Let's say I'm in my own house, with my own wireless router and two computers are on and connected to the internet. One computer is currently accessing a website which needs a login to access certain features. So, in my little knowledge of computers, would say that the login/pwd data is transfered like this: firstComputer -> wireless router -> website -> website processes information and authenticating (website is now allowed to send the features because the login/pwd is right) -> wireless router -> firstComputer. If the second computer is also connected to the same wireless router, can it intercept (get the data) that's being sent to and from the first computer? Are there any software examples of that? Thanks in advance.
Usually the data cannot be intercepted if you have encryption enabled. Be sure that you enable encryption in your WiFi settings. Usually WEP and WPA2 are available as encryption settings. I strongly recommend using WPA2 encryption because there have been cases of WEP being hacked.
Any data you broadcast can be intercepted.
However if they can understand the information in the intercepted data depends on a few things:
If you used no encryption at all then they can just read the data.
How hard this is depends on a lot of things. Cracking ancient WEP encryption takes about 10 seconds on a mid level computer. You might as well not use it.
Its successor, WPA is also to weak to withstand current day computers.
WPA2 still seems adequate today. Cracking a WPA2 link with a decent password can be done. The last article I read on that used a dozen amazon instances with massive GPU support and then it took about a day to crack it. This means two things: 1) Right now WPA2 is probably secure enough unless someone is very determined. 2) In a few years when computers will be faster, it will be to weak.
Using a key sniffer might be a lot easier than breaking these two layers.
Whatever you do, if you transmit things wireless they can be intercepted an cracked. But it might require more effort than it is worth.