this a easy one . So iam not gonna describe the whole thing jsut follow the steps thats all. Lets gets to it :) first you need some free tools . if you are using a kali linux distro you already have it in case you dont follow this commands one by one sudo apt-get install airmon-ng sudo apt-get install airodump-ng sudo apt-get install aireplay-ng sudo apt-get install aircrack-ng downlod this wordlist http://scrapmaker.com/download/data/wordlists/dictionaries/rockyou.txt and after this these we pretty much get everything we need next step type in ifconfig it will show the available device pick one in mind it will looks like wlan1 wlan0 something like that and iam gonna pick wlan0 next type in airmon-ng wlan0 start thats will start our wlan0 as monitor mode and show some process kill them all with kill pid then type in airodump-ng wlan0mon this will show all the available network pick the network and copy the essid,channel and bssi