’s also where I’ve lived for all of my (almost) 28 years since I popped (!) into being at Doncaster Royal Infirmary in the summer of 1982. For those unfamiliar with geography in the north of England, Doncaster’s a fairly large town (with a population just under 300,000) in South Yorkshire. It’s also the source of many a political furore at a local government level, and has been since the Donnygate scandal of the mid-to-late 1990s.

The fun never stops in Doncaster, and today is no different – the Audit Commission has published the results of their snap Corporate Governance Inspection, carried out over the first few months of this year. It’s a frank assessment of the state of Doncaster Metropolitan Borough Council, and it’s not pretty.

→ Continue reading ‘Up the proverbial creek, minus the paddle’…

PXE booting a Debian Squeeze install

Update: I’ve not tested myself, but the comment from Sombunall below points out that package names for the TFTP server and the DHCP server have changed since I wrote this post!

It’s often the case that there’s no easy way of installing a machine that doesn’t have any removable media. For instance, I have an old Compaq Deskpro EN that’s too old to support booting from USB, so using something like UNetbootin is out of the question. Luckily, there’s an an alternative, which is to PXE boot an installer over the network.

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Google Streetview in the UK… updated!

So the little birdies were correct – Google have just updated Streetview for the UK. They’ve spent the last year or so photographing the length and breadth of the country, and now it’s all there to see, including such wonders as this blurry-faced chap:-

Yeah, that’s me, on my way out to work. I’ll ignore any comments about my shirt…

iproute2: Life after ifconfig

The standard network tools ifconfig, netstat and route will be familiar to anyone with more than a passing interest in UNIX or any of its derivations. Linux is no exception, and if you hop on to your nearest Linux machine, you’ll find these installed. However, for the past few years ifconfig and its ilk (often collectively referred to as net-tools) have been deprecated in favour of the iproute2 suite.

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Fixing Likewise startup scripts on Debian Squeeze

Just a quick one, this…

If you install Likewise Open on Debian Squeeze, you may notice that it doesn’t start on boot-up. The reason is because the new dependency-based boot sequence doesn’t like the init scripts Likewise provides.

Luckily, it’s pretty easy to fix. First, make sure you have chkconfig installed (apt-get install chkconfig if not), change into your /etc/init.d directory and do this:-

for INIT in lsassd lwiod eventlogd dcerpcd netlogond lwregd srvsvcd; do \
   echo "Fixing '${INIT}'..."; \
   sed -i -e 's/^#LWI_STARTUP_TYPE_SUSE#/#/g' \
      -e 's/Default-Start: 3 5/Default-Start: 2 3 4 5/g' \
      -e 's/Default-Stop: 0 1 2 6/Default-Stop: 0 1 6/g' ${INIT}; \
for INIT in lsassd lwiod netlogond eventlogd dcerpcd; do \
   echo "Disabling ${INIT}..."; \
   chkconfig -d ${INIT}; \
for INIT in dcerpcd eventlogd netlogond lwiod lsassd; do \
   echo "Re-enabling ${INIT}..."; \
   chkconfig -a ${INIT}; \

This uncomments the SUSE parts of the init scripts, which chkconfig wants. It then calls chkconfig to first delete each entry, and then re-add it to make sure everything’s okay. Reboot, and you should have working domain authentication without having to manually start it up.

IPv6 for a Linux generation

IPv6 is nothing new – it was finally standardised back in 1998 in RFC 2460, and virtually all operating systems have supported it now for at least 5 years, so most people are in a position to give it a try.

If you’re one of the lucky ones, your ISP might provide native IPv6 connectivity (like AAISP), but for most of us, the main way to get connected to the rest of the IPv6 Internet is to use something we’ve already got – IPv4. And we’re going to tunnel over it.

→ Continue reading ‘IPv6 for a Linux generation’…

GnuPG – RSA key-pair mini-Howto with stronger digests

(Note: This was originally posted on my previous blog, but I’ve noticed that it’s being linked to, so I’ve reposted it here)

I’m not a mathematician (or a cryptographer) so I’m happy to take this post‘s word for it about a recent attack against SHA-1 (short PDF here). The post goes into detail about changing the preferred digests on a key, and is well worth a read.

The post also talks about using 2048-bit RSA keys, instead of the DSA/Elgamal default (which has a maximum size of 1024 bits). It goes into detail about how to migrate to an RSA key – if you’re going to migrate, I definitely recommend reading it.

However, I thought it would be nice to write a (very) quick guide on generating RSA private keys with GnuPG, as there are a few extra steps involved – but nothing complicated!
→ Continue reading ‘GnuPG – RSA key-pair mini-Howto with stronger digests’…

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