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To make myself a little more clear: I tried opening a .lst file (password list) in Kali Linux. The system was struggling to handle it and Leafpad didn't even start, but I noticed a significant performance difference. I ended up just hard rebooting.

When I open the password list with Aircrack-ng to crack a password, Aircrack-ng is able to use the password list just fine.

What makes Aircrack-ng more suitable to handle this large lst file without significantly impacting my laptop's performance? Is it the way Aircrack-ng reads the lst file?

just wondering
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2 Answers2

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The word "open" does not mean the same thing everywhere.

Random access

For a typical text editor, the reason to open a file is to load it for editing. Since most text editors allow you to edit by jumping all over the file to insert, delete, and/or change text, most text editors support this by loading the entire contents of the file into memory. Unfortunately, if a file is too large to fit comfortably in memory, performance will suffer when your system runs out of memory to do other things it needs to do.

Serial access

For aircrack-ng password cracking, the reason to open a file is not to edit it but to read passwords out of it. Unlike the text editor it does not need the ability to jump to any random point in the file at any time. In fact, it only needs to start at the beginning and read a few passwords at a time until it gets to the end. When it tries a password and it does not work, it does not need to remember that password anymore. This process uses a fairly small amount of memory that does not depend on how large the file is, which is why your system does not run out of memory.

jw013
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  • Thanks! Hopefully this isn't going too off topic, but I have one more question for you: how can I increase the speed of how many keys are being tested by aircrack-ng? Would an increase in RAM help? Or does the speed rely on the processor speed? – just wondering May 26 '14 at 18:14
  • @just There's not enough information to answer that for sure without knowing the specific hardware and software configuration being used. I would bet that most password protection schemes in use today are more CPU-bound than memory bound. – jw013 Jun 03 '14 at 03:21
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reply to : Thanks! Hopefully this isn't going too off topic, but I have one more question for you: how can I increase the speed of how many keys are being tested by aircrack-ng? Would an increase in RAM help? Or does the speed rely on the processor speed?

you can use your graphics card to churn out thousands of more passwords per second using oclhashcat

I have 2x Radeon R9 295 X2 - PCI-E and can churn through 500,000 passwords per second. vs the 2000 per second on just my i7 CPU!

Its pain in the butt to setup, but amazing once done. Mine is broken at the mo since the move to Kali 2016.1 rolling ed (hence why i'm here)

all you need to do is convert your cap file to a hashcat readable one

To Convert :

aircrack-ng -J NewHashCatCapName AircrackCapName.cap

To Crack

oclHashcat -m 2500 NewHashCatCapName.hccap /path/PasswordList.lst --force --gpu-temp-retain=55 --gpu-temp-abort=79

temp restrictions are there to stop your PC turning into a small fireball!

as i mentioned, im broken in Kali Rolling 2016.1, i cant install the ati graphics card drivers...so oclhashcat cant talk to them properly. there are plenty of out of date guides that dont work...even here :

How to install AMD Catalyst 15.7 (fglrx 15.20.1046) on Kali 2.0 (Sana)?

working on a new guide if i ever fix it myself :-)

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