panther is an EVM simulator that executes transactions locally on a ganache-fork (updated every time a new block is mined). It was inspired by helios. It's built on ganache.

Start Server

Before start, make sure node.js and npm are installed. Then in panther's main dir:

> npm install # install dependencies
> node index.js # start ganache server

ganache server is now listening on http://127.0.0.1:1337. It's running Ethereum Mainnet forked at the latest block. It will auto restart when each new block is mined. According to the log, the restart time is quick:

logs:

Firing off local ganache fork
Firing off new local ganache fork @block # 15095658
RestartGanache: 3.927ms
Firing off new local ganache fork @block # 15095659
RestartGanache: 4.653ms
Firing off new local ganache fork @block # 15095660
RestartGanache: 3.651ms
Firing off new local ganache fork @block # 15095661
RestartGanache: 4.194ms
Firing off new local ganache fork @block # 15095662
RestartGanache: 3.45ms
Firing off new local ganache fork @block # 15095663
RestartGanache: 3.488ms
... ...

Simulation Tests

Send ETH using vitalik.eth's account

One of ganache's fabulous features is unlockedAccounts: by unlocking arbitrary accounts, you have full access to these accounts. In test_scripts/simulate_eth_transfer.js, let's use vitalik's account to send you some eth:

> node test_scripts/simulate_eth_transfer.js

The log will be:

logs:

your previous balance: 1000000000000000000
======
tx:
{
hash: '0x65e37e564fc831c9ef2fdf84e784c3f6575e0b1d0053a1fd9ac196cbcd36883f',
type: 2,
accessList: [],
blockHash: '0xb758946803ef50990a163cdbb128fa169f5bc420decd16298c4c7e7e9aa477ac',
blockNumber: 15099333,
transactionIndex: 0,
confirmations: 1,
from: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045',
gasPrice: BigNumber { _hex: '0x7dc61ab9', _isBigNumber: true },
maxPriorityFeePerGas: BigNumber { _hex: '0x3b9aca00', _isBigNumber: true },
maxFeePerGas: BigNumber { _hex: '0x7dc61ab9', _isBigNumber: true },
gasLimit: BigNumber { _hex: '0x5208', _isBigNumber: true },
to: '0x548BAa103d34Db68F98e4FA0cb90738BC5548511',
value: BigNumber { _hex: '0x0de0b6b3a7640000', _isBigNumber: true },
nonce: 847,
data: '0x',
r: '0xc84fd9d3272fcb89087d42d81e005c6c55b9594aa9ee020b13c4a29f4f66bbed',
s: '0x070286428b663fad61e51a9b6546b4b2f56d17fdf58c2535615081972125bcde',
v: 1,
creates: null,
chainId: 1337,
wait: [Function (anonymous)]
}
======
your current balance: 2000000000000000000

Simulate arbitrary tx

As a front runner, we need to get arbitrary tx from mempool, rewrite some part of the tx, then simulate to check if we could get profit. Ganache can help with the simulation.

> node test_scripts/simulate_any_tx.js

The log will be as follows. Check eth balance before and after the tx to see if profitable.

logs:

your previous balance: 2505200241354634440210
======
tx:
{
hash: '0x95c04c45d2b4983e14621d5d7e962e51bbf3122afff06d8aace7658d5e957312',
type: 0,
accessList: null,
blockHash: '0x0e4348720b6126cebc2266bb15b3afcfba75bc55c0ebe0d7a38a17e096c1a432',
blockNumber: 15099334,
transactionIndex: 0,
confirmations: 1,
from: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045',
gasPrice: BigNumber { _hex: '0xe8d4a51000', _isBigNumber: true },
gasLimit: BigNumber { _hex: '0x5ec7', _isBigNumber: true },
to: '0xE85A08Cf316F695eBE7c13736C8Cc38a7Cc3e944',
value: BigNumber { _hex: '0x00', _isBigNumber: true },
nonce: 848,
data: '0x84097393000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045',
r: '0x216e5072a9d0355983d5ed67f23e6a3780f77eb132b66b453158b97eace8356a',
s: '0x258e7cb643790ac10998e1eab8ab99a6186b29bc17003b98c9d630e01ffc6c76',
v: 2710,
creates: null,
chainId: 1337,
wait: [Function (anonymous)]
}
======
your current balance: 2505178193354634440210