16,400+ GitHub Stars: This Free WAF Is on Fire

Tired of maintaining endless regex rules in traditional WAFs? Meet SafeLine, a free and open source Web Application Firewall with a semantic detection engine, dynamic protection, and over 16.4K GitHub stars. It’s built for real-world attacks—and it's free and open-source.

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🔄 Dynamic Protection: Scramble Your Frontend, Every Time

SafeLine can dynamically obfuscate HTML and JS on each page load, making your source code unreadable to crawlers and bots.

• /admin/login becomes a random encrypted path like /a8c9f1, and changes every refresh

• Real users see no difference. Crawlers see... nothing.

🧪 BurpSuite Test Result:
Crawler blocked from indexing. Browser loads normally. Extra latency: ~1ms.

💡 You can apply this selectively:

• Encrypt only admin paths

• Whitelist static files (CSS/JS) to avoid layout issues

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🤖 Bot Blocking That Actually Works

SafeLine doesn't rely on User-Agent headers. It verifies browser behavior:

• JS execution

• Fingerprinting

• Mouse movement

🚫 Bots fail.
✅ Humans pass once, then proceed freely.

🧪 Tested: A Python script was blocked after 3 requests. The IP was locked for 30 mins. No CAPTCHA required.

You can tweak thresholds and customize the lock screen.

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🧠 Semantic Detection: Not Just Rule Matching

SafeLine doesn’t use static signatures. It understands what the payload is trying to do.

• Detects SQL injection like 1 AND 1=1, even if obfuscated

• Blocks XSS via DOM-aware context, not pattern matching

🧪 Benchmark:

• 33,669 requests tested

• 575 malicious payloads

• ✅ Detection rate: 71.65%

• ❌ False positives: 0.07%

• ⚡ Avg Latency: 1ms, >2000 TPS per core

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🧱 Security for Admin Panel Access

• RBAC: Give ops read-only, engineers full control

• 2FA: TOTP-based, works with Microsoft Authenticator

• CLI fallback: docker exec safeline-mgt resetadmin if you lose 2FA

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🔬 Real-World Lab: WebGoat + SafeLine

docker run -d -p 8080:8080 registry.cn-shanghai.aliyuncs.com/kubesec/webgoat:v2023.8

Then reverse-proxy it via SafeLine under webgoat.test.

🧪 Test Attacks

• SQLi: ?id=1 UNION SELECT * FROM users → Blocked

• XSS: <img src=x onerror=alert(1)> → Blocked

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⚠️ Troubleshooting Tips

🛠 Hardware: 2C/4G recommended for <1ms latency.

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🚀 Final Thoughts

SafeLine isn't just another regex-based WAF. It's:

• Free & open source

• No signature maintenance

• Semantic detection that works

• Handles 2000+ TPS/core

If you're running a self-hosted app or CTF challenge, this is the WAF to try.

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🔗 Links

• 🌐 [GitHub Repository] (https://github.com/chaitin/safeline)

• 📚 [Official Docs] (https://docs.waf.chaitin.com/)

• 💬 [Discord Community] (https://discord.gg/dy3JT7dkmY)