Category Archives: Technology

Really everything related to technology

Electronics, Network, Open Source

My five ADSL modems

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bredbandsbolagetI previously blogged when my network hardware died. Here’s the recap and continuation of that story and how things evolved…

One day my ADSL modem could no longer get sync, I couldn’t send data and my (landline) phone was dead. My phone is connected into the ADSL modem through which it does IP telephony. Other times this has happened I could just switch off the modem for 10 seconds and then back on again it would work again for another 6 months or a year or so.

I’ve had ADSL at roughly 12mbit working flawlessly for several years so this was an unexpected breakage.

On 14 sep 16:16 I called my operator’s (Bredbandsbolaget) support about the issue when the modem hadn’t been able to get contact for a whole day – I was suspecting some kind of glitch in the service from the other end. The support person said that I had a “very old modem” and they immediately decided to send me a new modem by mail that would fix my problems.

xavi technologies x5258-p2At 16 sep 18:51 I called support again. I received modem #2 and installed it this day. The modem, Xavi Technologies X5258-P2, is a much more fancy model than what I had been using for the last couple of years – the new one had 4 Ethernet ports and wifi. Not that I really care about that cruft as I want to use my own wifi router anyway to get control of things better.

When I plugged in modem #2 I noticed that it lit up the ‘phone’ LED at once (which normally would only be on if I use the phone) and while internet data seemed to work, the phone did not. When I called support again to ask about this, they decided it was a broken modem they had sent me and would send me a replacement at once.

A few days later I got modem #3 and installed it. I also got the joy of sending back two ADSL modems.

3 oct 20:25 – I called the support again. Modem #3 hung occasionally and I wanted to get their help to fix the problem. The support guy I talked to claimed his sometimes happens if a wifi router is too close to the modem and adviced me to put my ADSL modem and wifi router further apart. It sounded like a suspicious analysis and theory to me, as why would the modem completely hang from this and if it did, why would it keep on running for days at times after a reboot? The support person also revealed that he had detailed logs going back a few weeks at least where he could see my ADSL modem power recycles and he could also see “bad CRC” counters going up before my restarts. I moved my devices two meters apart.

A little side-story: the modem has wifi support, but as I run my own wifi router behind it I don’t want the modem’s wifi. I noticed it ran on a different channel than my regular one so it wasn’t an immediate concern. It did however turn out that in order to switch it off I had to configure that with a Windows program and in order to install that program I had to enter a username and password that I didn’t have. Asking support for the credentials, they instead offered to simply disable the wifi from their end instead. That was fine by me, but again showed what fancy controls they have over these things.

For a week or so my connection actually was better and I actually thought my suspicions about the fishy advice were wrong. But no. It turned out I was only lucky for a few days as then it started hanging again every few days. It would stop transfering data in/out, and the “phone” led would blink slowly. How on earth could a device like this hang in any circumstance? I’ve been an embedded developer all my professional life, I know hanging is the worst possible thing. I much better but still ugly way to resolve a problem without any obvious way out, would be to reboot. A reboot would’ve been annoying as well, but far from as annoying as this.

Now, after all, I have a fiber installation coming “soon” so I figured I could possibly just shut up and endure this ADSL mess and it will go away or at least change drastically once I get my new connection…

But eventually it got too tedious, also partly because my kids and my wife also found it annoying and troubling – I had to give up the eduring. The fiber installtion also seemed to be delayed. Who knows how long I was supposed to remain on ADSL.

So, on 5 dec 18:38 I was back on the phone with the support people and complained about the hangs I frequently get with modem #3. The guy listened to me explaining the issue, he checked the reboot logs from his side and swiftly decided he would send me a new modem. He decided to send a modem of a different brand this time to see if this made things work better in my end.

zyxel-p-2601hn

On dec 8th I got modem #4. A different model this time compared to #2 and #3. It was now a Zyxel P-2601. I got home from work at 18:15, had a quick dinner and then I connected the new equipment. Would this really be the end of my troubles? Anticipation!

– Oh harsh reality, how thee can be rough and cold.

This modem can’t be powered on. If I flip the power switch and turns it on, all the leds switch on but as soon as my finger leaves the power-on toggle again the modem turns itself off… At 18:52 I tried to call support, but a voice claimed they had “internal systems problems” so I gave up.

12:45 on Friday Dec 9th I called again and reported my broken modem and the friendly support woman was a bit surprised I had gotten a broken device as she said “straight from the factory”. She even expressed some sympathy about the replacement unit, modem #5, not being able to reach me until Monday.

On Monday the 12th I got an invoice wanting to charge me 500 SEK for one of the broken modems they claimed I never sent back so I had to call customer service again and have them not do that. (I find 500 SEK for a broken ADSL modem quite a hefty charge when that’s basically the price for a completely new and working unit…)

December 13, modem #5 arrived and I connected it. It didn’t work at once but the phone worked which gave me a clue, so I connected a laptop directly to the ADSL modem and when I then tried to use a browser on that network I reached an admin interface web server and by using that I could switch the modem over to “bridge mode”. It turned out the default setting for this device is to function as a DHCP server and all sorts of other funny things that I didn’t want it to do.

At the time of this writing, number five has been running without problems for 72 hours.

Open Source, Technology, Web

Swedish FOSS-magasin

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foss-magasinClaes, our friend from foss-sthlm and several Open Source adventures, has just fired off a new initiative: FOSS-Magasin. The site launched for real on the evening November 19th.

Where there’s no real content on the site yet, Claes has set out a mission for himself and future contributors to create a site with technical content in Swedish that we geeks miss. This would be within areas such as FOSS, *nix, networking and more.

Tired of the poor state of technical and IT related media in Sweden that always seem to try to capture the really large audience and therefore always dumb down everything to a silly level, this is meant to be directed on more competent and interested readers.

The site is free and Claes is looking around for contributors to help hem get content to publish. I can only urge my Swedish friends to join up and help it get going, as I think it would be nice to get a proper Swedish tech site. For me, it will be especially interesting for things that actually happen in or otherwise is related to Sweden, as for all the rest I personally have no problems accessing English sites to get the info.

Windows

Who’s 0xabadbabe and why?

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It is Friday after all, so I’ll offer this little glimpse as an example from what I do at work…

A while ago, I was working for a customer (who shall remain unnamed here, but let’s call it Intel) doing system simulation software. I worked on this project for a year or so. I ran full x86 systems completely simulated. During that time I was chasing some nasty bugs in the simulated usb-disk device that caused my Windows boot to end up in a blue screen.

I struggled to figure out why Windows 7 would write 0xABADBABE to EHCI register index 0x1C – which is a reserved register – during boot some 10 milliseconds before the blue screen appears, and I was convinced that it was due to a flaw in the EHCI simulation code and thus was the first indication of the failure. If I didn’t have any simulated usb-disk inserted that write wouldn’t occur, and similarly that write would occur even if I inserted the usb-disk much later – like even after Windows 7 had started and I was passed the login screen.

An interesting exercise is to grep for this (little-endian so twist it around!) 32 bit pattern in a freshly installed windows 7 file system – I found it on no less than 16 places in a 20GB file system. This bgrep utility was handy for this.

To properly disassemble that code, I hacked up a quick bcut tool so that I could cut out a suitable piece of the 20GB file to pass to objdump, as objdump very inconveniently does not offer an option to skip an arbitrary amount from the beginning of a file! Also, as it is not really possible to easily tell on which byte x86 code starts at, I had to be able to fine-adjust the beginning of the cut so that objdump would show correctly (this is x86-64):

      callq  *0x9061(%rip)        # 0x9080
      mov    0x40(%rsi),%r11d
      mov    %rsi,0x58(%rdi)
      mov    %r11d,(%rdi)
      mov    0x40(%rsi),%eax
      mov    %rsi,0x60(%rdi)
      mov    %eax,0x4(%rdi)
      mov    0xa0(%r13),%rax
      movl   $0xabadbabe,0x1c(%rax)

But then, reading that code never gave me enough clues to figure out why the offending MOV is made.

Thanks to a friend with a good eye and useful resources, I finally learned that Windows does this write on purpose to offer some kind of break-point for a debugger. It always does this (assuming a USB device or something is attached)!

A red herring as far as I’m concerned. Nothing to bother about, just MOV on! I simply made the simulation accept this.

Oh. You want to know what happened to the blue screen? It had nothing at all to do with the bad babe constant, but turned out to be because the ehci driver finds out that some USB data structs the controller fills in get pointers that point to memory outside of the area the driver has mapped for this purpose. In other words it was a really hard to track down bug in the simulated device.

Network

Hear me talk at FSCONS 2011

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First, allow me to mention that I like FSCONS. I’ve been there several years, I’ve spoken there every year I’ve been there and I know and like a bunch of the persons in the team putting it together. Good stuff!

I wasn’t supposed to do any talk at FSCONS this year, and I did feel a little empty and lost because of it.

FSCONS… then an empty slot appeared, a question was asked, a subject was suggested and suddenly I ended up having agreed to do a talk and the void has been filled again. I’m glad. I hope someone else will be too and I will try to excite the audience with a talk titled “SPDY: An experimental protocol for a faster web” or something like that. It will have to do for now. It is currently planned to take place at 17:15 on Saturday 12th of November.

My thinking is to explain SPDY in detail, explain the reasoning behind it, the problems that have lead up to its creation and I’ll try to shed the lights on the alternatives and make some guesses what I think the future will hold in terms of web transports and what we will NOT see… I might even manage to acquire further insights of this from my ventures into libspdy.

If you have any related thoughts or questions, feel free to ask me ahead of time and I might be able to adjust my talk for it.

cURL and libcurl, Network

libspdy

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SPDY is a neat new protocol and possible contender to replace HTTP – at least in some areas and for some use cases. SPDY has been invented and developed mostly by Google engineers.

SPDY allows better usage of fewer TCP connections (since it sends multiple logical streams over a single physical TCP connection) and it helps clients overcome problems with TCP (like how a new connection starts slowly) while at the same time reducing latency and bandwidth requirements. Very similar to how channels are handled over an SSH connection.SPDY

Chrome of course already supports SPDY and Firefox has some early experimental support being worked on.

Of course there are also legitimate criticisms against SPDY as well, including subjects like how it makes caching proxies impossible (because everything goes over SSL), how it makes debugging a lot harder by using compressed headers, how it is impossible to extract just a single header from the stream due to its compression approach and how the compression state buffers make each individual stream use more memory than plain old HTTP (plain TCP) ones.

We can expect SPDY<=>HTTP gateways to appear so that nobody gets locked into either side of these protocols.

SPDY will provide faster transfers. libcurl is currently used for speed reasons in many cases. To me, it makes perfect sense to have libcurl use and try to use SPDY instead of HTTP exactly like how the browsers are starting to do it, so that the libcurl using applications will get their contents transferred faster.

My thinking is that we introduce some new magic option(s) that makes libcurl use SPDY, and for normal easy interface transfers it will remain to use a single connection for each new SPDY transfer, but if you use the multi interface and you enable pipelining you’ll instead make libcurl do multiple transfers over the same single SPDY connection (as long as you speak with the same server and port etc). From an application’s stand-point it shouldn’t make any difference, apart from being faster than otherwise. Just like we want it!

Implementation wise, I would like to use a reliable and efficient third-party library for the actual SPDY implementation. If there doesn’t exist any, we make one and run that one independently. I found libspdy, but I found some concerns about it (no mailing list, looks like one-man project, not C89 compliant, no API docs etc). I mailed the libspdy author, I hoping we’d sort out my doubts and then I’d base my continued work on that library.

After some time Thomas Roth, primary libspdy author, responded and during our subsequent email exchange I’ve gotten a restored faith and belief in this library and its direction. Not only did he fix the C89 compliance pretty quickly, he is also promising rather big changes that are pending to get committed within a week or so.

Comforted by what I’ve learned from Thomas, I’ll wait for his upcoming changes and I’ll join the soon to be created mailing list for the libspdy project and I’ll contribute some ideas and efforts to help shape it into the fine SPDY library we all want. I can only encourage other fellow SPDY library interested persons to do the same!

Updated: Join the SPDY library development

Network

Network hardware deaths

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Things went southwards already this morning. My wife was about to work from home and called me before 8am asking for help to get online as the wireless Internet access setup didn’t work for her.

As this has happened at some occasions before she knew she might need to reboot the wifi router to get things running again. So she did. Only this time, when she inserted the power plug again there was not a single LED turning on. None. She yanked it out again and re-inserted it. Nothing.

Okay, so she was not able to use the wifi and the router was dead.

At lunch, I took a short walk in the sunshine to my nearest “Kjell & Co” and got myself a new wifi router and brought it back with me home after work and immediately replaced the dead one with the new shiny one. I ran upstairs (most of my network gear is under the staircase on the bottom floor while my main computer andlink DIR 635d work space is on the upper floor), configured the new router with the static IP and those things that need to be there and…

…weird, I still can’t access the Internet!

I then decided to do the power recycle dance with the ADSL modem as well. I could see how the “WAN” led blinked, turned stable and then I could actually successfully send several ping packets (that got responses) before the connection broke again and the WAN led on the modem was again switched off. I retried the power cycle procedure but the led stayed off.

I called customer support for my ADSL service (Bredbandsbolaget) and they immediately spotted how old my modem is, indicating that it was probably the reason for the failure and set me up to receive a free replacement unit within 2-3 days.

This left me with several problems still nudging my brain:

  1. Why would suddenly two devices standing next to each other, connected with a cat5, break on the same day when they both have been running flawlessly like this for years? I had perfect network access when I went to bed last night and there were no power outages, lightning strikes or similar.
  2. Why and how could the customer service so quickly judge that the reason was the age of my modem? I get the sense they just knee-jerk the replacement unit because of the age of mine and there’s a rather big risk that when I plug in the new modem in a few days it will show the same symptoms…
  3. 2-3 days!! Gaaaah. Thank God I can tether with my phone, but man 3G may be nice and all but its not like my trusty old 12mbit ADSL I tend to get. Not to mention that the RTT is much worse and that’s a factor for me who use quite a lot of SSH to remote machines.

I guess I will find out when the new hardware arrives. I may get reason to write a follow-up then. I hope not!

Update on September 23rd:

A new ADSL modem arrived just two days after my call and yay, it could sync and I could use internet. Unfortunately something was still wrong though as my telephone didn’t work (I have a IP-telephony service that goes through the ADSL box). I took me until Sunday to call customer service again, and on Tuesday a second replace modem arrived which I installed on Thursday and… now even the phone works!

I never figured out why both devices died, but the end result is that my 802.11n wifi works properly with speeds above 6.5MB/sec in my house.

Mail

generic opt-in spam lists don’t exist

The last couple of days I’ve received a number of Swedish spam emails and I started digging up the Swedish companies behind them. The vast majority of all spams I get and have gotten during the years are English, so the Swedish ones stand out and they are a relatively new thing.

There seems to be a range of companies that now offer “email marketing” as a service to other companies. And there are lots of companies apparently willing to use such services. The other day the somewhat respected ISP company Crystone for example went ahead and spammed “a few hundred K recipients (link to a Swedish-speaking forum). I’ve long been annoyed by the repeated spam mails I get from the company Jajja, which apart from being in the snake oil business (SEO) seems to be a legitimate business that wants to be taken seriously. Of course, they have a shady history of bad business ethics (link to Swedish article about Jajja doing blog-comment spamming in 2007).

A can with spamCrystone’s excuse for their spam outburst was that they had bought this list of “verified” and “opt-in” addresses (from big-time spammer company mailcom.se) so they were quite surprised when large amounts of people started complaining and whining about their spam. mailcom.se, unsurprisingly, on their site boast to also have Jajja as customers. I have emailed mailcom.se and complained in strongly worded terms. I expect no response or effect.

Hejsan

Detta är ett av tjogtals (hundratals?) spam email jag fått från er. Ni har hittat/köpt denna email-address genom web-scraping och ni och era kunder är inget annat än spammare. Det är illegalt i Sverige och att betrakta som ett vedervärt sätt att försöka marknadsföra någonting.

Fy skäms!

The above is the email text I sent. It could be translated into English like:

Hello

This is one of the many (hundreds?) spam emails I’ve received from you. You found / bought this email address by web-scraping and you and your customers are nothing but spammers. It is illegal in Sweden and to be regarded as a horrible way of trying to market anything.

Shame on you!

Newsflash: there is no such thing as a blanket list with verified and opt-in email addresses. You may get people to opt-in for a particular and well explained purpose, but nobody ever asked anyone if they wanted to get stupid market emails from Crystone without compensation. Who would have opted-in to something like that?

Legality? People here in Sweden are quick to point out that sending market emails to companies and other business is not illegal here. Although, as is easily proven, these guys don’t know who they target as their list clearly is created by old fashioned web scraping techniques and they send to anyone, individuals and companies – without discrimination. Besides, my biggest complaints against spam is that it is a nuisance and a pain, if it is illegal or not is not the biggest concern to me. Spam is spam no matter what.

I’ve also explicitly tweeted about the spam service provided by quicknet.se. They’re at least somewhat open about it and add a header in their outgoing mails claiming them to be from “QuicNet_AB” (notice how the letter k is absent). I’ve received several spams via their domain gallerian.org so there’s no doubt who’s behind them. These mails also have ended up targeted to email addresses that are without any doubt harvested from the web. An employee of quicknet responded to me (in Swedish), apparently surprised by my allegations but I’ve received no further info. But frankly, I don’t care what excuse they can come up with. It will only be something lame as this is not a mistake.

Other seemingly popular Swedish spam companies include epostservice.se/com, epostarna.se and so on. I wish more people will react on the spam and object to the companies that buy these services (in good faith or not) and to the companies that provide these services. Tell them it’s all spam, no matter what excuses they can figure out!

PS. Yes, this is the same Crystone I’ve written about before…

Electronics, Open Source, Technology

I like a good firmware bump

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So I have this TV that I got for Christmas 2009. As it happens the guys at Philips clearly kept fixing the software and removed bugs after that moment. No surprise there really. I’ve been an embedded software developer for some twenty years by now. I know that software never gets “done” and that what ships in products is only what seems to be “good enough” at some point in time. Sometimes of course not even that good.

So the other day I took a photo of my TV firmware version. It shows how the firmware was made in April 2009. I did it during a discussion with a friend who happens to have the exact same TV as I do, and it then of course turns out he has a different (newer) firmware.

Oh right, I wonder if I can upgrade to a newer one? Once I’ve mastered the maze of the Philips web site I eventually found a download link and PDFs that told me how to. The list of fixes since my version was extensive and I noticed a few flaws mentioned that I have actually experienced!

The TV firmware download was a whopping 43MB. I realize this is because it is a full-fledged Linux system with kernel and God knows what else they’ve crammed in there. I decided to give it a closer check! The result of that was a little disappointing. It is quite clearly encrypted after some basic initial header.

hexdump -C firmware image

The data that starts on offset 0x220 is not x86 instructions and in fact nothing in the beginning of the file looks like x86 code (I just ran a quick “objdump -D –target binary -m i386” on the file). Of course, I don’t know what architecture my TV runs so perhaps even checking for x86 is wrong. I know MIPS is popular in DVDs, settop-boxes and related graphics stuff but…. Nah, I decided it really wasn’t worth the effort so I stopped investigating. I have no real intention of hacking on it anyway.

So I instead proceeded to the actual procedure of upgrading the thing.

Unzip the zip file and put the file in the root dir of a FAT32-formatted usb-stick. The instructions of course didn’t say it needs to be FAT32 but I used that and it worked, and I just smug in the dark to how a manufacturer like this just assumes that we would have FAT32 on our usb-sticks…

But I digress. When I inserted the upgrade USB, the TV switched itself off, was dark for a short while and then turned itself on again and showed the firmware upgrade screen.

The process was very fast, just like 30-40 seconds or something like that and then it was done and asked me to remove the “media” and restart. Of course we know that a usb stick is “media” so I removed it from the TV set.

The instructions were very clear that to “restart” the TV I must only press the ON/OFF button on the remote once and only once. So I was careful to do just that… 😉

Nothing strange happened, but after a brief moment of black screen the regular and familiar interface.

I jumped into the firmware version menu to check it out and yes, it shows an updated version now:

I did a quick check to see if I could detect my previous quirks now, but they may really be gone. They’ve been related to sound through HDMI and some graphical “glitches” when feeding the TV with full HD from a laptop.

So, with this firmware that was shipped many months after I got my TV, I seem to have gotten a better product.

I haven’t yet tested this new version to a significant degree so I don’t know yet if I’ve gotten some new nasty side-effects from it, as sometimes these kinds of firmware upgrades really cause you pain when something that formerly used to work so good suddenly turns out to not work that good any longer.

Network, Security

What SOCKS is good for

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You ever wondered what SOCKS is good for these days?

To help us use the Internet better without having the surrounding be able to watch us as much as otherwise!

There’s basically two good scenarios and use areas for us ordinary people to use SOCKS:

  1. You’re a consultant or you’re doing some kind of work and you are physically connected to a customer’s or a friend’s network. You access the big bad Internet via their proxy or entirely proxy-less using their equipment and cables. This allows the network admin(s) to capture and snoop on your network traffic, be it on purpose or by mistake, as long as you don’t use HTTPS or other secure mechanisms. When surfing the web, it is very easily made to drop out of HTTPS and into HTTP by mistake. Also, even if you HTTPS to the world, the name resolves and more are still done unencrypted and will leak information.
  2. You’re using an open wifi network that isn’t using a secure encryption. Anyone else on that same area can basically capture anything you send and receive.

What you need to set it up? You run

ssh -D 8080 myname@myserver.example.com

… and once you’ve connected, you make sure that you change the network settings of your favourite programs (browsers, IRC clients, mail reader, etc) to reach the Internet using the SOCKS proxy on localhost port 8080. Now you’re done.

Now all your traffic will reach the Internet via your remote server and all traffic between that and your local machine is sent encrypted and secure. This of course requires that you have a server running OpenSSH somewhere, but don’t we all?

If you are behind another proxy in the first place, it gets a little more complicated but still perfectly doable. See my separate SSH through or over proxy document for details.