IP address anonymizer module for nginx
ipscrubis an IP address anonymizer for nginx log files. It's an nginx module that generates an IP-based hash. You can use this hash to link requests from the same source, without identifying your users by IP address.
saltusing 128bits from
HASH(salt ++ IP address).
arc4randomto generate random nonces (see Theo de Raat's talk on arc4random for a great overview). On Linux this requires installing libbsd (package libbsd-dev on Ubuntu/Debian).
ALSO NOTE: the generated hash WILL change on each
PERIODtransition, so you will only have continuity within each
PERIOD. But because users can transition between networks at any time (e.g. wifi -> cellular), you'd have this type of issue even if you were storing raw IPs.
In threat scenario (1), the goal is to compute the masked IP corresponding to a target IP address. This will only be possible if the demand is made before the end of the current
Scenario (2) is defended against because the server operator does not know the salt, and cannot infer it based on the request timestamp, because the salt is generated from a nonce that is only stored in memory. The server operator would have to be an accomplice in this case, but that is more simply accomplished by the server operator just recording the unmasked IP. So this security/threat model does not defend against a malicious server operator, but that is not the point. It does defend against an honest server operator being compelled in threat scenarios (1) and (2).
ipscrubcan be built statically with nginx or as a dynamic module. See the
Makefilefor examples of both ways.
load_module ngx_ipscrub_module.so;(NOTE: only if you built as a dynamic module).
NOTE: nginx may still leak IP addresses in the error log. If this is a concern, disable error logging or wipe the log regularly.
This will have a non-zero exit code if you aren't up-to-date, so you can automate regular checks.
GDPR goes into effect on May 25, 2018. It legislates the handling of personal data about your users, including IP addresses.
What constitutes personal data?
Any information related to a natural person or ‘Data Subject’, that can be used to directly or indirectly identify the person. It can be anything from a name, a photo, [...], or a computer IP address.
The hashes generated by
ipscrublet you correlate nginx log entries by IP address, without actually storing IP addresses, reducing your GDPR surface area.
Copyright 2018 Mason Simon
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