November 2014 - Talk - lists.gtalug.org

Crypto Question: Where do you get your entropy
by D. Hugh Redelmeier 21 Jan '15

21 Jan '15

[Scott asked that we post our questions from tonight's meeting] Where do you get your entropy? Entropy (real bytes of random numbers, not pseudo-random numbers) is key for cryptography. - when generating keys for public-key cryptosystems (RSA, ECC, ...) - when generating session keys via a Diffie-Hellman exchange - challenging the other side in various ways (eg. proving liveness or proving possession of a private key) - probably other cases that I'm not remembering at the moment In many cases a Cryptographic Pseudo-Random Number Generator (PRNG) is good enough, but not these. Sometimes a Cryptographic PRNG can be used to "stretch" entropy: kind of like stretching soup by adding water or milk. Adversaries can easily break your cryptosystem if you don't have sufficient entropy. It's that bad. What sources do you use? /dev/random and /dev/urandom are the Linux channel for entropy. There are various sources that can be pooled by the kernel: - timing of unpredictable event (e.g. user keystokes, disk seek timing, ethernet packet timing, ...). The only one I kind of trust is the keystrokes thing, and that doesn't work for servers. Others might be controlled by or predictable to foes. Keystrokes are not as good as one would like. For example, USB keyboards have keystroke timing quantized by the USB scanning rate. - Recent Intel CPUs have true RNGs. (Assuming that they were not subverted by the US Government or something else. Or just plain buggy, something that might not be detectable) - external entropy source. - Scott mentioned several. One DIY example: harvest the americium pellet from a smoke detector and place it directly on a camera sensor. This makes a kind of Geiger Counter and Geiger Generator (I made that second term up). Physicists think that radioactive emissions are unpredictable (except for chain reactions) and thus should be good entropy generators. - Chris mentioned a Kickstarter(?) project that has produced what they claim is an entropy generator on a USB stick.

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Cubox Dev Platform OS images?
by Thomas Milne 11 Jan '15

11 Jan '15

Hey there, I still have my old, original Cubox Dev Platform from a few years ago. When I power it on now though I don't get any indication it is booting up at all. I tried looking for newer boot/OS images to load on the SD card but everything now seems to be for the Cubox-i. Anyone have laying around or know where I could find something like this?

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[OT] Dead motherboard or dead CPU?
by Kevin Cozens 04 Dec '14

04 Dec '14

Greetings, all. Someone recently reported a problem booting their computer. I've had my first ever major failure of a system where I can't boot my machine. My situation is a little different than in the previous thread about a boot problem. FYI, my machine is an HP m7680n with an Intel Core 2 Duo CPU that I have had for several years and gets a lot of use every day. When the machine powers up all the fans start spinning and the drives do their initial power on reset activities. The CPU doesn't seem to warm up AFAICT (unless I haven't let the system run long enough for it to warm up). The first time I had a problem starting up the system I power cycled the machine a few times and got it to boot. I did that on three consecutive days but starting with the fourth day power cycling the machine is no longer able to kick the machine in to showing signs of life. A POST card shows ---- instead of any actual code. All the LEDs on the POST card light that are related to power supply voltages. CLK is also lit up and the RESET LED comes on briefly at power up and power down. The IRDY and FRAME lights are always off. I have tried to boot after pulling all plug-in cards and even after also pulling the RAM and disconnecting the SATA drives. The power supply is a Corsair TX650M that is only a few months old. The separate four pin 12V connector to the MB is reading within tolerance. There are no signs of bad capacitors on the MB (ie. none that have bulges on the top). I don't have an ESR meter to propery test the individual capacitors. Am I looking at a motherboard failure or is it possible the CPU has died? I read the C2D is quite reliable so CPU failure seems less likely than an MB failure but anything is possible when dealing with electronics. -- Cheers! Kevin. http://www.ve3syb.ca/ |"Nerds make the shiny things that distract Owner of Elecraft K2 #2172 | the mouth-breathers, and that's why we're | powerful!" #include <disclaimer/favourite> | --Chris Hardwick

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refurb Acer C720 Chromebook cheap
by D. Hugh Redelmeier 04 Dec '14

04 Dec '14

This can run linux with a bit of work. Pretty good netbook. As described by several folks on this list. (Not yet me -- haven't got the conversion working yet.) $144.99 plus $4.99 shipping plus taxes. <http://www.newegg.ca/Product/Product.aspx?Item=N82E16834314635&cm_re=c720-_…> Other tricks: You can join the newegg "premier" program for a 30-day free trial and get free shipping ($60 per year afterwords). If you pay with VISA, you can get $25 off your first purchase of $150 or more. Read about that here <http://forums.redflagdeals.com/newegg-25-off-purchases-over-150-using-visa-…> Expires December 5. You would have to add something to your order to qualify for this since the c720 is less than $150. Sadly, newegg shipping is not reduced when you combine items within an order.

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Cache DNS issues.
by William Muriithi 26 Nov '14

26 Nov '14

‎Morning, I have cache dns running on a postfix based mail server. The bin‎d server do come up before postfix, but dns queries fail till the dns master come up. Doesn't slave servers keep data persistent? I mean, is it normal for slave to fail resolving queries on start up if the master us down? Thanks in advance ‎ William

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27" monitor $300
by Matt Price 25 Nov '14

25 Nov '14

this came in my email today -- reminded me of that long Dell thread, which I have not read in its entirety; but anyway thought I would share: http://slickdeals.net/f/7402732-27-monoprice-2560x1440-ips-panel-pro-led-mo… I have no idea if this is a good monitor or not, I'm not in the market so not making the necessary effort to find out...

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Who gave us a talk on shell scripting?
by David Collier-Brown 24 Nov '14

24 Nov '14

My brain leaks: I have his book at home, but I can't remember his name! --dave -- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest davecb(a)spamcop.net | -- Mark Twain

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Re: [GTALUG] [TLUG]: monitor, dell
by D. Hugh Redelmeier 23 Nov '14

23 Nov '14

| From: ted leslie <ted.leslie(a)gmail.com> | To: "tlug(a)ss.org" <tlug(a)ss.org> | Date: Sun, 16 Nov 2014 11:48:04 -0500 | Subject: [TLUG]: monitor, dell | Reply-To: tlug(a)ss.org | | People have posted good price stuff on here before: | | http://www.walmart.ca/en/ip/dell-27-2560-x-1440-led-ips-monitor/60001894778… | | 750$ monitor for 250$ ! pricing error? you tell me! | Like the lenovo portable someone posted here a while back, | if it is a pricing error, I assume they will not fulfil, | but I have ordered a couple any way, see what happens. | | -tl This was sent to the old list but got to me! I thought that the old infrastructure had been burned down. Ted has now subscribed to the new list and posted this but it awaits moderation. This is an astounding deal for a good 27" 2560x1440 monitor. I've ordered one. $307.61 including taxes, EHF, shipping. It might be a pricing error. Thanks Ted!

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teksavvy dsl 2 modem that runs OpenWRT
by Alex Volkov 23 Nov '14

23 Nov '14

Hello everyone, I need to get a DSL2 modem, and I like running OpenWRT when it comes to embedded devices -- I'm planning to run OpenVPN, ssh server and a few Python scripts. I'm assuming there could be a router out the with DSL2 modem capability. Could anyone recommend the most linux-friendly model that would have enough resources to run all the things I've mentioned? Thanks, Alex.

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Re: [GTALUG] how to open .asec file
by Peace River 22 Nov '14

22 Nov '14

Could anyone tell me a software I can open the .asec file? I saved some passwords in the keeper application with my old android phone. I then backup the file to my laptop. However, I am not able to open the file. the file name is com.callpod.android_apps.keeper-2.asec. I need to open it so that if by accident, I cannot get access to my old cellphone, I still have access to those passwords. Many thanks in advance! have a good weekend, Frank Yu

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