log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                     '$status $body_bytes_sent "$http_referer" '
                     '"$http_user_agent" "$http_x_forwarded_for"';

    set_real_ip_from    0.0.0.0/0;
    real_ip_header      X-Forwarded-For;

set_real_ip_from 为信任的代理服务器ip段