The silver police have always held the DNA information of criminals, and DNA information is the only information that everyone has. Then the problem is coming. Since DNA information can only identify one person, why have the police been unable to lock the criminal for so many years?
The answer is simple, because there is no DNA information of everyone in the world in the DNA database. If so, I believe that criminals will not get away with it for many years. . .
Who would have thought that the distant relatives of criminals were caught and extracted DNA information when committing crimes? The entry of DNA information into the information base is to link the criminal's DNA information with his ID card. When the police solve a case, they can leave DNA information according to the suspect's scene. If the match is successful in the database, they can lock the suspect.
The silver police have never given up their efforts and have been using the criminal's DNA information to compare the DNA information base. After a long-term matching query, a highly similar DNA message was left on the computer, which turned out to be a relative of the criminal, greatly narrowing the scope of investigation. After a lot of investigation, the police finally succeeded in locking the suspect and arrested him in a canteen of Baiyin Industrial School.
Why use IP address instead of MAC address to locate location information?
MAC address and IP address are unique in the world and can be used to locate computers. However, there is no database with one-to-one correspondence between MAC address and physical location in the world.
Is it difficult to build a database of MAC addresses and locations?
Yes, when a supplier sells a computer to a user, it can easily obtain the corresponding relationship between the user ID and the computer MAC, but the supplier cannot know whether the user is using it in China or taking it to Africa, so it is impossible to establish this database.
It is more feasible to establish an IP address database.
IP address belongs to the operator's assets, and it is easy for operators to bind their IP assets with geographical location, so IP Geographic Information Database (GeoIP) is produced. When the global IP geographic information base is integrated, the user's location information can be roughly obtained according to the user's IP.
The reader must have a big problem. Can the server get the MAC address of the client computer network card?
According to the communication mode of OSI reference model, the server cannot obtain the MAC address of the client network card.
Because the MAC address is located in the data link layer, the local data link layer will be terminated by the local gateway, and then the gateway will extract the IP message and above (there is no link layer information at this time) and continue to relay the IP message to the destination, so the server can easily obtain the IP of the client, but can't see the shadow of the client's MAC address.
Can't the server get the MAC address of the computer network card?
As long as there is the full support and cooperation of customers, it is not difficult. Because the data link layer cannot obtain the MAC address of the client, it can
Do you want the client to extract its own network card MAC address, operating system version number, graphics card serial number and hard disk serial number, and package them in an application layer message and transmit them to the server? As long as the operating system is opened through system functions, it should not be difficult to obtain this information. As described above, the user location information can be roughly located by the IP address of the network layer, and the server can easily obtain the user IP address. But you can't rely on IP addresses to lock computers or users!
Smartphones are at home, in the subway, in the company and in the shopping mall. With the constant change of WIFI hotspots, the ip of mobile phones is also changing. We can only rely on the IP geographic information base to find the corresponding relationship between IP addresses and locations.
No matter where the mobile phone moves, the MAC address of the mobile phone remains the same. This uniqueness can be used to lock the mobile phone (mobile computer) and then lock the user.
What are the benefits of locking users?
In the internet ecology where advertisements are everywhere, how to uniquely lock users (uniquely identified by MAC addresses), accumulate user preferences (search engines), and establish a personal preference database for each user, so that advertisers can immediately know which user it is when users log on to the website next time. Oh, it was "Wang". Wang likes traveling and delicious food, so we should launch targeted advertisements for "traveling and vacationing", which can be easily converted into money.