It was late at night. The room was still lit, and the red alerts flashing on my monitoring dashboard made my heart race. Traffic on our website had suddenly surged, and wave after wave of abnormal requests confirmed my worst fear: our site was under attack.
I immediately pulled up the logs, trying to trace the source. At that moment, my phone rang. It was my colleague, sounding anxious: “The site is down. Customers are complaining.”
This was no longer a minor outage—it was a business-critical incident.
I suddenly remembered a recommendation from a seasoned security expert during a technical meetup: an open-source Web Application Firewall called SafeLine WAF, built by Chaitin Tech. It was described as lightweight, powerful, easy to deploy, and completely free.
With no time to waste, I deployed it on the spot. Surprisingly, the setup was smooth, and the attack was contained almost immediately. That experience convinced me to introduce SafeLine WAF to more developers who need reliable, zero-cost web protection.
SafeLine WAF official site:
https://safepoint.cloud/landing/safeline
SafeLine WAF is a simple, practical, and powerful community edition WAF built by Chaitin Tech over nearly 10 years. Powered by industry-leading semantic detection technology, it acts as a reverse proxy to protect your web applications from attacks. Its core is driven by an intelligent semantic analysis engine designed for the community—to ensure attackers never cross your boundary.
Core Features
1. Web Attack Mitigation
SafeLine can detect and block all common web attacks, including SQL Injection, XSS, code injection, OS command execution, CRLF injection, XXE, SSRF, path traversal, and more.
2. Rate Limiting
By controlling request frequency, SafeLine protects services from CC attacks, brute-force login attempts, traffic surges, and various misuse scenarios.
3. Bot and Crawler Detection
Modern web traffic consists of both legitimate visitors and automated scanners, bots, worms, and exploit tools. SafeLine’s human verification ensures real users are allowed through while malicious automation is blocked.
4. Identity Authentication
This feature helps prevent unauthorized access vulnerabilities by enforcing user authentication before anyone can access specific resources.
5. Dynamic Protection
SafeLine can dynamically transform and encrypt HTML and JavaScript content. The rendered code becomes unique for every visit, making exploitation attempts significantly harder.
What Is a WAF?
WAF stands for Web Application Firewall. Unlike traditional network firewalls, a WAF operates at the application layer and is specifically designed to protect web systems communicating over HTTP/HTTPS.
A WAF can detect and block common web attacks such as SQL injection, XSS, CSRF, SSRF, WebShell upload and communication, and many others.
How to Install and Deploy SafeLine
Minimum Requirements
- Operating System: Linux
- Architectures: x86_64, arm64
- Docker: v20.10.14 or above
- Docker Compose: v2.0.0 or above
- Minimum Specs: 1 CPU / 1 GB RAM / 5 GB Disk
One-Command Installation (Recommended)
bash -c "$(curl -fsSLk https://waf-ce.chaitin.cn/release/latest/manager.sh)"
The official documentation also includes manual and offline installation options.
After Installation: How to Use It
Once installed, open your browser and access:
https://<safeline-ip>:9443/
Ensure that port 9443 is accessible from your network.
Testing SafeLine's Protection
The official website provides a demo where you can simulate attacks and observe SafeLine's protection in real time.
- Normal traffic is served without interruption.
- Malicious traffic triggers an immediate block with a clear warning message.
How SafeLine Works
SafeLine protects your web application by intercepting, filtering, and analyzing HTTP traffic between the internet and your server.
It covers a wide range of threats, including:
- SQL Injection
- XSS
- Command Injection
- Code Injection
- LDAP Injection
- XPath Injection
- RCE
- XXE
- SSRF
- Path Traversal
- Backdoors
- Brute Force
- CC Attacks
- Crawlers and Scrapers
Basic Architecture
External users send requests through the network to your web server. If a malicious actor is among them, their attack traffic also reaches your server.
By integrating SafeLine as a reverse proxy, it intercepts traffic before it reaches your server, detects and filters malicious requests, and forwards only safe traffic to the backend application.
This ensures that harmful traffic never reaches your environment.
Final Thoughts: Highly Recommended
SafeLine WAF is the result of nearly a decade of engineering by Chaitin Tech. It delivers enterprise-grade capabilities while being fully open-source, easy to deploy, and extremely lightweight.
If you run any website—whether personal, business, or production-critical—SafeLine gives you a reliable, practical, and free layer of protection against modern web threats.
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