Recently I took my annual leave and decided to visit my friend during the holidays. I stayed at a hotel for a few days but to my surprise, the hotel charged money to use their wifi. In $DEITY’s year 2000 + 18, can you imagine?
But they are not so cruel. You see, these generous people let you use the wifi for 20 minutes. 20 whole minutes. That’s almost half a Minecraft video.
If they let each device use the internet for a limited amount of time, they must have a way of identifying each device. And the way a router tells devices apart is by their MAC addresses. Fortunately for us, we can change our MAC address easily.
Enter macchanger
There is a really useful command-line tool called macchanger. It lets you manually change, randomize and restore the MAC address of your devices. The idea here is randomizing our MAC regularly (every 20 minutes) in order to use the free wifi over and over indefinitely.
There are 3 small commands you need to run. This is needed because macchanger can’t work while your network interface is connected to the router.
# Bring network interface down
ifconfig wlp3s0 down
# Get random MAC address
macchanger -r wlp3s0
# Bring the interface back up
ifconfig wlp3s0 up
In the commands above, wlp3s0 is the name of my network interface. You can find yours by running ip a. If you run those commands, you can fire up your browser and you will be greeted with the page asking you to pay or try it for 20 minutes. After your time is up, you can run the commands again and keep doing it.
But this is manual labor, and doing it 3 times an hour is too repetitive. Hmm. What’s a good tool to automate repetitive stuff?
Enter Selenium
First, lets get those commands out of the way. Using the os module, we can run macchanger from our script.
import os
interface = 'wlp3s0'
os.system(f'sudo ifconfig {interface} down')
os.system(f'sudo macchanger -r {interface}')
os.system(f'sudo ifconfig {interface} up')
After these commands our computer should automatically connect to the network as a completely different device. Let’s fire up a browser and try to use the internet.
d = webdriver.Chrome()
d.get('http://example.com')
d.get('https://www.wifiportal.example/cp/sponsored.php')
The sponsored.php URL is where I ended up after pressing the Free Wifi link, so the script should open the registration form for us. Let’s fill the form.
In my case, all it asked for was an email address and a full name. If there are more fields, you can fill them in a similar fashion.
num = random.randint(0, 99999)
email = f'test{num}@gmail.com'
d.find_element_by_name('email').send_keys(email)
d.find_element_by_name('name').send_keys('John Doe\n')
This should fill the form and press enter to submit it. Afterwards, the portal asked me if I wanted to subscribe to their emails or something like that. Of course, we click Reject without even reading it and close the browser.
d.find_elements_by_class_name('reject')[0].click()
d.close()
After this, you should have an internet connection. You can either run the script whenever you notice your connection is gone, or put it on a cron job / while loop.