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Run Besu and Teku on a testnet

Run Besu as an execution client and Teku as a consensus client on the Holesky and Sepolia Ethereum testnets.

note

Sepolia is a permissioned network and you can't run a validator client on it without requesting to become a validator first. You can connect your consensus client using the beacon node only, without any validator duties.

1. Install Besu and Teku​

Install Besu and Teku.

Ensure you meet the prerequisites for the installation option you use. For example, you must have Java 21+ if using the Besu and Teku binary distributions.

Ensure you meet the system requirements for Besu on public networks.

2. Generate the shared secret​

Run the following command:

openssl rand -hex 32 | tr -d "\n" > jwtsecret.hex

You will specify jwtsecret.hex when starting Besu and Teku. This is a shared JWT secret the clients use to authenticate each other when using the Engine API.

3. Generate validator keys​

If you're running Teku as a beacon node only, skip to the next step.

If you're also running Teku as a validator client, create a test Ethereum address (you can do this in MetaMask). Fund this address with testnet ETH (32 ETH and gas fees for each validator) using a faucet. See the list of Holesky faucets and Sepolia faucets.

note

If you can't get ETH using the faucet, you can ask for help on the EthStaker Discord.

Generate validator keys for one or more validators using the Holesky Staking Launchpad (or request to become validator on Sepolia).

info

Save the password you use to generate each key pair in a .txt file. You should also have a .json file for each validator key pair.

4. Start Besu​

Run the following command or specify the options in a configuration file:

besu \
  --network=holesky           \
  --rpc-http-enabled=true     \
  --rpc-http-host=0.0.0.0     \
  --rpc-http-cors-origins="*" \
  --rpc-ws-enabled=true       \
  --rpc-ws-host=0.0.0.0       \
  --host-allowlist="*"        \
  --engine-host-allowlist="*" \
  --engine-rpc-enabled        \
  --engine-jwt-secret=<path to jwtsecret.hex>

Specify the path to the jwtsecret.hex file generated in step 2 using the --engine-jwt-secret option.

You can modify the option values and add other command line options as needed.

5. Start Teku​

Open a new terminal window.

Beacon node only​

To run Teku as a beacon node only (without validator duties), run the following command or specify the options in the Teku configuration file:

teku \
  --network=holesky                            \
  --ee-endpoint=http://localhost:8551          \
  --ee-jwt-secret-file=<path to jwtsecret.hex> \
  --metrics-enabled=true                       \
  --rest-api-enabled=true                      \
  --checkpoint-sync-url=<checkpoint sync URL>

Specify:

You can modify the option values and add other Teku command line options as needed.

Beacon node and validator client​

To run Teku as a beacon node and validator in a single process, run the following command or specify the options in the Teku configuration file:

teku \
  --network=holesky                                         \
  --ee-endpoint=http://localhost:8551                       \
  --ee-jwt-secret-file=<path to jwtsecret.hex>              \
  --metrics-enabled=true                                    \
  --rest-api-enabled=true                                   \
  --checkpoint-sync-url=<checkpoint sync URL>               \
  --validators-proposer-default-fee-recipient=<ETH address> \
  --validator-keys=<path to key file>:<path to password file>[,<path to key file>:<path to password file>,...]

Specify:

You can modify the option values and add other Teku command line options as needed.

6. Wait for Besu and Teku to sync​

After starting Besu and Teku, your node starts syncing and connecting to peers.

{"@timestamp":"2023-02-03T04:43:49,555","level":"INFO","thread":"main","class":"DefaultSynchronizer","message":"Starting synchronizer.","throwable":""}
{"@timestamp":"2023-02-03T04:43:49,556","level":"INFO","thread":"main","class":"FastSyncDownloader","message":"Starting sync","throwable":""}
{"@timestamp":"2023-02-03T04:43:49,559","level":"INFO","thread":"main","class":"Runner","message":"Ethereum main loop is up.","throwable":""}
{"@timestamp":"2023-02-03T04:43:53,106","level":"INFO","thread":"Timer-0","class":"DNSResolver","message":"Resolved 2409 nodes","throwable":""}
{"@timestamp":"2023-02-03T04:45:04,803","level":"INFO","thread":"nioEventLoopGroup-3-10","class":"SnapWorldStateDownloader","message":"Downloading world state from peers for pivot block 16545859 (0x616ae3c4cf85f95a9bce2814a7282d75dc2eac36
cb9f0fcc6f16386df70da3c5). State root 0xa7114541f42c62a72c8b6bb9901c2ccf4b424cd7f76570a67b82a183b02f25dc pending requests 0","throwable":""}
{"@timestamp":"2023-02-03T04:46:04,834","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapsyncMetricsManager","message":"Worldstate download progress: 0.08%, Peer count: 8","throwable":""}
{"@timestamp":"2023-02-03T04:48:01,840","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapsyncMetricsManager","message":"Worldstate download progress: 0.23%, Peer count: 8","throwable":""}
{"@timestamp":"2023-02-03T04:49:09,931","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapsyncMetricsManager","message":"Worldstate download progress: 0.41%, Peer count: 11","throwable":""}
{"@timestamp":"2023-02-03T04:50:12,466","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapsyncMetricsManager","message":"Worldstate download progress: 0.61%, Peer count: 10","throwable":""}
{"@timestamp":"2023-02-03T04:51:20,977","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapsyncMetricsManager","message":"Worldstate download progress: 0.75%, Peer count: 10","throwable":""}
{"@timestamp":"2023-02-03T04:51:28,985","level":"INFO","thread":"EthScheduler-Services-29 (importBlock)","class":"FastImportBlocksStep","message":"Block import progress: 180400 of 16545859 (1%)","throwable":""}

If you're running Teku as a beacon node only, you're all set. If you're also running Teku as a validator client, ensure Besu and Teku are fully synced before submitting your staking deposit in the next step. Syncing Besu can take several days.

7. Stake ETH​

Stake your testnet ETH for one or more validators using the Holesky Staking Launchpad.

You can check your validator status by searching your Ethereum address on the Holesky Beacon Chain explorer. It may take up to multiple days for your validator to be activated and start proposing blocks.