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Sharon
Sharon

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Building a Realistic CTF? Here's Why We Picked SafeLine WAF

#ctf #safeline #waf #webdev

During a recent Capture The Flag (CTF) event focused on incident response, one question kept coming up:

"Why did you guys use SafeLine WAF in the challenge environment?"

Here’s the reasoning behind our choice — and why you might want to consider it too.

Why Add a WAF to a CTF?

CTF challenges, especially in incident response, should mirror real-world environments. That doesn’t just mean vulnerable apps — it also means realistic infrastructure like Web Application Firewalls (WAFs).

But we weren’t going to use just any WAF.

Why SafeLine?

SafeLine Dashboard

Before the event, we reached out to the SafeLine team to clarify the licensing — and to our surprise, not only is it fully open source, they actually encourage its use in CTFs and security training.

Here’s what won us over:

1. It’s Free and Open Source

SafeLine is 100% free to use and has consistently ranked high on GitHub’s trending WAF list.

It’s perfect for:

  • CTF events
  • Side projects
  • Security research
  • Startups that need protection but can’t afford a paid WAF

2. Ridiculously Easy to Deploy

One-liner install? Container support? Minimal config? Yes, yes, and yes.

bash -c "$(curl -fsSLk https://waf-ce.chaitin.cn/release/latest/setup.sh)"
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Deployment Screenshot

Deployment Step 2

Wait a minute or two, and you're ready to start protecting domains.

3. Protection That Just Works

Even the free Personal Edition of SafeLine includes:

  • CC attack protection
  • Bot challenges
  • Custom rules
  • User authentication
  • Real-time dashboards

For a free tool, the protection level genuinely impressed us. Our participants noticed it too — logs, alerts, and responses all worked out of the box.

Getting Started

Once installed, head to the web console to start configuring:

  • Add your domains
  • Turn on CC/bot protection
  • Enable authentication or captcha challenges
  • View real-time alerts

To safely test your config, switch to Audited Mode, run simulated attacks, and review the logs.

Console Screenshot

Attack Logs

What If Something Breaks?

If setup fails or you hit a weird edge case — don’t panic. While I’m not the developer (please don’t @ me), the official SafeLine team is very responsive.

Here’s where to get help:

Final Thoughts

If you're organizing a CTF, running a training, or just building a lab, SafeLine is a solid choice for adding real-world WAF protection:

  • Open-source and free
  • Fast to deploy
  • Strong, usable protection
  • Backed by an active dev community

Give it a spin — it’s one of those tools that just works.

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