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Start Besu

Nodes can connect to Ethereum Mainnet and public testnets.

Use the besu command with the required command line options to start a node.

Prerequisites​

Besu installed

Local block data​

When connecting to a network other than the network previously connected to, you must either delete the local block data or use the --data-path option to specify a different data directory.

To delete the local block data, delete the database directory in the besu/build/distribution/besu-<version> directory.

Genesis configuration​

Besu specifies the genesis configuration, and sets the network ID and bootnodes when connecting to Holesky, Sepolia, Ephemery and Mainnet.

info

The Ropsten, Rinkeby, and Kiln testnets are deprecated.

When you specify --network=dev, Besu uses the development mode genesis configuration with a fixed low difficulty. A node started with --network=dev has an empty bootnodes list by default.

The genesis files defining the genesis configurations are in the Besu source files.

To define a genesis configuration, create a genesis file (for example, genesis.json) and specify the file using the --genesis-file option.

Syncing and storage​

By default, Besu syncs to the current state of the blockchain using snap sync in:

  • Networks specified using --network except for the dev development network.
  • Ethereum Mainnet.

We recommend using snap sync for a faster sync, by starting Besu with --sync-mode=SNAP.

By default, Besu stores data in the Bonsai Tries format.

Run a node for testing​

To run a node that mines blocks at a rate suitable for testing purposes:

besu --network=dev --miner-enabled --miner-coinbase=0xfe3b557e8fb62b89f4916b721be55ceb828dbd73 --rpc-http-cors-origins="all" --host-allowlist="*" --rpc-ws-enabled --rpc-http-enabled --data-path=/tmp/tmpDatdir

You can also use the following configuration file on the command line to start a node with the same options as above:

network="dev"
miner-enabled=true
miner-coinbase="0xfe3b557e8fb62b89f4916b721be55ceb828dbd73"
rpc-http-cors-origins=["all"]
host-allowlist=["*"]
rpc-ws-enabled=true
rpc-http-enabled=true
data-path="/tmp/tmpdata-path"
Warning

The following settings are a security risk in production environments:

Run a node on Holesky testnet​

To run a node on Holesky specifying a data directory:

besu --network=holesky --data-path=<path>/<holeskydata-path>

Where <path> and <holeskydata-path> are the path and directory to save the Holesky chain data to.

See the guide on connecting to a testnet for more information.

Run a node on Sepolia testnet​

To run a node on Sepolia specifying a data directory:

besu --network=sepolia --data-path=<path>/<sepoliadata-path>

Where <path> and <sepoliadata-path> are the path and directory to save the Sepolia chain data to.

See the guide on connecting to a testnet for more information.

Run a node on Ephemery testnet​

To run a node on Ephemery specifying a data directory:

besu --network=ephemery --data-path=<path>/<ephemery-data-path>

Where <path> and <ephemery-data-path> are the path and directory to save the Ephemery chain data to.

See the guide on connecting to a testnet for more information.

Run a node on Ethereum Mainnet​

To run a node on the Ethereum Mainnet:

besu

To run a node on Mainnet with the HTTP JSON-RPC service enabled and available for localhost only:

besu --rpc-http-enabled

See the guide on connecting to Mainnet for more information.

Confirm node is running​

If you started Besu with the --rpc-http-enabled option, use cURL to call JSON-RPC API methods to confirm the node is running.

  • eth_chainId returns the chain ID of the network.

    curl -X POST --data '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' localhost:8545

  • eth_syncing returns the starting, current, and highest block.

    curl -X POST --data '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}' localhost:8545

    For example, after connecting to Mainnet, eth_syncing will return something similar to:

    {
      "jsonrpc": "2.0",
      "id": 1,
      "result": {
        "startingBlock": "0x0",
        "currentBlock": "0x2d0",
        "highestBlock": "0x66c0"
      }
    }