As long as you surf the Internet, it will exist automatically. If it's all turned off, you can't surf the internet.
You can spy on the user's information through the Trojan vulnerability access port, and even access the user's system.
Friends who often surf the Internet are probably familiar with the term port number. For example, if you want to open a web page, you will naturally connect to port 80 of the server. And if you want ftp, you have to connect 2 1. Recently, there are always friends who say that viruses or Trojans use a service or a port to infect or invade. The concept of port number is explained below.
I said the meaning of IP address the other day. For example, two computers communicate using TCP/IP. While playing Thor's Hammer III on the Internet, I was still using QQ to send files. These two computers each have an IP address, so they can communicate with each other. It's like computer A saying "Pass this package to computer B". His IP address is *. *. *. *. "So the bag was handed over.
If only one program and one service are transmitted on a computer at the same time, then direct transmission is very simple. However, in the above example, there are two transmissions between the two computers at the same time-both playing games and uploading files on QQ. That's the problem-computer A said, "Send this package to computer B ... the IP address is ...". Then computer B received it happily. At first glance, alas, alas, this package is the data of Thor's Hammer III game. Or QQ data? I can't tell them apart.
At this time, we should consider the role of port number.
Port is just an abstract concept. Ports are used to distinguish different services, or simply to mark which program the sent packets are for.
For example, if you receive a packet and it says it is sent to port 80, you must find out who port 80 is for. It looks like it's for an HTTP server. All right, give it this package.
The port number is represented by 2 bytes. It can represent from 1 to 65535. Among them, the range from 1 to 1024 is designated as easy to use, and it is called a well-known port. You can't just modify it. The next one is ok.