What is a reverse proxy?
proxy server
Simple understanding: In the same intranet, only one machine can access the Internet, and other machines also want to access the Internet, so we can only use the machine that can access the Internet, install proxy software in it, and through appropriate configuration, other machines can use the Internet to access the Internet. You can access the Internet as you wish by specifying the address of the proxy server and the listening port.
curl -x https://172.22.131.187:8080 https://fcm:googleapis.com/fcm/send
Scenes:
Server: DB server, AP server (2 sets), LB
Requirement: The DB server needs to send a PUSH request
Analysis: The DB server cannot be exposed on the public network anyway, so what should we do? So install squid in the AP server, and open port 443 of the AP server so that it can access the Internet, so in the DB server, by specifying the address of the proxy server -x https://172.22.131.187:8080 This is actually LB The address, the LB side is configured with the AP's 3128 port, I think it should be related to the role of load distribution in it. . . Finally use the proxy software on the AP server to send the request.
Question: Since the AP server has opened port 443, it is also possible to directly access www.baidu.com in the AP , but in fact, it is necessary to specify a proxy server to access. That is to say, it is unsuccessful to directly access curl https://www.baidu.com in the AP, and
curl -x tcp://172.22.143.61:3128 https://www.baidu.com can be successful. The reason for this is not clear. Pending investigation.