nginx - What is the difference between X-Forwarded-For and X-Real-IP?

Question

What is the difference between X-Forwarded-For and X-Real-IP? After testing, it was found that the IP obtained was the same.

曾经蜡笔没有小新 · Answer

Generally speaking, X-Forwarded-For是用于记录代理信息的，每经过一级代理(匿名代理除外)，代理服务器都会把这次请求的来源IP追加在X-Forwarded-For中

A request from 4.4.4.4, the header contains such a line

X-Forwarded-For: 1.1.1.1, 2.2.2.2, 3.3.3.3

means that the request is sent by 1.1.1.1 and passes through three layers of proxies. The first layer is 2.2.2.2 and the second layer is 3.3.3.3 , and the source IP of this request1.1.1.1发出，经过三层代理，第一层是2.2.2.2，第二层是3.3.3.3，而本次请求的来源IP4.4.4.4 is the third layer proxy

AndX-Real-IP，没有相关标准，上面的例子，如果配置了X-Read-IP, there may be two situations

// 最后一跳是正向代理，可能会保留真实客户端IP
X-Real-IP: 1.1.1.1
// 最后一跳是反向代理，比如Nginx，一般会是与之直接连接的客户端IP
X-Real-IP: 3.3.3.3

So, if there is only one layer of proxy, the values of these two headers are the same