I’ve never understood why some people consider their voting choices a matter of national security, so when via Andrew McMillan, I saw a good rationale for why you should share your opinion I found my excuse to write this post.

Party Vote
I’ll be voting for National. I’m philosophically much closer to National than Labour, particularly on economic and personal responsibility issues, but even if I wasn’t the thought of having Phil Goff as Prime Minister would be enough to put me off voting Labour. His early career seems strong, but lately it’s been one misstep and half-truth after another, the remainder of the Labour caucus and their likely support partners don’t offer much reassurance either. If I was left-leaning and the mess that Labour is in wasn’t enough to push me over to National this year then I’d vote Greens and hope they saw the light and decided to partner with National.

Electorate Vote
I live in Dublin, but you stay registered in the last electorate where you resided, which for me is Tamaki. I have no idea who the candidates there are, so I’ll just be voting for the National candidate for the reasons above.

MMP Referendum
I have no real objections to MMP and I think it’s done a good job of increasing representation in our parliament. I like that parties can bring in some star players without them having to spend time in an electorate. I don’t like the tendency towards unstable coalitions that our past MMP results have sometimes provided.

Of the alternatives, STV is the only one that I think should be seriously considered, FPP and it’s close cousin SM don’t give the proportionality of MMP and PV just seems like a simplified version of STV with limited other benefit. If you’re going to do preferential voting, you might as well do it properly and use STV.

So, I’ll vote for a change to STV, not because I’m convinced that MMP is wrong, but because I think it doesn’t hurt for the country to spend a bit more time and energy confirming that we have the right electoral system. If the referendum succeeds and we get another referendum between MMP and something other than STV in 2014, I’ll vote to keep MMP. If we have a vote between MMP and STV in 2014 I’m not yet sure how I’d vote. STV is arguably an excellent system, but I worry that it’s too complex for most voters to understand.

PS. Just found this handy list of 10 positive reasons to vote for National, if you’re still undecided and need a further nudge. Kiwiblog: 10 positive reasons to vote National

I had the first opportunity to use their services today when I needed an SSL cert to secure the IMAP server I run for my parents and I was very pleased with the experience. The web interface is a bit weird and you have to jump through some strange hoops, but to save paying more money to the SSL certificate cartel it seemed more than worthwhile.

Like most CAs these days the certificate which signs your server certificate is not the actual root certificate included in your operating system or browser, but an intermediate CA certificate which is in turn signed by the root certificate. This means that you have to ensure that your server includes the intermediate CA certificate alongside the server certificate so the client can validate the entire path back to the root.

Unlike Apache which explicitly allows you to specify a certificate chain file, the openssl methods used by Cyrus 2.2 only seem to recognise a single CA certificate in the file pointed to by tls_ca_file. All as not lost however, as the openssl libraries are actually quite smart and will automagically determine which intermediate certs they need to bundle into the handshake if you install them appropriately under /etc/ssl/certs (at least on Debian).

The trick is that you have to install the intermediate CA cert into a file named after the hash of the certificate, like so:

# wget http://www.startssl.com/certs/sub.class1.server.ca.pem -O /etc/ssl/certs/startcom-class1-intermediate.pem
# hash=$(openssl x509 -hash -noout -in /etc/ssl/certs/startcom-class1-intermediate.pem)
# ln -s ./startcom-class1-intermediate.pem /etc/ssl/certs/${hash}.0
# ls -l /etc/ssl/certs/${hash}.0
lrwxrwxrwx 1 root root 34 2011-06-13 07:43 /etc/ssl/certs/ea59305e.0 -> ./startcom-class1-intermediate.pem


Then in imapd.conf:

tls_cert_file: /etc/ssl/certs/your-server-cert.pem
tls_key_file: /etc/ssl/private/your-server-key.key
tls_ca_file: /etc/ssl/certs/startcom-ca.pem


Voila. Works everywhere I’ve tried so far.

Start Com – Highly Recommended. I’ll be using them for any future SSL certificate purchases (e.g. EV certs) that I need to make.

By default Linux will ignore IPv6 RAs if the interface is configured to forward traffic. This is in line with RFC2462 which states that a device should be either a Host or a Router. If you’re forwarding packets you’re a router and you’re therefore expected to be sending RAs, not receiving them. This policy does make a certain amount of sense but there are obviously situations where it can be useful to accept RAs and still forward packets over the interface[0]. The confusing part is that the Linux IPv6 stack allows the accept_ra sysctl to be set to 1 (enabled) at the same time as the forwarding sysctl is set to 1, yet all incoming RAs are ignored with no hint as to why. If you’re not aware that the default behaviour is to ignore RAs when forwarding is enabled it looks very much like autoconfiguration has simply broken.

The key piece of information is that makes everything as clear as mud is realising that the forwarding and accept_ra sysctl’s are not simple boolean enabled/disabled flags like many of their brethren. There are instead three possible values for each, all clearly documented in sysctl.txt, when you take the time to read it. Ironically the documentation states the type of the values as “BOOLEAN” even though they’re not… at least it helped me to feel better about my hasty assumption that the sysctl’s were boolean values.

accept_ra – BOOLEAN
Accept Router Advertisements; autoconfigure using them.

Possible values are:
0 Do not accept Router Advertisements.
1 Accept Router Advertisements if forwarding is disabled.
2 Overrule forwarding behaviour. Accept Router Advertisements
even if forwarding is enabled.

Functional default: enabled if local forwarding is disabled.
disabled if local forwarding is enabled.

The documentation for forwarding is similar, but much longer, so you can refer to the link above to see it.

Conclusion: If you want to autoconfigure IPv6 addresses on an interface that you’re also forwarding IPv6 traffic over, you need to set accept_ra to 2.

No doubt there are more IPv6 quirks and defaults like this waiting to trap me in the future

[0] Arguably you really don’t want to be autoconfiguring addresses on your router ever, but that’s a philosophical debate that isn’t really relevant to this post.

Almost as much fun as reading on the device has been learning about how it works. The Mobile Read forums have lots of step by step posts on how to do specific tasks like replacing the screensaver image, but they don’t give much background detail on how the Kindle is actually operating which is what really interests me. Luckily among all the step by step posts I also found a “usbnetwork” package which also adds an SSH server to the Kindle, so after installing that and then SSHing in to my Kindle I’ve been poking around.

Under the cover the Kindle reveals a fairly standard Linux installation. While the hardware and IO devices are obviously unique, compared to something like an Android phone, the Kindle is refreshingly “normal”.

Hardware

• Freescale MX35 ARMv6 based CPU with Java specific instruction support.
• 256MB RAM
• 4GB of internal flash presented as an SDHC device with four partitions. A ~700MB root partition, a ~30MB /var/local partition, another roughly 30MB kernel partition and then the rest (~3.1G) as the writeable “user” partition where your books and other content are stored. The root and /var/local partitions are ext3! (not jffs or some other more traditional flash based file system) while the user partition is vfat for easy use with Windows, etc.
• The board is code-named ‘luigi’ and there are lots of references to ‘mario’ and ‘fiona’ scattered around the device, and even in some URLs on Amazon’s website. Someone was obviously a Super Mario fan.
• The wireless chipset is Atheros based using the ar6000 drivers.
• The WAN (3G) modem presents itself as a USB serial device and is controlled via a custom daemon named ‘wand’ which uses the standard Linux pppd package to establish IP connections over a private APN Amazon (provided by Vodafone here in Ireland).
• The EInk display shows up as some special files under /proc rather than as a device. With a bit of digging I found some simple constants that when written to the proc files cause the screen to display the standard boot/progress/upgrading images. I haven’t deciphered how to make more complex updates to the display yet.

Software

• The kernel is based on Linux 2.6.26, with a bunch of hardware specific patches and drivers from lab126.com, an Amazon subsidiary who appear to be responsible for much of the low-level driver and device development.
• Lots of familiar open source projects are present, e.g. syslog-ng, DBus, busybox, pppd, wpa_supplicant, gstreamer, pango, openssl and the list goes on. You can download all the sources from Amazon’s website. I haven’t spent any time to see what if anything has been modified.
• There were a few unexpected finds as well such as GDB and powertop! No doubt useful for the developers, but highly unlikely to actually be used on a shipping Kindle.
• Boot-up is controlled by a set of sysv style init scripts which setup the filesystems and then start a handful of daemons to look after the low-level subsystems (network, power, sound) as well as the standard syslog and cron daemons you’d expect to see on any Linux box.
• Once the basic system is up and running the init scripts kick off the “framework” which lives under /opt/amazon/ebook and consists of lots of Java classes. The system uses the cvm Java environment from Sun/Oracle which is specialised for embedded low-memory devices like this. The framework appears to take over most of the co-ordination, management and interaction tasks once it has started up.

The application/framework code is heavily obfuscated apparently using the Allatori Java Obfuscator. The jrename and jd-gui utilities have proven very handy in helping to untangle the puzzle, although they still only leave you with a pile of Java source code with mostly single letter alphabetic variable and class names! I’ve been using IntelliJ’s support for refactoring/renaming Java code to slowly work through it (thanks in large part to error/log messages and string constants found through the code which can’t be obfuscated easily and help to explain what is going on), and I’m slowly beginning to piece together how the book reading functionality works. I’ll maybe write more on this in a future post.

In one of my initial tweets about the Kindle I mentioned that it seemed to be regularly uploading syslog data to Amazon based on some sendlogs scripts I’d noticed and a few syslog lines containing GPS co-ordinates that had been pasted on the Mobile Read forums. I can’t find any trace of GPS co-ordinates in any syslog messages I’ve seen on my device, but there is definitely information about the cell sites that my Kindle can see, the books that I’m opening and where I’m up to in them:

101206:235431 wand[2515]: I dtp:diag: t=4cfd77b7,MCC MNC=272 01,Channel=10762,Band=WCDMA I IMT 2000,Cell ID=1362209,LAC=3021,RAC=1
,Network Time=0000/00/00 00.00.00,Local Time Offset=Not provided,Selection Mode=Automatic,Test Mode=0,Bars=4,Roaming=1,RSSI=-88,Tx
Power=6,System Mode=WCDMA,Data Service Mode=HSDPA,Service Status=Service,Reg Status=Success,Call Status=Conversation,MM Attach St
ate=Attach accept,MM LU State=LU update,GMM Attach State=Attach accept,GMM State=Registered,GMM RAU State=Not available,PDP State=
Active,Network Mode=CS PS separate attach mode,PMM Mode=Connected,SIM Status=Valid; PIN okay; R3,MM Attach Error=No error,MM LU Er
ror=No error,GMM Attach Error=No error,GMM RAU Error=Not available,PDP Rej Reason=No error,Active/Monitored Sets=0;39;-11 1;180;-1
5,RSCP=-111,DRX=64,HSDPA Status=Active,HSDPA Indication=HSDPA HSUPA unsupp,Neighbor Cells=,Best 6 Cells=,Pathloss=,MFRM=,EGPRS Ind
ication=,HPLMN=,RPLMN=272;01 ,FPLMN=234;33 234;30 234;20 272;05 ,n=1:

101206:233416 udhcpc[5639]: Offer from server xxx.xxx.2.254 received
101206:233416 udhcpc[5639]: Sending select for xxx.xxx.2.10...


Interestingly you can see from the last two lines, that Amazon has taken some care to preserve privacy by not including the full IP address given to the device by my local Wifi network, so in light of that I find it interesting that they decided not to obfuscate the Cell and Book IDs in those respective log messages too. Seems rather inconsistent.

As to how and when these logs are sent to Amazon, the picture is a little bit murky. Every 15 minutes tinyrot runs out of cron and rotates /var/log/messages if it is greater than 256k in size. Rotated logs are stored into /var/local/log under filenames like messages_00000044_20101207000006.gz and alongside the log files are a set of state files named nexttosendfile, messages_oldest, messages_youngest. Something regularly sweeps through this directory to update the state and remove the old logs (after sending them up to Amazon I assume). I suspect that something is buried in the Java application code mentioned above.

On the whole the Kindle is a fascinating piece of technology. It delivers a wonderful reading experience on top of a familiar Linux system and is going to provide me with many more hours of entertainment as I unpack all the tricks and techniques that have gone into this device. I would recommended it as a present for geeks everywhere.

To set the context for that statement, Xero Business set the bar high. I first used the original version of Xero while it was still in beta and even then it was clear that it was an application that took accounting to a new level and would provide an order of magnitude improvement in how I maintained the accounts for our business. That promise held true once we started paying for it, even though the cost of Xero is more than 10% of our annual expenses, the time and hassle it saves makes it a worthwhile investment. By contrast today’s release of Xero Personal offers nothing new above existing personal finance websites or desktop packages and would take me extra time to use as it fails to handle many of the basic transactions that a normal household will encounter.

The way Xero Personal works is by having you manually upload your bank statements (the automatic import functionality that is so useful in the business version of Xero has been restricted to BNZ MoneyMap customers only). For each transaction you are asked to provide two pieces of information. The first is a category which serves as a basic form of account to track expenses and income. For each category you can set a spending or saving goal which Xero will help you track progress towards. The second is a name to identify the other party in the transaction. Xero Personal comes pre-loaded with some fairly generic categories. Annoyingly you’re restricted to no more than 8 additional custom categories and the names associated with each transaction are are simple strings – you can’t link a transaction to another account or entity. To represent a transfer you need two separate transactions, one in each account, which you assign to the special category “Transfer” so that Xero knows to essentially ignore it. Nothing links the transactions together or ensures that the values balance.

In addition to the basic categorisation functionality the application also attempts to track your assets and liabilities (bank accounts and credit cards show up automatically) so that it can compute your net worth. Unfortunately as soon as you try and use this you hit the problem that there is no way to link transactions from your accounts back to your assets and liabilities. This means unless you regularly and manually update your assets and liabilities the “net worth” calculation only takes into account changes in your cash position and becomes blatantly incorrect.

As an example, take the common case of a household with a weekly mortgage (or other loan) repayment. You want the weekly payment to decrease the balance of your current account, increase the balance of your interest expense category and decrease the value of your mortgage liability. Your net worth should decrease by the value of the interest expense only, as the decrease in the value your mortgage liability offsets the remainder of the decrease in the value of your current account.

Xero Personal doesn’t come close to being able to handle this example today. The ability to split payments to different categories has also been left out (even though it’s present in Xero Business and therefore presumably in the underlying engine) so your only option is to categorise the entire payment as a mortgage or housing expense, decreasing your net worth by the full value of the payment. Even if you could split the payment between two categories, one for the interest and one for the principal the inability to link the category for the principal to the liability account means the net worth calculation will still be incorrect.

Maybe I’m being to hard on this newly released product? It is a SaaS application after all and Xero has an excellent history of releasing regular updates to the business version of Xero. The reason I’m so surprised and disappointed by this initial release is that it essentially lacks any double-entry accounting support – many of the missing features are core functionality that is already implemented in the accounting platform that supports the business version. Assuming that Xero Personal is built on the same platform (and that would be the obvious choice wouldn’t it?) the fact that Xero Personal has been released and is being heavily promoted without these features (compared to the initial version of Xero Business which was fully functional and obviously awesome even in beta) suggests to me that it’s a conscious decision to significantly limit the scope and usefulness of the application rather than simply a limit on what could be implemented before the initial release.

I sincerely hope that I’m wrong and that the coming months bring significant improvements to the functionality of Xero Personal, but until it can support common transactions like mortgage repayments correctly I won’t be using it or recommending it to anyone.