That was your first comment when you actually saw the link . Unfortunately is true . It is possible in an unprotected network (such as a free Wi-fi network) to capture packets around the network and in those packets you will find usernames and passwords.
I’m not saying you , to do that , because it’s illegal . However this is the reality . You must be very careful when you log in on a website , most of all when you are using Wi-fi channels.
There are several tools available that captures packets on a network and i recommend Wireshark (a good approach for beginners) . With a handy user interface and intuitive instructions , you can easily start only by watching a video:
You can see how you do that here:
And here you can download Wireshark !
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