1. Grab the `OptimismPortalProxy` address and, using the wallet that you want to have ETH on your Rollup, send that address a small amount of ETH on Goerli (0.1 or less is fine). It may take up to 5 minutes for that ETH to appear in your wallet on L2.
1. Grab the L1 bridge proxy contract address and, using the wallet that you want to have ETH on your Rollup, send that address a small amount of ETH on Goerli (0.1 or less is fine). It may take up to 5 minutes for that ETH to appear in your wallet on L2.
When building applications for use with your OP Stack, you can continue to use [the Optimism JavaScript SDK](https://sdk.optimism.io/).
The main difference is you need to provide some contract addresses to the `CrossDomainMessenger` because they aren't preconfigured.
## Contract addresses
### L1 contract addresses
The contract addresses are in `.../optimism/packages/contracts-bedrock/deployments/getting-started`, which you created when you deployed the L1 contracts.
| Contract name when creating `CrossDomainMessenger` | File with address |
::: warning 🚧 OP Stack Hacks are explicitly things that you can do with the OP Stack that are *not* currently intended for production use
OP Stack Hacks are not for the faint of heart. You will not be able to receive significant developer support for OP Stack Hacks — be prepared to get your hands dirty and to work without support.
:::
OP Stack blockchains have a number of [predeployed contracts](https://github.com/ethereum-optimism/optimism/blob/develop/packages/contracts-bedrock/src/constants.ts) that provide important functionality.
Most of those contracts are proxies that can be upgraded using the `proxyAdminOwner` which was configured when the network was initially deployed.
The predeploys are controlled from a predeploy called [`ProxyAdmin`](https://github.com/ethereum-optimism/optimism/blob/develop/packages/contracts-bedrock/contracts/universal/ProxyAdmin.sol), whose address is `0x4200000000000000000000000000000000000018`.
The function to call is [`upgrade(address,address)`](https://github.com/ethereum-optimism/optimism/blob/develop/packages/contracts-bedrock/contracts/universal/ProxyAdmin.sol#L211-L229).
The first parameter is the proxy to upgrade, and the second is the address of a new implementation.
For example, the legacy `L1BlockNumber` contract is at `0x420...013`.
To disable this function, we'll set the implementation to `0x00...00`.
We do this using the [Foundry](https://book.getfoundry.sh/) command `cast`.
1. We'll need several constants.
- Set these addresses as variables in your terminal.
// CanonicalTransactionChainL2GasParamsUpdatedIterator is returned from FilterL2GasParamsUpdated and is used to iterate over the raw logs and unpacked data for L2GasParamsUpdated events raised by the CanonicalTransactionChain contract.
Rawtypes.Log// Blockchain specific contextual infos
}
// FilterL2GasParamsUpdated is a free log retrieval operation binding the contract event 0xc6ed75e96b8b18b71edc1a6e82a9d677f8268c774a262c624eeb2cf0a8b3e07e.
// WatchL2GasParamsUpdated is a free log subscription operation binding the contract event 0xc6ed75e96b8b18b71edc1a6e82a9d677f8268c774a262c624eeb2cf0a8b3e07e.
// CanonicalTransactionChainQueueBatchAppendedIterator is returned from FilterQueueBatchAppended and is used to iterate over the raw logs and unpacked data for QueueBatchAppended events raised by the CanonicalTransactionChain contract.
Rawtypes.Log// Blockchain specific contextual infos
}
// FilterQueueBatchAppended is a free log retrieval operation binding the contract event 0x64d7f508348c70dea42d5302a393987e4abc20e45954ab3f9d320207751956f0.
// WatchQueueBatchAppended is a free log subscription operation binding the contract event 0x64d7f508348c70dea42d5302a393987e4abc20e45954ab3f9d320207751956f0.
// CanonicalTransactionChainSequencerBatchAppendedIterator is returned from FilterSequencerBatchAppended and is used to iterate over the raw logs and unpacked data for SequencerBatchAppended events raised by the CanonicalTransactionChain contract.
Rawtypes.Log// Blockchain specific contextual infos
}
// FilterSequencerBatchAppended is a free log retrieval operation binding the contract event 0x602f1aeac0ca2e7a13e281a9ef0ad7838542712ce16780fa2ecffd351f05f899.
// WatchSequencerBatchAppended is a free log subscription operation binding the contract event 0x602f1aeac0ca2e7a13e281a9ef0ad7838542712ce16780fa2ecffd351f05f899.
// CanonicalTransactionChainTransactionBatchAppendedIterator is returned from FilterTransactionBatchAppended and is used to iterate over the raw logs and unpacked data for TransactionBatchAppended events raised by the CanonicalTransactionChain contract.
Rawtypes.Log// Blockchain specific contextual infos
}
// FilterTransactionBatchAppended is a free log retrieval operation binding the contract event 0x127186556e7be68c7e31263195225b4de02820707889540969f62c05cf73525e.
// WatchTransactionBatchAppended is a free log subscription operation binding the contract event 0x127186556e7be68c7e31263195225b4de02820707889540969f62c05cf73525e.
// ParseTransactionBatchAppended is a log parse operation binding the contract event 0x127186556e7be68c7e31263195225b4de02820707889540969f62c05cf73525e.
// CanonicalTransactionChainTransactionEnqueuedIterator is returned from FilterTransactionEnqueued and is used to iterate over the raw logs and unpacked data for TransactionEnqueued events raised by the CanonicalTransactionChain contract.
Rawtypes.Log// Blockchain specific contextual infos
}
// FilterTransactionEnqueued is a free log retrieval operation binding the contract event 0x4b388aecf9fa6cc92253704e5975a6129a4f735bdbd99567df4ed0094ee4ceb5.
// WatchTransactionEnqueued is a free log subscription operation binding the contract event 0x4b388aecf9fa6cc92253704e5975a6129a4f735bdbd99567df4ed0094ee4ceb5.
require.Equal(t,expectedL1Origin,verifier.SyncStatus().SafeL2.L1Origin.Number,"L1 origin is forced in, given enough L1 blocks pass by")
require.LessOrEqual(t,miner.l1Chain.GetBlockByNumber(expectedL1Origin).Time(),engine.l2Chain.CurrentBlock().Time(),"L2 time higher than L1 origin time")
require.LessOrEqual(t,miner.l1Chain.GetBlockByNumber(expectedL1Origin).Time(),engine.l2Chain.CurrentBlock().Time,"L2 time higher than L1 origin time")
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