A Performance Evaluation of Hash Functions for IP Reputation Lookup using Bloom Filters

IP reputation lookup is one of the traditional methods for recognition of blacklisted IPs, i.e., IP addresses known to be sources of spam and malware-related threats. Its use however has been rapidly increasing beyond its traditional domain reaching various IP filtering tasks. One of the solutions able to provide a necessary scalability is a Bloom filter. Efficient in memory consumption, Bloom filters provide a fast membership check, allowing to confirm a presence of set elements in a data structure with a constant false positive probability. With the increased usage of IP reputation check and an increasing adoption of IPv6 protocol, Bloom filters quickly gained popularity. In spite of their wide application, the question of what hash functions to use in practice remains open. In this work, we investigate a 10 cryptographic and non-cryptographic functions for on their suitability for Bloom filter analysis for IP reputation lookup. Experiments are performed with controlled, randomly generated IP addresses as well as a real dataset containing blacklisted IP addresses. Based on our results we recommend two hash functions for their performance and acceptably low false positive rate.