Fingerprinting nodes: Possible Solutions

The proposed modification to the GETADDR function in network protocols suggests limiting its responses to only include node addresses that correspond to the network type of the requesting node. This change aims to enhance privacy and security by preventing cross-network fingerprinting, where information could be inferred from different network types (e.g., IPv4, IPv6, Tor) inadvertently sharing address information. Under this new scheme, a node connected via IPv6 would only receive IPv6 addresses, and similarly, a Tor node would only obtain addresses of other Tor nodes.

This approach, however, introduces a dependency on hardcoded seed nodes, especially during the initial connection phases of a new node. Fresh nodes would require at least one connection to a node of each relevant network type to start populating their address tables with appropriate entries. This could potentially slow down the initial setup process and increase reliance on these hardcoded seed nodes, which are typically used to bootstrap network connections when node address information is not yet available.

By implementing such a restriction, it is anticipated that the distinctiveness of the address sets returned by GETADDR would significantly mitigate risks associated with nodes being identified across different network layers by aggregating diverse node data. This alteration seeks to fortify the underlying robustness of node interactions within varied network environments.