# Setting up a Network¶

It’s possible to create a new network or join an existing network. This page will outline the basics for creating a new network.

## The Chain Specification¶

The Casper node software creates a genesis block from the following inputs:

• chainspec.toml

• accounts.csv

### Chainspec.toml¶

A version of the chainspec is downloaded by the pull_casper_node_version.sh script installed with the casper-node-launcher debian package. This pulls the chainspec.toml file from the appropriate path at http://genesis.casperlabs.io/.

The production version of the file from which this is based on can be found at casper-node/resources/production/chainspec.toml in the code base. To create a custom network, this file can be updated as desired. Any changes to this file will result in a different genesis hash. Refer to the file itself for detailed documentation on each of the variables in the file.

### Accounts.csv¶

This file contains the genesis validator set information, starting accounts and associated balances and bond amounts. The file is comma-delimited. Information in the file is organized as:

• publickey,balance,bond

If an account is not bonded at genesis, specify a 0 for the bond amount.

Similar to the chainspec.toml, this is pulled from the appropriate path at http://genesis.casperlabs.io/.