HTTP / HTTPS / SOCKS proxy client protocol refers to the proxy server is connected, it refers to the interaction protocol between the client and the proxy server.
As proxy server supports HTTP protocol called HTTP proxy, SOCKS proxy support agreement called SOCKS proxy server. Acting as a proxy server supports HTTP / SOCKS protocol, you can either call the HTTP proxy server, it can also be called SOCKS server.
Supplementary: SOCKS protocol to work in lower than the HTTP, HTTPS level, so the HTTP protocol, HTTPS protocol can use SOCKS proxy (ie, can use the SOCKS protocol between HTTP, HTTPS protocol and proxy servers), but in turn, the SOCKS protocol can not via HTTP / HTTPS to the agent.
Attention and IE browser proxy (ie, the system proxy) settings are not the same concept!
Here IE proxy mean, what kind of protocol configuration which proxy to go (note not a protocol proxy server, IE supports only HTTP proxy). For example, here with you is to let go the HTTP protocol HTTPS proxy server (here refers only supports HTTPS proxy server proxy HTTPS, the proxy does not support other protocols such as HTTP), the HTTP protocol proxy will not be successful.
In fact, IE's proxy settings only support HTTP proxy . No matter how the figure above settings, using HTTP protocol are forwarded directly to the corresponding proxy server, that is, the proxy server must support the HTTP protocol proxy server (proxy server support other protocols such as HTTPS is superfluous, and will not use HTTPS proxy ). Here we may be in doubt, that is how HTTP proxy server can proxy HTTPS protocol it? In fact, with the HTTP tunneling (HTTP tunnel) (interest at your own access to relevant information), and no handshake between the client HTTPS and HTTP proxy server.
Above that, IE proxy only supports HTTP proxy, Google Chrome browser proxy configuration can only configure IE proxy, which is the only use of the HTTP proxy. For example, I want to use that HTTPS proxy how to do (in HTTPS protocol between the client and the HTTPS proxy server)?
You can use plug-Proxy SwithchyOmega:
"URL protocol" is the IE proxy settings in the "type", and IE proxy compared to more than a "agency agreement" option, proxy option that is what any agreement to go.
For example, configurable HTTP / HTTPS protocol to go SOCKS5 protocol proxy. In fact, this plug-in is called the interface provided by chromium (https://www.chromium.org/developers/design-documents/network-stack/socks-proxy):
As can be seen the SOCKS protocol FTP protocol has not been achieved by the agent. .
Concluded that the principles under ss / ss (R) of:
ss operating principle of the tool is basically the same with other agents, the use of specific transfer server data transfer is complete. After the server-side deployment is complete, you need to follow the specified password, encryption and port, use the client software to connect. After a successful connection to the server, the client will build a local Socks5 proxy on the user's computer. When browsing the network, network traffic will be assigned to local socks5 proxy, the client sends to the server after its encryption, the same encryption server will flow back to the client, in order to achieve proxy access.
Some people may ask, ss (R) is a Socks5 proxy, but I said above, the IE proxy (not installed by Proxy SwithchyOmega case) only supports HTTP proxy, why can also access google it?
In fact, ss (R) is enabled by default Socks5 proxy port in 1080, but it is for compatibility with HTTP proxy mode, use ss_privoxy.exe opened up a HTTP proxy (random port, refused to return to the default port 8123).
Moreover, SS (R) also supports HTTP proxy port in 1080.
We know that, IE's proxy settings only supports HTTP proxy. It is also because ss (R) support HTTP proxy mode, in order to make IE and others do not support Socks5 proxy (but supports HTTP proxy) software proxy.
浏览器一般会自动启用系统代理，而其它软件则需要自身支持HTTP代理或Socks5代理，而且一般需要进行手动配置才可以进行代理。
补充：分别使用HTTP协议和SOCKS5协议访问ss本地Windows客户端情况（注：事先要下载curl小工具）：
可看出，HTTPS协议使用HTTP代理是通过了HTTP隧道。
注：
socks5 和 socks5h 的区别仅用于 curl。在 curl 中，socks5 会使用本地DNS，socks5h 会使用代理提供的远程DNS。
在其它软件中，socks5h 基本不起作用，使用 socks5 即可。一旦设置了代理，多数时候会采用远程DNS。
可见，因为ss本地Windows客户端(相当于本地代理服务器)不支持HTTPS协议，因此不会响应Client hello