Understanding Squid's forward and reverse proxies

In fact, whether it is a forward proxy or reverse proxy, the direction of access are: client-agent Server--

Under what circumstances is the forward proxy, and under what circumstances is the reverse proxy?

The forward proxy semantically focuses more on allowing the proxy server to help request a URL. Just like you want to visit QQ, Baidu. You give these URLs to the proxy server, let the proxy server to help access.
There are two characteristics here.
1, the server visited (QQ, Baidu) only know is the Proxy server request (proxy server IP), and do not know that you requested;
2, you can clearly know the real server you want to request (QQ, Baidu)
3. The client must set the address and port of the proxy server in the browser. (after setting, it means that as long as the URL entered on this browser, all of them to the proxy server to help access)


The difference between a reverse proxy and a forward proxy is. The client knows only the address of the proxy server and does not know the actual server. The client can only passively request the proxy server to go to the proxy server.
Access the real server. There are also several features here
1, the client requests an address (such as the address of the proxy server), it does not know whether this address is the address of the proxy server or the real address
2, the real address is determined by the proxy server. Assuming that the address of the server is www.a.com, it is configured agent to Baidu, then you see the content is Baidu, another day it is configured to QQ,
You enter the same www.a.com, see the content is QQ. These are not the clients can decide.
3, the client does not need to set up a proxy server in the browser.



The summary is:

The forward proxy, whose real server is clear to the client. You just use the proxy server to get it to ask for the address you want to access.

The reverse proxy, whose real server is transparent to the client. You never know whether the address of the generation access is a proxy server or a real server. such as direct access to www.baidu.com.
It may be the ultimate server, or it may be a proxy server, we have no way to know.

Understanding Squid's forward and reverse proxies