Question 1

Why does running sed on Varnish default.vcl break regsub() and ban() expressions?

Accepted Answer

Varnish Configuration Language (VCL 4.0/4.1) embeds regular expressions inside double-quoted strings in regsub(), regsuball(), and ban() calls, alongside multi-line acl and backend blocks. A naive sed quote replacement corrupts string boundaries and causes varnishd -C compilation to fail. VarnishVclShield targets only secret literals, ACL CIDRs, and backend .host strings in browser RAM.

Question 2

What security risks happen if I leak backend .host IPs or X-Purge-Token from default.vcl?

Accepted Answer

Exposing backend .host origin IPs lets attackers bypass your Varnish or Fastly edge layer and DDoS your origin servers directly, while leaking req.http.X-Purge-Token or acl purge CIDRs allows unauthorized cache invalidation floods and HMAC signature forgery.

Question 3

How do I sanitize a Varnish .vcl file before pasting it into Claude, ChatGPT, or Cursor?

Accepted Answer

Paste your default.vcl or Fastly custom VCL snippet into VarnishVclShield. Within 50ms in local browser RAM, all backend .host IPs and acl purge CIDRs are mapped to RFC 5737 documentation addresses while X-Purge-Token headers and digest.hmac_sha256() secrets are masked.

Question 4

Does VarnishVclShield upload my Varnish VCL configurations to any cloud server?

Accepted Answer

Never. VarnishVclShield executes 100% inside your browser's local RAM with zero network egress. Your origin server IPs, internal VPC CIDR ranges, and HMAC signing keys never leave your machine.

Question 5

How does VarnishVclShield compare to Fastly / Varnish Enterprise tools ($49/mo) or CyberChef?

Accepted Answer

Enterprise CDN suites cost $49/mo+ ($588/yr) and require cloud account sync, while generic CyberChef regex recipes lack VCL 4.1 grammar awareness for acl blocks, backend definitions, and VMOD digest calls. VarnishVclShield is purpose-built for VCL at a $19 one-time buyout or €3.99 24h pass.

Question 6

What is included in the $19 Lifetime PRO Offline Workstation?

Accepted Answer

Unlocking PRO removes the 30% preview blur on bottom VCL subroutines, enables multi-file VCL include batch scrubbing (default.vcl + backends.vcl + acl.vcl), and downloads a self-contained air-gapped HTML workstation with a 14-day refund guarantee.

Raw Varnish default.vcl or Fastly Custom VCL Configuration

📊 Step 4 · Processed Output

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VarnishVclShield — Free Interactive In-Browser Studio

Raw Varnish default.vcl or Fastly Custom VCL Configuration

📊 Step 4 · Processed Output

Zero Cloud Upload Guarantee

Verify Results Before Paying

Unlock 100% Export & Offline App