ENR Decoder

A simple Python script for decoding Ethereum Node Record (ENR) strings.

The script:

• removes the enr: prefix (if present),
• performs Base64 URL decoding,
• performs RLP decoding,
• prints key fields (signature, seq, id, ip, tcp, udp),
• tries to parse the eth entry (ForkID: fork_hash, next_fork).

Requirements

• Python 3.8+
• Packages:
  • rlp
  • eth-utils

Install dependencies

pip install rlp eth-utils

Usage

python3 enrdecode.py "enr:-FDSjiog..."

Or without the prefix:

python3 enrdecode.py "-FDSjiog..."

Example output

--- ENR: enr:-FDSjiog... ---
Signature: 0x1234abcd...
Sequence No: 1
Scheme: v4
IP Address: 1.2.3.4
TCP Port: 30303
UDP Port: 30303

>>> ETH ENTRY (ForkID) <<<
Fork hash:       0x...
Next fork block: 0

Error cases

• Invalid Base64 input:
  • Base64 decode error: ...
• Invalid RLP data:
  • RLP decode error: ...
• Wrong number of arguments:
  • the script prints usage instructions.

Notes

• The script does not verify the ENR cryptographic signature, it only decodes content.
• The eth field may have a different format; in that case, the script prints an Unexpected ... format message.