正向代理：

所谓正向代理就是内网服务器主动要去请求外网的地址或服务，所进行的一种行为。

内网服务---访问--->外网

反向代理：

所谓反向代理就是外网要访问内网服务而进行的一种行为。

外网----请求--->内网服务

正向代理

worker_processes  1;

events {
    worker_connections  1024;
}

http {
    include       mime.types;
    default_type  application/octet-stream;
    client_max_body_size 1024M;
    sendfile        on;
    keepalive_timeout  1800;
    gzip  on;

    server {
        listen 80;
	    charset utf-8;
        location / {
            root   html;
            index  index.html index.htm;
        }	
	    location /baidu {
		    proxy_pass https://www.baidu.com/;
	    }
    }
}

反向代理

worker_processes  1;

events {
    worker_connections  1024;
}

http {
    include       mime.types;
    default_type  application/octet-stream;
    client_max_body_size 1024M;
    sendfile        on;
    keepalive_timeout  1800;
    gzip  on;

    upstream project1host {
        server 192.168.1.1:8081;
    }
    upstream project2host {
        server 192.168.1.2:8081;
    }
    upstream project3host{
        server 192.168.1.3:8081;
    }

    server {
        listen 80;
	    charset utf-8;
        location / {
            root   html;
            index  index.html index.htm;
        }	
	    location /project1 {
		    proxy_pass http://project1host/project1; 
		    proxy_set_header Host $host:$server_port; 
		    proxy_set_header X-Real-IP $remote_addr; 
		    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; 
		    proxy_set_header X-NginX-Proxy true; 
	    }
	    location /project2 {
		    proxy_pass http://project2host/project2; 
		    proxy_set_header Host $host:$server_port; 
		    proxy_set_header X-Real-IP $remote_addr; 
		    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; 
		    proxy_set_header X-NginX-Proxy true; 
	    }
	    location /project3 {
		    proxy_pass http://project3host/project3; 
		    proxy_set_header Host $host:$server_port; 
		    proxy_set_header X-Real-IP $remote_addr; 
		    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; 
		    proxy_set_header X-NginX-Proxy true; 
	    }
    }
}