Intranet concept
That is to say, the so-called local area network, such as the school's local area network, the IP address of each computer in the local area network is different in this local area network and cannot be repeated. But the intranet IP in the two LANs can have the same IP.
(When connected to WIFI, the phone IP can generally be found in "Settings" - "About Phone" - "Status Information" - "IP Address"
Extranet concept
That is, the Internet, the network connected to the outside of the LAN through a server or a router , this IP address is unique. That is to say, all computers in the internal network are connected to this external network IP, and exchange data externally through this external network IP. That is to say, the intranet IPs of all computers in a local area network are different from each other, but share one external network IP. (The IP found by ipconfig/all is the internal network IP of your machine; what you see on the webpage is the IP you use to connect to the Internet, that is, the external network, but if you connect to WIFF, the same IP address used by the same WIFF )
The access in the LAN uses the intranet IP + port access. Generally, the LAN can access the external network IP, but the external network cannot access the internal network IP address.
1. Noun concept
Intranet
That is, a local area network refers to a computer group composed of multiple computers interconnected in a certain area. Usually within a radius of several kilometers. Local area network can realize functions such as file management, application software sharing, printer sharing, scheduling within the working group, e-mail and fax communication services. A local area network is closed and can consist of two computers in an office, or thousands of computers in a company.
Extranet
That is, the wide area network, also known as the public network. It is a remote network that connects computers in LANs or MANs in different regions. It usually spans a large physical range, covering a range from tens of kilometers to thousands of kilometers. It can connect multiple regions, cities and countries, or span several continents and provide long-distance communication, forming an international network. remote network. A WAN is not the same as the Internet.
2. The difference between internal network and external network
1. The difference in ip address setting. Generally, the internal network has its own IP number segment, and it will not conflict with the Internet number segment. The internal network starts from below the router, and the IP is all based on IPs starting with 192. Generally, it is not possible to have an external network IP, because it is a waste of resources for individuals or small groups to use the external network, so they usually go online through the internal network, and the external network IP is generally used for companies, schools and other institutions.
2. Intranet computers need a unified exit to connect to the external network, which may restrict some unnecessary access, while the external network can access the Internet without a router or switch, and can be directly accessed by the outside world without any equipment. Connect directly to the computer.
3. Compared with the external network, the internal network will have an extra layer of security firewall (external network routing), relatively speaking, the ability to resist attacks from the external network will be better; the disadvantage of the internal network is that it may be attacked from the inside; because To share bandwidth, the relative network speed may be slower (the more terminals, the slower).
4. The ip of the internal network can be changed frequently, and the rules can be defined by yourself; while the ip of the external network is generally fixed. When you install broadband, your ip will be fixed.
Consequences of intercommunication between intranet and extranet
This is obviously a security risk, because when you go to the Internet, you will inevitably suffer from some viruses, Trojan horses and the like. In this way, if you are switching to the intranet, similarly, such a Trojan horse will also spread within the intranet. No matter whether you are on the intranet or an extranet, all your data and information are on this computer. The data and information when using the Internet will leave some traces, which is an unsafe factor. In case you are hit by a Trojan virus or the like, some information will be lost, so it is recommended to use a dedicated plane for the intranet.
How to prevent intercommunication between intranet and extranet
Network security should start from two aspects: terminal management and network access. It mainly solves the authentication management of terminal devices connected to the enterprise network. Only trusted terminal devices can access the network to achieve the purpose of overall network security. It can block the connection of illegal devices, ensure the security of network devices, and at the same time detect the illegal outreach of terminal computers, and strictly prevent security risks such as network-in-network and private routing.