🛡️ Caddy WAF Middleware

A robust, highly customizable, and feature-rich Web Application Firewall (WAF) middleware for the Caddy web server. This middleware provides advanced protection against a comprehensive range of web-based threats, seamlessly integrating with Caddy and offering flexible configuration options to secure your applications effectively.

🛡️ Core Protections

• Regex-Based Filtering: Deep URL, data & header inspection using powerful regex rules.
• Blacklisting: Blocks malicious IPs, domains, ASNs & optionally TOR exit nodes.
• Geo-Blocking: Restricts access by country using GeoIP.
• Rate Limiting: Prevents abuse via customizable IP request limits.
• Anomaly Scoring: Dynamically blocks requests based on cumulative rule matches.
• Multi-Phase Inspection: Analyzes traffic throughout the request lifecycle.
• Sensitive Data Redaction: Removes private info from logs.
• Custom Response Handling: Tailored responses for blocked requests.
• Detailed Monitoring: JSON endpoint for performance tracking & analysis.
• Dynamic Config Reloads: Seamless updates without restarts.
• File Watchers: Automatic reloads on rule/blacklist changes.
• Observability: Seamless integration with ELK stack and Prometheus.
• Rules generator: available here

Simple at a glance UI :)

Security & Performance (SOTA)

• Zero-Copy Networking: Uses unsafe.String to eliminate memory allocations during request body inspection.
• Wait-Free Concurrency: Atomic counters ensure accurate metrics and rule hit counting without lock contention.
• Circuit Breaker: geoip_fail_open prevents database failures from causing service outages.
• DoS Protection: io.LimitReader enforces strict request body limits to prevent memory exhaustion.
• ReDoS Safety: Built on top of Go's regexp (RE2), guaranteeing linear time execution for all regex rules.

🚀 Quick Start

curl -fsSL -H "Pragma: no-cache" https://raw.githubusercontent.com/fabriziosalmi/caddy-waf/refs/heads/main/install.sh | bash

Example Output:

2025/01/29 13:50:49.791 INFO    Provisioning WAF middleware     {"log_level": "info", "log_path": "debug.json", "log_json": true, "anomaly_threshold": 10}
2025/01/29 12:50:49.918 INFO    http.handlers.waf       Tor exit nodes updated  {"count": 1093}
2025/01/29 13:50:49.918 INFO    WAF middleware version  {"version": "v0.0.0-20250128221917-c99e875aaf7c"}
2025/01/29 13:50:49.918 INFO    Rate limit configuration        {"requests": 100, "window": 10, "cleanup_interval": 300, "paths": ["/api/v1/.*", "/admin/.*"], "match_all_paths": false}
2025/01/29 13:50:49.918 WARN    GeoIP database not found. Country blocking/whitelisting will be disabled        {"path": "GeoLite2-Country.mmdb"}
2025/01/29 13:50:50.359 INFO    IP blacklist loaded     {"path": "ip_blacklist.txt", "valid_entries": 223770, "invalid_entries": 0, "total_lines": 223770}
2025/01/29 13:50:50.489 INFO    DNS blacklist loaded    {"path": "dns_blacklist.txt", "valid_entries": 854479, "total_lines": 854479}
2025/01/29 13:50:50.490 INFO    WAF rules loaded successfully   {"total_rules": 33, "rule_counts": "Phase 1: 17 rules, Phase 2: 16 rules, Phase 3: 0 rules, Phase 4: 0 rules, "}
2025/01/29 13:50:50.490 INFO    WAF middleware provisioned successfully

📑 Table of Contents

1. 🚀 Installation
2. 🛠️ Basic Configuration
3. 📚 Full Documentation
4. 📜 License
5. 🙏 Contributing

---

🚀 Installation

Prerequisites

• Go 1.25 or higher
• Caddy v2.10.x or higher (for building with this plugin)
• xcaddy (for building Caddy with plugins)

# Step 1: Clone the caddy-waf repository from GitHub
git clone https://github.com/fabriziosalmi/caddy-waf.git

# Step 2: Navigate into the caddy-waf directory
cd caddy-waf

# Step 3: Clean up and update the go.mod file
go mod tidy

# Step 4: Fetch and install the required Go modules
go get github.com/caddyserver/caddy/v2
go get github.com/caddyserver/caddy/v2/caddyconfig/caddyfile
go get github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile
go get github.com/caddyserver/caddy/v2/modules/caddyhttp
go get github.com/oschwald/maxminddb-golang
go get github.com/fsnotify/fsnotify
go get -v github.com/fabriziosalmi/caddy-waf
go mod tidy

# Step 5: Download the GeoLite2 Country database (required for country blocking/whitelisting)
wget https://git.io/GeoLite2-Country.mmdb

# Step 6: Build Caddy with the caddy-waf module
xcaddy build --with github.com/fabriziosalmi/caddy-waf=./

# Step 7: Fix Caddyfile format
caddy fmt --overwrite

# Step 8: Run the compiled Caddy server
./caddy run

---

🛠️ Basic Configuration

Here's a minimal Caddyfile example to get started:

{
    auto_https off
    admin localhost:2019
}

:8080 {
    log {
        output stdout
        format console
        level INFO
    }

    handle {
        header -Server
    }

    route {
        # WAF Plugin runs on all requests first
        waf {
            metrics_endpoint /waf_metrics
            rule_file rules.json
            ip_blacklist_file ip_blacklist.txt
            dns_blacklist_file dns_blacklist.txt
        }

        # Match the waf metrics endpoint specifically and stop processing
        @wafmetrics path /waf_metrics
        handle @wafmetrics {
            # Do not respond here so it goes to the WAF plugin
        }

        # All other requests, respond with "Hello World"
        handle {
            respond "Hello world!" 200
        }
    }
}

For more detailed configuration options, rules format, and usage instructions, please refer to the Full Documentation.

---

📚 Full Documentation

For complete documentation, including configuration options, rule format details, protected attack types, testing strategies, and more, please refer to the /docs directory in this repository.

📑 Table of Contents

1. Installation - Instructions for installing the Caddy WAF middleware.
2. Configuration Options - Detailed explanation of all available configuration settings.
3. Rules Format (rules.json) - A comprehensive guide to defining custom rules using the JSON format.
4. Blacklist Formats - Documentation of the formats used for defining IP and DNS blacklists.
5. Rate Limiting - How to configure rate limiting, including parameters and usage.
6. Country Blocking and Whitelisting - Details on how to configure country-based blocking and whitelisting.
7. Protected Attack Types - An overview of the wide range of web-based threats that the Caddy WAF is designed to protect against.
8. Dynamic Updates - How to dynamically update the WAF rules and other settings without downtime.
9. Metrics - Details about the WAF's metrics endpoint and the different metrics collected.
10. Prometheus Metrics - Instructions on how to expose WAF metrics using the Prometheus format.
11. ELK Observability - Instructions on how to configure caddy-waf ELK stack observability.
12. Rule/Blacklist Population Scripts - Documentation on the provided scripts to automatically fetch, update and generate rules and blacklists.
13. Testing - Guidance on how to test the WAF's effectiveness using the provided testing tools.
14. Docker Support - Instructions on how to build and run the WAF using Docker.

---

📜 License

This project is licensed under the AGPLv3 License.

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🙏 Contributing

Contributions are highly welcome! Feel free to open an issue or submit a pull request.