Stuff I have written/presented
«Almost free» — Some experiences with the Raspberry Pi, CI20, BananaPi, CuBox-i... And whatever will follow
Submitted by gwolf on Fri, 06/12/2015 - 19:46
I know very little about hardware.
I think I have a good understanding on many aspects of what happens inside a computer, but my knowledge is clearly firmer on what happens once an operating system is already running. And even then, my understanding of the lower parts of reality is shaky at most — At least according to my self-evaluation, of course, comparing to people I'm honored to call "my peers".
During the last ~18 months, my knowledge of this part of reality, while still far from complete, has increased quite a bit — Maybe mostly showing that I'm basically very cheap: As I have come across very cheap (or even free for me!) hardware, I have tried to understand and shape what happens in levels below those where I dwell.
I have been meaning to do a writeup on the MIPS Creator CI20, which was shipped to me for free (thanks++!) by Imagination Technologies; I still want to get more familiar with the board and have better knowledge before reporting on it. Just as a small advance, as this has been keeping me somewhat busy: I got this board after their offer to Debian Developers, and prompted because I'll be teaching some modules on the Embedded Linux diploma course dictated by Facultad de Ingeniería, UNAM — Again, I'll blog about that later.
My post today follows Riku's, titled Dystopia of things, where he very clearly finds holes in the Internet of Things offering of one specific product and one specific company, but allows for generalizations on what we will surely see as the model. Riku says:
This is not exactly the situation on the boards/products (it's a disservice to call the cute CuBox-i just a board!) I mention I'm using, but it's neither too far. Being used to the easy x86 world, I am used to bitching on specific hardware that does not get promptly recognized by the Linux kernel — But even with the extra work UEFI+SecureBoot introduces, getting the kernel to boot is something we just take for granted. In the MIPS and ARM worlds, this is not so much of a given; I'm still treating the whole SPL and DeviceTree world as a black box, but that's where a lot of the work happens.
The boards I am working on try to make a point they are Open Hardware. The CI20 is quite impressive in this regard, as not only it has a much more complete set of on-board peripherials than any other, but a wealth of schematics, datasheets and specifications for the different parts of its components. And, of course, the mere availability of the MIPSfpga program to universities worldwide is noteworthy — Completely outside of my skillset, but looks most interesting.
However... Despite being so much almost-Free-with-a-capital-F, all those boards fail our definitions of freedom in several ways. And yes, they lead us to a situation similar to what Riku describes, to what Stallman feared... To a situation not really better to where we stand on openly closed-source, commodity x86 hardware: Relying on binary blobs and on non-free portions of code to just use our hardware, or at least to use many of the features that would be available to us otherwise.
As an example, both the CI20 and the CuBox-i vendors provide system images able to boot what they describe as a Debian 7 system, based on a 3.0 Linux kernel (which Debian never used; IIRC the CuBox-i site said it was derived from a known-good Android kernel)... Only that it's an image resulting of somebody else installing and configuring it. Why should we trust their image to be sane? Yes, the resulting installation is quite impressive (i.e. the CI20's 3D demos are quite impressive for a system that feels otherwise sluggish, and out of my ARM experience, I'd wager it feels sluggish mostly because of a slow SSD)...
I have managed to do clean Debian installs on most of my ARM machines (the CuBox-i as described in my previous blog post; this post from Elena ``of Valhalla'' prompted me into trying the already well documented way of running the official Debian Installer, which worked like a charm and gave me a very nice and responsive Debian 8 install — Modulo yes, the Banana's non-free video interface, which AFAICT uses the non-free Mail binary driver... And which I haven't had the time to play with yet. Of course, my CuBox is in a similar situation, where it works like a charm as a personal server, but is completely worthless as a set-top box.
So, with those beautiful, small, cheap SoC systems, we are close to where we stood twenty years ago with x86 Linux: Good support for a small set of peripherials, but a far cry from having a functional system with exclusively free software. ,
Still... Playing with these boards has taught me a lot, and has clearly taught me I'm still standing on the first steps of the n00b level. I have a lot to learn to be able to responsibly teach my part of the diploma course, and I'm very thankful for the differences in hardware (and, of course, for the hardware manufacturers, specially for the MIPS Creator CI20 and the Lemaker Banana Pi for giving me boards to work on!)
I shall keep posting on this topic.
Submitted by gwolf on Tue, 05/19/2015 - 18:36
Today I feel more special than I have ever felt.
Or... Well, or something like that.
Thing is, there is no clear adjective for this — But I successfully finished my Specialization degree! Yes, believe it or not, today I can formally say I am Specialist in Informatic Security and Information Technologies (Especialista en Seguridad Informática y Tecnologías de la Información), as awarded by the Higher School of Electric and Mechanic Engineering (Escuela Superior de Ingeniería Mecánica y Eléctrica) of the National Polytechnical Institute (Instituto Politécnico Nacional).
In Mexico and most Latin American countries, degrees are usually incorporated to your name as if they were a nobiliary title. Thus, when graduating from Engineering studies (pre-graduate universitary level), I became "Ingeniero Gunnar Wolf". People graduating from further postgraduate programs get to introduce themselves as "Maestro Foobar Baz" or "Doctor Quux Noox". And yes, a Specialization is a small posgraduate program (I often say, the smallest possible posgraduate). And as a Specialist... What can I brag about? Can say I am Specially Gunnar Wolf? Or Special Gunnar Wolf? Nope. The honorific title for a Specialization is a pointer to null, and when casted into a char* it might corrupt your honor-recognizing function. So I'm still Ingeniero Gunnar Wolf, for information security reasons.
So that's the reason I am now enrolled in the Masters program. I hope to write an addenda to this message soonish (where soonish ≥ 18 months) saying I'm finally a Maestro.
As a sidenote, many people asked me: Why did I take on the specialization, which is a degree too small for most kinds of real work recognition? Because it's been around twenty years since I last attended a long-term scholar program as a student. And my dish is quite full with activities and responsabilities. I decided to take a short program, designed for 12 months (I graduated in 16, minus two months that the university was on strike... Quite good, I'd say ;-) ) to see how I fared on it, and only later jumping on the full version.
Because, yes, to advance my career at the university, I finally recognized and understood that I do need postgraduate studies.
Oh, and what kind of work did I do for this? Besides the classes I took, I wrote a thesis on a model for evaluating covert channels for establishing secure communications.
Submitted by gwolf on Wed, 05/13/2015 - 23:46
The discussion regarding the legality and convenience of Uber, Cabify and similar taxi-by-app services has come to Mexico City — Over the last few days, I've seen newspapers talk about taxi drivers demonstrating against said companies, early attempts at regulating their service, and so on.
I hold the view that every member of a society should live by its accepted rules (i.e. laws) — and if they hold the laws as incorrect, unfair or wrong, they should strive to get the laws to change. Yes, it's a hard thing to do, most often filled with resistence, but it's the only socially responsible way to go.
Private driver hiring applications have several flaws, but maybe the biggest one is that they are... How to put it? I cannot find a word better than illegal. Taxi drivers in our city (and in most cities, as far as I have read) undergo a long process to ensure they are fit for the task. Is the process incomplete? Absolutely. But the answer is not to abolish it in the name of the free market. The process must be, if anything, tightened. The process for granting a public driver license to an individual is way stricter than to issue me a driving license (believe it or not, Mexico City abolished taking driving tests several years ago). Taxis do get physical and mechanical review — Is their status mint and perfect? No way. But compare them to taxis in other Mexican states, and you will see they are in general in a much better shape.
Now... One of the things that angered me most about the comments to articles such as the ones I'm quoting is the middle class mentality they are written from. I have seen comments ranging from stupidly racist humor attempts (Mr. Mayor, the Guild of Kidnappers and Robbers of Iztapalapa demand the IMMEDIATE prohibition on UBER as we are running low on clients or the often repeated comment that taxi drivers are (...) dirty, armpit-smelly that listen to whatever music they want) to economic culture-based discrimination Uber is just for credit card users as if it were enough of an argument... Much to the opposite, it's just discrimination, as many people in this city are not credit subjects and do not exist in the banking system, or cannot have an always-connected smartphone — Should they be excluded from the benefits of modernity just because of their economic difference?
And yes, I'm by far not saying Mexico City's taxi drivers are optimal. I am an urban cyclist, and my biggest concern/fear are usually taxi drivers (more so than microbus drivers, which are a class of their own). Again , as I said at the beginning of the post, I am of the idea that if current laws and their enforcement are not enough for a society, it has to change due to that society's pressure — It cannot just be ignored because nobody follows the rules anyway. There is quite a bit that can be learnt from Uber's ways, and there are steps that can be taken by the company to become formal and legal, in our country and in others where they are accused of the same lacking issues.
We all deserve better services. Not just those of us that can pay for a smartphone and are entitled to credit cards. And all passenger-bearing services require strict regulations.
Guests in the Classroom: Felipe Esquivel (@felipeer) on the applications on parallelism, focusing on 3D animation
Submitted by gwolf on Fri, 05/08/2015 - 10:44
I love having guests give my classes :)
This time, we had Felipe Esquivel, a good friend who had been once before invited by me to the Faculty, about two years ago. And it was due time to invite him again!
Felipe knows his way around the different aspects of animation. For this class (2015-04-15), he explained how traditional ray-tracing techniques work, and showed clear evidences on the promises and limits of parallelism — Relating back to my subject and to academic rigor, he clearly shows the speed with which we face Amdahl's Law, which limits the efficiency of parallelization at a certain degree perprogram construct, counterpointed against Gustafson's law, where our problem will be able to be solved in better detail given more processing abilities (and will thus not hit Amdahl's hard ceiling).
Submitted by gwolf on Mon, 04/27/2015 - 22:24
That's all I need to enjoy the best best party ever.
Oh! Shall I mention that we got a beautiful present for the kids from our very dear DebConf official Laminatrix! Photos not yet available, but will provide soon.
Submitted by gwolf on Sun, 04/26/2015 - 23:34
(No, I'm not talking about a future Ubuntu release... After all, what kind of weird animal would a weekend be?)
This weekend we took the kids outside for the first time (not counting, of course, visits to the pediatrician). We were quite anxious... Of course, they were born somewhat under weight and at 7½ months of gestation. But this Saturday we feelt adventurous, and took the kids out for a day among people!
It might not sound like a big deal, but... Well, we took a not such beautiful or scenic route: We took them to the supermarket, and had a small lunch out. For the first time in the already two months they have been with us.
Dinner with friends at home, having a very good time, and –as expected– a... Very hard night for us. All that excitement had the babies very nervous.
Today –again, for the first time– we took the children out to visit some friends of ours. Again, it was great, they behaved very nicely, and were lovely all around.
Lets see what this night holds in place for us.
Anyway, with them growing slowly but steadily... We are very happy, thankful parents. For the first time since Regina is with me in Mexico, this time we decided we would not have a birthday party (yes, I'm 30 minutes away from being 39 year old). I cannot imagine a fuller, better celebration than what we are having. This two babies are the real event in our lives.
Oh... And by the way, this weekend also saw the release of a great new Debian release: Debian 8, codenamed Jessie. Thanks, folks, for such a great birthday present ;-) For reasons that should by now be obvious, I wasn't able to go to either of the release parties I knew of in Mexico City (even one of them was ~500m from home!)
Submitted by gwolf on Wed, 04/08/2015 - 11:47
Once again, on March 11 I had a great guest to save me some work and give a talk at my class! This time it was César Yáñez, and he talked about memory management algorithms, emphasizing on ARC.
Thanks a lot!
Submitted by gwolf on Sun, 03/15/2015 - 17:49
My good friend Felipe Esquivel is driving a crowdfunded project: the first part of the "Natura" short film. I urge every reader of my blog to support Felipe's work!
Not only that: It might be interesting for my blog's readers that a good deal of the work of Chamán Animation's work (of course, I am not qualified to state that "all of" their work — But it might well be the case) is done using Free Software, specifically, using Blender.
So, people: Go look at their work. And try to be part of their work!
Submitted by gwolf on Sat, 02/28/2015 - 08:26
Welcome little babies!
Yesterday night, we entered the hospital. Nervous, heavy, and... Well, would we ever be ready? As ready as we could.
A couple of hours later, Alan and Elena Wolf Daichman became individuals on their own right. As is often the case in the case of twins, they were brought to this world after a relatively short preparation (34 weeks, that's about 7.5 months). At 1.820 and 1.980Kg, they are considerably smaller than either of the parents... But we will be working on that!
Regina is recovering from the operation, the babies are under observation. As far as we were told, they seem to be quite healthy, with just minor issues to work on during neonatal care. We are waiting for our doctors to come today and allow us to spend time with them.
And as for us... It's a shocking change to finally see the so long expected babies. We are very very very happy... And the new reality is hard to grasp, to even begin understanding :)
PS- Many people have told me that my blog often errors out under load. I expect it to happen today :) So, if you cannot do it here, there are many other ways to contact us. Use them! :)
Submitted by gwolf on Fri, 02/06/2015 - 12:51
I would expect brute-force login attacks to be more common. And yes, at some point I got tired of ssh scans, and added rate-limiting firewall rules, even switched the daemon to a nonstandard port... But I have very seldom received an IMAP brute-force attack. I have received countless phishing scams on my users, and I know some of them have bitten because the scammers then use their passwords on my servers to send tons of spam. Activity is clearly atypical.
Anyway, yesterday we got a brute-force attack on IMAP. A very childish atack, attempted from an IP in the largest ISP in Mexico, but using only usernames that would not belong in our culture (mosty English firstnames and some usual service account names).
What I find interesting to see is that each login was attempted a limited (and different) amount of times: Four account names were attempted only once, eight were attempted twice, and so on — following this pattern:
1 • 2 •• 3 •• 4 ••••• 5 ••••••• 6 •••••• 7 ••••• 8 •••••••• 9 ••••••••• 10 •••••••• 11 •••••••• 12 •••••••••• 13 ••••••• 14 •••••••••• 15 ••••••••• 16 •••••••••••• 17 ••••••••••• 18 •••••••••••••• 19 ••••••••••••••• 20 •••••••••••• 21 •••••••••••• 22 ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
(each dot represents four attempts)
So... What's significant in all this? Very little, if anything at all. But for such a naïve login attack, it's interesting to see the number of attempted passwords per login varies so much. Yes, 273 (over ¼ of the total) did 22 requests, and another 200 were 18 and more. The rest... Fell quite shorter.
In case you want to play with the data, you can grab the list of attempts with the number of requests. I filtered out all other data, as i was basically meaningless. This file is the result of:
Submitted by gwolf on Fri, 01/02/2015 - 12:25
Having seen the end of December and the beginning of January, this is the time of year where we say "Happy new year!"
But this is a very interesting new year: We have also went past our much announced deadline for the <2048 bit keys to be removed from the Debian keyrings. And yes, our highly efficient keyring-maint team managed to deliver on the promised time — And, I'd say, with much success. Lets see the numbers — Only before that, refer to Jonathan's mail to debian-devel-announce for further, fuller information.
So, first of all, how do overall numbers look? Just remember, the following are not the number of DDs, just the number of active keys. That is, the holders to the 252 DD and 35 DM keys we removed are still valid Debian Developers/Maintainers, but have to get a new key accepted to perform many of their tasks in the project.
The graph above shows the sharp change between tags 2014.12.31 and 2015.01.01. But my definition of success is that we managed to get the number down to just 252+35=287 from what we had back in August, when we did our DebConf presentation and started the aggressive push: 490 DD keys and 49 DM keys. Since then, 34 DDs requested their retirement, becoming emeritus, and practically all of the rest managed to get their key transition done!
So, lets go again easiest-to-hardest. First, the Non-uploading Debian Developers keyring:
As this is the newest keyring in existence, and is also the smallest one, we were already without <2048 keys since 2011. Nothing to see, move along.
Then, as for the Debian Maintainers:
We did have a sensible migration from weaker to stronger keys, but it was not as sharp as I'd have liked. That makes sense, after all, since DMs have less involvement and compromise in the project in regard to DDs. So, we only processed 15 DM keys since August, which is almost a third of the keys we needed to process to reach the ideal 100% migration.
Now, as for our biggest and oldest keyring, and the one that denotes more project involvement, here is the graph for the uploading Debian Developers:
And yes, here you can see the sharp turn we saw in the second half of this year: By DebConf time, we were happy because the red and yellow lines had just crossed. But we were still sitting at 490 DD keys needing to be migrated. Half of the DD keys (compared to almost a fourth for the DM keys).
I'm almost sure we anticipated in our presentation (I know, I should check the video) that, by January 1st, we would have to retire around 300 keys. And I'm very, very happy and proud that we managed to get the number down to 252.
And, yes, people leave things to the end: We already have some more pending requests in the Request Tracker to introduce new keys for our fellow friends who were disabled. We will be working to make keyring pushes more frequent than our usual monthly uploads until requests go back to a sane level.
So, if everything runs smoothly, this will probably be the last of my posts in this regard. This has been quite an interesting (and exhausting!) experience!
Submitted by gwolf on Wed, 12/24/2014 - 11:49
I have long wanted to echo Gregor's beautiful Debian Advent Calendar posts. Gregor is a dear project member and a dear friend to many of us Debianers, who has shown an amount of stamina and care for the project that inspires everybody; this year, after many harsh flamefests in the project (despite which we are moving at a great rate towards a great release!), many people have felt the need to echo how Debian –even as often seen from the outside as a hostile mass of blabbering geeks– is actually a great place to work together and to create a deep, strong social fabric — And that's quite probably what binds the project together and ensures it will continue existing and excelling for a long time.
As for the personal part: This year, my Debian involvement has –once again– reduced. Not because I care less about Debian, much to the contrary, but because I have taken several responsabilities which require my attention and time. Technically, I'm basically maintaining a couple of PHP-based packages I use for work (most prominently, Drupal7). I have stepped back of most of my DebConf responsabilities, although I stay (and will stay, as it's an area of the project I deeply enjoy doing) involved. And, of course, my current main area of involvement is keyring-maint (for which I have posted here several status updates).
I have to say that we expected having a much harder time (read: Stronger opposition and discussions) regarding the expiry of 1024D keys. Of course, many people do have a hard time connecting anew to the web of trust, and we will still face quite a bit of work after January 1st, but the migration has been a mostly pleasant (although clearly intensive) work. Jonathan has just told me we are down to only 306 1024D keys in the keyring (which almost exactly matches the "200-300" I expected back at DC14).
Anyway: People predicting doomsday scenarios for Debian do it because they are not familiar with how deep the project runs in us, how important it is socially, almost at a family level, to us that have been long involved in it. Debian is stronger than a technical or political discussion, no matter how harsh it is.
And, as a personal thank-you: Gregor, your actions (the GDAC, the RC bug reports) inspire us to stay active, to do our volunteer work better, and remind us of how great is it to be a part of a global, distributed will to Do It Right. Thanks a lot!
Submitted by gwolf on Tue, 12/23/2014 - 23:47
Much ink has been spilled lately (well, more likely, lots of electrons have changed their paths lately — as most of these communications have surely been electronic) on the effects, blame, assurance and everything related to the (allegedly) North Korean attack on Sony's networks. And yes, the list of components and affectations is huge. Technically it was a very interesting feat, but it's quite more interesting socially. Say, the not-so-few people wanting to wipe North Korea from the face of the Earth, as... Well, how did such a puny nation dare touch a private company that's based in the USA?
Of course, there's no strong evidence the attack did originate in (or was funded by) North Korea.
And... I have read very few people talking about the parallels to the infamous Stuxnet, malware written by USA and Israel (not officially admitted, but with quite a bit of evidence pointing to it, and no denial attempts after quite a wide media exposure). In 2010, this worm derailed Iran's nuclear program. Iran, a sovereign nation. Yes, many people doubt such a nuclear program would be used "for good, not for evil" — But since when have those two words had an unambiguous meaning? And when did it become accepted as international law to operate based on hunches and a "everybody knows" mentality?
So, how can the same people repudiate NK's alleged actions and applaud Stuxnet as a perfect weapon for peace?
Submitted by gwolf on Wed, 11/26/2014 - 10:49
On November 14, as a great way to say goodbye to a semester, a good friend came to my class again to present a topic to the group; a good way to sum up the contents of this talk is "everything you ever wondered about persistent storage".
As people who follow my blog know, I like inviting my friends to present selected topics in my Operating Systems class. Many subjects will stick better if presented by more than a single viewpoint, and different experiences will surely enrich the group's learning.
So, here is Rolando Cedillo — A full gigabyte of him, spawning two hours (including two hiccups where my camera hit a per-file limit...).
Rolando is currently a RedHat Engineer, and in his long career, he has worked from so many trenches, it would be a crime not to have him! Of course, one day we should do a low-level hardware session with him, as his passion (and deep knowledge) for 8-bit arcades is beyond any other person I have met.
Submitted by gwolf on Tue, 11/25/2014 - 00:41
The line of BASIC code that appears as the subject for this post is the title for a book I just finished reading — And enjoyed thoroughly. The book is available online for download under a CC-BY-NC-SA 3.0 License, so you can take a good look at it before (or instead of) buying it. Although it's among the books I will enjoy having on my shelf; the printing is of a very enjoyable good quality.
And what is this book about? Well, of course, it analizes that very simple line of code, as it ran on the Commodore 64 thirty years ago.
And the analysis is made from every possible angle: What do mazes mean in culture? What have they meant in cultures through history? What about regularity in art (mainly 20th century art)? How would this code look (or how it would be adapted) on contemporary non-C64 computers? And in other languages more popular today? What does randomness mean? And what does random() mean? What is BASIC, and how it came to the C64? What is the C64, and where did it come from? And several other beautiful chapters.
The book was collaboratively written by ten different authors, in a Wiki-like fashion. And... Well, what else is there to say? I enjoyed so much reading through long chapters of my childhood, of what attracted me to computers, of my cultural traits and values... I really hope that, in due time, I can be a part of such a beautiful project!
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