Ethereum Node Record (ENR)

Overview

Meaning and scope

An Ethereum Node Record, or ENR, is a signed data record used to describe an Ethereum network node for discovery and connection. It can include the node’s public identity key, IP address, ports, supported protocols, and sequence number. The node signs the record so peers can verify its authenticity.

Mechanism and operation

Ethereum’s discovery protocols need a portable way to advertise how peers can reach a node. An ENR encodes key-value fields under a versioned, signed structure. The identity key binds the record to one node identity. A sequence number increases whenever the operator updates information, allowing peers to prefer the newest valid record. Fields can describe IPv4 or IPv6 addresses, UDP and TCP ports, and protocol-specific capabilities. ENRs are distributed through discovery mechanisms, bootnode lists, operator configuration, or direct sharing. Operators should protect the node identity key and update records when addresses or ports change.

Practical payment example

Two peers exchange authenticated node records and use advertised endpoints to discover one another without assuming the address remains permanently reachable.

Operational checks

Publishing private or internal network details can create security exposure. Firewalls and network-address translation can also make advertised endpoints unusable. Applications should parse ENRs through tested libraries rather than manually decode base64 and RLP fields. An ENR supports peer discovery and authenticated node metadata.

Distinctions and limits

A valid signature proves that the identity key signed the record, but it does not prove that the IP is reachable, safe, or operated by a trusted organization. It is infrastructure information for networking, not a credential that authorizes transactions or a proof that the node follows the canonical chain. Infrastructure teams should rotate or update ENRs through controlled deployment processes.

Related reading

Related definitions: node, Ethereum.