rlp_enodes — EVM Bootstrap Node Filter

Automated system that downloads the latest all.json crawl from the Ethereum discv4-dns-lists repository, filters nodes by EVM-compatible chain, selects only those advertising the dominant (current-head) fork ID, ranks them by score and recency, and writes clean JSON files of the top bootstrap peers for use with your discv4 peer-discovery library.

Output structure

Each chain produces a single file directly in output/:

output/
  ethereum-mainnet.json
  ethereum-sepolia.json
  ethereum-holesky.json
  ethereum-hoodi.json
  bnb-smart-chain.json
  bnb-smart-chain-testnet.json
  polygon-mainnet.json
  polygon-amoy.json
  base-mainnet.json
  base-sepolia.json
  gnosis-chain.json
  .state          ← SHA-256 of last processed all.json (for change detection)

Each {chain}.json is an array of objects sorted by score (descending) then lastResponse (most recent first), capped at topN (default 100):

[
  {
    "enr":          "enr:-...",
    "nodeId":       "04d70a61...",
    "score":        3371,
    "lastResponse": "2026-03-14T20:54:48Z",
    "forkId":       "4d518ce1",
    "forkNext":     0,
    "ip":           "162.55.86.114",
    "port":         30311
  },
  ...
]

Automation

A GitHub Actions workflow runs every 6 hours but only regenerates output when all.json has actually changed (SHA-256 comparison against output/.state). It also triggers on pushes to main that change source files, and can be run on-demand.

Local usage

# Build
go build -o filter_nodes .

# Run (downloads all.json from the internet)
./filter_nodes

# Use a local copy of all.json (faster for development / testing)
./filter_nodes -input /path/to/all.json

# Discovery mode: print ranked fork-hash summary to identify unknown chains
./filter_nodes -discover

# Combine: discovery on a local file
./filter_nodes -input /path/to/all.json -discover

Supported filter strategies

Strategy	Description
geth_network	Uses go-ethereum's forkid.NewStaticFilter to accept any node on the same genesis chain regardless of fork level. Supported networks: mainnet, sepolia, holesky, hoodi.
enr_field	Accepts nodes that carry a specific ENR key (e.g. bsc for BNB Smart Chain).
fork_hash_list	Accepts nodes whose eth fork hash is in the configured forkHashes list.

Compound AND filter

Set both enrField and forkHashes together with either "enr_field" or "fork_hash_list" as filterType to require both conditions simultaneously. This is used to distinguish BNB Smart Chain testnet (Chapel) from mainnet — both advertise the bsc ENR key but at different fork hashes.

Configured chains

Chain	Chain ID	Filter
Ethereum Mainnet	1	geth_network: mainnet
Ethereum Sepolia	11155111	geth_network: sepolia
Ethereum Holesky	17000	geth_network: holesky
Ethereum Hoodi	560048	geth_network: hoodi
BNB Smart Chain	56	enr_field: bsc
BNB Smart Chain Testnet	97	enr_field: bsc + fork_hash_list (compound)
Polygon PoS Mainnet	137	fork_hash_list
Polygon Amoy Testnet	80002	fork_hash_list
Base Mainnet	8453	fork_hash_list
Base Sepolia Testnet	84532	fork_hash_list
Gnosis Chain (xDai)	100	fork_hash_list

Adding or updating chains

1. Edit chains_config.json.
2. Run ./filter_nodes -discover (or -input + -discover) to print a ranked table of all fork hashes observed in the crawl. Chain-specific ENR keys (e.g. bsc(2709)) help identify which hash belongs to which chain.
3. Cross-reference the top hashes with the chain's release notes.
4. Add the hash(es) to the chain's forkHashes array.
5. Re-run to verify results.

Known Ethereum fork hash progression (March 2026)

Chain	Fork	Hash	Timestamp / Block
Mainnet	Cancun	9f3d2254	1710338135
Mainnet	Prague	c376cf8b	1746612311
Mainnet	Osaka	5167e2a6	1764798551
Mainnet	BPO1	cba2a1c0	1765290071
Mainnet	BPO2	07c9462e	1767747671 (current)
Sepolia	Cancun	88cf81d9	1706655072
Sepolia	BPO2	268956b6	current
Holesky	Cancun	9b192ad0	1707305664
Holesky	BPO2	9bc6cb31	current
Hoodi	Prague	0929e24e	1742999832 (current)

Dependencies

• github.com/ethereum/go-ethereum — for ENR decoding (p2p/enode, p2p/enr), fork ID filtering (core/forkid), and chain configurations (params).