Hello there,

Recently, I've become increasingly concerned about the constant monitoring of my online activities by various social networks and Internet services, regardless of my consent.

To illustrate, let's take a simple example: last week, I spent a few hours browsing through watches on eBay. I didn't use any search engine like Google or Yandex to find them, I simply visited eBay directly. I don't have any browser toolbars installed and I use private browsing mode whenever possible. Moreover, I always make sure to click the "log out" button before leaving any website where I logged in.

Yet, despite all these precautions, advertising networks persistently bombard me with watch advertisements day and night. It's understandable that eBay shared the information with advertisers, but how did they manage to identify me? Additionally, we all remember the infamous analysis of Facebook cookies, which are notorious for their invasive tracking practices.

Overall, this situation saddens me. I'm even considering going online using a virtual machine and reverting to a previous snapshot after each website visit.

This leads me to the idea of only providing my data to others when I truly want to. Perhaps the simplest solution would be a local DNS proxy equipped with a comprehensive database of advertisers, search engines, social networks, and so on. By default, the entire database would be directed to 127.0.0.1, only allowing access when the proxy detects that I deliberately navigate to a particular website like facebook.com.

Banning browsers from downloading data from other domains is not a feasible option as it would disrupt the functionality of many websites that rely on multiple interconnected domains.

I wonder if such a solution already exists in the world?

It's no surprise that eBay includes the code for doubleclick.net, which is essentially Google in full force.

For instance, Kaspersky automatically blocks all ads in any browser without the need for additional plugins that consume Firefox's memory.

Moreover, you can also disable third-party cookies (cookies from external websites).

The only solution that provides relief for me is modifying the hosts file, where most pages that typically display banners instead show a message stating "this page does not exist."

Currently, I have around 150 entries manually added in the file to block specific advertisements.

On a related note, it's worth mentioning that there are various browser extensions available that can assist in blocking ads and improving online privacy.

Implementing this solution won't be a straightforward task; it would also require developing a browser plugin.
For both the DNS server and the proxy server, it doesn't make a difference whether you manually entered the address in the browser's address bar or if it was embedded within a webpage. Therefore, there are essentially two options: either create a customized ad-blocking extension for your specific needs or set up a squid server where you can manually allow or block the sites you dislike.

consider the ongoing cat-and-mouse game between users seeking privacy and advertisers trying to track their behavior. Privacy-focused tools and techniques are continually evolving to adapt to new tracking methods, making it important to stay informed and explore diverse approaches to safeguard personal information.

The fact that you're seeing ads for watches after browsing eBay, even though you took various precautions, is a clear sign that online tracking is more pervasive than many people realize.

To start off, let me tell you that the main culprits behind such tracking are cookies and similar technologies like local storage and tracking pixels. When you visit a website like eBay, they often set cookies that can be accessed not only by eBay itself but also by third-party advertisers. These third-party advertisers have scripts running on eBay's site, which means they can recognize you as you browse different websites, even if you log out or use private browsing mode. The private mode mainly hides your activity from other users of the same device and doesn't prevent sites from tracking you.

Now, you mentioned something quite interesting—using a local DNS proxy to block unwanted tracking. This idea is actually a great approach and something similar already exists. The concept you are describing is like what the Pi-hole does. Pi-hole is a network-wide ad blocker that works as a DNS sinkhole, blocking requests to known ad-serving domains. When a device on your network makes a DNS request to a known advertising or tracking domain, Pi-hole can return a false address, like 127.0.0.1, effectively blocking the request.

Implementing a Pi-hole or a similar DNS-based ad blocker would work exactly as you described, it would block unwanted requests while still allowing essential requests for the functionality of a website. Additionally, you can manually whitelist any domains you wish to access, ensuring that essential services are not blocked. The DNS-based approach is quite efficient because it prevents unwanted traffic from even reaching your network.

Another solution could be using browser extensions like uBlock Origin or Privacy Badger, which are designed to block trackers and intrusive ads. These tools analyze the domains and scripts being loaded by the websites you visit, and they can block requests to known trackers, much like your DNS proxy idea but at the browser level. However, these tools can sometimes break website functionality, but usually, you can quickly whitelist certain elements if needed.

While a VM and snapshot approach would provide a high level of privacy, it's indeed a bit cumbersome for daily browsing. It would require a lot of storage and time to revert to snapshots constantly, and you might still leak some information if the VM is running for an extended period.
While there's no perfect solution that completely anonymizes your online activity (without impacting your web experience), tools like Pi-hole, uBlock Origin, and Privacy Badger can significantly reduce the amount of tracking that happens. Using these tools, along with good browsing habits (like clearing cookies regularly and avoiding logging into services unless necessary), can give you more control over your online footprint. If you're comfortable with some technical setup, the DNS proxy idea is definitely a viable route to explore for enhanced privacy.