Proxy

正向代理 Forward Proxy (Proxy Server)

In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource

Instead of connecting directly to a server that can fulfill a request for a resource, such as a file or web page, the client directs the request to the proxy server, which evaluates the request and performs the required network transactions. This serves as a method to simplify or control the complexity of the request, or provide additional benefits such as load balancing, privacy, or security. Proxies were devised to add structure and encapsulation to distributed systems. A proxy server thus functions on behalf of the client when requesting service, potentially masking the true origin of the request to the resource server.

反向代理（Reverse Proxy）

In computer networks, a reverse proxy is an application that sits in front of back-end applications and forwards client (e.g. browser) requests to those applications. Reverse proxies help increase scalability, performance, resilience and security. The resources returned to the client appear as if they originated from the web server itself.

Large websites and content delivery networks use reverse proxies, together with other techniques, to balance the load between internal servers. Reverse proxies can keep a cache of static content, which further reduces the load on these internal servers and the internal network. It is also common for reverse proxies to add features such as compression or TLS encryption to the communication channel between the client and the reverse proxy.

Reverse proxies are typically owned or managed by the web service, and they are accessed by clients from the public Internet. In contrast, a forward proxy is typically managed by a client (or their company) who is restricted to a private, internal network, except that the client can ask the forward proxy to retrieve resources from the public Internet on behalf of the client.

反向代理（reverse proxy），是指以代理服务器来接受internet上的连接请求，然后将请求转发给内部网络上的服务器，并将从服务器上得到的结果返回给internet上请求连接的客户端，此时代理服务器对外就表现为一个反向代理服务器。

反向代理的作用就比较多了，这里简单列举一下：

保护和隐藏原始资源服务器
加密和SSL加速
负载均衡
缓存静态内容
压缩
减速上传
安全
外网发布

Types

A proxy server may reside on the user’s local computer, or at any point between the user’s computer and destination servers on the Internet. A proxy server that passes unmodified requests and responses is usually called a gateway or sometimes a tunneling proxy. A forward proxy is an Internet-facing proxy used to retrieve data from a wide range of sources (in most cases anywhere on the Internet). A reverse proxy is usually an internal-facing proxy used as a front-end to control and protect access to a server on a private network. A reverse proxy commonly also performs tasks such as load-balancing, authentication, decryption and caching.

Protocols

SOCKS

Proxy Solutions

microsocks

https://github.com/rofl0r/microsocks

$ git clone https://github.com/rofl0r/microsocks.git
$ cd microsocks; sudo make install
$ which microsocks
/usr/local/bin/microsocks
$ microsocks

Verify

# connect to https://ifconfig.co via 127.0.0.1:1080
$ curl https://ifconfig.co --socks5 127.0.0.1:1080 [--proxy-user sockd:sockd]

Dante

https://github.com/Lozy/danted

3proxy

https://github.com/3proxy/3proxy

$ sudo systemctl stop 3proxy.service

【Network】代理（Proxy）