关于nginx的限速模块

nginx 使用 ngx_http_limit_req_module和ngx_http_limit_conn_module 来限制对资源的请求

这种方法，对于CC攻击（Challenge Collapsar）or DDOS（分布式拒绝服务）有一定的用处

1、HttpLimitReqModule

限制request 事实上就是 the processing rate of requests coming from a single IP address，使用的是漏桶算法（Leaky Bucket）

Leaky Bucket有两种处理方式，具体可以看wiki

										Syntax: limit_req zone=name [burst=number] [nodelay];
									

										Default:    —
									

										Context:    http, server, location
									

										limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s;
									

										 
									

										server {
									

										    location /search/ {
									

										        limit_req zone=one burst=5 nodelay;
									

										    }
									

下面这个配置可以限制特定UA（比如搜索引擎）的访问

									limit_req_zone  $anti_spider  zone=one:10m   rate=10r/s;
								

									limit_req zone=one burst=100 nodelay;
								

									if ($http_user_agent ~* "googlebot|bingbot|Feedfetcher-Google") {
								

									    set $anti_spider $http_user_agent;
								

									}
								

2、ngx_http_limit_conn_module

这个模块就是 limit  the number of connections from a single IP address

Not all connections are counted. A connection is counted only if it has a request processed by the server and the whole request header has already been read

									Syntax: limit_conn zone number;
								

									Default:    —
								

									Context:    http, server, location
								

示例

									http {
								

									    limit_conn_zone $binary_remote_addr zone=addr:10m;
								

									    ...
								

									    server {
								

									        ...
								

									        location /download/ {
								

									            limit_conn addr 1;
								

									            #带宽限制,对单个连接限数，如果一个ip两个连接，就是500x2k
								

									            limit_rate 100k;  
								

									        }
								

									    }
								

									}
								

Sets the shared memory zone and the maximum allowed number of connections for a given key value. When this limit is exceeded, the server will return the 503 (Service Temporarily Unavailable) error in reply to a request

• $binary_remote_addr是限制同一客户端ip地址
• $server是限制同一server最大并发数
• limit_conn为限制并发连接数，nginx 1.18以后用limit_conn_zone替换了limit_conn

配置完之后，我们可以使用ab或者webbench来测试一下

									ab -n 5 -c 1 http://www.test.org/test.php
								

正常情况下可以这样来配置

									map $remote_addr $rt_filtered_ip {
								

									        default $binary_remote_addr;
								

									        1.2.3.4 "";
								

									        4.4.4.4 "";
								

									}
								

									 
								

									or
								

									 
								

									geo $rt_filtered_ip {
								

									    default        $binary_remote_addr;
								

									 
								

									    127.0.0.1      "";
								

									    192.168.1.0/24 "";
								

									    10.1.0.0/16    "";
								

									 
								

									    ::1            "";
								

									    2001:0db8::/32 "";
								

									 
								

									    1.2.3.4        ""
								

									}
								

									 
								

									limit_conn_zone $binary_remote_addr zone=perip:10m;
								

									limit_conn_zone $server_name zone=perserver:10m;
								

									limit_conn_zone $host$uri zone=peruri:10m;
								

									limit_req_zone $rt_filtered_ip zone=qps:10m rate=1r/s;
								

									 
								

									server {
								

									 
								

									 
								

									        location = /wp-login.php {
								

									            limit_req zone=qps burst=5 nodelay;
								

									            limit_conn perip 10;
								

									            limit_conn perserver 100;
								

									            limit_rate 500k;
								

									            include fastcgi_params;
								

									            fastcgi_pass 127.0.0.1:9000;
								

									        }
								

									}
								

									 
								

									ab -n 100 -c 10 example.com/wp-login.php
								

									 
								

									$binary_remote_addr是限制同一客户端ip地址；
								

									$server_name是限制同一server最大并发数；
								

									limit_conn为限制并发连接数；
								

									limit_rate为限制下载速度；
								

参考

https://en.wikipedia.org/wiki/Leaky_bucket

http://nginx.org/en/docs/http/ngx_http_limit_conn_module.html

http://nginx.org/en/docs/http/ngx_http_limit_req_module.html

https://rtcamp.com/tutorials/nginx/block-wp-login-php-bruteforce-attack/