When using the Internet, your PC transfers a lot of data in the background. Advertising companies, but also criminals and secret services have an interest in it. In this way you protect yourself from annoying snoopers.

When surfing the Internet, you leave more traces than you might think. Whenever you visit a website, the site operator learns your approximate location and some technical details about your PC, such as which browser version you are using.

In the background your PC transmits a lot of data – mostly unnoticed. “Computer Bild” tells you here how third parties spy on you and what means there are to protect themselves. In most cases, just a few clicks are enough to be much safer on the net.

Which data traces make me identifiable?

If you open a website, the server you are using will know your IP address. Your Internet provider assigns this number, which is comparable to a house number or telephone number, to your router. It allows conclusions to be drawn about your place of residence.

An exact identification on street level is not possible, however, all loaded sides experience your approximate residential area. In addition to your IP address, your PC also transmits information about the operating system, screen resolution, browser plug-ins and installed fonts.

Web pages also recognize you by means of so-called cookies: These small text files store web pages on your hard disk as soon as you visit them. Flash cookies make it possible to track you even across browsers: Regardless of the surfing program used, advertising companies receive a detailed picture of your surfing habits.

What do third parties do with my data?

Websites use the data transmitted in the background to tailor their content to you. For example, if a website recognizes you by means of a cookie, it will greet you with your name.

However, it is also possible for websites to display targeted advertising: for example, you may receive purchase suggestions for products that match the keywords you have entered and that you can buy near you. Statistical surveys are also possible. Some websites regularly publish an overview of how many of their visitors use which operating system.

Especially tricky: Specially prepared websites detect weak points in your software and smuggle malware onto your PC. Those who know your e-mail address can also send you intrusive advertising mails. In many cases, unsubscribing from e-mail advertising is unsuccessful and you continue to receive unsolicited messages.

Fingerprint of your browser

Even if your IP address changes due to a new Internet connection and you delete treacherous cookies, websites often still recognize you. In many cases, the sum of the information transmitted is sufficient.

The US Electronic Frontier Foundation (EFF) shows how clearly your identity can be assigned with the online service Panopticlick. When you perform the test, Panopticlick analyzes the information you automatically send, such as operating system, resolution or browser plug-ins, and calculates how many PCs with the same configuration have performed the test so far.

The probability is very high that your browser is unique among the 3.7 million systems tested to date (as of January 2014). The result is a digital fingerprint of your browser that theoretically identifies you at any time.

Protection against Internet espionage: this helps

To prevent strangers from evaluating your surfing habits, reduce the amount of information transmitted. It also helps to be on the move with false data: if you change your IP address using an anonymization program, for example, you fake websites of a different origin.

In the photo gallery above, “Computer Bild” shows you the best free programs that allow you to surf undetected. For example, the programs presented exchange your IP number, prevent secret contact with Facebook and prevent Google from recording the addresses of visited pages.

How anonymizers work

If you call up a website, anonymization programs act as mediators: They switch between you and the desired page and forward all data traffic to the respective remote peer. The visited website only sees the IP address of the software provider, but not yours – this is known only by the program manufacturer.

The disadvantage of anonymization software is that you can surf the Internet slower with your stealth activated. If you use an anonymizer, you also have to trust the provider completely. After all, your entire surfing session runs on one of its servers.

If the obfuscation works, you can find out on How is my IP: Call the page once with and once without anonymization. The displayed IP addresses should differ from each other, you can read more about it in this forum: https://www.nickles.de/.

Only enter as much data as necessary

The recommended programs reliably disguise you, but help little if you use web services with clear names. If you want to protect your privacy, you should either not use sites that require registration, such as social networks, or use false names.

  • The Fake Name Generator helps to create false identities. Based on predefined criteria, the page generates complete personal profiles at the push of a button.
  • Also be careful when it comes to publishing information on the Internet: as you know, the Internet forgets nothing.
  • Even if you delete content later, it is often still stored in a Google cache or on Archive.org. Your potential future employer might find embarrassing party photos of you costing you the job.

Using alternatives to big websites

For more discretion, it is advisable to switch to less popular Internet services. DuckDuckGo, for example, is an alternative to Google. According to its own information, the site does not store any user information.

Anonymous on the Internet via UMTS stick

What many users do not know: USB sticks, with which you can access the Internet via a mobile phone network, also contribute to your anonymity. The access providers ensure that you get an IP address that you can use to communicate with other websites.

  • Advantage: The IP address is given not only to you, but also to many other users of the provider. In addition, these are usually dynamically distributed addresses so that you can access the Internet with a new number when you dial in later. This means that third parties are not in a position to trace the IP address assigned to you by the mobile phone provider back to you – you are lost in the mass of users.
  • Attention: Surfing via UMTS stick does not guarantee complete anonymity! Using your SIM card and the serial number of the stick (International Mobile Equipment Identity, or IMEI for short), the mobile phone provider will locate you easily. The method therefore only helps to withhold your own identity from website operators.

Fend off malware and spyware

If malware reaches your PC, such as a Trojan horse or spyware, it can spy on you. You can protect yourself by using an antivirus program and regularly updating installed programs.