Aircrack causing system to overheat

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What steps will reproduce the problem?
1. Normal usage, tested on a Toshiba Satellite Pro L300D-EZ1002X
2. After capturing the WPA handshake and the password file is defined
3. Aircrack-ng runs for approximately 10 minutes & the CPU overheats
4. The laptop completely shuts itself off

What version of the product are you using? On what operating system?
r68 on BackTrack Live (Text Mode)

Please provide any additional information below.
To work around the overheating issue, I wrote the following script:
###########################################################
ps ax | grep air | awk '{print $1; count++; if (count==2) exit}' > pid.txt
echo `cat pid.txt`
while true; do
   echo stopping `cat pid.txt`
   kill -stop `cat pid.txt`
   sleep 30
   echo starting `cat pid.txt`
   kill -cont `cat pid.txt`
   sleep 30
done
###########################################################
Running the script in a separate terminal allowed the system to operate for a 
full 2 hours and successfully crack a WPA password.

Original issue reported on code.google.com by lederj...@gmail.com on 22 Apr 2011 at 1:08

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Does the CPU overheat when using aircrack-ng alone? If so, this would be a 
problem with aircrack-ng, and not Wifite.

You could specify the dictionary as "none" to avoid cracking at all and simply 
capturing the handshake; you could then crack the .CAP file using your script.  
Newer revisions (r74) have a "crack with pyrit" option. This would probably 
cause overheating as well, but it may not; perhaps the overheating with a 
problem with aircrack-ng solely.

Your script looks good, but I don't want to use that method to crack WPA for 
everyone. It seems like CPU overheating involves a problem with either the 
hardware or aircrack-ng; neither of which I have any control over.

I will leave this issue as "New" status so that other people can find it and 
use your script to resolve any overheating problems they may encounter.

Original comment by der...@gmail.com on 22 Apr 2011 at 10:02

• Added labels: Priority-Low, Type-Other
• Removed labels: Priority-Medium, Type-Defect

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or the drivers ?

how old / what are the specs.

Original comment by illskills1982 on 25 May 2011 at 8:29

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The problem will be with your laptop, not with any programs running on it. 
Aircrack uses 100% CPU. Some laptops (could be a CPU fan issue) are known to 
overheat (Toshiba notoriously) when using 100% CPU for an extended period.

Tip: buy a new laptop.

Original comment by pho...@gmail.com on 1 Dec 2011 at 11:26

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You can limit Aircracks usage of the CPU with cpulimit. Install it and run it 
in a new terminal while Aircrack is running wild, then type: 
cpulimit -p {PID} -l {X} 
where PID is the process ID of Aircrack (you can find it using htop, or any 
other process monitor) and X is the % of CPU usage you want to allow to 
Aircrack (example: cpulimit -p 17019 -l 80, would limit the process 17019 to 
80% of CPU usage)
I haven't noticed, but I assume it slows the whole process down. It does keep 
Aircrack running though, by keeping the computer alive for however long it 
takes to finish. 

Original comment by dtodoro...@gmail.com on 15 Sep 2013 at 10:27

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I have the same problem on my Win7/linux PC... Only I disabled the 
auto-power-off on temperature in the bios, so the second time it SHOULD have 
ran until it fried my hardware... Yet, it still gets maybe half million keys 
tried and then it crashes my PC, right to power off. (same issue as others, 
processes some then crashes) I also disabled the timeout for the HDD, 
ScreenSaver, etc.

I just tested on a new laptop (DELL) and it crashes to power off within 15 
seconds of 100% usage. Obviously because of my beefy desktop it takes longer 
for the desktop to crash.

I even used cpulimit, set at 300 (not 600 - I has 6 cores) which limited each 
CPU to ~50%... Still same problem, crashes to power off (after more time) even 
after dropping to 240%. I will post results of dropping to 200% from 600%.

It has to be aircrack-ng... NO program uses 100% CPU because it is bad 
practice, slows the PC, and could possibly fry your CPU & memory... A proper 
program(er) will throttle the process enough so as not to crash the end user's 
PC. Running a PC at 100% on all or some cores may be damaging to your 
hardware...

BruteForce is no good if the program being used to bruteforce crashes the PC 
every time.

Check this... My Specs (the ones that matter) on my barebones PC: ECS A880GM-M6 
CPU: AMD Phenom II X6 1100T Black Edition Six-Core with 16 GB memory -- and it 
STILL CRASHES!

I have a fatter than average PC. Brute forcing is the first thing I have 
actually needed the fat computer for... I bought & built it to do excessive 
things like brute-forcing. Other than brute forcing, I use my 6 cores to open 5 
or more windows with 10+ tabs in each bahahahhaa

I tried the script as is on BT5, and it does not work. It does not like blank 
lines, so I took em' out... Weird thing, it adds a ? to pid.txt (pid.txt?) on 
BT5 (not a big deal). Getting past that I have had issues within the "while do 
/ done" statement. I put just a simple while statement with an echo inside of 
it, and upon running it says "unexpected end of file" instead of repeating the 
echo over and over. I have been trying to get it to work, I added #! /bin/bash 
and it still does not work. As soon as I remove the "while do / done" section 
and execute it runs fine. Something buggy either with BT5 or aircrack-ng... I 
added an exit 0 at the end... I checked all your `, ', and " and they are all 
fine. 

Installing the headers did nothing for me.

Thanks already for everyone's contribution to this awesome open source 
program!!!

P.S. Thanks to the person who reminded me I was going to clean my PC out! Its 
prolly caked in dust from being a few years old.

Good Day Everyone!

Original comment by shawnr...@gmail.com on 13 Nov 2013 at 7:44

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CONFIRMED FIX -- 100% -- Sorry for double post, but there is a solution I 
wanted everyone to see. 

I am now running at 600% (100% x 6 cores) and now aircrack-ng is running about 
~5000k/s give or take. The problem is nothing other than BruteForce needs 
80-100% CPU to work, and because your PC full of dust, it overheats when 
normally it wouldn't (watching videos, youtube, email, etc.) because in those 
cases the CPU usage is usually below 60% depending on your installation. Thus, 
50% CPU usage + dust works fine, because it can still cool itself! But then you 
try to BF and the problem arises from pushing the temperature threshold and 
triggering instant shut down.

Your CPU is likely overheating (as others mentioned) and shutting off. Most 
likely culprit: Dust!

Why so? Well most people do not use their CPU to BruteForce, they use it for 
things like word processing, browsing net, videos, etc. All of these things 
still work with the dust in the CPU because they use less than 50% CPU 
(usually). When you do something like BruteForcing, its running at a 
substantially higher temperature just from the mathematical processing... Then 
add in a lack of airflow to your 100% CPU usage, and the computer freaks out 
and shuts down instantly to prevent damage.

After I cleaned the dust out of the parts (dust in between CPU Fan + HeatSync 
was like 1CM thick) everything ran flawlessly.

Even if you think it is fine, don't be so quick to dismiss the simple issue... 
Take a look inside and see for yourself (flashlight will help). I even doubted 
I had to clean mine because I did a year ago... But even still, I found it 
needed a very heavy cleaning. I am a Phone/DSL/IPTV technician, and born and 
raised with a commodore 64, so it's safe to say I know what I doing :D 

You will want to clean your PC if it has not been cleaned within the past year, 
or if you have a Laptop/Netbook - they collect dust easier/faster - it gets 
stuck more because of confined space & lack of airflow.

PLEASE DO NOT do anything to your PC unless your warranty is void or you have 
RTFM and/or know how to break apart and rebuild a computer. 

If you have a Laptop/NetBook with this issue, you will need more than just 
basic knowledge of computers. Because of their compact size, everything is 
crammed inside with little space, and they are usually difficult to figure how 
to take them apart. For example, lets say you want to open the case, so you 
take the screws in the bottom out, but it still does not come apart - this 
happened to me. Maybe pop the keyboard out (seriously) because there's usually 
one or two screws under there ;)

Note: Use compressed air (preferably) and/or a vacuum to clean the dust -- BE 
CAREFUL NOT TO SUCK PARTS OFF YOUR MOTHERBOARD! Just hover over top where the 
dust is, usualy it comes out. If not, blast some compressed air while using 
vacuum to catch the dust.

NOTE: Make note of disassembly, so you can reassemble later! I am not liable :P

Parts you _REALLY_ should clean:

1) CPU, CPU Fan, & HeatSync - CAREFULLY pull them apart, clean and replace the 
old thermal compound between HeatSync & CPU (if you have some) otherwise just 
try not to get crap stuck to it (its white paste-ish). Blow down the CPU Fan 
and the HeatSync. Leave them out until you reassemble.

2) Power Supply - and the fan inside of it... Yes I took my PSU apart while the 
PSU itself was still under warranty. I was able to get the cover off, the fan 
off and clean it without breaking the warranty seal. Set aside for reassembly.

3) Remove all case fans, and wash them with water (be sure to dry before 
putting back) Any other HeatSync's you see, blow/suck them down bahahaha

4) re-assemble in opposite order of disassembly (good luck)

5) Notice the cPU's power comes back, and aircrack-ng doesn't crash to power 
off, even at 100% CPU! (thanks to cleaning!)

If you still have difficulty even after cleaning do "sudo apt-get install 
cpulimit" and then run "cpulimit -e aircrack-ng -l 80"

In the above 'cpulimit' command, the 80 is a %. To find your max %, multiply 
100% by the number of CPU CORES - in my case, 6 cores = 600% max. You may need 
to do something more like "cpulimit -e aircrack-ng -l 400" leaving 200% CPU 
space buffer.

To the one who I disagreed that the CPU should not run at 100%, in this case 
(of BruteForcing) you were correct (sorry for misinfo :P). It is normal to be 
at 100% while bruting.

Sorry for the LONG email, but its somewhat noob friendly :)

One last tip, to stop DMESG outputting to console edit the file 
"/proc/sys/kernel/printk" and put on one line "6    6   6   6" save + exit. You should 
no longer have DMESG sending errors/warnings to your console and screwing up 
HTOP or aircrack-ng's output

Good Luck to everyone with this problem! Thanks to all those who helped!

Original comment by shawnr...@gmail.com on 13 Nov 2013 at 11:27