Archive for the 'English' Category

Resistance is futile

Tuesday, July 10th, 2012

This afternoon over lunch, my company at the table was discussing blogging and thus I was remined of my lack thereof. Of course, it is the most prevalent cliche excuse abound, but yes: I’ve been busy. Let me quickly fill you in on the past months and then go into my current most addictive passion: OHM2013 (the sequel to HAR2009). Just to be sure, as this is my personal blog the below is all my own opinion & observations and doesn’t reflect the opinion of my cats, the companies I work for, the board of Stichting IFCAT Foundation or any deity whatsoever.

What have I been doing?

Last month I started a new job. No more freelancing for me, I was totally fed up with the acquisition part of it and needed some stability income-wise. I’m now developer crypto & high security with Fox-IT, a move I had not anticipated a few months ago. Although I should have seen it coming, since about half of my friends and acquaintances seem to have been recruited by them in recent months. Anyway, that meant I had to finish up some important work at the Digital Methods Initiative, where I was part-time employed before. In between, the usual stream of requests from journalists and documentary makers, being an extra in the upcoming Blender open movie (codenamed Mango) and more distractions.

So that had me tied up for a while, and at the same time things were gearing up for OHM2013. At first we kinda took it slow, but now we’re switching to full pre-event modus. And that means that apart from the $dayjob, any spare hour I can find is spent preparing for this next edition of the 4-yearly Dutch hackercamps. Meanwhile, I had some other projects that demanded plenty of time. There was Limesco. The radioshow. Electronics- and software-projects I was working on. But time has come: I’m suspending all activity on other projects to focus fully on OHM2013 now.


Rumour has it that various interested parties are observing a lack of info coming forth the current OHM2013 core group, and I must agree. That has been intentional though: there are a few brilliant camps coming up these months (of which I’ll visit haxogreen, eth0:2012 summer and EMFcamp, and so should you!) and I think they deserve the full beam of the spotlight. However, I can also understand that people are eager to know more about what’s going on. I will try to keep up with some informal blogs from time to time on what I am doing with regards to OHM2013, to hopefully fill that gap.

The first part of such an event is as always: location, location, location. Together with a great bunch of volunteers, we have been looking over many potential event locations. It’s been difficult, surprisingly, to find the perfect location but I believe we have settled on one that comes close. It is a bit too early to tell you all where it will be, what with the negotiations still going on at this point. However, keep an eye on the OHM2013 site, it is quite realistic that the official announcement will be on there within weeks.

Also not official, but pretty much decided is the date. If all goes well, we should end up with july 31st until August 4th 2013. Statistical data seems to suggest these days give the best probabilities for nice weather, so what could possibly go wrong? This also doesn’t overlap with too much other relevant events.

So currently, I am mostly busy finalizing the formal details regarding the terrain: a contract, permit and what have you. Meanwhile, the proto-NOC is already putting focus on finding out options for the uplink. Preparations for the program committee (nay, content committee) are also well under way and various people are joining the effort to bring a diverse and inspiring line-up of lectures and workshops. One thing I wanted to try this time, and has been met with approving nods so far, is an ‘off the record’ track. Lectures to be scheduled in a tent where there is no recording equipment, no P/A and a strong request to not record or report on the content of the lectures. This will hopefully accommodate those lectures that bring some interesting and hard-core content, but are reluctant to jump on the fully open and public space that these events have become over the decades. Curious to see how that is going to work out, and if there is even a demand for such a stage among potential speakers.


I have said it before, but I will repeat it once more: it is great to see all the enthusiasm among the community about OHM2013. Even better is that when thinking about the essential teams that it is not difficult to find the people with experience to head those teams. Slowly, the team-leads are reporting for duty. If all is well, Eelco (who is in charge of leading the teamleads :) will soon put more info on that on the wiki.

After HAR2009 we have witnessed a huge growth in hackerspaces being founded in The Netherlands and Belgium specifically. I have no doubt this can be led back to the great fun those founders had at HAR2009. This network of ‘hacker branch offices’ provides an awesome backbone to our community. And I have made it my personal mission to have OHM meetings in each and every Dutch hackerspace in the next months. So far we have had board meetings at Sk1llz, RandomData, Bitlair and  RevSpace. At TechInc we have had a location team meetup, and of course there was the kick-off party at Hack42.

Apart from all the volunteers in those teams, these events never happen without the sponsorship of a number of friends. Now that we have more concrete plans regarding the location, date and (as a corollary) the budget, efforts to secure enough support to make ends meet and keep ticket prices well-affordable are about to start up.

And now..

..i’m going back to work! Plenty of things to organize. Hope you enjoyed this blog post and that it squelched some of that thirst for information!

Flattr this

How lack of sleep turned my vision red (or: combating insomnia with science)

Saturday, October 22nd, 2011

If, like me, you tend to suffer from sleeplessness you will know it can be exhausting; being awake until the early morning, knowing the number of hours until the alarm buzzes is rapidly decreasing. Staying up late and waking up late might seem like a solution, but it only gets more exhausting. As it turns out, knowing the role a hormone named melatonin plays in your natural wake-sleep cycle enables you to take action to change some of your habits to induce better, more and healthier sleep.

Now, melatonin is the opposite of adrenaline. The latter has an effect of making you more aware, short-cutting the rational mind and switching back to your pre-historic instincts. Melatonin, however, is a hormone produced by the pineal gland somewhere in the middle of your brain and leads to calmness and sleepiness.

Normally, the production and re-uptake of melatonin is synchronous with sunset and sunrise. When the sun rises, the blue and to a lesser degree the green light (or more precisely, light with a wavelength above 530nm) on your retina will inhibit the production of melatonin. In the absence of such light, melatonin is produced and makes one sleepy.

Delayed inhibitation

Now, it is not as simple as stated above of course. For one, melatonin is produced from serotonin, a neurotransmitter that is associated with mood. Depression is caused by a lack of serotonin (in many cases because the serotonin re-uptake is too active or due to a lack of physical activity during the day), so it is no surprise that both insomnia and depression go hand in hand.

Some people also have a delayed inhibition, either by some internal cause but usually due to external light. Especially within IT, people tend to stay up late and sit behind their laptop screens. And guess what, these emit the green light inhibiting the production of melatonin!

Reprogramming the brain

There are various methods one could utilize to help the brain stay in sync with the day and night outside. In many countries, melatonin supplements can be bought (over the counter or in higher dosage with a prescription). Since melatonin is a hormone produced by the body, it is relatively safe to take synthesized melatonin from these supplements.

While these can be very effective (I have found very positive effects with a dosage of 3mg, although off-the-shelf dosage is usually around 0.1mg), there has been very little study regarding the long-term effects. Given that the role in the circadian rhythm is just one of many for melatonin, it might be wise to exercise some caution.

Reprogram your brain

A better and more natural way of resetting your biological rhythm is to pay attention to the light in your environment. This starts in the morning (yes, waking up properly is an important condition for a good nights rest). When you wake up, stare outside for 5 to 10 minutes and get a good dose of green light. This will reset your pineal gland, and stop the production of melatonin.

In winter, it might still be dark when you get up. In that case, you might want to consider getting a full-spectrum lamp, or at least a lamp that has as significant amount of greens and blues in its spectrum. Fluorescent lighting might also do the trick, but be aware that these normally produce very narrow spikes in the visible spectrum on the green, blue and red wavelengths and might therefore be less effective.

Software to make you sleep better

In the evening, a good start is to do the inverse: dim the light, use incandescent light which tends to lack greens and blues. But also take a look at your computer or laptop screen. This is a very rich source of green and blue light, so staying up late behind your laptop will inhibit the onset of melatonin production and delay your sleepiness.

One, quite ridiculous, suggestion is to stop working on your laptop an hour before you plan to get to sleep. I know, it’s heretic. Luckily, we can be a bit smarter about it by simply reducing the green and blue emitted from the screen!

Until recently I used the compiz compositing window manager for the sole reason that it let’s me apply a rendering function to my screen. Rendering functions are transformations applied within your graphics card that combine the red, green, blue and alpha value your software draws on the screen into the output you see.

Compiz has a ‘color filter’ plugin, which can be used to apply a rendering filter. I wrote a simple rendering function (in GPU assembly) that averages the red, green and blue channels and then writes this average to the red channel (leaving the blue and green channel dark). This has the effect of making your desktop monochrome, like a black-and-white tv but with red light instead of white.

This worked wonders. Next to dimming the roomlights in the evening, switching to this red view had a great effect on my ability to fall asleep.

But, recently I switched to xmonad; is a much more rudimentary and efficient window manager. It does support compositing somewhat, but only for useless effects such as transparent terminal backgrounds.

After discussing the matter at my hackerspace, I was put onto the path forward. To start with, one can use gamma correction to color-shift the image on the screen. This is a tedious process though, and getting it right requires some insight in how gamma-values actually influence color.

Luckily, there is software that takes care of all of that. The first I tried was f.lux, but it wasn’t optimal. For one, it was not open source, you could only get a binary. But more annoying, I tend to have at least 2 monitors and f.lux only works on one. So while my laptop screen would redshift, my external screen wouldn’t and the effect would be ruined.

But a bit of additional research led me to redshift. This is open-source and available in most linux distributions (for eg., apt-get install redshift in debian, or apt-get install gtk-redshift to get the applet as well).

I start it after I log in to an X session  (a windows version is available as well) and tell it where I am (by specifying latitude and longitude). It then knows when sunset and sunrise take place, and starts shifting the color of my display in small steps towards less green and blue and more red in the evening and back to the normal whiteness again in the morning.

Note that your phone also is a source of melatonin-production-inhibiting light. If, like me, you tend to check some rss feeds and maybe twitter in bed before you close your eyes, consider using something to redshift your phone display in the evening. Personally, I use an android phone with Cyanogenmod. This aftermarket firmware for your android phone already contains something called ‘rendering effects’. I placed a widget on my home screen that lets me choose between normal and ‘monochrome red’.

Good night, sleep well

The body is an intriguing complex of interacting processes, and while the above tends to work out really well it is not the panacea of sleep problems. There are many other interactions that may interfere with your ability to get a good healthy night of sleep.

For example, depression is known to cause a lack of serotonin and therefore may lead to decreased melatonin production. However, an unhealthy sleep rhythm (not in sync with planetary movement) has again a catalytic effect on depression.

I found that the above techniques (look into the light in the morning, redshift in the evening) greatly increased my ability to sleep at the right times and long enough, and be awake during the day without having to rely on stimulants. I feel more energetic and migraine has become a rare event as opposed to a weekly recurring disaster.

Your mileage may, of course, vary. But just give it a try. And let me know!

Ps: if you use caffeine to wake up in the morning or stay up late, disregard the above entirely; your circadian rhythm is too fucked up and the effects of my advice will likely be unnoticeable.

Flattr this

PostgreSQL conference Europe in Amsterdam

Wednesday, October 5th, 2011

PostgreSQL Conference Europe 2011 starts 2 weeks from today in the beautiful city of Amsterdam in the Netherlands. This is the fourth annual conference hosted by PostgreSQL Europe, following on from extremely successful events in Prato (Italy), Paris and Stuttgart, and is aimed at developers, DBAs, technologists and decision makers either using, or considering using the world’s most advanced Open Source database.

This year we have four days on the schedule, with a kick-off day of training sessions hosted by respected PostgreSQL developers such as Greg Smith, Bruce Momjian, Magnus Hagander, Guillaume Lelarge and more. Topics will cover performance tuning, application development, database administration, replication & high availability and geospatial. The training sessions are available on their own, or as part of a regular conference attendance at additional – but very reasonable – cost.

We had a record number of talk proposals submitted this year but we’ve resisted the urge to host even more sessions in parallel – in fact we’ve reduced the number of parallel sessions to three as we all know how frustrating it can be when more than one that you want to see are at the same time. Instead we’ve extended the conference by a day to accomodate over 40 different sessions, which has the added bonus of allowing an additional night of social activities – always a great way to discuss the latest technologies, trends and ideas with other Postgres users over a beer or two.

We’ve got a great range of topics for this year, covering new features in PostgreSQL 9.1 and beyond, developing applications, running Postgres in the cloud, hacking PostgreSQL internals, tools and add-on products and managing large databases, presented by a wide cross-section of users and developers, including a number of this year’s Google Summer of Code students who will talk about their work. You can view the complete schedule on the conference website:

Our opening keynote this year will be presented by Ram Mohan, EVP and CTO of Afilias who manage the .info, .org and .mobi top level domains using Postgres. Ram will be discussing the business decisions and strategy around their use of PostgreSQL. Our closing keynote will be presented by Ed Boyajian, President and CEO of EnterpriseDB who will discuss PostgreSQL’s role in the post-Oracle era.

So, if you haven’t done so already, head on over to the website at to register as an attendee to avoid missing out on what promises to be an outstanding conference in an fantastic location. See you in Amsterdam!

Flattr this

Queer Geeks

Friday, August 19th, 2011

Recently at the Chaos Communication Camp I sat down with a group of ‘queer geeks’. We shared, with the world, our experience with and our feelings surrounding being queer in the hacker-scene. We convened in the middle of a rainy night in a make-shift studio in a tent and had a very profound discussion on the camp radio Binary Voice. I have not really expressed myself in that session a lot, but listening back to the recording I can not help but wanting to elaborate.

At the end of the show I say I think it is fantastic to be queer. While that sounds like an easy thing to proclaim, I have not always thought so. In fact, up until around 20 I really hated myself for being gay. My environment constantly gave me a lot of signals that being gay is somehow wrong, and although I never had to endure the physical violence that, for example, Mitch Altman had to endure it did scar me psychologically.

I denied that part of myself until I ended up with suicidal tendencies with a psychiatrist. During those sessions I first explored this part of my identity. By then, I had reverted to substance abuse (alcohol, weed, xtc, hallucinogens, you name it) to aid in the impossible task of pretending I had no sexual preference for boys. I mean, sexuality is such an integral part of our being, to deny that is like to deny that one breathes.

Imagine the constant struggle, fantasizing about boys and falling in love with your male classmates while at the same time strongly believing it is wrong and must never surface. That’s hard. Really hard. I don’t think I can aptly describe what that did to me to anyone who has not gone through the same struggle.

When I came out to friends and family and labelled myself gay, I thought I was there. I partied like mad in the local gay scene, thought I was complete. Yet, the years of denial and coping mechanisms were not easily dismissed. Somehow, the feeling it was somehow wrong persisted. It was hard for me to assimilate within a new group and tell them I am queer. It really felt like an obstacle, I feared I would not be accepted for who I am.

The way the world was treating me still lead to a lot of frustration. The Dutch word ‘homo’ was (and still is) being used as a derogate term. It is a word some reserve for their worst enemies, for the people they deject the most. I got really angry about that, but instead of using that anger to change things in a positive way I let it build up inside me like a cancer.

I still feel hurt when people use the word ‘gay’ as a derogate term. Within certain subcultures of the hacker scene, especially those where kids measure their hacking abilities bragging about their conquests in some sort of nerdy masochism, it is socially acceptable to use language that hurts people. It is encouraged even. Bashing queers is, unfortunately, an easy way to get accepted within certain peer groups.

Usually the usage of the word gay as a way of dismissing someone is out of carelessness though. I have rarely found anyone who really has problems with queerness. It is habitual use of language, no conscious speech act. I tend to say something when I observe this. I try to explain how that same careless use of words almost drove me to end my life, kill myself.

I hope that will make people think. I know it has made people think. And I hope that with that I can contribute in making it easier for young kids out there who have similar issues as I did have.

For myself, I have found peace in that regard. I am openly queer, and will take every opportunity I can to let the world know. I love my life as such, and while I am still struggling with the psychological scars and addictive behaviour left from that time I do celebrate my queerness every opportunity I get.

It really makes me cry when I think of those young ones out there who might be gay, bisexual or whatever and are going through what I went through. I want to help them become themselves. I am glad that The Netherlands has the COC, an organisation that furthers queer emancipation but also supports anyone who is going through the process of coming out of the closet. I know some of my friends take issues with their political ways, but for me the real value of the COC is the sheer support one gets from being safe among peers who have had similar issues. When I finally acknowledged my homosexuality at 20, it helped me so much just to be able to go there and talk, listen and make friends with like-minded people. I have deep respect for the volunteers going into the classrooms, educating adolescents about the rich tapestry of queerness.

A few years after I came out, I had a profound experience. A friend whom I knew from the hardcore scene (gabber, speed, happy is for homos) called me, and started talking about how he heard about my coming out. To my surprise, he told me he was gay too. I had never expected this to come from that particular peer group, yet just by being openly queer it all of a sudden became acceptable for others as well. And that, for me, acknowledges the fact that just by being myself I can help.

I am therefore very proud of the show we did at CCC. We had a unique gathering of queer geeks at the table, openly talking about their deepest feelings, most horrible experiences and also the joy of being who you are. I really hope kids (and adults!) out there who struggle with their own sexual identity listen to it and can find support in the wise words spoken. Already a day after the show, Mitch told me about people coming out right there and then.

As a final thought, I want to emphasize that just putting the label ‘gay’ on myself is not the end but merely the beginning of the exploration of my own sexuality. Yes, I really like guys. And for a while I even went to the other extreme: I would deny every feeling I could possibly have for someone of the female (or whatever other) sex. I am slowly coming around, and realize things aren’t binary.

I have several friends who also do not tend to fit in the dominant social paradigm (to quote Mitch from the aforementioned show) of the monogamous heterosexual relationship, and are finding ways to deal with that while still existing within that dominating model. It is hard sometimes, but it is a lot of fun as well. And true hapiness, I believe, can only be found by following ones heart without regarding what others might think or judge you by.

Anyway, I encourage each and everyone (also if you do not consider yourself to be queer) to go and download that recording. And most of all, I encourage everyone out there to be themselves. And if that is hard somehow, know that there are a whole bunch of persons that have gone through it already and that are more than willing to talk. To listen. Do not hesitate to contact any of us on the panel (me, Mitch, Jimmy, Maha, Socialhack, Willow, Fabien and Tomate).

Be excellent!

Flattr this

Reverse tethering for android

Friday, June 17th, 2011

Since I’m on a road-trip and don’t have a SIM-card with data for every country I’m visiting (I’m fine in Germany and Belgium, but did not get a SIM-card for the Czech republic where i’m just for 24 hours) and never connect with my phone to an untrusted wifi network, I thought i’d do the reverse of tethering: connect my phone to my laptop (which has a tunnel to my server-rack in the datacenter) and surf through that. So mostly as a note for myself, here’s what I did:

Connected the USB between phone and laptop, then enabled tethering (this is Cyanogen 2.2 on a G1, rooted). This brings up the usb0 nic on both ends with some default ip’s. Then went into the terminal on the phone (probably can do this with adb shell as well) and checked I could ping:

# ifconfig usb0
usb0: ip mask flags [up broadcast running multicast]
# ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=0.519ms

With that running, it is time to enable forwarding on my linux laptop:

sysctl -w net.ipv4.ip_forward=1

And enable some firewall rules to have traffic from the phone get NATTED on the outgoing tunnel endpoint on my laptop (tap0, remember usb0 is the usb nic that connects to my phone):

iptables -A FORWARD -i tap0 -o usb0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A POSTROUTING -t nat -o tap0 -j MASQUERADE
iptables -A INPUT -i usb0 -j ACCEPT
iptables -A FORWARD -i usb0 -o tap0 -j ACCEPT

Then I set the default route:

route add default gw

And finally, I need to tell the android that my nameservers are and

# setprop net.dns1
# setprop net.dns2

And we’re done!

Flattr this