nginx反向代理1024，假如只用一个VPS、同一个IP反代1024，访问量大了，访问会出现验证码的问题，所以采用负载均衡来分摊流量。
前端服务器 192.168.1.2 nginx 配置模板如下：
upstream 1024{
ip_hash; #根据客户端ip，计算hash值并映射到相应服务器.
server 192.168.1.3 weight=1 max_fails=3 fail_timeout=5;
server 192.168.1.4 weight=1 max_fails=3 fail_timeout=5;
server 192.168.1.5 weight=1 max_fails=3 fail_timeout=5;
server 192.168.1.6 weight=1 max_fails=3 fail_timeout=5;
}
server {
listen 80;
server_name test.com www.test.com;
location / {
proxy_pass http://1024; #要和第一行的upstream名字一致.
proxy_redirect off;
proxy_set_header User-Agent $http_user_agent;
proxy_set_header Referer http://www.t66y.com;
proxy_set_header Accept-Encoding "";
sub_filter "www.t66y.com" "www.test.com";
sub_filter_once off;
}
access_log /root/test.com.log;
error_log /root/test.com.error.log;
}