IPhash

IPhash is a term used to describe a class of techniques that map IP addresses to fixed-length representations using hashing. It is not a single standard but a concept applied in network infrastructure and data processing to balance privacy with operational needs. The goal is to reduce exposure of raw IP addresses in logs and analytics while enabling efficient indexing or routing decisions.

In practice, IPhash may employ cryptographic hash functions with salting for privacy-preserving logging, or non-cryptographic hashes for fast, deterministic routing in load balancers. In the latter use, an IP-derived hash selects an upstream server, helping to preserve session affinity so that requests from the same client tend to reach the same backend.

Security and privacy considerations: hashing reduces immediate visibility of the address but is not inherently anonymous. Salting or peppering the hash with additional data helps prevent reverse-engineering, but the presence of auxiliary information can still enable re-identification in some cases. Compliance with privacy regulations may require data minimization and strict access controls.

Limitations: hashed IPs can still leak information under certain circumstances, and collisions can occur with small hash sizes. Additionally, IP hashing can distort geographic or network analysis and may complicate cross-system comparisons if standardization is lacking.

Implementation note: systems such as Nginx provide an ip_hash directive that uses the client's IP to select an upstream server, illustrating the practical use of IP-based hashing for load distribution. Other platforms implement similar techniques under different names.

See also: hash function, IP address, load balancing.