My previous blog on interrupt-free computing has been very well read. I've had a look at some practical implementation possibilities and can share some more details about how to go about it and potential problems. No perfect solution They say that a certain billionaire is so rich that he would not spend 5 seconds bending over to pick up a $100 banknote on the ground because he makes $500 in 5 seconds anyway. A man from Ethiopia may well run a marathon for the same $100. This little anecdote underlines the point that no two people have exactly the same priorities and it is hard to provide a one-size-fits-all solution. A good technical solution needs to let the user have some control over their own priorities as that will go a lot further in respecting their preferences, their objectives and their environment. A practical example: some users may not want to be disturbed by a VoIP call while watching a movie with their PC. Other users may be quite happy to receive these interruptions. Some users may want to only allow this interruption from a subset of possible callers. Building blocks In the original blog on this subject I suggested that Thunderbird and it's popular plugin, Mozilla Lightning calendar would provide one useful framework for integrating events, alerts and to-do items of various grades of importance. I already use these applications myself, from the re-branded icedove and iceowl-extension packages on Debian. They are also available in Fedora and many other distributions. Priority with Lightning An initial look at Lightning reveals a Priority attribute for tasks. It can be set to the values High, Medium or Low. These don't map to the concepts of Urgency and Importance from the Eisenhower method discussed in the original blog. Potential hacks: there are two ideas that come to mind, with no coding changes:

• One possibility is to set Due dates for any item that has the Urgent characteristic and no date for items without the characteristic. In this case, the Priority attribute can then be used to distinguish Important and non-Important tasks.
• The other possibility is to use the Categories feature to define four categories: Urgent-Important, non-Urgent-but-Important, Urgent-non-Important and neither-Urgent-Important.

A more elegant solution would be to develop an additional plugin that provides new attributes for the Urgency and Importance characteristics. For server-side storage of these attributes, it would be feasible to use extension properties as defined in RFC 2445, for example, X-urgency and X-importance This approach would make it easier to view a large range of tasks across multiple domains with the most urgent and important tasks at the top. Ideally, the Categories attribute of tasks can be used to distinguish tasks that relate to work (or project/client) from personal tasks (such as planning a holiday) Challenges with Lightning Some of the challenges that I've identified after reviewing this solution:

• the Categories in Lightning don't appear to be synchronized with the Tags used in Thunderbird for email.
• Furthermore, the Tags are not synchronized automatically with the list of server-side IMAP keywords and somebody having multiple Thunderbird profiles (e.g. on both a desktop and a laptop) needs to manually synchronize the lists of tags and categories between all their devices.
• Many people use mobile devices such as smartphones and tablets to access their email, calendar and tasks. The lightweight mail/calendar clients on these devices don't support the full range of features for classification of content. Furthermore, their low-resolution user interfaces may even make it difficult to replicate the same experience on a mobile device. There is some hope, for example, rooting a tablet device and installing Linux would allow it to run a proper installation of Thunderbird with the various plugins described above.

Feeding system events and other data into the pipeline Given the text-based nature of the iCalendar format, it should be easy enough for any application that is capable of generating mail to generate these iCal events with X-Urgency and X-importance properties. These events - such as alerts about security updates - could then be dispatched through the system's mailer. Some additional effort may be needed to avoid duplication. The notification system in the desktop UI may then prioritize events from the mailbox rather than showing all alerts in real-time. Only applications that implicitly need to do so (such as VoIP/chat clients) would display notifications to the user directly. Conclusion: Interrupting the user Finally, after gathering all the events for the user in a mailbox like this, it would be possible for the plugin to be configured to interrupt the user only when some event reaches the user's own urgency/importance threshold. For example:

• The user may want to be interrupted for Urgent items with a deadline in less than 24 hours, but if the task has a work' category, only interrupt during business hours
• For all other items, the user only sees them when they open Lightning or some other calendar/task management application to explicitly review things that they need to do.

Some weeks ago, our Prime Minister was slashdotted when she suspended her usual racist attacks on refugees to attack foreign IT workers and the companies that employ them with absurd accusations of "rorts" and "stealing" jobs. Today, she's introduced new laws in the parliament aiming to further bastardization of intelligent, skilled and educated workers and anybody who associates with them, including Australian employers. Unwarranted attention on a minority of IT workers This is not just some random bill before the parliament. There are just two weeks left before the parliament concludes and an election campaign begins. It is clear that what we are seeing now is the Real Julia coming though, choosing to make the small minority of foreign workers in our country at the center of people's thoughts as they go to vote in September. A debt of gratitude to foreign workers These verses from our national anthem, Advance Australia Fair say a lot about how Australia became what it is today:

For those who've come across the seas

We've boundless plains to share;

With courage let us all combine

To Advance Australia Fair.

The last 200 years of Australia's history has been a story of immigration. It is not something to be afraid of: our forefathers celebrated it. Foreign workers: why Australia needs you Australia has had some appalling flops in IT and engineering:

• The OECD has criticised the amount of public infrastructure that hasn't been upgraded since the 1960s as a major risk for Australia's future economic growth
• London spent 100 million to build their Oyster card ticket system for public transport. Melbourne's attempts to replicate it were delivered 10 years late and with a budget of nearly $1.5 billion.
• Major technology problems have repeatedly hit companies such as Vodafone trying to do business in Australia while keeping up with fast-moving technology.

There is no doubt in my mind that additional foreign workers would have made a positive contribution to all of these problems or can do so in the future. The sun never sets on IT Every day, I collaborate with dozens of IT specialists all over the world through the virtual workplace that is the Internet, particularly in the free and open source software community. Many of these people, I've never even met and in most cases I don't even know where they are, where they were born or what is the colour of their skin. Those details wouldn't make any difference to the way that we work in IT today. How many IT managers have time to waste dealing with more real world bureaucracy when they've experienced online, global productivity? How many IT workers feel demotivated by having to explain trivial details about their personal life to a Government bureaucrat who doesn't understand their skills and just looks at their colour? If you think about it, any immigration officer who really understands IT wouldn't be an immigration officer. They would be working in IT themselves. Immigration officers, who don't understand IT, are now going to be further empowered to bully companies away from employing some talented workers on the basis of race or nationality. Hiring managers will be intimidated into these prejudiced and biased decisions by delays, processing fees and invasive demands for sensitive documents about business planning and recruitment strategies. Australia's immigration system already has a horrendous reputation. Any visa application seems to take more than a year: no small company can keep a job position vacant that long. Families can't plan their children's schooling. Other life events come and go. There are exhorbitant fees, 1000% higher than in other western countries. Fewer and fewer self-respecting skilled workers are willing to put their spouses and children through the degrading medical examinations. Judging the impact of poor immigration policy While the economic impact of this immigration mess on industry is hard to quantify with an exact figure, we can take some insight from the education system. As the visa system has been hijacked by racists over the last 10 years, there has been a dramatic fall in participation (and revenues) from foreign students. In one year, enrolments (and revenue) fell 30%. This is not just bad for the balance sheets of the universities, it also means that in a future where commerce is global, Australians are more and more isolated and inexperienced culturally. IT workers and their employers have plenty of choices: Australia's close neighbor, Singapore, is one of them. Visas are granted in 2 weeks, no degrading medical exam required, low taxes and tropical sunshine all year round. Many companies that find it impractical to deal with Australia's bureaucracy end up moving their best Australian workers to places like Singapore to be part of a global team. This can't be good for the workforce that is left behind without jobs. The training delusion Government officials continue to rant and rave about companies failing to train Australian workers. The new laws supposedly force companies to "fix" this problem and train Australian workers. This, too, is a delusion: employers are not to blame. Some of the best Australian workers are already long gone to places like Singapore, London and the US. With talented foreign workers denied the opportunity to come and fill the void, there is less opportunity for skills to be acquired by more junior workers in Australian workplaces. It is also extremely difficult for more junior workers to get a foot in the door in the international job market and the primary reason for this is the Australian Government's failure to fund university programs beyond a bachelor's degree. Compare this to Europe and the US where all competent graduates are funded through to a Masters or PhD program. The bottom line is that more junior workers are denied the opportunity to get the best training either at home or abroad and in both cases it's not the foreign workers that can be blamed: it's the Government's own fault. Why do we need skilled foreign workers when Australians can win Nobel Prizes? The Australian press recently went into a frenzy when an Australian won the Nobel Prize for physics. There was a catch though: he's a migrant from the United States (just don't tell the Prime Minister). Dr. Schmidt migrated to Australia 20 years ago when the immigration system was not the same as today. Today, future Nobel Prize winners are being shown a brick wall - maybe we even have one of them rotting away in our death camps or left in the sea for sharks to eat. The BBC recently revealed that Britain's successor to Stephen Hawking may be a young girl who migrated from India - it is chilling to imagine where a child like this may be hidden away under Australia's immigration system. Bureaucracy leads to fraud and exploitation It's been clearly demonstrated that wherever you have elaborate, artificial systems of bureaucracy it leads to inefficiency, it suppresses innovation and in the worst cases it enables fraud and exploitation. The typical examples usually involve police in some third-world African nation setting up road blocks and collecting fees from travellers who want to pass the queues. This type of opportunism has also been found in Australia's immigration system, with one Federal politician already directly implicated and jailed for his role in a visa racket. Gillard's own bullet man A Queensland pensioner made international headlines recently when he was caught sending bullets in the mail to the Prime Minister. His demands were clear: stop immigration. While most world leaders refuse to let nutcases like this dictate their actions, Gillard appears to have been transcribing his racist letters directly into these newest immigration laws. It is a sad reality that Australian politics regularly seeks to appeal to the worst instincts in people like bullet man. The ultimate political failure When politicians stoop to the level of demonizing immigrants it is usually a clue that the politicians themselves are past their use-by dates and out of fresh policy ideas. When former French president Sarkozy tried to play the racist card in his campaign for re-election, it bit him in the bum and he was swept from power by the socialists. As always in politics, there is an element of hypocrisy at work: neither our Head of Government (the Prime Minister) nor our Head of State (the Queen) was born in Australia. Gillard was born in Wales and migrated to Australia as a child. If Australians don't vote for her in September, will she be given 28 days notice to pack her bags and go back home'? From the frying pan and into the fire The scariest thing is that if Australians see through this racist charade and refuse to vote for it, we could end up with something equally obnoxious: the other major political party is now gaining worldwide attention for their campaign linking gay marriage and homosexuals to bestiality. Which prejudice is the lesser evil: racism or homophobia?

Many people are taking a fresh look at IT security strategies in the wake of the NSA revelations. One of the issues that comes up is the need for stronger encryption, using public key cryptography instead of just passwords. This is sometimes referred to as certificate authentication, but certificates are just one of many ways to use public key technology. One of the core decisions in this field is the key size. Most people have heard that 1024 bit RSA keys have been cracked and are not used any more for web sites or PGP. The next most fashionable number after 1024 appears to be 2048, but a lot of people have also been skipping that and moving to 4096 bit keys. This has lead to some confusion as people try to make decisions about which smartcards to use, which type of CA certificate to use, etc. The discussion here is exclusively about RSA key pairs, although the concepts are similar for other algorithms (although key lengths are not equivalent) The case for using 2048 bits instead of 4096 bits

• Some hardware (many smart cards, some card readers, and some other devices such as Polycom phones) don't support anything bigger than 2048 bits.
• Uses less CPU than a longer key during encryption and authentication
• Using less CPU means using less battery power (important for mobile devices)
• Uses less storage space: while not an issue on disk, this can be an issue in small devices like smart cards that measure their RAM in kilobytes rather than gigabytes

So there are some clear benefits of using 2048 bit keys and not just jumping on the 4096 bit key bandwagon The case for using 4096 bits

• For some types of attack, security is not just double, it is exponential. 4096 is significantly more secure in this scenario. If an attack is found that allows a 2048 bit key to be hacked in 100 hours, that does not imply that a 4096 bit key can be hacked in 200 hours. The hack that breaks a 2048 bit key in 100 hours may still need many years to crack a single 4096 bit key
• Some types of key (e.g. an OpenPGP primary key which is signed by many other people) are desirable to keep for an extended period of time, perhaps 10 years or more. In this context, the hassle of replacing all those signatures may be quite high and it is more desirable to have a long-term future-proof key length.

The myth of certificate expiration Many types of public key cryptography, such as X.509, offer an expiry feature. This is not just a scheme to force you to go back to the certificate authority and pay more money every 12 months. It provides a kind of weak safety net in the case where somebody is secretly using an unauthorised copy of the key or a certificate that the CA issued to an imposter. However, the expiry doesn't eliminate future algorithmic compromises. If, in the future, an attacker succeeds in finding a shortcut to break 2048 bit keys, then they would presumably crack the root certificate as easily as they crack the server certificates and then, using their shiny new root key, they would be in a position to issue new server certificates with extended expiry dates. Therefore, the expiry feature alone doesn't protect against abuse of the key in the distant future. It does provide some value though: forcing people to renew certificates periodically allows the industry to bring in new minimum key length standards from time to time. In practical terms, content signed with a 2048 bit key today will not be valid indefinitely. Imagine in the year 2040 you want to try out a copy of some code you released with a digital signature in 2013. In 2040, that signature may not be trustworthy: most software in that era would probably see the key and tell you there is no way you can trust it. The NIST speculates that 2048 bit keys will be valid up to about the year 2030, so that implies that any code you sign with a 2048 bit key today will have to be resigned with a longer key in the year 2029. You would do that re-signing in the 2048 bit twilight period while you still trust the old signature. Fortunately, there are likely to be few projects where such old code will be in demand. 4096 in practice One of the reasons I decided to write this blog is the fact that some organisations have made the 4096 bit keys very prominent (although nobody has made them mandatory as far as I am aware). Debian's guide to key creation currently recommends 4096 bit keys (although it doesn't explicitly mandate their use) Fedora's archive keys are all 4096 bit keys. The CACert.org project has developed a 4096 bit root These developments may leave people feeling a little bit naked if they have to use a shorter 2048 bit key for any of the reasons suggested above (e.g. for wider choice of smart cards and compatibility with readers). It has also resulted in some people spending time looking for 4096 bit smart cards and compatible readers when they may be better off just using 2048 bits and investing their time in other security improvements. In fact, the "risk" of using only 2048 rather than 4096 bits in the smartcard may well be far outweighed by the benefits of hardware security (especially if a smartcard reader with pin-pad is used) My own conclusion is that 2048 is not a dead duck and using this key length remains a valid decision and is very likely to remain so for the next 5 years at least. The US NIST makes a similar recommendation and suggests it will be safe until 2030, although it is the minimum key length they have recommended. My feeling is that the Debian preference for 4096 bit PGP keys is not based solely on security, rather, it is also influenced by the fact that Debian is a project run by volunteers. Given this background, there is a perception that if everybody migrates from 1024 to 2048, then there would be another big migration effort to move all users from 2048 to 4096 and that those two migrations could be combined into a single effort going directly from 1024 to 4096, reducing the future workload of the volunteers who maintain the keyrings. This is a completely rational decision for administrative reasons, but it is not a decision that questions the security of using 2048 bit keys today. Therefore, people should not see Debian's preference to use 4096 bit keys as a hint that 2048 bit keys are fundamentally flawed. Unlike the Debian keys (which are user keys), the CACert.org roots and Fedora archive signing keys are centrally managed keys with a long lifetime and none of the benefits of using 2048 bit keys is a compelling factor in those use cases. Practical issues to consider when choosing key-length Therefore, the choice of using 2048 or 4096 is not pre-determined, and it can be balanced with a range of other decisions:

• Key lifetime: is it a long life key, such as an X.509 root for an in-house CA or an OpenPGP primary key? Or is it just for a HTTPS web server or some other TLS server that can be replaced every two years?
• Is it for a dedicated application (e.g. a closed user group all using the same software supporting 4096 bit) or is it for a widespread user base where some users need to use 2048 bit due to old software/hardware?
• Is it necessary to use the key(s) in a wide variety of smartcard readers?
• Is it a mobile application (where battery must be conserved) or a server that is likely to experience heavy load?

I recently had the opportunity to contribute to an O'Reilly community book project, developing the book Monitoring with Ganglia in collaboration with other members of the Ganglia team

The project itself, as a community book, pays no royalties back to the contributors, as we have chosen to donate all proceeds to charity. People who contributed to the book include
Robert Alexander, Jeff Buchbinder, Frederiko Costa, Alex Dean, Dave Josephsen, Bernard Li, Matt Massie, Brad Nicholes, Peter Phaal and Vladimir Vuksan and we also had generous assistance from various members of the open source community who assisted in the review process. Ganglia itself started at University of California, Berkeley as an initiative of Matt Massie, for monitoring HPC cloud infrastructure My own contact with Ganglia only began in 2008 when I was offered the opportunity to work full-time on the enterprise-wide monitoring systems for a large investment bank. Ganglia had been chosen for this huge project due to it's small footprint, support for many platforms and it's ability to work on a heterogeneous network as well as providing dedicated features for the bank's HPC grid. This brings me to one important point about Ganglia: it's not just about HPC any more. While it is extremely useful for clusters, grids and clouds, it is also quite suitable for a mixed network of web servers, mail servers, databases and all the other applications you may find in a small business, education or ISP environment. Instantly up and running with packages One of the most compelling features, even for small sites with less than 10 nodes, is the ease of installation: install the packages on Debian, Ubuntu, Fedora, OpenCSW and some other platforms, and it just works. Ganglia nodes will find each other over multicast, instantly, no manual configuration changes necessary. On one of the nodes, the web interface must be installed for viewing the statistics. Dare I say it: it is so easy, you hardly even need the book for a small installation. Where the book is really compelling is if you have hundreds or thousands of nodes, if you want custom charts or custom metrics or anything else beyond just installing the package. If monitoring is more than 10% of your job, the book is probably a must-have. Excellent open source architecture Ganglia's simplicity is largely thanks to the way it leverages other open source projects such as Tobi Oetiker's RRDtool and PHP Anybody familiar with these tools will find Ganglia is particularly easy to work with and customise. Custom metrics: IO service times One of my own contributions to the project has been the creation of ganglia-modules-linux, some plugins for Linux-specific metrics and ganglia-modules-solaris providing some similar metrics for Solaris. These projects on github provide an excellent base for people to fork and implement their own custom metrics in C or C++ The book provides a more detailed account of how to work with the various APIs for Python, C/C++, gmetric (command line/shell scripts) and Java. The new web interface For people who had tried earlier versions of Ganglia (and for those people who installed versions < 3.3.0 and still haven't updated), the new web interface is a major improvement and well worth the effort to install. It is available on the most recent packages (for example, it is in Debian 7 (wheezy) but not in Debian 6.) It was originally promoted as a standalone project (code-named gweb2) but was adopted as the official Ganglia web interface around the release of Ganglia 3.3.0. This web page provides a useful overview of what has changed and here is the original release announcement.