Transactions sent to a public blockchain network, such as Ethereum, are initially held in the mempool before they are accepted in a block. While waiting in the mempool, these ‘in-flight’ transactions are publicly visible and vulnerable to front-running attacks, such that malicious parties use information in the transaction for their own gain and at a direct cost to the transaction owner. In this work, we introduce open-source simulation software for identifying and mitigating these attacks on Ethereum blockchains. Designed for education and research, the software introduces simple smart contracts that elaborate front-running vulnerabilities such as displacement attacks, sandwich attacks, and priority gas auctions. Users can run these attacks in a safe environment, monitor the detailed mechanics of attacks, and mitigate attacks using the MEV-geth protocol for in-flight transaction privacy.