::: 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.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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