In computer networks, a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers. These resources are then returned to the client as though they originated from the server itself (or servers themselves).While a forward proxy acts as an intermediary for its (usually nearby) associated client(s) and returns to them resources accessible on the Internet, a reverse proxy acts as an intermediary for its (usually nearby) associated server(s) and only returns resources provided by those associated server(s).
The role of using a reverse proxy server
Protect and hide the original resource server
User A is always considered it to access server B instead of the original proxy Z, but practical on the occasion of user A reverse proxy server accepts the response from the original source server to obtain user A B needs resources, and then sent to the user A. Because firewall, proxy server only allows access to the original resource server Z B. Although in this virtual environment, the firewall and reverse proxy to protect the joint action of the original resource server B, but User A did not know.
Load balance
When the reverse proxy server more than one time, we can even make them into a cluster, when more users access the resource server B, let different proxy servers Z(X) to answer a different user, and then send different users required resources.
Of course, the reverse proxy server the same as forward proxy server has cache role, it can cache the original resource server B resources, rather than every time the resource server B requests to the original data, especially some static data, such as images and documents, if these reverse proxy server and the user can do X from the same network, then the user X to access the reverse proxy server X, you will get a high quality speed. This is the core of CDN technology.
We do not explain the CDN, so removed the most critical core technology Intelligent DNS. CDN technology is actually just showing the use of this principle is precisely the reverse proxy .
Reverse proxy and forward proxy opposite conclusion, for the client it looks like the original server and the client does not require any special settings . Client to the reverse proxy namespace (name-space) contents send normal request, then the reverse proxy will determine where to (origin server) forwarded the request, and will receive the content back to the client, just like these content was originally its own the same.
Basically, the online program to do a lot of pros and cons to the agent, the agent software can do most positively can do a reverse proxy. The most popular open-source software is squid, both can do forward proxy, there are a lot of people used to do the front-end reverse proxy server . Another MS ISA can also be used to do in the Windows platform forward proxy . Reverse Proxy WEB service is the most important practice in recent years is the most fire Nginx it. Some say the Internet Nginx forward proxy can not do, in fact, is wrong. Nginx forward proxy can also be done, but relatively few people use it.