Monthly Archives: October 2011

IPv6: finale in the key of D-Link

Background knowledge: this post requires some knowledge of networking, at least to the point of knowing what IPv4 and IPv6 are, and what is meant by subnet notation like “/60″ and “/64″.

I believed for a very brief time that I’d beaten IPv6 into shape but soon my husband started complaining that sometimes it worked, sometimes it didn’t, and basically questioning whether it was worth any more late nights. (I would poke things, we would jointly debug them, IPv6 involved us skipping dinner two nights in a row in the end.)

Basically what would happen was that anything we tried to connect to over IPv6, most noticeably Google itself (because they trust Internode’s IPv6 routing enough to have turned on IPv6 access for their customers) would either work or just hang. I vaguely suspected some kind of routing error.

Here’s something to try if you have mysterious intermittent IPv6 dropouts or hangs: watch the output of radvdump closely. What you are looking for is any router advertisements coming from a second source: rogue RAs was the search term I was using somewhat in vain.

Unfortunately, if you find such a thing, there are essentially two options (much as you do if someone has put a rogue DHCP server on a network). One is to remove the rogue device from the network, the other is to firewall its announcements away from your clients. Unfortunate in my case, that is, because it emerged that the source of the announcements was our D-Link wireless router (which, per the previous entry, we run as a switch). Removing a wireless switch from our network would have the unacceptable side-effect of re-introducing strings of blue cable to our home, and it’s pretty hard to firewall your switch itself. So in our case, the answer for the present time is to give up on home IPv6.

Overall, although the reason we gave up on IPv6 was not a Linux problem, I have to say that I was really surprised how immature Linux’s tools are at this point. The fundamentals exist: kernel support, DHCPv6 and stateless configuration servers and clients. As an IPv6 client, Linux is doing OK. If you connect a Linux machine to a network that happens to be using IPv6, it’ll likely Just Work. But at the tools and packaging level there’s still loads of gaps along the lines of:

  • iptables and ip6tables are entirely separate programs, so you get to have your firewall configuration fun twice! (However, UFW handles this fairly nicely, if you’re in the market for a thin-ish wrapper around iptables.)
  • configuring ppp for IPv6 is like ppp for IPv4 circa 1999 or 2000 or so. Things like the “oh yeah, for a reason no one knows, you won’t get a default route, so here’s a little script that will bring one up for you” (see Shane Short’s blog entry)
  • radvd is a fairly crucial tool, but there aren’t a lot of example config files for different situations that I could find, and the man page assumes that you know a lot about router advertisements already
  • if you want to use Ubuntu’s supported DHCP server (isc-dhcp-server) for DHCPv6, you need to write it a second init script and config file yourself

So after all that you might be tempted to use a dedicated router for IPv6 and I’d sympathise except that the D-Link device does it even worse than Linux. Not promising. I can’t see that moving many ADSL users over to IPv6 is going to happen any time soon.

IPv6: prelude in the key of radvd

Background knowledge: this post requires some knowledge of networking, at least to the point of knowing what IPv4 and IPv6 are, and what is meant by subnet notation like “/60″ and “/64″.

I’ve just changed ISPs, because I wasn’t much of a fan of my old ISP’s demand that either we enter into a new 12 month contract before 27 November or they’d consider us re-contracted at that date. My new ISP is Internode, Australia’s favourite geek ISP, in part because they offer native IPv6 and it’s even supported by customer service. It took me an entire 24 hours to succumb to the temptation of wrecking my perfectly good home network by attempting to make it IPv4/IPv6 dual stack, partly motivated by Geoff Huston’s “the sky is falling” keynote at 2011. I like doing my bit to hold up the sky.

I use a Linux machine as our router rather than a consumer router device, that is, my ADSL modem is set to bridge mode and we use our wireless router just as a switch; neither of them do routing. (Or shouldn’t, but we’ll get to that.) In terms of resources for doing this with Internode, or any other ISP who will advertise your IPv6 routes via DHCPv6, here’s some useful material:

The main problem I had is that for as yet unexplained reasons, while this radvd.conf stanza worked fine when my Linux server ran Ubuntu 11.04 with radvd 1.7, it doesn’t work on Ubuntu 11.10 with radvd 1.8:

prefix ::/64 {
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr on;

radvd 1.8 was advertising this in such a way as to get my Linux client to give this error (in /var/log/syslog):

IPv6 addrconf: prefix with wrong length 60

That is, it seems to have been advertising the entire /60 that Internode routes to each customer rather than a single /64. We ended up having to do something like this:

prefix 2001:db8:aaaa:bbbb::/64 {
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr on;

That is, because Internode’s IPv6 allocations are static, we just manually picked a /64 out of the /60 allocated to us, and advertised that. I’m not clear if this a bug or a change in the way radvd works or a mistake of mine, we never got a chance to find out because of a showstopper which you’ll see in the next, and at this stage, final post in my adventures in IPv6.

Tiger Beatdown vs Australia

Tiger Beatdown is perhaps not enormously well known among the Australian poliblogs, mostly because it isn’t one, although one Australian writes for it.

But they’ve had a couple of pieces of local interest lately.

First in early October Flavia Dzodan looked into the multinational security firms that are behind a lot of immigration detention facilities and other jails:

Evidently, G4S track record of detainee safety in Australia was so poor that the government was forced to cancel the contracts. Instead, new ones were awarded to Serco, whose care of immigrants seems to follow the same sickening pattern:

At the detention center Serco runs in Villawood, immigrants spoke of long, open-ended detentions making them crazy. Alwy Fadhel, 33, an Indonesian Christian who said he needed asylum from Islamic persecution, had long black hair coming out in clumps after being held for more than three years, in and out of solitary confinement.

“We talk to ourselves,” Mr. Fadhel said. “We talk to the mirror; we talk to the wall.”

Naomi Leong, a shy 9-year-old, was born in the detention camp. For more than three years, at a cost of about $380,000, she and her mother were held behind its barbed wire. Psychiatrists said Naomi was growing up mute, banging her head against the walls while her mother, Virginia Leong, a Malaysian citizen accused of trying to use a false passport, sank into depression.

The key point for me is the question about to what extent these firms are lobbying, and successfully influencing, refugee policy. To what extent is it market maintainence?

Why ostensibly disparate nations like the US, The Netherlands, France or Australia (just to name a few), all seemed to have gotten on board with the anti immigrant sentiment at once. Why, within a short period of time, media seemed inundated with these stories of threats, fear and unrestrained menace. However, the same media that quickly exposes the threats of lawless, uncontrolled immigration rarely addresses the profiteers behind these trends. Every detainee is a point in the profit margins of these corporations. Every battered immigrant body forced to live in these conditions represents an extra income for these multi-national businesses. Nothing is gratuitous, as Mr. Buckles so poignantly said, There’s nothing like a political crisis to stimulate a bit of change. Especially if said crisis can create monstrous profits off the backs of undocumented migrants who sometimes lose their lives under the care of these corporations.

And now Emily Manuel is making the case for Occupy Australia:

I’ve lived in Australia and the U.S and I know from personal experience that the substantially lower standard of living in the U.S is something few Australians can truly understand. Things are not perfect in Australia economically – not with the astronomical housing prices – but we can’t say that the middle class has collapsed in the same way as in the U.S.

We do ourselves no favours when we uncritically mimic American models without changing them to suit local conditions. The cultural cringe is no more useful in activism than it is in other areas. The 99/1% slogan is powerful stuff indeed but doesn’t adequately address the income distribution of Australia as accurately in the United States. Activism must respond to local needs to be successful…

While we don’t have lobbyists in the same way, this is still a problem in Australia. If things have been getting so much better over the last decade, why have student fees been ballooning while full-time lecturers are replaced by casual tutors? Why is there no Medicare bulk billing? Why is the Medicare gap ever-increasing? How can the poor and working classes afford housing, in some of the most expensive markets in the world? For that matter, why do we pay student fees at all? If things have been so good, why do we deserve less as citizens than we did in the 70s and 80s? Why do we accept less?

We are blowing up the very same bubbles that have burst so dramatically in the U.S, and it is the same process of destroying the social fabric that the welfare state held together – it’s just we started off from a much better place, from a more cohesive social whole (G_d bless you, Gough Whitlam). With privatisation and economic rationalism, we have treated Australians with the same cannibalistic attitude that created the US 99%. Not citizens with rights and responsibilities any longer but consumers, markets to be exploited…

That is how well our democracy is functioning – when the top 0.02% of businesses and 10% of households won’t pay a tax for the benefit of the rest of us…

So yes: Australian apathy and irony have frequently served to protect us from U.S-style extremism, but what happens when enough people step forward to say something our political classes and media classes don’t want to hear? And what happens when we need serious changes to survive as a country and our politicians are unwilling to do anything about it? This is a problem that concerns all of us, in Australia and indeed worldwide, as we face climate change.

It is for this reason that we must have an Occupy movement in Australia that addresses the dictatorship of capital in our lives, that produces a democracy that truly centres the needs of the people. We need to protest. We need the right to protest. We need to be out in the streets to put the lie to the false consensus of the neoliberal press that there is no alternative to the status quo. And yes, we need to make sure that our needs are taken care of by our political system, even – especially – when they conflict with the needs of business. It is time that we made clear that running a “democracy” primarily for the rich is no longer a possibility in Australia.

Tiger Beatdown tends to long-form posts, so I suggest reading the originals. (And I suggest commenting there if you want to substantively engage with the arguments.)

GNOME Shell versus Unity

I upgraded my laptop to Ubuntu 11.10 today. I used Metacity+GNOME Panel through the previous version of Ubuntu as Unity crashed annoyingly on my laptop (tending to leave me looking at my background image, which is a cute picture of my son but even so) so this is my first Ubuntu version with the new shiny.

What’s annoying me right now is that they both have features I really like. I’ve only played around for a few hours so possibly one can be configured to have the good features of the other; these are from the default functionality on 11.10.

Unity: my laptop doesn’t have a lot of screen real estate, so I love the integration of the menu bar of windows into the top panel (called global menu). I like having those 20 pixels or so back!

GNOME Shell: I love the Activities mode in general! The presence of workspace previews that don’t require me to keep holding down the Alt part of the Alt-Tab combo is lovely, and the favourites menu on the left seems easier to edit than Unity’s. On the balance, I’d say I prefer GNOME Shell, but damn, global menu is a killer feature on my smaller screen. I’ll watch the global menu patch closely.

(Meanwhile, while writing this entry I discovered that Firefox’s right-click menu is broken in Unity—it disappears as soon as I move my mouse—which is a rather compelling reason to use GNOME Shell.)


I just got a call from a childcare centre who has had my son’s name down for nineteen months. I’m not even sure if they were offering him a place, most likely they are just culling their waiting list in preparation for the 2012 enrolment season. Nineteen months long waiting lists, on the very edge of the metropolis.

I’m sure there’s plenty of info out there already about the economic inefficiencies generated by private childcare in countries like Australia and the US where supply doesn’t meet demand and there’s little government intervention in the market. One of the most noticeable for us is geographic lock-in. If it takes a year or more to get our son care at a new location, we can’t move, until, oddly enough, all of our children are school age and thus likely to be badly disrupted academically and socially by a move. The next most obvious is all the mother-work in this. Applying to 20 centres (… many of which ask for a $20 waiting list fee). Ringing them all once a month or more just to keep a tick next to our name as “really wants a place”. (It likely doesn’t advance you up the list, what with all the other mothers ringing monthly too, and they certainly don’t give us any actual news until a place actually appears.)

I should put in a little bit of background for people from countries with at least some government provided childcare. Childcare in Australia for children 8 weeks to 5 years is provided by for-profit and non-profit suppliers in a private market. Waiting lists for first born children in Sydney (younger siblings of an enrolled child often receive some preferential treatment) who aren’t in certain disadvantaged and at-risk groups are somewhere in the realm of nine to twenty four months. (Employers are supposed to keep permanent jobs open to a returning mother for a year.) Costs are in the realm of $70 to $110 dollars per day for infants (median maybe $90?) and $60 to $100 per day for children over age two. There are government subsidies on a sliding scale that for some families might halve this cost.

The alternatives are local government certified “family carers” caring in their own homes, who have similar waiting lists, nannies at around $200 per day, or family. I don’t see a lot of solutions aside from nationalisation: the private market obviously sees no need even for centralised waiting lists and for whatever reason it certainly doesn’t see the need to create enough places to meet demand. All I have is a couple of lessons:

#1 you do not put your child’s name down at birth you put it down when you are pregnant, if they let you, and if they don’t, take the forms to the hospital with you and post them from there within hours of your child’s birth. (Sydney hasn’t quite reached the stage that I am told New York City is at, of ringing them all to give them notice that you have stopped using contraception, and might therefore require their services at some point in the next two years.)

#2 most childcare places open up in January and February, with enrolments in October. It’s obvious why when you think about it: (southern) January is when the five year olds leave to start kindergarten, so it’s the time when by far the most vacancies are created. That doesn’t mean put the kid’s name down in October for a place the following January, it means putting them down as early as possible and then concentrating your phone calls in October.

This can be frustrating depending on your child’s month of birth. Born January or February? You may well have to keep them out for a full year. Born November or December? You may have to enrol them much younger than you would have been comfortable with if you are lucky enough to be offered a place (although only for a day a week, already enrolled children almost always get the pick of newly opened spots on other days).

For the record, my January-born first son got a place that July, in a centre that had recently re-opened after bankruptcy and was taking immediate enrolments. That same centre, whose youngest enrolment at the time was a child 9 weeks old, is a year later asking us to re-confirm 2012 enrolments four months ahead because of their enormous waiting list. They currently have no children born in 2011 enrolled, implying a waiting list of 9 months at the very least We’re ourselves presently awaiting results of the 2012 enrolments closer to the city, to see if we get to move closer to my husband’s work in the next 12 months, or if we’re staying out here for the foreseeable future.

Ada Lovelace Day: Mahananda Dasgupta, nuclear fusion researcher

7th October is Ada Lovelace Day, a day to blog about your heroines in science, technology, engineering and math.

Mahananda Dasgupta is a professor in the Department of Nuclear Physics at the Australian National University. Dasgupta’s research takes place at the heavy-ion accelerator facility and investigates quantum tunnelling when heavy nuclei collide. Her Pawsey Medal award in 2006 cites cutting-edge contributions includ[ing] precision measurements of unprecedented accuracy.

Dasgupta moved to Australia from India for a postdoctoral position in the 1990s, and eventually was appointed to a tenured position in 2003. She became the first woman to hold a tenured position in the Research School of Physical Sciences and Engineering at the ANU in its entire 50+ years of existence! (I was very surprised to find this, the School must be enormous in terms of academic staff, it comprises nine research departments.)

How do we retain that female workforce [in science]?

By strong and meaningful mentoring, which doesn’t just mean a quick meeting once a month or web-based mentoring, but real mentors who encourage women or younger people to devise strategies about how best to use their time, and what roles to apply for to advance their career.

Every person at that early stage needs support. We need to champion women scientifically – not “she’s a good person”, but “she’s an excellent physicist who’s done this great work”… Equally, the employers’ responsibility to provide childcare is very important… If we are expanding and building infrastructure – why are we not building childcare facilities?

I was educated in India where, if a student is sharp, they’re encouraged to show it through participating in discussions or taking on extra-educational activities… It does strike me that in Australia we give a lot of kudos to those who excel in sports, but if you excel in studies you are a dork, particularly among other students… Sometimes, following talks I give in schools, students come to the carpark to ask me science questions, rather than asking them in front of the class… How do we get away from that? I believe that to make real long-term progress we must respect and encourage intellectual achievements.

Mahananda Dasgupta, The Conversation: So seriously, why aren’t there more women in science?

Dasgupta is active both in advocating careers in science in general, volunteering herself as a science careers lecturer at schools, and in speaking on behalf of women in science. In 2004 she was the Woman in Physics Lecturer for the year, and in 2011 she represented the Group of Eight universities (the eight universities that consider themselves Australia’s best research universities) at a Women in Science and Engineering summit at Parliament House. Her 2011 Georgina Sweet Australian Laureate Fellowship from the Australian Research Council calls upon her to increase the profile of Women in Science through outreach activities, and work towards advancing early career researchers as well as facilitate leadership pathways for senior women researchers.

Recognition Dasgupta has received for her work includes:

  • the Australian Academy of Sciences’ Pawsey Medal in 2006, for outstanding work in physics by a scientist under 40
  • her election as a Fellow of the Australian Academy of Science in 2011
  • an Australian Laureate Fellowship in 2011

I can’t embed them in the post for licencing reasons, but David Hine has a couple of photos of Dasgupta with her experimental equipment: Dr Mahananda Dasgupta and Dr Mahananda Dasgupta and Dr David Hinde.


Ada Lovelace Day: Fan Chung, leading mathematician

7th October is Ada Lovelace Day, a day to blog about your heroines in science, technology, engineering and math.

This is an expanded version of a post at Geek Feminism last year.

“Don’t be intimidated!… I have seen many people get discouraged because they see mathematics as full of deep incomprehensible theories. There is no reason to feel that way. In mathematics whatever you learn is yours and you build it up—one step at a time. It’s not like a real time game of winning and losing. You win if you are benefited from the power, rigor and beauty of mathematics. It is a big win if you discover a new principle or solve a tough problem.

Fan Chung

Fan Chung is a leading mathematician, specialising in combinatorics and later graph theory. She is Distinguished Professor of Mathematics and Computer Science at UC San Diego.

I first heard of Chung in Paul Hoffman’s The Man Who Loved Only Numbers: The Story of Paul Erdős and the Search for Mathematical Truth; Chung and her husband Ron Graham were two of Erdős’s closest collaborators. Hoffman tells a great story about how when Chung had finished, and come first in, her PhD qualifying exams at the University of Pennsylvania, her eventual PhD advisor Herbert Wilf gave her a textbook on Ramsey theory to browse and she came back and explained that she’d improved one of the proofs. That was a core part of her PhD dissertation, completed in a week. Those kinds of stories are told about the best mathematicians.

Chung has worked both in academia and in industry, having spent twenty years at Bell Labs and Bellcore in both information technology and mathematics before returning to the University of Pennsylvania, where she did her doctorate. After her time in industry she is deeply concerned with mathematical breadth, and is known for her “nose” for problems that cross several subfields.

Many mathematicians would hate to marry someone in the profession. They fear their relationship would be too competitive. In our case, not only are we both mathematicians, we both do work in the same areas. So we can understand and appreciate what the other is working on, and we can work on things together-and sometimes make good progress.

Fan Chung, describing her relationship with husband Ron Graham

If my count is right, Chung’s publication list shows 79 papers co-authored with Ron Graham. I’ve always admired stories of professionally companionate marrages: even Joan Didion and John Gregory Dunne can’t compete on those numbers.

Chung’s website has a copy of a chapter about her in Claudia Henrion’s Women in mathematics: the addition of difference. Among other things it talks about her move to the United States from Taiwan for her graduate work, and her thoughts on having a child while at graduate school.

[Graduate school] is a wonderful time to have a child. You don’t have to attend classes; you only have to write your thesis.

Fan Chung

Hrm, yes, well. Perhaps I will give that advice in 20 years time. Perhaps not…