nginx配合modsecurity实现WAF功能
一.准备工作
系统：centos 6.5 64位、 ngx_openresty-1.7.10.1， modsecurity 2.9.0
openresty: http://openresty.org/download/ngx_openresty-1.7.10.1.tar.gz
modsecurity for Nginx: https://www.modsecurity.org/tarball/2.9.0/modsecurity-2.9.0.tar.gz
OWASP规则集： https://github.com/SpiderLabs/owasp-modsecurity-crs
依赖关系：
modsecurty依赖的包：pcre httpd-devel libxml2 apr
yum install httpd-devel apr apr-util-devel apr-devel pcre pcre-devel libxml2 libxml2-devel
openresty依赖的包：pcre 、zlib、 openssl
yum install zlib zlib-devel openssl openssl-devel pcre pcre-devel
二.启用standalone模块并编译
下载modsecurity for nginx 解压，进入解压后目录执行：
./autogen.sh ./configure --enable-standalone-module --disable-mlogc make
三.openresty添加modsecurity模块
在编译standalone后，openresty编译时可以通过"--add-module"添加modsecurity模块：
./configure --prefix=/opt/openresty --with-pcre-jit --with-ipv6 --without-http_redis2_module --with-http_iconv_module -j2 --add-module=../modsecurity-2.9.0/nginx/modsecurity/ make && make install
四.添加规则
modsecurity倾向于过滤和阻止web危险，之所以强大就在于规则，OWASP提供的规则是于社区志愿者维护的，被称为核心规则CRS（corerules）,规则可靠强大，当然也可以自定义规则来满足各种需求。
1.下载OWASP规则：
git clone https://github.com/SpiderLabs/owasp-modsecurity-crs mv owasp-modsecurity-crs /opt/openresty/nginx/conf/ cd /opt/openresty/nginx/conf/owasp-modsecurity-crs/ && mv modsecurity_crs_10_setup.conf.example modsecurity_crs_10_setup.conf
2.启用OWASP规则：
复制modsecurity源码目录下的modsecurity.conf-recommended和unicode.mapping到nginx的conf目录下，并将modsecurity.conf-recommended重新命名为modsecurity.conf。
mv modsecurity.conf-recommended /opt/openresty/nginx/conf/modsecurity.conf cp unicode.mapping /opt/openresty/nginx/conf/
编辑modsecurity.conf 文件，将SecRuleEngine设置为 on
sed -i 's/^SecRuleEngine.*/SecRuleEngine On/' /opt/openresty/nginx/conf/modsecurity.conf
owasp-modsecurity-crs下有很多存放规则的文件夹，例如base_rules、experimental_rules、optional_rules、slr_rules，里面的规则按需要启用。
需要启用的规则使用Include到modsecurity.conf即可。
Include owasp-modsecurity-crs/modsecurity_crs_10_setup.conf Include owasp-modsecurity-crs/base_rules/modsecurity_crs_41_sql_injection_attacks.conf Include owasp-modsecurity-crs/base_rules/modsecurity_crs_41_xss_attacks.conf Include owasp-modsecurity-crs/base_rules/modsecurity_crs_40_generic_attacks.conf Include owasp-modsecurity-crs/experimental_rules/modsecurity_crs_11_dos_protection.conf Include owasp-modsecurity-crs/experimental_rules/modsecurity_crs_11_brute_force.conf Include owasp-modsecurity-crs/optional_rules/modsecurity_crs_16_session_hijacking.conf
五.配置nginx
在需要启用modsecurity的主机的location下面加入下面两行即可：
ModSecurityEnabled on; ModSecurityConfig modsecurity.conf;
下面是几个示例配置，php虚拟主机：
server {
listen 80;
server_name test.net www.test.net;
location ~ \.php$ {
ModSecurityEnabled on;
ModSecurityConfig modsecurity.conf;
root /web/wordpress;
index index.php index.html index.htm;
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $Document_root$fastcgi_script_name;
include fastcgi_params;
}
}
upstream负载均衡：
upstream online {
server 192.168.1.100:8080;
server 192.168.1.101:8080 backup;
}
server {
listen 80;
server_name test.net www.test.net;
location / {
ModSecurityEnabled on;
ModSecurityConfig modsecurity.conf;
proxy_pass http://online;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
泛域名解析，反向代理方式：
upstream real_webserver {
server 192.168.0.12;
server 192.168.0.13;
}
server {
listen 80;
server_name _ ;
location {
ModSecurityEnabled on;
ModSecurityConfig modsecurity.conf;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://real_webserver;
}
}
六.测试
我们启用了xss和sql注入的过滤，不正常的请求会直接返回403。以php环境为例，新建一个phpinfo.php内容为：
<?php phpinfo(); ?>
在浏览器中访问：
http://www.52os.net/phpinfo.php?id=1 正常显示。
http://www.52os.net/phpinfo.php?id=1 and 1=1 返回403。
http://www.52os.net/phpinfo.php?search=<scritp>alert('xss');</script> 返回403。
说明sql注入和xss已经被过滤了