logstash/logstash — pull request #261 by avishai-ish-shalom (2012-12-08 10:21:51+00:00)
Title: Anonymize filter

From the mailing list it seems users want to do something like this and having a built in way may save them a lot of trouble.
This filter is best used in tandem with the geoip filter, so you would get the ASN/geo data then obfuscate the original IP address (probably deserves a cookbook entry after this is merged).

I not familiar with locality sensitive hashes for IP addresses, although one can simply hash the network/ASN instead of the address. If you think more hash modes are necessary let me know.