Monthly Archives: June 2009
Today my Linux box died. Cause and nature of death is mysterious (the heat may or may not be a coincidence). But there’s what should be to a big clue to anyone “in the know“, and I’d like any clues on what hardware short of the entire box might be worth replacing.
I was doing something perfectly normal, when the mouse stopped responding. It had frozen up completely. So had the keyboard: ctrl-alt-backspace (restart X11) and ctrl-alt-del (reboot) had no effect. Pinging it from another box gave no response. Yet the desktop display was still there, frozen in what I had been doing.
OK, hard reset. Now it won’t come back: the monitor insists there’s no signal, and the num-lock on the keyboard never even lights, as one expects in a power sequence. Escalate the hardness of restarts to disconnect from the power and leave for a couple of hours, still the same.
That smells of sudden-death to something in hardware. So how come the display stayed up when it originally froze? Surely if it was the processor, motherboard or memory, that would’ve gone at the moment of failure?
For a few weeks I’ve been suffering nasty twinges in my right elbow. What brings them on can be a bit unpredictable: on the one hand I can carry weight, but against that a simple shrug can cause agony. I suspect use of a computer mouse doesn’t help, so I’m using the laptop rather more than before, and contemplating trying a mouse left-handed at the desktop.
This afternoon I went for my first swim since the elbow deteriorated last week. For the first couple of minutes swimming it was agony, but I stayed in and moved carefully. Soon it was much-improved, and it remained rather better than it has been when I got out. Now – six hours on – it’s a dull ache, but no major pain.
I shall have to try making the swim a daily dose of therapy 🙂
This coming Sunday, June 28th, we are performing two lovely but rarely-heard works at the Guildhall in Plymouth: Donizetti’s Requiem, and Puccini’s Messa di Gloria.
These are a little like Verdi’s more famous requiem: nominally-ecclesiastical works by operatic composers. As with Verdi, the operatic heritage is always evident, and Donizetti’s 1835 work in places foreshadows Verdi’s later one. The Puccini mass is an early work, but the genius of his later career shines through in abundance together with a young man’s playfulness.
We’ve thoroughly enjoyed preparing these works (more than I expected), and I can recommend them to any music lover in the area! If you don’t already have tickets, get them now!
Slowloris has been getting quite a lot of attention recently. So what is it, and should we be worried?
Well, it’s a Denial of Service (DoS) attack over HTTP. We’ve been aware of the method for some time, and it has been discussed in public. As far as I know it’s not been happening in the wild. Nevertheless, it is something we should take seriously: probably more so than we have hitherto done.
I’ve been test-driving it over the weekend against Apache on OpenSolaris and Linux platforms.
The bad news is that it can indeed take a badly-configured apache server down, and the worse news is that that includes a low-traffic out-of-the box configuration. Even with the Event MPM, slowloris can tie up one worker thread per connection.
The good news is that slowloris itself runs out of steam long before Apache. With the Worker or Event MPM, it’s trivial to handle more connections than slowloris can make. Running both slowloris and apache on the same box, I was able to observe slowloris eating over 99% of the CPU, while apache effortlessly responded to requests even as it shared the remaining <1% with all the normal trappings of a Gnome desktop.
The other good news is that all the above was without any of the defences available for apache, such as mod_evasive (which specifically defends against DoS attacks).
I’ll write this up at more length elsewhere, including probably an article in the apache httpd wiki.
[POSTSCRIPT] Don’t take any of the above as definitive. It just describes my experimenting with it when the story broke. Other people have reported different experiences. Use an accept filter and use mod_reqtimeout, and look for more recent posts on the subject.
They say bad money drives out good. The same is true of noise. Tavistock gets a number of buskers, most of them at best entertaining and at worst harmless. But there’s one who uses electronic amplification and is a serious nuisance for several streets around. The council say they’ve had complaints but can’t do anything without some big fuss, and new bylaws that would impact on every busker. The police say they’ve had complaints, but can only move him on if he’s on the public pavement, which they had already done long ago …
He was there this morning, so I went out to escape. I walked the long/scenic way to Morrisons for a big shop, meaning I must’ve walked 3-4 miles in total, plus the shopping. On my return with shopping, the bad busker was still there, and I was mightily pissed off.
But on my way home is our main square. There parked up was a big people-carrier, bearing the logo “Geoffrey Cox”. That’s our MP. I wonder if he has any thoughts on the issue of “minor” nuisance? Miracle – he was open for me to just sit down and have a word! So I took the opportunity to air my thoughts on the subject.
Of course with a politician you can never quite tell if he’s listening or just being polite, but when I mentioned persistent car alarms and building alarms as an example of “minor nuisance”, he agreed with some enthusiasm, and said he suffers from it in his London residence. So that seemed like a good launch point for my basic suggestion:
- Statutory quick&easy fixed penalties for perpetrators.
- Statutory modest damages to victims through a simple and easy process.
- Make insurers by default liable for the cost.
The beauty of making insurers liable is that someone with the power to make things happen is incentivised to do just that. An insurer can insist on standards for alarms, and disallow the defective crap that causes all the nuisance. Everyone wins – except perhaps a few cowboys who undercut the makers and installers of alarms that are fit for purpose.
He seemed to like the idea of fixed penalties. So there’s just the faint chance he’ll now raise it with his colleagues. Of course, something like existing ASBO laws might equally well apply to perpetrators of minor nuisance (and would, one imagines, work better for bad-busker), but that would require more imagination on the part of the minions who administer the law, as well as the actual lawmakers.
Been house-hunting again today.
Specifically, I went to view an apartment, which is in fact more a wing of a grand old house. Set down a private drive, on the steep slope down one of our many estuaries, with fantastic views from the grounds and from parts of the house – most importantly the spacious and elegant sitting room. The house itself includes extravagant luxuries such as classical columns, and much of it is covered in ivy. A spacious three-bedroom, two-bathroom place (the long bedroom would become my office) in a quiet and beautiful location within comfortable cycling distance of Plymouth: what more could I ask?
Well, there are drawbacks. Much of it could use redecoration, and the agent tells me the landlord is very particular about how it gets done. Running costs are going to be very high, with lots of large, single-glazed sash windows (five in the sitting room alone, and excluding the french-style doors on the dining area which is open-plan to it), and no gas supply at all. But encouragingly, they are in decent condition, and every one I tried opens and closes cleanly and easily.
The agent’s particulars are unclear on the subject of furniture: in one place it says part-furnished, elsewhere it says unfurnished. Today it looked not very far off fully-furnished, and the agent said they’d prefer a tenant who’ll accept the furniture. While some of the furniture is nice and I’d be happy to keep it, other items fall a long way short of the quality of the flat itself. Most importantly, I’d need to get rid of the main bed as seen, though the two singles in my prospective office could stay (in the smaller room) as spare beds.
Most unusual here seems to be the relationship of the landlord, agent and prospective tenants. Apparently the agent will present a report and recommendation, whereupon I – having expressed my interest – may or may not be invited back for a second visit and to meet the landlord. Not at all like the usual scenario, where they’ll just take any tenant who’ll pay and who ticks the right boxes!
Overall, it’s the nicest place I’ve seen for some time, and I think I’ll take it if offered. Unless, like buses, good properties come in batches, and I take somewhere else first!
Went to the Plymouth Symphony Orchestra concert at St.Andrews Church last night. St.Andrews is the main church in central Plymouth, and its fine organ makes it a venue for organ+orchestra works. The programme included Saint-Saëns’ Organ Symphony, and also a Poulenc concerto for organ, strings and timp, along with shorter works by Vaughan Williams and Delius. Both the Poulenc and the Delius were new to me, and for me the revelation of the evening was the Poulenc.
OK, that makes a good concert. So what was to spoil it? Well, two things, both loosely the responsibility of the concert organisers. They did one thing right, by reminding people to turn off mobile phones. But on the other hand, a phone going off is a brief irritation, not a long-drawn-out one. That makes them, comparatively speaking, a trivial side-issue.
First, two St Johns Ambulance ladies, sat by the door. One was wearing day-glo bright yellow, and something even more reflective (indoors, ferchrissake). The evening sun shining on it was painfully dazzling in my peripheral vision for much of the first 20 minutes (flashing as she moved). OK, that only affects a few of us, sitting in a line to the reflected sunlight, but surely she shouldn’t be wearing that stuff indoors! The hats both St Johns ladies wore throughout were probably also mildly annoying to people sitting behind them.
The second nuisance must’ve affected far more of us – probably a majority of the audience – and for far longer. Someone was clattering coins. I’m fairly sure it was front-of-house noisily counting up the takings, amplified by some kind of box, or maybe just a table and surrounding wooden pews, etc. And just as the ting of the little triangle can penetrate a full orchestra, so can the irritating and unmusical clatter of coins. Please keep it quiet, or take it outside!
Apart from that, nice concert!
 An observation which includes the cathedral.
 With more comfortable seating, adequate facilities, and without pillars obscuring lines of sight, it could be a very fine venue.
This time last year, Lidl consulted us about plans to build a new shop here in Tavistock. I was in favour then, and I’m in favour now for exactly the same reasons: new housing creates demand for new retail capacity; Lidl will complement our existing retailers (especially the nicer independent shops and market); and above all, Lidl promised no muzak when I went to the consultation 🙂
What’s changed now and deserves documenting here is that they’ve reached the stage of actually building the store. I look forward to shopping there, and will be especially pleased if I can abandon the muzak-infested supermarkets (Morrison, Somerfield, Coop) altogether in favour of Lidl and the small shops. And Tescos in Plymouth a couple of times a year …
In other retail news, the old Woolworths premises in the high street has evidently found a new tenant, and is being refurbished. But the three former estate agents that have shut down are still vacant and looking unloved. And I fear the Woolworths-replacement will be a waste of space: the word “fashion” in the name is a bit of a giveaway.