Understanding of forward proxy and reverse proxy

Both forward proxy and reverse proxy are client access proxy servers , Then access the real services through the proxy server , But there is a fundamental difference between forward proxy and reverse proxy , as follows ：

1、 Reverse proxy

When using reverse proxy , What the user actually accesses is the reverse proxy server to a port , Then the reverse proxy forwards the request of this port to one or more subsequent services , The specific changes are determined by the setting of one or more reverse proxy servers （ Generally based on weight 、 Source IP Select the final forwarding service address ）.

It can be seen that , When using reverse proxy , The client cannot decide the final service address , For him, , The agent is the final address he visits .

The role of reverse proxy is to solve the problem of excessive user requests , The server will have a processing limit . So use a reverse proxy server to accept requests , Then load balancing is used to distribute the requests to multiple real servers . It can not only improve efficiency, but also have a certain degree of security .

2、 Forward agency

When using a forward proxy , Set the proxy address on the client as the proxy server address , When the client sends a request, it accesses the address of the final service , Instead of accessing a port of the proxy like the direction proxy . Then the proxy forwards the request to the real service .

It can be seen that , When using a forward proxy , Clients can decide the service address they want to access . But for him, he didn't know that the request was sent to the proxy server , Sending the request to the proxy server is done by other services on the client .

 

As shown in the figure above , If the intermediate server is deployed to a forward proxy server , that local When the client sends an access request , Actually, it's an access server1、2 perhaps 3, The proxy server address set locally is the address of the intermediate proxy server .

If the intermediate server is deployed to a reverse proxy server , that local When the client sends an access request , Access the proxy server to the address , The proxy server sends the request to server1、2、3 On .