The school's campus network is always turned off. Average 5 minutes will be once, and it is still a 2-minute look to re-connect, it is really irritating. My friend tells me that a method can no longer drop the line, try it out, search online, learn the principle, write it now, let everyone share.
We have to visit a website, usually enter the website of this website in the visit, and then carriage return, this time, the DNS server will automatically parse it into an IP address. In fact, we are accessing the website through IP, the URL is only It is a mission. Then in the local area network, the Ethernet device does not know the IP address, so it is also necessary to convert the IP address to a MAC address, which is the protocol for this conversion.
The Internet is exchanged by TCP / IP, so you must install the TCP / IP protocol. In each computer installed, there is an ARP cache table, the IP address and MAC address in the table are one One correspondence:
IP address
MAC address
10.6.13.1
00-00-00-00-01
10.6.13.2
00-00-00-00-02
10.6.13.3
00-00-00-00-03
......
......
When 10.6.13.2 is sent to 10.6.13.1, first look for if there is a MAC address of 10.6.13.1 in the ARP cache table. If there is, it will communicate directly. If not, it is necessary to send a broadcast information on the network. Ask 10.6.13.1 MAC address, then other computers do not respond to inquiry, only 10.6.13.1 respond, it sends its own MAC address to 10.6.13.2, so that 10.6.13.2 knows 10.6.13.1 MAC address. They can communicate between them, and 10.6.13.2 also update their own ARP cache tables. You can take directly from 10.6.13.1 MAC addresses to communicate. The ARP cache table also adopts the aging mechanism. If there is no use in a certain line, it will be deleted, which greatly reduces the length of the table and speeds up the query speed. So what is the gateway? As the name suggests, the gateway is a "gateway" connected to another network. There are many kinds of gateways in accordance with different classification standards. The gateway in the TCP / IP protocol is the most common, and the "gateway" we told here is referred to as the gateway under the TCP / IP protocol. So what is the gateway? The gateway is essentially a network to other networks of IP addresses. For example, network A and network B. The IP address of network A is "192.168.1.1 ~ 192. 168.1.254", the subnet mask is 255.255.255.0; the IP address of Network B is "192.168.2.1 ~ 192.168. 2.254 ", the subnet mask is 255.255.255.0. In the case where there is no router, the two networks cannot be communicated between TCP / IP communication, even two network connects on the same switch (or hub), the TCP / IP protocol will also be subjected to subnet mask (255.255) .255.0) Determines the host in the two networks in a different network. To implement communication between the two networks, you must pass through the gateway. If the host found that the host of the network A is not in the local network, turn the packet to its own gateway, then forward the gateway to the gateway of the network B, the gateway of the network B will forward to the network B Host. The same is true of the process of forwarding a packet to a network A to a network A. So, only the IP address of the gateway is set, the TCP / IP protocol can implement mutual communication between different networks. So which machine IP address is this IP address? The IP address of the gateway is an IP address of the device with routing function. It has a router with a route function, enabling a server (substantially equivalent to one router), the proxy server (also equivalent to a router). Oh, is it a little dizziness, which one is not you? To be honest, I am a little dizzy. In fact, there is no understanding of things, because general users only need to use, do not need to understand, understanding the network management. Now let's actually do this click "Start" - "Run" - Enter CMD, Enter the ARP -A as shown above, 192.168.1.1 Physical address (MAC address) is 00-AA-00-62 -c6-09, TYPE is Dynamic (this is a picture I binding the story, so static). Make a note of its Mac, then enter Arp -s 192.168.1.1 00-AA-00-62-C6-09, which adds a 192.168.1.1 to 00-AA-00-62 in your ARP cache table. C6-09 correspondence.
In our school (Xihua University), if you don't want to know the above, just don't want to turn off the line, then step by step 1 1 in the command prompt to enter "arp -a" at this time, it is possible to get a lot of IP and it Mac, but pay attention, we only want to get the gateway Mac (the general gateway is the most beginning of the current network segment, such as the IP I get through DHCP is 10.6.13.6, then the gateway is 10.6.13.1)
2 Enter "ARP -S Gateway IP Gateway Mac"
3 Enter "EXIT" to exit 4 to get it ---------------------
Tip: ARP -D command can also delete a correspondence.
I observed, before the binding, the IP and MAC address of the gateway were Dynamic (dynamic), which is Invalid (invalid), and the binding is Static (static). I still don't know why I am dropped, after a period of time ARP cache table, the gateway has changed. But once I bind it into my table, I didn't get rid of the line today, and my roommate lost N-back! And I don't know why INVALID is changed in the gateway, causing me to drop the line. Is there someone in the destruction? Send a package to change my cache table (can ARP spoof)? Don't understand it.
I didn't pay attention to the network protocol and configure this, it seems to learn more.
