求助一个 nginx+uwsgi+iptables 环境下遇到的问题。

cat /etc/nginx/conf.d/default.conf

server {
    listen       80;
    server_name  www.xxx.xxx;
    
    charset utf-8;

    location /test {
        include uwsgi_params;
        uwsgi_pass 127.0.0.1:3031;
    }
}

cat /etc/mblog/mblog.ini

[uwsgi]
socket = 127.0.0.1:3031
pidfile = /run/mblog.pid
wsgi-file = /usr/share/web_workspace/wsgi.py 
logto = /var/log/mblog.log
enable-threads = true
callable = app
processes = 2
threads = 2

iptables -nL

Chain INPUT (policy DROP)
target     prot opt source               destination         
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:10086
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            udp dpt:53
ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0           
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:80
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:443

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

主要的配置和环境就是以上的信息。现在遇到了这个问题： 访问 www.xxx.xxx 后，就一直在等待响应。。最终就是超时。 看了下 nginx 的日志，就是 uwsgi 的超时导致的。。 如果关掉 iptables 后，就可以正常访问了。。 所以是哪一步出问题了？？

nginx 的 errorlog

2016/07/04 13:06:06 [error] 3689#3689: *1 upstream timed out (110: Connection timed out) while connecting to upstream, client: xxx.xxx.xxx.xxx, server: www.xxx.xxx, request: "GET / HTTP/1.1", upstream: "uwsgi://127.0.0.1:3031", host: "www.xxx.xxx"