How to install aircrack-ng on Raspberry Pi
Step 1: open a terminal, create a new download folder or use your already existing.
Step 2: install an OpenSSL dependency of aircrack-ng.
sudo apt-get install libssl-dev
If you won't do that you will run into this error later:
fatal error: openssl/hmac.h: No such file or directory
Step 3: install SubVersion
sudo apt-get install subversion
Step 4: download the aircrack sourcecode
svn co http://svn.aircrack-ng.org/trunk/ aircrack-ng
Step 5: Change directory to aircrack-ng
Step 6: pray that you get no errors and type
Step 7: install
sudo make install
Step 8: Done