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Showing posts from 2014

Stalling Aircraft

Modern passenger planes cruise at very high altitude and very close to their stall speed, flying on a knife edge, in order to minimize fuel consumption.  The problem is that when a plane encounters turbulent air due to a storm or a side wind, it can stall unexpectedly, while still traveling at high speed. It appears to me, that in the relentless pursuit of lower drag and lower fuel consumption, the designers have compromised aircraft stability and safety.  The situation now, that a passenger plane can stall at 30,000 feet and then fall out of the sky, with the total loss of aircraft, crew and passengers, unable to recover despite the best efforts of an experienced flight crew, because the plane was designed to save every last drop of fuel, is inexcusable. Aircraft designers should always put stability and safety first and should not be driven by marketing only. Postscript In October 2018, a brand new Boeing 737 Max crashed in Indonesia with great loss of life, because it had


I've been playing with FreeCAD for a few hours, since I need to make little Nylon brackets and things at Shapeways . The program is absolutely amazing for its price - Zero Dollars - which is a nice way to say that there are a few hiccups, but once one knows how to avoid the hiccups, then it works perfectly... :) Antique Radio Ham Speaker Mic, circa 2015 To aid with error checking of CAD files before uploading them to Shapeways, also install the free Meshlab .  Note that uploading a file to Shapeways takes a while, because they also do a conversion and error check, so be patient.  If you checked it with Meshlab, then it should work. I made the above widget by drawing four cubes, resizing them and subtracting  three from the other, then subtracting four cylinders for the mounting holes and finally applying fillets to the edges.  That's all there is to it.  Made out of Nylon, it makes a strong base for a little step motor. In general, I would say that FreeCAD i

Tor Exit Nodes Compromised ExcludeExitNodes node,node,… A list of identity fingerprints, nicknames, country codes and address patterns of nodes to never use when picking an exit node---that is, a node that delivers traffic for you outside the Tor network. Note that any node listed in ExcludeNodes is automatically considered to be part of this list too. See also the caveats on the "ExitNodes" option below.  Tor users should note and temporarily avoid the affected mirrors below: http://globe223ezvh6bps.onion http://atlas777hhh7mcs7.onion http://compass6vpxj32p3.onion


Sony, the company that distributed millions of MS Windows root kits on CD in 2005 , has now been hacked through a Windows SMB exploit . I don't have much sympathy with this crowd, since they cost the IT world an enormous amount of money to clean up their root kit mess and blaming their current disaster on North Korea just doesn't fly with me.  I don't see how someone can download terabytes of data over the North Korean antiquated  internet link.   Clearly the Sony IT staff and management were stupid in 2005 and they are still stupid today. They haven't learned anything. On November 4, 2005.  Thomas Hesse , Sony BMG's Global Digital Business President, told reporter Neda Ulaby , "Most people, I think, don't even know what a rootkit is, so why should they care about it?" Now suddenly, they care deeply... If I apply Occam'

SSH Daemon on a Mac

A Mac is a weird thing that doesn't always know whether it wants to be BSD or Linux. Enable Remote Login You should only need to enable remote login: $ sudo systemsetup -setremotelogin on If the above doesn't work, here is the magical incantation to start a SSH Server: $ sudo launchctl start /System/Library/LaunchDaemons/ssh.plist One can then check it with a Telnet client: $ telnet localhost ssh   Trying ::1...   Connected to localhost. Escape character is '^]'.   SSH-2.0-OpenSSH_6.2 ^]   telnet> q   Connection closed.  Now you can use scp and ssh from another machine on the LAN, but one needs to know what the IP address is: $ ifconfig en0 | grep inet  inet6 fe80::5626:96ff:fece:371f%en0 prefixlen 64 scopeid 0x4  inet netmask 0xffffff00 broadcast Run SSHD On A Different Port If you want to allow internet access to your Mac and don't want to be bothered by script kiddies all the time, then you need to c

Apple Mac NTFS Read/Write Support

Apple Macs have NTFS support, but for some inexplicable reason, it defaults to read only when you plug a NTFS removable disk in. There must be a way to change this, but the simple workaround is to mount the annoying thing manually: First open a terminal and become super user: $ sudo su password Plug the removable disk in, then: # dmesg Look to see what device name is used, probably disk2s1. To ensure that it is free, in case it was 'helpfully' auto mounted already: # umount /dev/disk2s1 Make a directory as a mount point: # mkdir mnt Mount the device read/write : # mount -t ntfs -o rw,auto,nobrowse /dev/disk2s1 mnt Now open Finder and copy to/from the new mount point. When you are done, unmount it with: # sync # umount /dev/disk2s1 Hot Mac Problems Another unrelated issue is with a Mac running very hot due to the mdworker thread.  This stupid thing is the Mac spotlight index utility.  If I want to find something, I use the find utility, I don&#

Biometric Insecurity

Judge Steven C. Frucci ruled this week that giving police a fingerprint is akin to providing a DNA or handwriting sample or an actual key, which the law permits. A pass code, though, requires the defendant to divulge knowledge, which the law protects against, according to Frucci's written opinion. This is a very important strike against using Biometrics for security.  Use of biometrics for authentication may be OK, but security not.  A big problem is that most common users confuse the two. The problem with using fingerprint or voice biometrics is that you leave samples of it everywhere you go. You leave your prints on glasses and door handles.  You leave your voice every time you use a phone and it gets recorded 'for customer satisfaction' reasons.  You leave a picture of your face every time you use a bank machine.  You leave your DNA whenever you use a hair brush. Any semi-savvy crook can lift it and use it against you and worst of all - You Cannot Ever Chang

Serial Ports Revisited

We were trying to test a pair of radios with a data loop-back and were again making the same old mistakes and then wondering what the heck is going on. It is just amazing how many times I have sat down and scratched my head with these things - it feels like I never learn or remember! The mistake we make over and over again is to expect the wrong read/write behaviour from a serial port utility: A serial port is a bidirectional device. A program will grab the device file handle and open the device file either as 'Read', 'Write' or 'Read/Write'. Simple programs like ' cat ', ' echo ', ' bash ' (read, write), ' head ', ' tail ' and ' of ', all open the device file as either ' Read ' or ' Write ', never ' Read/Write '. Complex programs like ' cutecom ', ' minicom ', ' screen ' and ' netcat ', open the device file as ' Read/Write '. So, one ca


A few notes for those new to Linux printing on how to waste perfectly good trees. FTP First walk over to the printer and write down the IP address from the little LCD display. Many network printers have an unsecured FTP server that your company IT is blissfully unaware of (or more likely, they know only True Card Carrying Geeks will use it in a moment of sheer desperation, so they leave it be, even though it can potentially be abused).  If you upload a postscript file to a printer, it will print it immediately - no questions asked.  This works without having anything special installed on your Linux machine. The process works something like this: In your application, select Print to File , then save the file as .  Open a terminal and connect with FTP, then put the file:  $ ftp 172.22.8 . 12 Login: [enter] Password: [enter] ftp> put ftp> bye La voila! CUPS with IPP The CUPS service is maintained by Apple and it works very well indeed.   Usual

Diabetic Foods and Cooking

A few notes on sugar free cooking. As my doctor put it, I am not diabetic, but I should eat as if I am. It appears that the most important dietary modification to diabetes and weight control, is to avoid any food that digests rapidly. At first the list looks daunting: Wheat, potato, rice, alcohol, glucose, sucrose... essentially all common carbohydrates must be avoided - which makes one wonder what is left, since that is about 90% of all the junk on the supermarket shelves! Oats and Rye I don't mind going on a caveman diet of meat, salad and nuts, since I'm a committed carnivore already, but wheat bread is curiously addictive and getting over it is not easy.  There are many different kinds of wheat: Spelt, Durham... so be careful that you don't buy an alternative that isn't an alternative at all. Rye bread is commonly available at bakeries, but it is a little chewy - an automatic consumption limiter. My wife is an engineer of economics, loves cooking and

Reversing the Telephone Table

Are you also fed-up with telemarketer calls?  Chris Blasco wrote a nice piece about social engineering a telemarketer into resetting his own phone set: Being somewhat incredulous after reading that, I researched it myself.  It turns out that it really is that easy to reset a Yealink phone, but resetting a Polycom may require a password and for a Cisco, you need to enter the configuration menu first, so your mileage may vary. Here is a handy list: This may become a new sport - at least until the telemarketers wizen up.

Canoeing in Cinque Terre

A Real Canadian always has a canoe at the ready.  We have inflatable canoes stashed with relatives in multiple countries.  These water toys are cheap, relatively light weight (about 25kg) and easy to transport in the boot of a car.  This summer, we took our European Sea Eagle to Northern Italy. We rented a tiny little apartment in Manarola, roughly in the middle of this picture, next to the old tower, directly above the harbour. Nowadays, I mostly use my Samsung phone camera - it has some spherical distortion, but the quality and warmth is very pleasing. Cinque Terre is a crazy place which really should be on your bucket list.  Many of the buildings are from the 15th century, but the craziest building period was in the 19th and 20th. Note that the best way to get there is by rail from La Spezia.  The railway runs up the coast in an infinite series of tunnels, so it is mostly invisible and doesn't spoil the park.  We went by car and dragging the canoe and luggage betwee

PIC16F1708 Macros

So Easy, a Caveman can PIC it The PIC processors have a small and primitive instruction set.  This makes it easy to learn, but doing anything remotely useful usually requires four or more instructions, liberally sprinkled with BANKSEL instructions, which all make the resulting code hard to read and error prone. Your Own Development Kit As you can see above, it is very easy to make a little development kit of your own, using Vero board and a DIP size PIC.  Once things are working, then you can use Eagle schematic and PCB designer to make a tiny surface mount board, or you can just spray the Vero model with conformal coating and stick it into a soap box with a blob of RVT... Your Own High Level Language The solution is to make your own high level language of sorts with macros.  The upshot of macros is that if you find a bug in one, then you can fix that bug in many places all at once.  The downside is that debugging complex macros can be hard, since the PICKit3 debugger ha

PIC16F1708 a Dilly

I always wondered what is a dilly, why would you pick it and what could you possibly do with it in a circus, but those English are crazy - it must be something in the water. The last time I used a Microchip PIC processor - some time before the dinosaurs in the previous century - there were only a handful of different chips.  Nowadays there are over 300.  A problem with this proliferation is that it is now much more difficult to find relevant information on the exact chip that you want to use and getting started with the infernal things can be very time consuming. I wanted to use a  PIC16F1708, which includes an  ADC , DAC and even a couple of Op Amps for anti-aliasing filters, an all in one CODEC chip for an audio interface widget. Here are a few tips on things that I discovered along the way. No Power When trying out the evaluation board I got with the PICkit3, I kept getting the error:  Target device was not found. You must connect to a target device to use PICkit 3.