technology
On technology
Successful connect to WPA2 with Linux Mint 17
I found myself having odd problems connecting to WPA2 encrypted wireless networks with a new laptop. There must be more elegant solutions to this problem, but this worked for me. The problem was that I couldn’t connect to a nearby hotspot secured with WPA2 whether I used the default config tool for mint, Wicd Network Manager, or the command line. Errors were either “bad password” or the more detailed errors below.
As with any system variation mileage may vary, my errors look like:
wlan0: CTRL-EVENT-SCAN-STARTED wlan0: SME: Trying to authenticate with 68:72:51:00:26:26 (SSID='WA-bullet' freq=2462 MHz) wlan0: Trying to associate with 68:72:51:00:26:26 (SSID='WA-bullet' freq=2462 MHz) wlan0: Associated with 68:72:51:00:26:26 wlan0: CTRL-EVENT-DISCONNECTED bssid=68:72:51:00:26:26 reason=3 locally_generated=1
and my system config is reported as:
# lspci -vv |grep -i wireless 3e:00.0 Network controller: Intel Corporation Wireless 7260 (rev 6b) Subsystem: Intel Corporation Dual Band Wireless-AC 7260 # uname -a Linux dgzb 3.16.0-38-generic #52~14.04.1-Ubuntu SMP Fri May 8 09:43:57 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
I found useful commands for manually setting up a wpa_supplicant.conf file here, and for disabling 802.11n here. The combination was needed to get things working.
The following successfully connects to a WPA2-secured network:
$ sudo su $ iw dev ... Interface [interfacename] (typically wlan0, assumed below) $ iw wlan0 scan ... SSID: [ssid] ... RSN: (if present means the network is secured with WPA2) $ wpa_passphrase [ssid] >> /etc/wpa_supplicant.conf ...type in the passphrase for network [ssid] and hit enter... $ sh -c 'modprobe -r iwlwifi && modprobe iwlwifi 11n_disable=1' $ wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf
(should show CTRL-EVENT-CONNECTED)
(open a new terminal leaving the connection open, ending the command disconnects)
$ sudo su $ dhclient wlan0
(should be connected now)
United’s Magic Trays
@United has new coach trays that are coated with a material that has an amazing coefficient of friction. They are not sticky at all—there’s no adhesion effect—it is all friction. Even low surface energy plastics don’t slide on it at all.
The approximately 75-80° angle in the picture is the point at which the cup topples over itself. It isn’t adhered to the surface and it doesn’t appear to slide at all before toppling.
This would be the perfect coating for a smart phone pad in a car.
Microsoft Spyware Now Being Installed On Win 7
If you’re the sort of person who isn’t entirely happy about the idea of Microsoft claiming the right to copy your personal files, photos, emails, chat logs, diary entries, medical records, etc over to their own servers to sell to whoever they want for whatever they can get for your personal data – into markets that already exist for insurance companies to deny you insurance based on algorithmic analysis of your habits or your friends habits or for financial institutions to set your interest rates based on similar criterion, or perhaps even for law enforcement to investigate you without a warrant, then OBVIOUSLY you would never, ever install Windows 10 under any circumstances.
Well, Microsoft seems to have fully jumped on the Google/Facebook gravy train and is now completely invested in stealing your data and selling it to the highest bidder (Apple has been exfiltrating your data for a long time, but so far for internal use). I’ve become more suspect of Microsoft’s updates since they made the Windows 10 advertisement an important (not optional) update (important for what? their bottom line, obviously). Turns out that the latest updates to Windows 7 are pushing Microsoft’s new business model of stealing your data for profit to Windows 7 and 8.
Staying safe is going to require ever more vigilance. It may be possible to block windows components from reaching out to microsoft’s servers at the personal firewall level and certainly it can be done at the corporate firewall level (and should be), but blocking Microsoft is a somewhat complex issue. You can’t run Windows safely without installing security patches because the underlying OS is so completely insecure that new, critical, exploitable flaws are discovered every single week. If you don’t constantly patch these security failures, you will be hacked by people other than microsoft. If you install the wrong microsoft patch, you will be hacked by microsoft. Debian anyone? Also, software developers developing enterprise software, please, please, please stop developing for that horrible, insecure, performance hobbling abomination of a tarted-up single-user OS “Server” and focus on a secure, stable server OS like FreeBSD. Please. I hate, hate having to fork over $1k to microsoft for each box to run their horrible OS just so I can run your software. Why do you support that extortion? Do you despise your customers that much? Stop.
If you care about corporate governance and data security or HIPAA compliance, you are probably violating some critical requirements by installing windows 10 or these new updates to your existing Win7/8 base if you do not block data exfiltration to Microsoft’s servers. This is spyware. These updates are stealing your data and sending it to Microsoft. If your business is subject to data privacy laws, these updates put you in violation of those laws. Microsoft is doing something that is extremely significant and extremely evil and completely wrong. Take action or you may very well be facing personal or corporate consequences. srsly.
I am a strong believer in data privacy and extremely suspect of what I consider highly disingenuous business practices like Google’s but I recognize that there are reasonable people out there who think Google isn’t evil. However, this windows 10 issue, now being pushed to windows 7, goes well beyond Google taking advantage of people’s historical assumptions about the security of email to offer them a free look-alike honey trap to gather their data. Windows 10 and these Win 7 updates are intrusive, not merely misleading. Do not update. Srsly. Do not update. Block the spyware “hotfixes.”
- Russia considers banning windows 10
- Bit torrent trackers ban Windows 10 users
- Windows 10 steals so much data it breaks your data plan and costs you money
- Windows 10 is spyware, plain and simple, including a keylogger.
Stop Gap Fixes
In researching these updates, I came across this article on techworm that has a nice summary of the Malware updates Microsoft is pushing out (with some additional amendments I found):
- KB2952664 (this one reappears no matter how often you unselect it or hide it – so memorize it as evil)
- KB2976978
- KB2977759
- KB2990214
- KB3021917
- KB3022345
- KB3035583
- KB3044374
- KB3068708
- KB3075249
- KB3080149
- KB3112343
- KB3123662
- KB3123862 (new)
- KB3173040 NEW – “final” full screen nag advertisement for Win10 malware
With a whiff of irony, this google search “telemetry site:https://support.microsoft.com/en-us/kb” shows these patches and many more…
Do not automatically install Microsoft updates. You must turn that feature off or you will keep getting additional spyware installed. Go to windows update and verify your settings. I have mine set so windows downloads the updates (so the updates are waiting locally), but I don’t let windows install them automatically. That gives me a chance to review the updates and look for spyware.
When you get updates, you now have to check each one of them to find out if it is spyware or not. The list above is current as far as I know, but clicking on the “more information” link to the right of the updates list will get you microsoft’s marketing speak obfuscation of the true purpose. Any update that “adds telemetry points” or something like that is spyware. Uncheck the install and hide the update. Note that some of these were moved from “optional” to “important.” Microsoft is absolutely intent on stealing your data and is taking some pretty underhanded steps to make it difficult for you to avoid it.
If updates get past you or it turns out later that a seemingly important or innocuous update was spyware (the fun part is that you now have to be vigilant and look all this stuff up), then you can uninstall them from the “installed updates” control panel.
Work to be done
I’ll start looking into firewall settings to block communication to microsoft’s servers. This is a standard anti-malware technique and should work here, except that microsoft has so many servers it is more challenging to block them than your typical malware botnet.
We need something like a variant of Peer Guardian to block microsoft’s servers using the standard P2P crowd-sourcing model to keep the list up to date. I’m not aware of anything like this yet, but I’m looking. Microsoft has become more of an enemy to privacy than the RIAA ever was.
UPDATE: this superuser answer includes a list of telemetry endpoints to block at your firewall or router. Alternatively you can edit your hosts file and add these entries from DSL reports.
Larger Significance
This shift in business focus by Microsoft from providing a product people are willing to pay for to stealing data from people to sell on the commercial market has some significant lessons for the entire software model.
It isn’t just that Microsoft is now adopting Google’s business model of giving away “free” goodies as traps to collect product (you) to sell to the highest bidder, but that the model of corporate trust that underpins most of the security assumptions the internet is built on is manifestly false and unsustainable. If any hacker tried to create these spyware updates, locked-down computers that only install signed code would refuse to install them. Ignoring for the moment that the signed code model is idiotically flawed as signing keys are stolen all the time, this microsoft spyware is properly signed with legitimate keys. It will be installed on locked down computers without complaint and will not show up in commercial anti-virus software. But it is spyware. It contains keyloggers and extremely productive data exfiltration code that is currently copying wholesale data dumps from unfortunate victims to Microsoft’s servers in such volume that their data caps are being hit.
If a non-commercial third party (e.g. “hacker”) did this, they’d be prosecuted. It makes no difference to you that your data is being stolen by Microsoft rather than by some clever teenager in a former eastern block country: your data is being stolen. But the model that has been promoted, a model of centralized corporate trust to validate the “security” of your system has been utterly and irrevocably shattered. This isn’t an accident, isn’t something that better data management might have prevented, this is an intentional ex post facto rewrite of the usual, customary, and regular assumptions we have about the privacy of our computer systems and one that significantly impacts the security of almost everyone in the world: military, medical, legal, fiduciary, as well as personal.
And even if you trust Microsoft (for whatever bizarre, irrational reason), Microsoft is creating a whole series of security holes in their already crappy and insecure operating system that will be exploited by third parties. By adding keyloggers and data exfiltration tools to the core OS, they’re making it even easier for non-corporate hackers to jump on the data theft gravy train. Everyone profits but you. You lose.
Disk Checks for Large Arrays
If you have a large array of disks attached to your server, which is obviously going to be running FreeBSD or OpenBSD if you care about security, stability, and scalability; there are some tricks for dealing with large numbers of disks (like having 227 4TB disks attached to a single host).
Using Bash (yes there are security issues, but it is powerful)
# for i in `seq 0 227`; do smartctl -t short /dev/da$i; sleep 15; done 1Thanks Jared
executes a short smart test on all disks. Smartctl seems to max out at 32 concurrent tests, so sleep 15 ensures the 3 minute tests are finishing before new ones are executed. If you’re in a hurry, sleep 5 should do the trick and ensure all of them execute.
to get results try something like:
# for i in `seq 0 227`; do echo "/dev/da$i"; smartctl -a /dev/da$i; sleep .5; done
Bulk Fixes
Problem with the disks – need to clear existing formatting?
unmount each disk
# for i in `seq 0 227`; do umount -f /dev/da$i; done
unlock (if needed)
# sysctl kern.geom.debugflags=0x10
Overwrite the start of each disk
# for i in `seq 0 227`; do dd if=/dev/zero of=/dev/da$i bs=1k count=100; done
Overwrite the end of each disk
# for i in `seq 0 227`; do dd if=/dev/zero of=/dev/da$i bs=1m oseek=`diskinfo da$i | awk '{print int($3 / (1024*1024)) - 4;}'`; done
Recreate GPT (for ZFS)
# for i in `seq 0 227`; do gpart create -s gpt /dev/da$i; sleep .5; done
Destroy multipaths
# for i in `seq 1 114`; do gmultipath destroy disk$i; done
Disable multipath completely
# for i in `seq 1 114`; do gmultipath destroy disk$i; done
# gmultipath unload
# mv /boot/kernel-debug/geom_multipath.ko /boot/kernel-debug/geom_multipath.ko.bad
# mv /boot/kernel/geom_multipath.ko /boot/kernel/geom_multipath.ko.bad
Footnotes
| 1. | ↑ | Thanks Jared |
A Solution for Mosh Scrollback
Mosh is a pretty good tool, almost indispensable when working in places with crappy internet. While it is designed to help with situations like “LTE on the beach,” it actually works very well in places where internet connectivity is genuinely bad: 1500msec RT, latency, 30% packet loss, and frequent drops in connectivity that last seconds to hours, otherwise known as most of the world. On a good day I lose an SSH connection randomly about every 3-6 hours but I’ve only ever lost a Mosh session when my system went down.
It does a lot of things, but two are key for my use: it syncs user input in the background while local echoing what you type so you can finish your command (and correct a typo) without waiting 1500msec for the remote echo to update; and it creates persistent connections that survive drop off of almost any type except killing the terminal application on one end or the other (anything between can die and when it recovers, you catch up). This means compiles finish and you actually get the output warnings…
…well…
…some of them. Because Mosh’s one giant, glaring, painful, almost debilitating weakness is that it doesn’t support scrollback. So compared to tmux or something else that you can reconnect to after your SSH session drops, you really lose screen content, which is a PITA when ls-ing a directory. I mean, it isn’t that much of an efficiency gain to have to type “ls | less” instead of just “ls” every time you want to see a directory.
I found a solution that works for me. I also use Tmux with Mosh because Tmux will survive a dead client and working with Windows client reboots are a fact of life (I know, sad, but there are some tools I still need on windows, hopefully not for much longer).
Tmux has a facility for creating a local log file, which I then “tail -f” using a separate SSH window. If the SSH client disconnects, no loss, I can pick up the log anytime. It is just mirroring everything that the mosh terminal is doing and the scroll bar scroll back works fine. And it is a raw text file, so you can pipe the output through grep to limit what’s displayed to something of interest and review the log asynchronously as, say, a build is progressing.
Although there are some nice advantages to this, when/if Mosh supports scrollback, it’ll be far more convenient having it in the same window, but for now this is the easiest solution I could come up with.
FreeBSD:
# portmaster sysutils/tmux # portmaster net/mosh # ee ~/.tmux.conf -> bind-key H pipe-pane -o "exec cat >>$HOME/'#W-tmux.log'" \; display-message 'Logging enabled to $HOME/#W-tmux.log' -> set -g history-limit 30000 Start a Mosh session (for example with Mobaxterm on windows) # tmux # [CTRL]-b H start SSH session (Mobaxterm or Putty on windows) # tail -f csh-tmux.log ("csh" will be the name of the mosh window - so really "(MoshWindowName)-tmux.log"
You can tmux the ssh session too and still have scrollback and then just reconnect into the same tail command, which preserves the whole scrollback. If you’re on a connection like I’m on, your scrollback logfile will drop off a couple of times a day, but you won’t lose your Mosh session, and it’ll be waiting for you when you’re reminded that you need to see those security warnings from the compile that just scrolled off the Mosh screen forever.
Low Voltage LED Lighting
My kitchen has had halogen lighting for 20 years, from back when it was a slightly more efficient choice than incandescent lighting and had a pleasing, cooler (bluer, meaning the filament runs hotter) color temperature.
Progress has moved on and while fluorescent lights still have a lead in maximum luminous efficacy (lm/w), for example the GE Ecolux Watt-Miser puts out 111 lm/W, they’re less versatile than LEDs and installation is a hassle while low voltage LEDs are easy to install and look cool.
System Design
The goal of this project was to add dimmable, pleasing light to the kitchen that I found aesthetically interesting. I wanted a decent color rendering index (CRI), ease of installation, and at reasonable cost. I’ve always liked the look of cable lighting and the flexibility of the individual, adjustable luminaires.
I couldn’t find much information on how variable output LEDs work and what can be used to drive them. I have a pretty good collection of high quality power supplies, which I wanted to take advantage of, but wasn’t sure if I’d be able to effectively dim the bulbs from the documentation I found. So I did some tests.
Test Configuration
I bought a few different 12V, Dimmable LEDs and set up a test configuration to verify operation and output with variable voltage and variable current. The one bit of data I had was that using standard commercial controllers, the lowest output is typically stated to be around 70% of maximum output: that is the dimming range is pretty limited with standard (PWM/Transformer) controllers. The results I found were much more encouraging, but revealed some quirks.
I used a laboratory-grade HP power supply with voltage and current control to drive the LEDs, decent multimeters to measure voltage and current, and an inexpensive luminance meter to measure LED output.
I measured 3 different LEDs I selected based on price and expected compatibility with the aesthetics of the project and because they looked like they’d have different internal drivers and covered a range of rated wattage.
Test Results
These bulbs have internal LED controllers that do some sort of current regulation for the diodes that results in a weird voltage/current/output response. Each bulb has a different turn-on voltage, then responds fairly predictably to increasing input voltage with increasing output, reaches the controller stabilizing voltage and runs very inefficiently until voltage gets over the rated voltage and then becomes increasingly efficient until, presumably, at some point the controller burns out. I find that the bulbs all run more efficiently at 14V than at the rated 12V.
As a side note, to perform the data analysis, I used the excellent xongrid plugin for excel to perform Kriging interpolation (AKA Gaussian process regression) to fit the data sets to the graphing function’s capabilities. The graphs are generated with WP-Charts and the table with TablePress.
Watts v. Volts
This chart shows the wattage consumed by each of the three LEDs as a function of input voltage, clearly demonstrating both that the power consumption function is non-linear and that power consumption in watts improves when driven over the rated 12V. Watts are calculated as the product of the measured Volts * Amps. Because of the current inversion that happens as the controllers come fully on-line, these LEDs can’t be properly controlled near full brightness with a current-controlled power supply, though it works well to provide continuous and fairly linear dimming at low outputs, once the voltage/current function changes slope, the current limiting controller in the power supply freaks out.
4W LED 5W LED 7.5W LED
Lux v. Volts
This chart shows the lux output by each of the three LEDs as a function of input voltage, revealing the effect of the internal LED driver coming on line and regulating output, which complicates controlling brightness but protects the LEDs. The 5W LEDs have a fairly gentle response slope and start a very low voltage (2V) so are a good choice for a linear power supply. The 4W LEDs don’t begin to light up until just over 6V, and so are a good match for low-cost switch mode supplies that don’t go to zero.
4W LED 5W LED 7.5W LED
Lux/W v. Volts
This chart shows the luminous efficiency (Lux/Watt, Lumen measurement is quite complicated) by each of the three LEDs as a function of input voltage, showing that overdriving the LEDs past the rated 12V can significantly improve efficiency. There’s some risk it will overheat the controller at some point and result in failure. I’ll update this post if my system starts to fry LEDs, but my guess is that 14V, which cuts the power load by 20% over 12V operation with the 7.5W lamps I selected, will not significantly impact operational lifetime.
4W LED 5W LED 7.5W LED
Total System Efficiency
The emitter efficiency is relatively objective, but the total system efficiency includes the power supply. I used a Daiwa SS-330W switching power supply I happened to have in stock to drive the system, which cost less than a dimmable transformer and matching controller, and should be significantly higher quality. The Daiwa doesn’t seem to be easily available any more, but something like this would work well for up to 5A total load and something like this would handle as many as 40 7.5W LEDs on a single control, though the minimum 9V output has to be matched to LEDs to get satisfactory dimming. It is important not to oversize the power supply too much as switch mode supplies are only really efficient as you get close to their rated output. An oversized switchmode power supply can be extremely inefficient.
With the Daiwa, driving 13 7.5W LEDs, I measured 8.46A at 11.94V output or 101 Watts to brightly illuminate the entire kitchen, and providing far more light than 400W of total halogen lights. I measured the input into the power supply at 0.940A at 121.3V or 114 Watts. That means the power supply is 88.6% efficient at 12V, which is more or less as expected for a variable output supply.
Increasing the output voltage to 14.63 Volts lowered the output current to 5.35A or 78 Watts without lowering the brightness at the installation; I measured at 168 lux at both 12.0V at 14.6V. The input current at 14.63V dropped to 0.755A or 91.6 Watts, meaning the power supply is slightly less efficient at lower output currents (as is usually the case).
- Overdriving the 12V rated LEDs to 14.63V improves plug efficiency by 20%.
At the low end, the SS-330W’s minimum output is 4.88V, which yields 12 lux at the counter or a 14x dimming ratio to 7% of maximum illumination, a far better range than is reported for standard dimmer/transformer combinations.
Parts
- 7.5W LED modules from JackyLED
- Daiwa power supply (alternate version)
- 16 gauge speaker cable
- MR-16 cable lamp mounts
- Digital light meter
Raw Data:
(MS Excel file, you will need the xongrid plugin to update the data as rendered in the graphs)