Proxy

A proxy forwards requests and responses.

A proxy is used for:

  • Load balancing: let multiple machines work together.

  • health check: remove crashed machine

  • security: protect the source server

  • filter the data

  • cache

Attributes

  • Via: the host name or domain name of all proxy machines.

    Via: proxy1, proxy2

  • X-Forwarded-For: All the IP addresses of request machine, client (the leftest one) and proxy machines.

  • X-Real-IP: the IP address of the client.

The PROXY protocol

PROXY + ip address type + request ip address + response ip address + request port + response port + \r\n

PROXY TCP4 1.1.1.1 2.2.2.2 55555 80\r\n

The client is 1.1.1.1:55555.

HTTP cache with Proxy

Server-side

client-proxy-cache

client-side:

server-proxy-cache.png