nginx实现负载均衡，也是反向代理的过程

 upstream panel_gateway {
        server 172.16.2.173:27002;
        server 172.16.2.174:27002;
    }
server {
        listen      10088 ssl;
        server_name  smartpanel.andshi.cn;
        ssl_certificate    cert/1794716__andshi.cn.pem;
        ssl_certificate_key  cert/1794716__andshi.cn.key;
        ssl_session_timeout        5m;
        ssl_session_cache          shared:SSL:1m;
        ssl_protocols              TLSv1.2;
        ssl_ciphers                HIGH:!ADH:!MD5:!RC4;
        ssl_prefer_server_ciphers  on;
        client_max_body_size       100m;
        location / {
            root   /data/smartpanel-web/dist;
           index  index.html;
            if ($request_filename ~ .*\.(js|css|png)$)
            {
                add_header Cache-Control public;
            }
        }
        location /root/ {
             proxy_pass   http://panel_gateway/;
        }
  反向代理：请求的来源也就是客户端是明确的，但是请求具体由哪台服务器处理的并不明确了

正向代理

server {
        listen       80;
        server_name  xiaohost.com  www.xiaohost.com;
 
        charset utf-8;
 
         proxy_set_header        Host            $http_host;
         proxy_set_header        X-Real-IP       $remote_addr;
         proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
 
         location / {
                proxy_pass    http://192.168.1.2:80;
      }
}
正向代理：客户端非常明确要访问的服务器地址；服务器只清楚请求来自哪个代理服务器，而不清楚来自哪个具体的客户端；正向代理模式屏蔽或者隐藏了真实客户端信息。