Nginx 如何进行安全配置？有哪些安全最佳实践？

Nginx 的安全配置对于保护 Web 服务器免受各种攻击至关重要。合理的安全配置可以有效防止常见的安全威胁。

基础安全配置：

nginx
# 隐藏 Nginx 版本号
server_tokens off;

# 限制请求方法
if ($request_method !~ ^(GET|HEAD|POST)$ ) {
    return 405;
}

# 限制请求体大小
client_max_body_size 10m;

# 限制请求头大小
client_header_buffer_size 1k;
large_client_header_buffers 4 4k;

# 超时设置
client_body_timeout 10;
client_header_timeout 10;
keepalive_timeout 5 5;
send_timeout 10;

防止常见攻击：

1. 防止 SQL 注入：

nginx
location ~* \.(php|jsp|asp)$ {
    if ($args ~* "union.*select.*\(") {
        return 403;
    }
    if ($args ~* "concat.*\(") {
        return 403;
    }
}

2. 防止 XSS 攻击：

nginx
location ~* \.(php|html|htm)$ {
    if ($args ~* "<script>|</script>|javascript:|onerror=|onload=|onclick=") {
        return 403;
    }
}

3. 防止文件包含攻击：

nginx
location ~* \.(php|inc|config)$ {
    if ($args ~* "\.\./") {
        return 403;
    }
}

4. 防止目录遍历：

nginx
location ~* /\.\. {
    deny all;
}

访问控制：

nginx
# IP 白名单
location /admin {
    allow 192.168.1.0/24;
    allow 10.0.0.0/8;
    deny all;
}

# IP 黑名单
location / {
    deny 192.168.1.100;
    deny 192.168.1.101;
    allow all;
}

# 基本认证
location /admin {
    auth_basic "Restricted Area";
    auth_basic_user_file /etc/nginx/.htpasswd;
}

防止 DDoS 攻击：

nginx
# 限制连接数
limit_conn_zone $binary_remote_addr zone=conn_limit:10m;

server {
    limit_conn conn_limit 10;
    
    # 限制请求速率
    limit_req_zone $binary_remote_addr zone=req_limit:10m rate=10r/s;
    limit_req zone=req_limit burst=20 nodelay;
    
    # 限制带宽
    limit_rate_after 10m;
    limit_rate 1m;
}

SSL/TLS 安全配置：

nginx
server {
    listen 443 ssl http2;
    server_name example.com;

    # 证书配置
    ssl_certificate /etc/nginx/ssl/example.com.crt;
    ssl_certificate_key /etc/nginx/ssl/example.com.key;

    # SSL 协议
    ssl_protocols TLSv1.2 TLSv1.3;

    # 加密套件
    ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384;
    ssl_prefer_server_ciphers on;

    # SSL 会话缓存
    ssl_session_cache shared:SSL:50m;
    ssl_session_timeout 1d;
    ssl_session_tickets off;

    # OCSP Stapling
    ssl_stapling on;
    ssl_stapling_verify on;
    ssl_trusted_certificate /etc/nginx/ssl/chain.crt;

    # HSTS
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
    
    # 其他安全头
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; style-src 'self' 'unsafe-inline';" always;
}

文件安全：

nginx
# 禁止访问隐藏文件
location ~ /\. {
    deny all;
    access_log off;
    log_not_found off;
}

# 禁止访问敏感文件
location ~* \.(htaccess|htpasswd|ini|log|sh|sql|bak|old|swp|tmp)$ {
    deny all;
    access_log off;
    log_not_found off;
}

# 禁止访问备份文件
location ~* \~$ {
    deny all;
    access_log off;
    log_not_found off;
}

# 禁止目录浏览
autoindex off;

# 禁止访问特定目录
location ~* ^/(admin|config|backup|tmp)/ {
    deny all;
}

防止恶意 User-Agent：

nginx
# 阻止恶意爬虫
if ($http_user_agent ~* (bot|crawl|spider|scraper)) {
    return 403;
}

# 阻止特定 User-Agent
if ($http_user_agent ~* (wget|curl|python-requests)) {
    return 403;
}

防止图片盗链：

nginx
location ~* \.(jpg|jpeg|png|gif|ico|svg)$ {
    valid_referers none blocked example.com *.example.com;
    if ($invalid_referer) {
        return 403;
    }
}

日志安全：

nginx
# 自定义日志格式，记录更多安全信息
log_format security '$remote_addr - $remote_user [$time_local] '
                    '"$request" $status $body_bytes_sent '
                    '"$http_referer" "$http_user_agent" '
                    '$request_time $upstream_response_time '
                    '$http_x_forwarded_for';

# 访问日志
access_log /var/log/nginx/access.log security;

# 错误日志
error_log /var/log/nginx/error.log warn;

# 敏感路径不记录日志
location ~* \.(css|js|jpg|jpeg|png|gif|ico|svg|woff|woff2)$ {
    access_log off;
}

防止缓冲区溢出：

nginx
# 限制缓冲区大小
client_body_buffer_size 128k;
client_header_buffer_size 1k;
large_client_header_buffers 4 4k;
client_max_body_size 10m;

# 代理缓冲区
proxy_buffer_size 4k;
proxy_buffers 8 4k;
proxy_busy_buffers_size 8k;

安全最佳实践：

定期更新：保持 Nginx 和系统补丁最新
最小权限原则：使用非 root 用户运行 Nginx
禁用不必要的模块：减少攻击面
配置防火墙：限制不必要的端口访问
使用 HTTPS：启用 SSL/TLS 加密
定期审计日志：监控异常访问
实施 WAF：使用 Web 应用防火墙
备份配置：定期备份配置文件
测试配置：使用 nginx -t 测试配置
监控性能：使用监控工具跟踪性能指标

完整安全配置示例：

nginx
user nginx;
worker_processes auto;
worker_rlimit_nofile 65535;

# 隐藏版本号
server_tokens off;

events {
    worker_connections 1024;
    use epoll;
}

http {
    # 基础安全
    client_max_body_size 10m;
    client_header_buffer_size 1k;
    large_client_header_buffers 4 4k;
    
    # 超时设置
    client_body_timeout 10;
    client_header_timeout 10;
    keepalive_timeout 5 5;
    send_timeout 10;
    
    # 限流
    limit_req_zone $binary_remote_addr zone=req_limit:10m rate=10r/s;
    limit_conn_zone $binary_remote_addr zone=conn_limit:10m;
    
    # 日志
    log_format security '$remote_addr - $remote_user [$time_local] '
                        '"$request" $status $body_bytes_sent '
                        '"$http_referer" "$http_user_agent"';
    access_log /var/log/nginx/access.log security;
    error_log /var/log/nginx/error.log warn;
    
    # Gzip
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_types text/plain text/css text/xml text/javascript application/json application/javascript;
    
    server {
        listen 80;
        server_name example.com;
        
        # 重定向到 HTTPS
        return 301 https://$server_name$request_uri;
    }
    
    server {
        listen 443 ssl http2;
        server_name example.com;
        
        # SSL 配置
        ssl_certificate /etc/nginx/ssl/example.com.crt;
        ssl_certificate_key /etc/nginx/ssl/example.com.key;
        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256;
        ssl_prefer_server_ciphers on;
        ssl_session_cache shared:SSL:50m;
        ssl_session_timeout 1d;
        
        # 安全头
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header X-XSS-Protection "1; mode=block" always;
        
        # 限流
        limit_req zone=req_limit burst=20 nodelay;
        limit_conn conn_limit 10;
        
        # 禁止访问隐藏文件
        location ~ /\. {
            deny all;
            access_log off;
        }
        
        # 禁止访问敏感文件
        location ~* \.(htaccess|htpasswd|ini|log|sh|sql|bak|old|swp|tmp)$ {
            deny all;
            access_log off;
        }
        
        # 管理后台访问控制
        location /admin {
            allow 192.168.1.0/24;
            deny all;
            
            auth_basic "Restricted";
            auth_basic_user_file /etc/nginx/.htpasswd;
            
            proxy_pass http://backend;
        }
        
        # 主站点
        location / {
            proxy_pass http://backend;
            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_set_header X-Forwarded-Proto $scheme;
        }
    }
}