muellis blog – Page 7 – …und alle so “Yeaahh!”

mrmcd14 in Darmstadt – DOM-based XSS

After last year’s fabulous event, I was really looking forward to this year’s mrmcd in Darmstadt, Germany. It outgrew last year’s edition and had probably around 250 to 300 people attending. Maybe even more. In fact, 450 clients generated 423 GB traffic during the conference which lasted 60 hours or so. That’s around 2MB/s. That’s megabytes. Per second. Every second. I find that quite impressive. Especially as the outdoor area was very inviting to just hang around, grab a beer, and chat to your fellow hackers. So some people must have had an amazing demand of … updates…

This year’s theme was construction sites. As IT, and especially security, is a major, never ending, and dangerous construction site. It was well done, with a lot of warning tape, the people wearing helmets, hi-vis vests, some security boots, etc. Although it couldn’t excel last year’s aviation theme, but the watermark was set extremely high. Anyway, the speakers received cool gadgets, like a tool set, a level, and other very well done gadgets. The talks were opened by Unicorn who, as you can see, was wearing proper safety gear. We were given instructions as to how to behave in case of fire, flood, or lack of alcohol. A nifty feature of this event is the availability of carbo hydrates in form of various food stuffs. It’s very cool to always being able to walk up to the buffet and fill up energy reserves.

The keynote was involuntarily given by dodger who did not miss the opportunity to show us various constructions sites, such as the Utah Data Center. Ultimately, (now I am maybe over interpreting things), it’s also hackers like us who make those possible. We usually decide for ourselves where to go and what to do. It was a good round-up on how we as a community work or should work. Also with some political references which I think is important as I have the feeling that many people lose that focus too easily.

An interesting series of talks was given by Ange Albertini, who first presented the PDF file format. It was interesting to see how the format actually looks like. I knew already a little but I’ve never really cared about the details. This was a very interesting and visually appealing talk. Pretty much like his other presentations which were again on file formats and on crypto.

My own talk was scheduled after the second night. I was positively surprised to see a half-filled room on a Sunday morning, after two nights of demanding partying… Anyway, I had an interested crowd which I think I could entertain. You can find my slides here. I was talking on DOM-based Cross-site Scripting. I presented a modified Chrome browser which is able to stop all identified DOM-based XSSs. I will need a separate post to cover the details. As a brief summary: Both WebKit and V8 were modified to track taint, that is, to annotate strings with the information of the source. Such a source could be the document.URL or the window.name. This taint information is evaluated whenever it is about to be compiled to code. The simple approach of blocking every tainted string to compile is not followed as it breaks the Web. Instead, the compiler will notice which token is about to be generated and only allow generation if and only if the string is untainted or of a data type (String, Boolean, Number). If the tainted token is, for example, function call, assignment or pretty much anything else, then it is replaced with an illegal token in order to abort compilation. There is a video of the talk here:

As we are on videos, the video team is just plainly amazing. It released videos of the event pretty much after they finished. And in a quality that is hard to excel. You check the videos of this conference, but also others. You may find some gems that are well worth watching. Be aware though, some talks are also very much on the vapor-ware side of things… I guess I don’t need to point to specific talks as it should be easy to identify…

I am already looking forward to next year’s event. The watermark has, again, been set high and I expect the next year to be able to raise that bar. But I hope it will be able to stay small enough to not lose the cosy and comfy feeling. Maybe I shouldn’t blog about that fantastic event to not generate too much attention 😉

LibreOffice Con in Bern, Switzerland

I was invited to give a talk in Bern, Switzerland, for the LibreOffice Conference. The LibreOffice people are a nice crowd with diverse backgrounds. I talked to design people, coders doing rather low-level GL things, marketing folks, some being new to Free Software, and to some being old farts. It sounds like a lot of people and one is inclined to think of boat loads of people attending the conference when having the community statistics in mind. But it has been a very cosy event, with less than a hundred people. I found that surprising, but not necessarily in a bad way.

I couldn’t make it to many talks, because the conference took place on week days. But judging from the schedule there were many interesting talks. The only thing I didn’t like about the schedule was the weird formatting. Seriously, who makes the track’s name more visible than the talk’s title..? Also grouping by room and not by time is a bit weird.

Anyway, my talk went well although it was in the first slot after the free beer party 😉 You can find my slides in the collection. I was talking about GNOME in general, but with a twist for those who migrate from proprietary software to Free Software. I hope I could convey that the GNOME desktop might be a viable alternative to proprietary products.

As this was a great, comfortable conference, I’m looking forward to visiting next year’s event.

Attending the DANTE Tagung in Karlsruhe

Much to my surprise, the DANTE Tagung took place in Karlsruhe, Germany. It appears to be the main gathering of the LaTeX (and related) community.

Besides pub-based events in the evenings, they also had talks. I knew some people on the program by name and was eager to finally see them IRL. One of those was Markus Kohm, from the KOMAScript fame. He went on to present new or less used features. One of those was scrlayer which is capable of adding layers to a page, i.e. background or foreground layers. So you can add, e.g. a logo or a document version to every page, more or less like this:

DeclareNewLayer[{
    background,
    topmargin,
    contents={\hfill
        \includegraphics[width=3cm, heigth=2cm]
                                  {example-image}
}%
}[{Logo}
\AddLayersToPageStyle{@everystyle@}{Logo}

You could do that with fancyhead, but then you’d only get the logo depending on your page style. The scrlayer solution will be applied always. And it’s more KOMAesque, I guess.

The next talk I attended was given by Uwe Ziegenhagen on new or exciting CTAN packages.
Among the packages he presented was ctable. It can be used to type-set tables and figures. It uses a favourite package of mine, tabularx. The main advantage seems to be to be able to use footnotes which is otherwise hard to achieve.

He also presented easy-todo which provides “to-do notes throughout a document, and will provide an index of things to do”. I usually use todonotes which seems similar enough so I don’t really plan on changing that. The differences seem to be that easy-todo offer more fine grained control over what goes into a list of todos to be printed out.

The flowchart package seems to allow drawing flowcharts with TikZ more easily, especially following “IBM Flowcharting Template”. The flowcharts I drew so far were easy enough and I don’t think this package would have helped me, but it is certain that the whole process of drawing with TikZ needs to be made much easier…

Herbert Voß went on to talk about ConTeXt, which I had already discovered, but was pleased by. From my naïve understanding, it is a “different” macro set for the TeX engine. So it’s not PDFTeX, LuaLaTeX, or XeTeX, but ConTeXt. It is distributed with your favourite TeXLive distribution, so it should be deployed on quite a few installations. However, the best way to get ConTeXt, he said, was to fire up the following command:

rsync -rlpt rsync://contextgarden.net/minimals/setup/.../bin .

wow. rsync. For binary software distribution. Is that the pinnacle of apps? In 2014? Rsync?! What is this? 1997? Quite an effective method, but I doubt it’s the most efficient. Let alone security wise.

Overall, ConTeXt is described as being a bit of an alien in the TeX world. The relationship with TeXLive is complicated, at best, and conventions are not congruent which causes a multitude of complications when trying to install, run, extend, or maintain both LaTeX and ConTeXt.

The next gathering will take place in the very north of Germany. A lovely place, but I doubt that I’ll be attending. The crowd is nice, but it probably won’t be interesting for me, talk-wise. I attribute that party to my inability to enjoy coding TeX or LaTeX, but also to the arrogance I felt from the community. For example, people were mocking use cases people had, disregarding them as being irrelevant. So you might not be able to talk TeX with those people, but they are nice, anyway.

Reverse sshuttle tunnel to connect to separate networks

I had to solve that the split horizon DNS problem in order to find my way out to the Internet. The complementary problem is how to access the internal network form the Internet. The scenario being, for example, your home network being protected by a very angry firewall that you don’t necessarily control. However, it’d be quite handy to be able to SSH into your machines at home, use the printer, or connect to the internal messaging system.

However, everything is pretty much firewalled such that no incoming connections are possible. Fortunately, outgoing connections to an SSH server are possible. With the RemoteForward option of OpenSSH we can create a reverse tunnel to connect to the separate network. All it requires is a SSH server that you can connect to from both sides, i.e. the internet and the separate network, and some configuration, maybe like this on the machine within the network: ssh -o 'RemoteForward=localhost:23 localhost:22' root@remotehost and this for the internet machine:

Host dialin
    User toor
    HostName my.server
    Port 23

It then looks almost like this:

      
+---------------------------------------+                       
|Internet                               |                       
+---------------------------------------+
|  +-----------+                        |                       
|  |My machine | +------------+         |                       
|  +-----------+              |         |                       
|                             |         |                       
|                  +----------v--+      |                       
|                  |             |      |                       
|                  | SSH Server  |      |                       
|                  |             |      |                       
|                  +----------+--+      |                       
|                         ^   |         |                       
+------------------------ |   | --------+                       
                          |   |                                 
+------------------------ |   | --------+                       
|XXXXXXXX   Firewall  XX  |   | XXXXXXXX|                       
+------------------------ |   | --------+                       
                          |   |                                 
+------------------------ |   | --------+
| ACME.corp  10/8         |   |         |                       
+------------------------ |   | --------+
|                         |   |         |                       
|               +---------+---|------+  |                       
|   XMPP  <-+   |             |      |  |                       
|           |   |             |      |  |                       
|           |   |             v      |  |                       
|   Print <----------+ ssh -R        |  |                       
|           |   |      via corkscrew |  |                       
|           |   |                    |  |                       
|   VCS   <-+   +--------------------+  |                       
|               |  My machine        |  |                       
|               +--------------------+  |                       
|                                       |                       
+---------------------------------------+

“But…” I hear you say. What about the firewall? How would we connect in first place? Sure, we can use corkscrew, as we’ve learned. That will then look a bit more convoluted, maybe like this:

ssh -o ProxyCommand="corkscrew proxy.acme.corp 80 ssh.my.server 443" -o 'RemoteForward=localhost:23 localhost:22' root@lolcathost

What? You don’t have corkscrew installed? Gnah, it’s dangerous to go alone, take this:

cd
wget --continue http://www.agroman.net/corkscrew/corkscrew-2.0.tar.gz
tar xvf corkscrew*.tar*
cd corkscrew*
./configure --prefix=~/corkscrew; make; make install

echo -e  'y\n'|ssh-keygen -q -t rsa -N "" -f ~/.ssh/id_rsa

(echo -n 'command="read",no-X11-forwarding,no-agent-forwarding '; cat ~/.ssh/id_rsa.pub ;echo;echo EOF)

As a bonus, you get a SSH public key which you can add on the server side, i.e. cat >> ~root/.ssh/authorized_keys <<EOF. Have you noticed? When logging on with that key, only the read command will be executed.

That’s already quite helpful. But how do you then connect? Via the SSH server, of course. But it’s a bit of a hassle to first connect there and then somehow port forward via SSH and all. Also, in order to resolve internal names, you’d have to first SSH into the separate machine to issue DNS queries. That’s all painful and not fun. How about an automatic pseudo VPN that allows you to use the internal nameserver and transparently connects you to your internal network?

Again, sshuttle to the rescue. With the same patches applied to /etc/NetworkManager/dnsmasq.d/corp-tld, namely

# resolves names both, .corp and .acme
server=/acme.corp/10.2.3.4
server=/corp.acme/10.3.4.5

you can make use of that lovely patch for dns hosts. In the following example, we have a few nameservers defined, just in case: 10.2.3.4, 10.3.4.5, 10.4.5.6, and 10.5.6.7. It also excludes some networks that you may not want to have transparently routed. A few of them are actually standard local networks and should probably never be routed. Finally, the internal network is defined. In the example, the networks are 10.1.2.3/8, 123.1.2.3/8, and 321.456.0.0/16.

sshuttle --dns-hosts 10.2.3.4,10.3.4.5,10.4.5.6,10.5.6.7 -vvr dialin 10.1.2.3/8 123.1.2.3/8 321.456.0.0/16 \ --exclude 10.0.2.1/24 \ --exclude 10.183.252.224/24 \ --exclude 127.0.1.1/8 \ --exclude 224.0.0.1/8 \ --exclude 232.0.0.1/8 \ --exclude 233.252.0.0/14 \ --exclude 234.0.0.0/8

This setup allows you to simply execute that command and enjoy all of your networks. Including name resolution.

GUADEC 2014 in Strasbourg

This year, GUADEC took place in the lovely Strasbourg in France. It was really nice to attend the conference and to hang around with people who care about Free Software. In fact, the venue itself ran Debian which was nice to see 🙂

Unfortunately, I wasn’t able to attend many of the great talks as I wasn’t available for all days. And when I was, I was busy meeting people. Although it felt smaller than the last GUADEC, I think I’ve never met so many people who I wanted to talk to.

The conference offered a two-track program. Interestingly many of them looking out for a future of GNOME. John Stowers gave one of the more important talks, I think. He was describing the situation in academia. Python is very popular in the scientific computing space, he said. He was not satisfied with JavaScript being the new “default” language for GNOME applications, because the contestants are numerous and powerful. So we would compete at least against the Web and Qt. The former apparently being nice on other platforms such as Windows. GNOME’s bindings, however, were very good, he said. The technological foundation is excellent and we should leverage that potential and make people use it. However, GNOME’s story on Windows is not all too good, he said. GTK+ is becoming more and more irrelevant and even Wx appears to be as popular as Gtk. I also heard others claiming that the Windows situation is a problem. What I don’t understand is whether there are technical problems blocking easy to use ports. Apparently introspected GNOME libraries for Pyhon on Windows exist, but I don’t understand why that doesn’t do the job.

Another talk related to the future of GNOME was given byAllan Day. In order for GNOME to be successful, amongst other things, a focus on quality must be established, he said. Various ways to improve the current release process were mentioned and the audience engaged in a vivid discussion. I don’t remember the detail so I hope this will be followed up and discussed more broadly in the GNOME community.

“Why do we do desktop”, asked Matthew Garrett in his presentation. When I read that title for the first time I thought the question of the desktop becoming irrelevant was being picked up. But that was not the case. Instead, he wanted GNOME to differentiate from the existing desktops which, as he claimed, are continuing to be simple multiplexors for running several programs (such as clocks) at the same time. In contrast to existing desktop, GNOME should become the secure desktop. Other desktops, he said, would only exist in order to sell more things to the user, i.e. to tie the user to an existing ecosystem. An advantage of GNOME is it being free from corporate control. Decisions are made very transparently which enables it to focus on brining privacy and security to the user. Even if the user is not aligned with our core values and principles. As such, every user deserves as much privacy and security as we can possible provide.

Many thanks to the local team for having organised the conference. I hope next year in Gothenburg will be at least as good.

Getting cheaper Bahn fares via external services

Imagine you want to go from some random place in Germany to the capital. Maybe because it is LinuxTag. We learned that you can try to apply international fares. In the case of Berlin, the Netzplan for Berlin indicates that several candidate train stations exist: Rzepin, Kostrzyn, or Szczecin. However, we’re not going to explore that now.

Instead, we have a look at other (third party) offers. Firstly, you can always get a Veranstaltungsticket. It’s a ticket rated at 99 EUR for a return trip. The flexible ticket costs 139 EUR and allows you to take any train, instead of fixed ones. Is that a good price? Let’s check the regular price for the route Karlsruhe ←→ Berlin.

The regular price is 142 EUR. Per leg. So the return trip would cost a whopping 284 EUR. Let’s assume you have a BahnCard 50. It costs 255 EUR and before you get it, you better do the math whether it’s worth it. Anyway, if you have that card, the price halves and we have to pay 71 EUR for a leg or 142 for the return trip. That ticket is fully flexible, so any train can be taken. The equivalent Veranstaltungsticket costs 139, so a saving of 3 EUR, or 2%.

Where to get that Veranstaltungsticket you ask? Well, turns out, LinuxTag offered it, itself. You call the phone number of the Bahn and state your “code”. In the LinuxTag case it was “STATION Berlin”. It probably restricts your destination options to Berlin. More general codes are easily found on the Web. Try “Finanz Informatik”,
“TMF”, or “DOAG”.

I don’t expect you to be impressed by saving 2%. Another option is to use bus search engines, such as busliniensuche.de, fernbusse.de, or fromatob.de. You need to be a bit lucky though as only a few of those tickets are available. However, it’s worth a shot as they cost 29 EUR only.

That saves you 80% compared to the original 142 EUR, or 60% compared to the 71 EUR with the BC 50. That’s quite nice, already. But we can do better. There is the “Fernweh-Ticket” which is only available from LTUR. It costs 26 EUR and you need to poll their Web Interface every so often to get a chance to find a ticket. I intended to write a crawler, but I have not gotten around to do it yet…

With such a ticket you save almost 82% or 63% compared to the regular price. Sweet! Have I missed any offer that worth mentioning?

Finding (more) cheap flights with Kayak

People knowing me know about my weakness when it comes to travel itineraries. I spend hours and hours, sometimes days or even weeks with finding the optimal itinerary. As such, when I was looking for flights to GNOME.Asia Summit, I had an argument over the cheapest and most comfortable flight. When I was told that a cheaper and better flight existed that I didn’t find, I refused to accept it as I saw my pride endangered. As it turned out, there were more flights than I knew of.

Kayak seems to give you different results depending on what site you actually open. I was surprised to learn that.

Here is the evidence: (you probably have to open that with a wide monitor or scroll within the image)

In the screenshot, you can see that on the left hand side kayak.de found 1085 flights. It also found the cheapest one rated at 614 EUR. That flight, marked with the purple “1”, was also found by kayak.com and kayak.ie at different, albeit similar prices. In any case, that flight has a very long layover. The next best flight kayak.de returned was rated at 687 EUR. The other two Kayaks have that flight, marked with the green “3”, at around 730 EUR, almost 7% more than on the German site. The German Kayak does not have the Ethiad flight, marked with the blueish “2”, at 629 as the Irish one does! The American Kayak has that flight at 731 EUR, which is a whopping 17% of a difference. I actually haven’t checked whether the price difference persists when actually booking the flights. However, I couldn’t even have booked the Ethiad flight if I didn’t check other Kayak versions.

Lessons learnt: Checking one Kayak is not enough to find all good flights.

In addition to Kayak, I like to the the ITA Travel Matrix as it allows to greatly customise the queries. It also has a much more sane interface than Kayak. The prices are not very accurate though, as far as I could tell from my experiments. It can give you an idea of what connections are cheap, so you can use that information for, e.g. Kayak. Or, for that other Web site that I use: Skyscanner. It allows to list flights for a whole months or for a whole country instead of a specific airport.

What tools do you use to check for flights?

GPN 2014 in Karlsruhe

The Gulash Programmier Nacht (GPN) took place in Karlsruhe, Germany. The local subsidiary of the Chaos Computer Club organised that event, which apparently took place for the 14th time. So far, I wasn’t able to attend, but this time I made it.

It’s a 200 to 300 people event, focussed at hacking, making, and talks around that. It’s very cosy and somewhat similar to the mrmcds. Most of the talks were held in German, a few in English, but I think that could easily change if there is a demand.

The conference was keynoted by tante, who talked about the political aspects of code and the responsibility every developer has. It was good to hear someone saying that you do create reality for people with the software you write and that you are indeed responsible for the view on the world the users of your software have. There were a few other interesting thoughts and I think I agree with the results of the analysis conducted to a great extent. But I think a few areas are not well covered. For example, he said that you limit the people with your software. I don’t think that’s necessarily true. If you provide your users with enough freedoms, i.e. by choosing a Free Software license, than I don’t think his argument is valid anymore.

On the more funny side, a chemist taught us about chemistry based on the stories of Walter White. It was a funny talk with many interludes of the TV series. She explained what the people in the episodes were doing and how close that is to reality. Turns out, it is quite close and at least stupid mistakes were not done.

We also learned about Perl 6. If you think Perl is ugly, he said, it’s not modern Perl. The new and shiny Perl 6 allows you to write short code while looking nice, he said. He showed some features that make it easy to write command line tools. You can simply declare an argument to your main function and Perl would expose that to the user, e.g. by presenting a help screen. It would also detect the types provided and do some magic fancy stuff like checking whether the provided argument is an existing (or empty) file.

A very interesting talk was given on the Enigma, the German crypto machine. He showed the machine that broke the crypto and now stands in Bletchley Park. He told stories about the development and operation of that machine. Very interesting indeed. Also well done on a technical level, the slides were really well done.

I was invited to give talk on GNOME. As you can see in the video, my battery didn’t even last the full 90 minutes slot I was assigned. Something is certainly wrong, either this Linux thing or my battery. Anyway, the talk itself went very well, and it was particularly well attended for that early slot. I was also positively surprised by the audience asking many questions and while I specifically asked for flames, I didn’t get that many.

GNOME.Asia Summit 2014

I was fortunate to be able to attend this year’s GNOME Asia Summit in Beijing, China.

It was co-hosted with FUDCon, the Fedora Users and Developers Conference. We had many attendees and the venue provided good facilities to talk about Free Software and the Free Desktop.

The venue was the Beihai University somewhat north of Beijing. Being Chinese, the building was massive in size. So we had loads of space, anyway 😉 The first day was reserved for trainings and attendees could get their feet wet with thinks like developing a GNOME application. I took part myself and was happy to learn new GNOME APIs. I think the audience was interested and I hope we could inspire a few attendees to create their next application using GNOME technologies.

I was invited to keynote the conference. It was my first time to do such a thing and I chose to give a talk that I would expect from a keynote, namely something that leads the conference and gives a vision and ideas about what to discuss during the conference. I talked on GNOME, GNOME 3, and GNOME 3.12. I tried to promote the ideas of GNOME and of Free Software. Unfortunately, I prepared for 60 minutes rather than 45, so I needed to cut off a good chunk of my talk :-/ Anyway, I am happy with how it went and especially happy with the fact that I wasn’t preaching to the choir only, as we had e.g. Fedora people in the audience, too.

We had RMS explaining Free Software to the audience and I think the people enjoyed his talking. I certainly did, although I think it doesn’t address problems we face nowadays. People have needs, as the discussion with the audience revealed. Apparently, people do want to have the functionality Facebook or Skype offers. I think that addressing these needs with the warning “you must not fall for the convenience trap” is too short sighted. We, the Free Software community, need to find better answers.

The event was full of talks and workshops from a diverse range of topics, which is a good thing for this conference. Of course, co-hosting with FUDCon helped that. The event is probably less technical than GUADEC and attendees can learn a lot from listening and talking to other people. I hope we can attract more Asian people to Free Software this way. I am not entirely sure we need to have the same setup as with GUADEC though. With GUADEC, we change the country every year. But Asia is about ten times larger than Europe. In fact, China alone is larger than all of Europe. It makes it somewhat hard for me to justify the moving around. We do need more presence in Asia, so trying to cover as much as possible might be an approach to attract more people. But I think we should investigate other approaches, such as focussing on an annual event in one location to actually create a strong Free Software location in Asia, before moving on. I wouldn’t know how to define “strong” right now, but we have absolutely no measure of success right now, anyway. That makes it a bit frustrating for me to pour money over Asia without actually seeing anything in return.

Anyway, Beijing is fun. We went to see the Great Wall and enjoyed the subway 😉

I would like to thank the organisers for having provided a great place us, the Free Software community, to spread the word about the benefits of free computing. I would also like to thank the GNOME Foundation for enabling people like me to attend the event.

[Update: Here is the recording of the talk]

Installing OpenSuSE 13.1 on an Lenovo Ideapad S10-3t

I tried to install the most recent OpenSuSE image I received when I attended the OpenSuSE Conference. We were given pendrives with a live image so I was interested how smooth the OpenSuSE installation was, compared to installing Fedora. The test machine is a three to four year old Intel Ideapad s10-3t, which I received from Intel a while ago. It’s certainly not the most powerful machine, but it’s got some dual core CPU, a gigabyte of RAM, and a widescreen touch display.

The initial boot took a while. Apparently it changed something on the pendrive itself to expand to its full size, or so. The installation was a bit painful and, at the end of the day, not successful. The first error I received was about my username being wrong. It told me that I must only contain letters, digits, and other things. It did not tell me what was actually wrong; and I doubt it could, because my username was very legit. I clicked away the dialogue and tried again. Then it worked…

When I was asked about my partitioning scheme I was moderately confused. The window didn’t present any “next” button. I clicked the three only available buttons to no avail until it occurred to me that the machine has a wide screen so the vertical space was not sufficient to display everything. And yeah, after moving the window up, I could proceed.

While I was positively surprised to see that it offered full disk encryption, I wasn’t too impressed with the buttons. They were very tiny on the bottom of the screen, barely clickable.

Anyway, I found my way to proceed, but when attempting to install, YaST received “system error code -1014” and failed to partition the disk. The disk could be at fault, but I have reasons to believe it was not the disks fault:

Apparently something ate all the memory so that I couldn’t even start a terminal. I guess GNOME’s system requirements are higher than I expected.