rex — Reth Node Explorer

Use engine capabilities to call engine_exchangeCapabilities on the authenticated Engine API. This is the safest first Engine command because it only exchanges method names. It does not submit a payload, update forkchoice, or start payload building.

Command

rex engine \
  --jwt-secret ./jwt.hex \
  capabilities

Example Output

ENGINE CAPABILITIES

Auth RPC:          http://127.0.0.1:8551
Requested methods: 16
Supported methods: 12

Supported by execution client:
  - engine_newPayloadV1
  - engine_newPayloadV2
  - engine_forkchoiceUpdatedV1
  - engine_forkchoiceUpdatedV2
  - engine_getPayloadV1
  - engine_getPayloadV2
  - engine_exchangeTransitionConfigurationV1
  - engine_getPayloadBodiesByHashV1
  - engine_getPayloadBodiesByRangeV1

How It Works

Rex sends a conservative consensus-client capability list and prints the method list returned by the execution client. The request is signed with a short-lived JWT built from the secret passed through --jwt-secret. The token is sent in the HTTP Authorization: Bearer ... header.

Common Mistakes

Use http://127.0.0.1:8551, not the public :8545 RPC port.
Use the same jwt.hex file that Reth received through --authrpc.jwtsecret.
Keep the machine clock sane. Engine API JWT validation checks the issued-at timestamp.