> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Consensus client configuration

> Learn how to configure consensus clients (op-node, kona-node) for your OP Stack node.

The consensus client (also called the rollup node) builds, relays, and verifies the canonical chain of blocks.
This guide covers configuration for the most popular consensus client implementations.

<Info>
  Always run your consensus client and execution client in a one-to-one configuration.
  Don't run multiple execution client instances behind one consensus client, or vice versa.
</Info>

## Consensus clients

Choose the consensus client that best fits your needs:

<Tabs>
  <Tab title="op-node">
    ## op-node configuration

    [op-node](https://github.com/ethereum-optimism/optimism/tree/develop/op-node) is the reference implementation of the OP Stack consensus client, written in Go.

    ### Minimal configuration

    The minimum required flags for running op-node:

    ```bash theme={null}
    op-node \
      --l1=https://ethereum-rpc-endpoint.example.com \
      --l1.beacon=https://ethereum-beacon-endpoint.example.com \
      --l2=http://localhost:8551 \
      --l2.jwt-secret=/path/to/jwt-secret.txt \
      --network=op-mainnet \
      --rpc.addr=0.0.0.0 \
      --rpc.port=9545
    ```

    ### Sequencer configuration

    If you're running a sequencer node, use these additional flags:

    ```bash theme={null}
    --rpc.addr=0.0.0.0 \
    --rpc.port=9545 \
    --rpc.enable-admin \
    --sequencer.enabled \
    --sequencer.l1-confs=4 \
    --p2p.sequencer.key=<your-sequencer-private-key>
    ```

    <Warning>
      Keep your sequencer private key secure and never commit it to version control.
      Use environment variables or secure key management systems in production.
    </Warning>

    ### l2.enginekind

    The kind of engine client, used to control the behavior of optimism in respect to different types of engine clients.
    Supported values are `geth` (default) and `reth`.

    ### Complete reference

    For all available configuration options, see the [op-node configuration reference](/node-operators/reference/op-node-config).
  </Tab>

  <Tab title="kona-node">
    ## kona-node configuration

    [kona-node](https://github.com/op-rs/kona/tree/main/bin/node) is an experimental Rust-based implementation of the OP Stack consensus client.

    <Warning>
      kona-node is experimental and may not be production-ready. Use with caution.
    </Warning>

    ### Basic configuration

    kona-node follows a similar configuration pattern to op-node:

    ```bash theme={null}
    kona-node \
      --l1-rpc-url=https://ethereum-rpc-endpoint.example.com \
      --l2-rpc-url=http://localhost:8551 \
      --jwt-secret=/path/to/jwt-secret.txt \
      --network=op-mainnet
    ```

    ### JWT secret

    Generate the JWT secret using:

    ```bash theme={null}
    openssl rand -hex 32 > jwt-secret.txt
    ```

    ### Additional resources

    For more details on kona-node configuration, see:

    * [kona-node GitHub repository](https://github.com/op-rs/kona/tree/main/bin/node)
    * [kona documentation](https://op-rs.github.io/kona/)
  </Tab>
</Tabs>

## JWT secret

To communicate with execution client and enable the Engine API, you'll also need to generate a JWT secret file and enable the consensus client's authenticated RPC endpoint.
To generate the JWT secret file:

```bash theme={null}
openssl rand -hex 32 > jwt-secret.txt
```