After a recent article, reader Peter Schmidt wrote to ask:
Terry, I recently bought a new desktop, am using IE7 w/ popups blocked. I took your advice and bought a Linksys router. My question is this; based on how you describe a router works, that only the websites I request can reach my computer, how do popups get past the router?
I wrote back to Peter to explain in more detail. I had written that only responses to requests from your computer could follow back to you through the router, which isn’t quite the same thing as Peter’s high-level interpretation.
If you ask for a web page, that’s one type of request.
So is a dns request, where you put in www.google.com, but the computer has to go to the net to find out which IP address that corresponds to www.google.com
When you check for email, there are a bunch of requests that are sent.
Actually, when YOU request a web page like www.google.com, you’re not just making one request. Your computer does an individual request for every unique item on the page – every image is a separate request, each embedded sound file is, each CSS file is a separate request. A web page can be a minimum of 1 request to a reasonable maximum of 50 or more (by the time you count advertising – watch the browser status bar some time).
Now, let’s think about what might happen if you get some adware or spyware. It will "call home" and your router will treat it as a legitimate communication from your computer (that’s why you should use antispyware/antiadware like CounterSpy that I use).
But, the more probable answer is that a web site you visited included the popup code in its web page that you downloaded. Again, you contacted the web site asking for the page, and the page response probably included the code that generated the advertising popup on your computer.
Peter wrote back:
Thanks for such a thorough reply Terry! Now I understand. And can see more
clearly the need for a 2-way anti-spyware program.
and