This post is the eighth post in a series of ten posts. The previous post explored the seventh law: you are the weakest link. With our increasingly connected word, this law becomes more and more important. Most connections are bidirectional. The consequence is that information flows both ways. If you receive information from the Internet, the Internet may collect information from you. If your apparatus is going to the Internet, the Internet may come to your device. Some of these ingress connections may not be solicited.

Controlling what is exchanged, and monitoring who is using the connections is the role of network security. Fortunately, network security is a rather mature science. Thus, the first rule should be the following one.

Do not connect directly to the Internet; the access to the Internet should be carefully controlled. It should have at least a firewall and anti-malware filtering. When possible, implement a Demilitarized Military Zone (DMZ) to create an isolation buffer between the Internet and your network that may discard attackers to intrude it. Not everybody may need to install a DMZ or can install a DMZ, especially at home. However, everybody should install a firewall between his network and the Internet. In a consumer environment, the firewall should by default ban every ingress communication.     
Many specialists claim (rightly) that the notion of perimetric defense is outdated. This does not mean that local networks should not be protected against intrusions or leaks. These network security mechanisms remain mandatory but not sufficient.

Thou will be traced; the digital world increasingly keeps records of all the activities of users. Many Web enterprises build their business model on monetizing the results of this data collection. This data collection may be known and announced, but sometimes also hidden. For instance, spying techniques such as fingerprinting canvas stealthily collect information when people visit web pages. A recent study disclosed that more than 5% of the sites used fingerprinted canvas. This constant monitoring is a threat to privacy and also a potential mine of information for attackers. Some tools, such as the TOR browser, help in preserving anonymity on the Internet.

If you find this post interesting, you may also be interested in my second book “Ten Laws for Security.”  Chapter 9 explores in details this law. The book is available for instance at Springer or Amazon.