Internet sharing technology, there are generally two ways, one is proxy type, one is Nat gateway type, about the difference and principle, many people around are not very clear, I would like to say that my understanding, if there is wrong, welcome correct.
1. First, the application example:
Server side, with Wingate is proxy, with Sygate is NAT
Client, you need to set up a proxy server in IE, is to use proxy, the client only need to set the gateway can be NAT
2. How it works:
NAT works at the network layer, while proxy works in the application layer
Because of this, the NAT mode of the client only need to set a gateway address, http,qq,ftp can be used. Proxy mode, you need to specify for each application protocol server, such as the need to set up in IE, QQ need to set, MSN needs to set, FTP also need to set, Increases the complexity of client usage.
Nat in most cases simply modifies the address and port in the packet and then forwards the data after recording the corresponding relationship.
Proxy is different from the Nat,proxy client needs to access the Internet, will notify the proxy server software to do, and then proxy server to play the client request to complete, and then return the results to the client. Proxy server to analyze the contents of the packet, figure out what to do, and then as their own identity to "proxy" to complete the request, and send the results back to the client.
such as HTTP, parse out the direction of the request, and then the identity of the proxy host, the request sent to the remote Web server, the remote data returned, it is the identity of the host to the client to send the data. At the same time, the data is put in the cache, if other customers have the same content request, the data is directly from the cache, do not need to present to the Internet server request data.
Because proxy is implemented on the implementation of the Protocol on the application layer, it brings some additional management functions and the cache function.
That's an analogy.
nat= Cargo terminal, whatever you are, just send it.
Proxy= agents, the first to see what you buy, clear and then help you to buy, may be directly from the warehouse to pick up, may also go to other places to transfer goods, there may not be agents you want to buy goods.
3. Finally, the pros and cons
For the client:
NAT is easy to set up without client software
Proxy for each application, or to install a client software, the settings are relatively complex. And does not necessarily support all applications, such as VPN client login many proxies will not be able to proxy the application.
For the server:
Proxy requires more resources (memory, hard disk, etc.) to store the cache content, which is why the performance is higher in the case of a large number of users.
NAT is equivalent to a soft router, in the case of small and medium-sized traffic, the speed is also good, less resources, so the application of universal use. In terms of security, the two are not different.
NAT and Proxy are service software on a server that is connected to the Internet.
The advantages of proxy in the client management, take ISA2004 to say, installed Firewall client machine. The server can be finer managed to restrict client access to a protocol and port. |
