Building things fast is great. Developers love speed, access, and cutting down friction. But sometimes, in the race to make things easy, a tiny misstep can crack open doors—big, scary doors you didn’t mean to unlock.
TL;DR: A VPN tunnel set up to help developers access internal services accidentally exposed sensitive admin endpoints. This happened because of poor segmentation and flat firewall rules. Luckily, it was caught before any damage was done. The infra team jumped in, tightened up network access, and put proper segmentation in place to keep production safe in the future.
The Tunnel That Opened Too Much
The story starts with good intentions. Developers needed access to internal APIs for testing and debugging. To help, the DevOps team spun up a VPN tunnel. Nothing fancy—just a simple VPN to route dev machines into the internal VPC. It worked. Too well, maybe.
At first, it seemed perfect. Developers could test faster. Logging into staging resources became seamless. Debugging errors took minutes instead of hours.
But lurking unnoticed was a problem. This VPN tunnel wasn’t just reaching staging. It was swimming into production too.
So… What Actually Went Wrong?
Let’s break it down.
- Shared VPC: Production and staging services both lived in the same Virtual Private Cloud.
- Flat firewall rules: There were no strict checks on what IPs or services the VPN users could access.
- Admin endpoints: These were supposed to be locked down. But because the network was too open, they were reachable from the dev VPN.
Essentially, the VPN spilled developer traffic into places it shouldn’t go. This wasn’t because someone was careless, but because security hadn’t been baked deep into the setup. It was a classic case of “it works… a little too well.”
Discovery: The “oops” Moment
It started with a simple security audit. The security team ran internal scans and noticed something strange. A dev IP was trying to query a production admin endpoint. Nothing malicious—it looked like someone was testing an API tool with the wrong environment variable set.
Alarms went off. Literally.
A deep dive began. The security team partnered with the cloud engineers to trace packets, analyze routes, and finally discovered the unwanted highway the VPN had constructed straight into production.
Time To Lock the Doors
Fixing the issue wasn’t glamorous. But it was urgent. Here’s what the team did:
1. Segmentation, Segmentation, Segmentation
Staging and production were moved into separate VPCs. This was step one. Think of it like moving your office desk out of the kitchen so your snacks stop vanishing.
- Each environment got its own private cloud space.
- No more shared subnets or auto-forwarded routes.
2. Tightening Firewall Rules
Next, IP-based firewall controls were applied.
- Only specific IPs on the VPN network could access staging systems.
- Production access was outright blocked at the routing layer for dev users.
- Admin endpoints were restricted to whitelisted IPs from the internal ops network.
This cut off any accidental poking around. It also meant if someone messed up an environment variable or internal proxy setting, they wouldn’t get into trouble—or prod.
3. Logging and Monitoring
Because what good is locking the door if you don’t have a peephole?
- The team added detailed logs on VPN connections.
- Every request to sensitive endpoints was audited.
- SIEM (Security Information and Event Management) tools raised alerts for odd access patterns.
The Human Side of it All
Let’s take a step back. Nobody really did anything “wrong.” The VPN worked as planned. Devs weren’t trying to attack the system. But mistakes happen in systems without tight boundaries.
The good news? This became a teachable moment.
What Changed in the Culture:
- “Assume breach” mindset: Everyone was encouraged to think in terms of “what if someone got in—what could they do?”
- Secure-by-default: New VPN setups now consider production lock-outs as the default, not a feature request.
- Shared checklists: Teams now consult a shared VPN rollout checklist that includes routing reviews, environment segmentation, and access restriction best practices.
How You Can Avoid This Kind of Snafu
If you’re running infrastructure or just setting up access tunnels for developers, here’s what you should always check:
Quick Checklist Before Spinning Up Developer VPNs:
- Are your environments segmented into different VPCs?
- Do you have IP restrictions per environment?
- Are admin endpoints only accessible from narrow IP ranges?
- Is audit logging enabled across VPN ingress/egress?
- Are firewall rules explicitly blocking developer access to production?
- Are environment variables correctly pointing to staging, not prod?
Bonus: Tools That Can Help
Several tools made this recovery easier. If you’re in a similar spot, consider:
- Tailscale or OpenVPN: For tightly-controlled VPN tunneling with user-level authentication.
- Terraform + AWS VPC Modules: For repeatable, segmented network setup.
- Cloud NAT Gateways & Route Tables: To cleanly separate staging/production traffic.
- CloudTrail + GuardDuty (in AWS): For discovering and alerting on unusual access patterns.
All these help turn a reactionary approach into a proactive one.
The Happy Ending
In the end, no data was leaked. Nothing bad happened. But it easily could have. Thanks to logging and observability, the issue was caught early. And the response was quick and coordinated.
Now, things are safer. Devs still have access—but the right kind. Production is better protected. And a few checkboxes later, everyone can sleep a bit easier at night.
Final Thought
Security isn’t just about patches and passwords. It’s about boundaries. And sometimes, the simplest tunnels end up going places they shouldn’t. Always build with those invisible walls in mind.
You don’t want a shortcut to become a trapdoor.