Running Debian without Unity on a machine that is 64 bit capable!

Sorry Bryan,

I can show you plenty of hardware that is perfectly 64 bit capable but probably never will run Ubuntu and/or Unity.

First, what is 64 bit for you? Looking at ubuntu.com/download and getting images from there, one gets the impression, that 64 bit is amd64 (also called x86_64). If one digs deeper to cdimage.ubuntu.com, one will find non-Intel images too: PowerPC and amrhf. As the PowerPC images are said to boot on G3 and G4 PowerPCs, these are 32 bit. Armhf is 32 bit too (arm64/aarch64 support in Linux is just evolving). So yes, if 64 bit means amd64, I do have hardware that can run Unity.

But you asked if I have hardware that is 64 bit capable and can run Ubuntu/Unity, so may I apply my definiton of 64 bit here? I have an old Sun Netra T1-200 (500MHz UltraSPARC IIe) running Debian's sparc port, which has a 64 bit kernel and 32 bit userland. Unity? No wai.

I do not own any ia64 or s390/s390x machines, but I am sure people do. And guess what, no Unity there either :)

Sorry for ranting like this, but 64 bit really just means that the CPU can handle 64 bit big addresses etc. End even then, it not always will do so ;)

powerdyn - a dynamic DNS service for PowerDNS users

You may not know this, but I am a huge PowerDNS fan. This may be because it is so simple to use, supports different databases as backends or maybe just because I do not like BIND, pick one.

I also happen to live in Germany where ISPs usually do not give static IP-addresses to private customers. Unless you pay extra or limit yourself to a bunch of providers that do good service but rely on old (DSL) technology, limiting you to some 16MBit/s down and 1MBit/s up. Luckily my ISP does not force the IP-address change, but it does happen from time to time (once in a couple of month usually). To access the machine(s) at home while on a non-IPv6-capable connection, I have been using my old (old, old, old) DynDNS.com account and pointing a CNAME from under die-welt.net to it.

Some time ago, DynDNS.com started supporting AAAA records in their zones and I was happy: no need to type hostname.ipv6.kerker.die-welt.net to connect via v6 -- just let the application decide. Well, yes, almost. It's just DynDNS.com resets the AAAA record when you update the A record with ddclient and there is currently no IPv6 support in any of the DynDNS.com clients for Linux. So I end up with no AAAA record and am not as happy as I should be.

Last Friday I got a mail from DynDNS:

Starting now, if you would like to maintain your free Dyn account, you must now log into your account once a month. Failure to do so will result in expiration and loss of your hostname. Note that using an update client will no longer suffice for this monthly login. You will still continue to get email alerts every 30 days if your email address is current.

Yes, thank you very much...

Given that I have enough nameservers under my control and love hacking, I started writing an own dynamic DNS service. Actually you cannot call it a service. Or dynamic. But it's my own, and it does DNS: powerdyn. It is actually just a script, that can update DNS records in SQL (from which PowerDNS serves the zones).

When you design such a "service", you first think about user authentication and proper information transport. The machine that runs my PowerDNS database is reachable via SSH, so let's use SSH for that. You do not only get user authentication, server authentication and properly crypted data transport, you also do not have to try hard to find out the IP-address you want to update the hostname to, just use $SSH_CLIENT from your environment.

If you expected further explanation what has to be done next: sorry, we're done. We have the user (or hostname) by looking at the SSH credentials, and we have the IP-address to update it to if the data in the database is outdated. The only thing missing is some execution daemon or ... cron(8). :)

The machine at home has the following cron entry now:

*/5 * * * * ssh -4 -T -i /home/evgeni/.ssh/powerdyn_rsa powerdyn@ssh.die-welt.net

This connects to the machine with the database via v4 (my IPv6 address does not change) and that's all.

As an alternative, one can add the ssh call in /etc/network/if-up.d/, /etc/ppp/ip-up.d/ or /etc/ppp/ipv6-up.d (depending on your setup) to be executed every time the connection goes up.

The machine with the database has the following authorized_keys entry for the powerdyn user:

no-agent-forwarding,no-port-forwarding,no-pty,no-X11-forwarding,no-user-rc,\ 
command="/home/powerdyn/powerdyn/powerdyn dorei.kerker.die-welt.net" ssh-rsa AAAA... evgeni@dorei

By forcing the command, the user has no way to get the database-credentials the script uses to write to the database and neither cannot update a different host. That seems secure enough for me. It won't scale for a setup as DynDNS.com and the user-management sucks (you even have to create the entries in the database first, the script can only update them), but it works fine for me and I bet it would for others too :)

Update: included suggestions by XX and Helmut from the comments.

Wheezy, ejabberd, Pidgin and SRV records

TL;DR: {fqdn, "jabber.die-welt.net"}.

So, how many servers do you have, that are still running Squeeze? I count one, mostly because I did not figure out a proper upgrade path from OpenVZ to something else yet, but this is a different story.

This post is about the upgrade of my "communication" machine, dengon.die-welt.net. It runs my private XMPP and IRC servers. I upgraded it to Wheezy, checked that my irssi and my BitlBee still could connect and left for work. There I noticed, that Pidgin could only connect to one of the two XMPP accounts I have on that server. sargentd@jabber.die-welt.net worked just fine, while evgeni@golov.de failed to connect.

ejabberd was logging a failed authentication:

I(<0.1604.0>:ejabberd_c2s:802) : ({socket_state,tls,{tlssock,#Port<0.5130>,#Port<0.5132>},<0.1603.0>}) Failed authentication for evgeni@golov.de

While Pidgin was just throwing "Not authorized" errors.

I checked the password in Pidgin (even if it did not change). I tried different (new) accounts: anything@jabber.die-welt.net worked, nothing@golov.de did not and somethingdifferent@jabber.<censored>.de worked too. So where was the difference between the three vhosts? jabber.die-welt.net and jabber.<censored>.de point directly (A/CNAME) to dengon.die-welt.net. golov.de has SRV records for XMPP pointing to jabber.die-welt.net.

Let's ask Google about "ejabberd pidgin srv". There indeed are some bugs. But they are marked as fixed in Wheezy.

Mhh... Let's read again... Okay, I have to set {fqdn, "<my_srv_record_name>"}. when this does not match my hostname. Edit /etc/ejabberd/ejabberd.cfg, add {fqdn, "jabber.die-welt.net"}. (do not forget the dot at the end) and restart the ejabberd. Pidgin can connect again. Yeah.

Opera, standards and why I should have stayed in my cave

So you probably heard that I have that little new project of mine: QiFi the pure JavaScript WiFi QR Code Generator. It's been running pretty well and people even seem to like it.

One of its (unannounced) features is a pretty clean stylesheet that is used for printing. When you print the result will be just the SSID and the QR code, so you can put that piece of paper everywhere you like. That works (I tested!) fine on Iceweasel/Firefox 10.0.12 and Chromium 25.0. Today I tried to do the same in Opera 12.14 and it failed terribly: the SSID was there, the QR code not. And here my journey begins...

First I suspected the CSS I used was fishy, so I kicked all the CSS involved and retried: still no QR code in the print-out.

So maybe it's the QR code library I use that produces a weird canvas? Nope, the examples on http://diveintohtml5.info/canvas.html and http://devfiles.myopera.com/articles/649/example5.html don't print either.

Uhm, let's Google for “opera canvas print”... And oh boy I should not have done that. It seems it's a bug in Opera. And the proposed solution is to use canvas.toDataURL() to render the canvas as an image and load the image instead of the canvas.

I almost went that way. But I felt that urge need to read the docs before. So I opened http://www.w3.org/html/wg/drafts/html/master/embedded-content-0.html#dom-canvas-todataurl and https://developer.mozilla.org/en-US/docs/DOM/HTMLCanvasElement and started puking:

When trying to use types other than "image/png", authors can check if the image was really returned in the requested format by checking to see if the returned string starts with one of the exact strings "data:image/png," or "data:image/png;". If it does, the image is PNG, and thus the requested type was not supported. (The one exception to this is if the canvas has either no height or no width, in which case the result might simply be "data:,".)
If the type requested is not image/png, and the returned value starts with data:image/png, then the requested type is not supported.

Really? I have to check the returned STRING to know if there was an error? Go home HTML5, you're drunk!

Okay, okay. No canvas rendered to images then. Let's just render the QR code as a <table> instead of a <canvas> when the browser looks like Opera. There is nothing one could do wrong with tables, right? But let's test with the basic example first:

Yes, this is 2013. Yes, this is Opera 12.14. Yes, the rendering of a fucking HTML table is wrong. Needles to say, Iceweasel and Chromium render the example just fine. I bet even a recent Internet Explorer would...

That said, there is no bugfixworkaround for Opera I want to implement. If you use Opera, I feel sorry for you. But that's all.

Update: before someone cries "ZOMG! BUG PLZ!!!", I filled this as DSK-383716 at Opera.

QiFi - the pure JS WiFi QR Code Generator

Some time ago, the QR Code Generator - WiFi Access made quite some noise on the mighty Internet. Sure, it is cool to be able to share your WiFi-access with someone by just showing him a QR code he can scan on his phone and the phone will auto-connect to the WiFi. But I get a strange feeling telling someone I do not know my WiFi credentials. No, I do not mean my guests, I know them. I mean that shiny web-service that will generate a QR code for me.

The geek in you will now say: "So? Open up a terminal, install qrencode, pipe it the string WIFI:S:<SSID>;T:<WPA|WEP|>;P:<password>;; and you got our QR code". Yeah, that works. But was it one or two semicolons at the end? And was it really just WPA even if my WiFi uses WPA2? Oh and how do I encode that umlaut again? I do not want to remember this.

Thus, without too much rumble, may I present you: QiFi - the pure JS WiFi QR Code Generator. QiFi is a QR code generator for WiFi access in pure JavaScript. It will generate the QR code on your machine, in your browser, not leaking your precious credentials to anyone (but your guests). Don't trust me? Read the code. Fork the code. Host the code yourself.

I hope you will find QiFi at least slightly useful ;-)