Nginx 直接输出IP地址，无需后端

server {
    listen 80;
    listen [::]:80 ipv6only=on;
    server_name ip.larva.com.cn;

    location / {
        if ($request_method !~* GET|OPTIONS) {
            return 403;
        }
        if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS';
            #
            # Custom headers and headers various browsers *should* be OK with but aren't
            #

            add_header 'Access-Control-Allow-Headers' '*';
            #
            # Tell client that this pre-flight info is valid for 20 days
            #

            add_header 'Access-Control-Max-Age' 1728000;
            add_header 'Content-Type' 'text/plain; charset=utf-8';
            add_header 'Content-Length' 0;
            return 204;
        }
        if ($request_method = 'GET') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS';
            add_header 'Access-Control-Allow-Headers' '*';
            add_header 'Access-Control-Expose-Headers' '*';
            add_header 'Content-Type' 'text/plain; charset=utf-8';
        }

        return 200 $remote_addr;
    }

    location /port {
        if ($request_method !~* GET|OPTIONS) {
            return 403;
        }
        if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS';
            #
            # Custom headers and headers various browsers *should* be OK with but aren't
            #

            add_header 'Access-Control-Allow-Headers' '*';
            #
            # Tell client that this pre-flight info is valid for 20 days
            #

            add_header 'Access-Control-Max-Age' 1728000;
            add_header 'Content-Type' 'text/plain; charset=utf-8';
            add_header 'Content-Length' 0;
            return 204;
        }
        if ($request_method = 'GET') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS';
            add_header 'Access-Control-Allow-Headers' '*';
            add_header 'Access-Control-Expose-Headers' '*';
            add_header 'Content-Type' 'text/plain; charset=utf-8';
        }

        return 200 '$remote_addr:$remote_port';
    }

    location /json {
        if ($request_method !~* GET|OPTIONS) {
            return 403;
        }
        if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS';
            #
            # Custom headers and headers various browsers *should* be OK with but aren't
            #

            add_header 'Access-Control-Allow-Headers' '*';
            #
            # Tell client that this pre-flight info is valid for 20 days
            #

            add_header 'Access-Control-Max-Age' 1728000;
            add_header 'Content-Type' 'text/plain; charset=utf-8';
            add_header 'Content-Length' 0;
            return 204;
        }
        if ($request_method = 'GET') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, OPTIONS';
            add_header 'Access-Control-Allow-Headers' '*';
            add_header 'Access-Control-Expose-Headers' '*';
            add_header 'Content-Type' 'application/json; charset=utf-8';
        }

        return 200 '{"ip":"$remote_addr","port":$remote_port}';
    }
}