Hey everyone! We're a small fintech company, and we've recently discovered a potential issue with DNS leaking private IPs. I'm seeking some practical advice on how to fix this and avoid exposing private IP details in the future.
Here's what we're dealing with:
We have a public Route53 record for superadmin.example.com that resolves to a private IP when queried through public DNS. Essentially, it works like this: superadmin.example.com → CNAME → internal-ELB-[MASKED].elb.amazonaws.com → 10.x.x.x (which is a private IP). We only set up a CNAME in Route53, so we're puzzled as to why public resolvers are revealing a private IP.
We have a few constraints:
1. We can move the record to a private hosted zone soon, but our developers need to access it from their laptops through the office network.
2. If we set up a private zone now, we risk disrupting other public subdomains in the same VPC since it would ignore public zone names.
3. We need careful planning since multiple public domains operate within the same VPC.
My main concerns are:
1. How do we prevent private IPs from being exposed through public DNS, especially when using a private ELB?
2. How can we provide remote developers access without revealing internal IPs?
3. Is using a private hosted zone along with a VPN a suitable approach given the VPC behavior?
4. Would a public ALB with IP whitelisting (secured with TLS, WAF, and strong auth) be okay? What risks should we be wary of?
5. Any best practices or tools available to monitor public zones for private IP leaks and avoid unexpected exposure?
Looking for any tips or experiences from those who have dealt with similar setups in AWS/Route53 and internal ELBs. Thanks a ton!
5 Answers
The straightforward answer is you can't avoid this completely. Knowing a private IP isn't harmful if your security is strong. For remote devs, you really should implement either an ALB as a public-to-private proxy or set up a reliable VPN.
Could you clarify what you meant about the VPC resolving DNS names? Typically, you'll have a public resolver in your VPC, and using private Route53 zones is totally doable. Just set up the right DNS resolution for your remote VPN connections, and it should work smoothly!
Concerned about exposing private IPs? Just remember, these addresses are not routed on the internet, so they can essentially remain hidden. If your developers need access, consider creating a secure connection or a bastion host for remote access.
It's also worth exploring AWS Verified Access for enabling remote teams to connect to internal systems securely. Always separate your strategies for accessing applications versus managing infrastructure.
Honestly, worrying about a changing private IP isn't as critical as it seems. It's tough for an outsider to do anything with such an address. Instead, focus on providing proper internal access for your team. Tools like Session Manager are super helpful for accessing private resources without needing to expose anything to the public.
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