February 2017 - wlug - list.wlug.org.nz

An Ordinary User’s Adventures In Linux
by Lawrence D'Oliveiro 30 Sep '17

30 Sep '17

I helped an elderly friend set up his new PC yesterday. His previous machine, over a decade old, was running Windows XP. I had set up an Ubuntu dual-boot a few years back, and he liked playing the games. But then the Linux boot stopped working--there was a message to the effect “hd0 out of disk”, which sounded like a GRUB problem (“hd0” being a GRUB disk name, not a Linux disk name). I booted up SystemRescueCD, and found that disk space was ample. I did an fsck on the Linux volume, and found no filesystem problems. I ran a badblocks scan, and it reported several bad sectors, though oddly they only seemed to be in the Windows partition (if I interpreted the numbers correctly). Naturally I searched online, but the hits I found for that error message didn’t seem very helpful. Reinstalling GRUB didn’t help, so I concluded there were likely other hardware problems, so time for a new machine. He got an entry-level dual-core AMD box from PBTech--their own house build, in a CoolerMaster case--for well under a grand. Nothing fancy, but good enough for his needs--mainly Web browsing, e-mail, a little bit of word processing, and those games. The PBTech box came without an OS. He could have got Windows 10 for it, but considering he would be facing a learning curve coming from XP regardless, I suggested going 100% Linux for all his daily needs, to see if that would work. He could always spend the $160-odd extra on Windows later if need be. So I set it up with Linux Mint, since that seems to be everybody’s favourite :). He was already using Firefox on Windows, so moving all his Web bookmarks across was easy. The Mint install put an icon for Thunderbird on the desktop by default, so I decided to try that for e-mail. Getting his address book across from Outlook Express was fairly straightforward, once I figured out how to map the exported CSV field names correctly. The mail messages were slightly more fiddly, but I found this extension <https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/> which directly loads Microsoft’s .dbx files, and that seemed to work OK. Then he wanted to play CDs. When we put in an audio CD, it came up with options to run Banshee (media player) or Brasero (disc burner). The Banshee media player wouldn’t play the CD directly, it insisted on ripping it to the hard drive first. This was not really what he wanted. I had a look round, and found KsCD, which will indeed play audio CDs without trying to rip them to audio files first. As far as I know, this is the only GUI Linux app that can do so. So, day 1 ended on a reasonably successful note. He was already noticing how much faster the new machine was. So we’ll see how it goes from here...

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Look before you paste from a website to terminal
by Peter Reutemann 11 Mar '17

11 Mar '17

'Most of the time when we see a code snippet online to do something, we often blindly copy paste it to the terminal. Even the tech savy ones just see it on the website before copy pasting. Here is why you shouldn't do this.' -- source: https://lifepluslinux.blogspot.co.nz/2017/01/look-before-you-paste-from-web… Hint: hidden commands thanks to HTML/CSS. Cheers, Peter -- Peter Reutemann Dept. of Computer Science University of Waikato, NZ +64 (7) 858-5174 http://www.cms.waikato.ac.nz/~fracpete/ http://www.data-mining.co.nz/

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Engineering Around Social Media Border Searches
by Lawrence D'Oliveiro 08 Mar '17

08 Mar '17

In the wake of the plan floated by the US Government to demand passwords to social media accounts from people wanting to enter the country, here <http://freedom-to-tinker.com/2017/02/10/engineering-around-social-media-bor…> is a discussion of some likely countermeasures that should still give the cover of plausible deniability.

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Researchers find “severe” flaw in WordPress plugin with 1 million installs
by Peter Reutemann 01 Mar '17

01 Mar '17

'More than 1 million websites running the WordPress content management system may be vulnerable to hacks that allow visitors to snatch password data and secret keys out of databases, at least under certain conditions. The vulnerability stems from a "severe" SQL injection bug in NextGEN Gallery, a WordPress plugin with more than 1 million installations. Until the flaw was recently fixed, NextGEN Gallery allowed input from untrusted visitors to be included in WordPress-prepared SQL queries. Under certain conditions, attackers can exploit the weakness to pipe powerful commands to a Web server's backend database.' -- source: https://arstechnica.com/security/2017/02/severe-vulnerability-in-wordpress-… Cheers, Peter -- Peter Reutemann Dept. of Computer Science University of Waikato, NZ +64 (7) 858-5174 http://www.cms.waikato.ac.nz/~fracpete/ http://www.data-mining.co.nz/

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New $10 Raspberry Pi Zero comes with Wi-Fi and Bluetooth
by Peter Reutemann 01 Mar '17

01 Mar '17

'The newest member of the Raspberry Pi product line costs just $10 plus tax and includes Wi-Fi and Bluetooth capability. The "Raspberry Pi Zero W" is an updated version of the Raspberry Pi Zero. While it lacks some niceties, like Ethernet and full-sized USB-A ports, it's smaller than the flagship Pi and a fraction of the cost. The original Raspberry Pi Zero was released in November 2015 at a price of just $5/£4. The new Pi Zero W is almost identical to the original, but doubles the price to $10 and adds a wireless chip that supports 802.11b/g/n Wi-Fi (2.4GHz-only) and Bluetooth 4.0.' -- source: https://arstechnica.com/information-technology/2017/02/new-10-raspberry-pi-… Cheers, Peter -- Peter Reutemann Dept. of Computer Science University of Waikato, NZ +64 (7) 858-5174 http://www.cms.waikato.ac.nz/~fracpete/ http://www.data-mining.co.nz/

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CSS font-size parameter
by Ian Stewart 27 Feb '17

27 Feb '17

Hi All, There was discussion at last nights meeting regarding the CSS "font-size" property and which units to use. E.g. px (pixels), % (percentage), pt (point), or em (a unit in the field of typography originally based on the width of an "M"), . Note that there are more than just these four units, see here<https://www.w3.org/Style/Examples/007/units.en.html>. If you buy-off on the statements from w3schools.com, then this<http://%20https://www.w3schools.com/TAgs/ref_pxtoemconversion.asp> web-page provides a pixel to em converter, and to quote from their CSS page<https://www.w3schools.com/css/css_font.asp>... "Note: If you do not specify a font size, the default size for normal text, like paragraphs, is 16px (16px=1em)." "The em size unit is recommended by the W3C. 1em is equal to the current font size. The default text size in browsers is 16px. So, the default size of 1em is 16px. The size can be calculated from pixels to em using this formula: pixels/16=em." Although admitting there is much debate over which is the better approach, Kyle Schaeffer, on his website<http://kyleschaeffer.com/development/css-font-size-em-vs-px-vs-pt-vs/>, adds in an addendum from 2011... "Generally, when I create a new design, I will use percent on the body element (body { font-size: 62.5%; }), and then use the em unit to size it from there." Or, for some quotes from wikipedia...<https://en.wikipedia.org/wiki/Em_(typography)> "One em was traditionally defined as the width of the capital M in the current typeface and point size..." "In Cascading Style Sheets, the em unit is the height of the font in nominal points or inches." ...And finally there is one "rem" to save us all... "To make style rules that depend only on the default font size, another unit was developed: the rem. The rem, or root em, is the font size of the root element of the document. Unlike the em, which may be different for each element, the rem is constant throughout the document." More on rem's here<https://www.w3.org/Style/Examples/007/units.en.html#future> cheers, Ian.

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Running Emacs As A Daemon With systemd
by Lawrence D'Oliveiro 26 Feb '17

26 Feb '17

Some instructions here <http://blog.refu.co/?p=1296> for creating a systemd “.service” file for running Emacs. Initially he did it as a privileged systemwide service, then he figured out how to make it per-user without needing special privileges. (Found in a user comment to this article <http://www.phoronix.com/scan.php?page=news_item&px=systemd-233>.)

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Image-To-Image Translation In TensorFlow
by Lawrence D'Oliveiro 24 Feb '17

24 Feb '17

This page <http://affinelayer.com/pixsrv/index.html> lets you create schematic renditions of various kinds of objects, and then synthesize corresponding photorealistic representations of those objects, based on pieces of images taken from the training databases. You can draw your own outlines, or just click the “Random” buttons to see what it does. Results range from entertaining to disturbing.

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“Smart Contracts” May Not Be So Smart
by Lawrence D'Oliveiro 23 Feb '17

23 Feb '17

To review, “smart contracts” are a feature of some blockchain-based systems, which allow an interaction between multiple parties to be encoded as a set of rules which will be executed automatically by the system, so that neither the parties nor anyone else can prevent those rules from being enforced. ... To give just one example, a legal contract need not try to anticipate absolutely every relevant event that might occur. If some weird thing happens that is not envisioned in a regular legal contract, the parties can work out a modification to the contract that seems reasonable to them, and failing that, a judge might decide the outcome, subject to established legal principles. Similarly, a single error or “bug” in writing a regular contract, causing its literal meaning to differ from what the parties intended, is unlikely to lead to extreme results because the legal system will often resolve such a problem by trying to be reasonable. Contrast this with “smart contracts” where a bug in a “contract’s” code can lead to a perverse result that may allow one party to exploit the bug, extracting much of the value out of the arrangement with no recourse for the other parties. That’s what happened with the DAO in Ethereum, leading to a controversial attempt to unwind a legal-according-to-the-rules set of transactions, and dividing the Ethereum community. <http://freedom-to-tinker.com/2017/02/20/smart-contracts-neither-smart-not-c…>

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Catching Fishing Pirates With Signals Analysis
by Lawrence D'Oliveiro 22 Feb '17

22 Feb '17

Every vessel on the ocean broadcasts its identity and location using the automatic identification system (AIS), which is mostly used to prevent ships from colliding. These days it can also be used to track ship locations, as most AIS data is relayed through satellites. If you want to hide on the sea, the first thing you do is make your vessel "dark" by turning off your AIS broadcasts. What's interesting about pirate fishing vessels, however, is that they need to rendezvous with legitimate reefers if they want to get paid for their catch. To find the pirates, Amos told Ars, he and Bergman needed to look for odd patterns in the behavior of reefers. The group partnered with Global Fishing Watch to work on mapping satellite AIS data, and those patterns began to emerge. "Often with reefers they come to a halt in the middle of the ocean," Amos said. "We don’t see other broadcasting vessels, but we can be confident based on what that ship is doing that they must be rendezvousing with dark vessels." <https://arstechnica.com/tech-policy/2017/02/to-catch-a-thief-with-satellite…> I guess this counts as a “big data” application...

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