Ubuntu 默认进入3000端口：
在/etc/nginx/si.../default 里面加入
location / {
proxy_pass http://127.0.0.1:3000;
client_max_body_size 50m;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
}
