How to Configure Flashbots Private RPC to Avoid Sandwich Attacks

If you send a transaction on Ethereum Mainnet using the default Infura or Alchemy RPC, you are broadcasting your intent to the entire world before it happens. This "Dark Forest" is where predators live. MEV bots spot your transaction, frontrun it to raise the price, and backrun it to pocket the difference.

The Solution: Flashbots Protect. By using a private RPC, your transaction bypasses the public mempool entirely and goes directly to miners (validators). It cannot be seen, so it cannot be sandwiched.

1. Setting up in MetaMask

This is the easiest win for retail users and manual traders.

1. Open MetaMask Settings > Networks > Add Network > Manually.
2. Network Name: Flashbots Protect
3. RPC URL: https://rpc.flashbots.net
4. Chain ID: 1
5. Currency Symbol: ETH
6. Block Explorer: https://etherscan.io

[!IMPORTANT] Transactions sent here will not show up on Etherscan as "Pending". They will just appear as "Success" or "Fail". Do not panic if you don't see it immediately.

2. Setting up in FRB Agent

The FRB Agent uses private bundles by default, but you can configure specific relays for redundancy.

// config.json snippet
{
  "Network": "ethereum",
  "Relays": [
    "https://relay.flashbots.net",
    "https://rpc.titanbuilder.xyz",
    "https://beaverbuild.org"
  ],
  "PrivateRPC": true
}
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By adding multiple relays, you increase your inclusion probability. If Flashbots filters your transaction (e.g. for OFAC reasons), Titan might pick it up.

3. Protecting Your Smart Contract Deployments

When deploying a new contract (like a sniper bot or a token), using a private RPC is mandatory. If you deploy via public mempool, bots will analyze your bytecode, simulate it, and if there is an initialization vulnerability or an obvious arbitrage opportunity, they will exploit it in the same block as your deployment.

Foundry Command:

forge script script/Deploy.s.sol --rpc-url https://rpc.flashbots.net --broadcast
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fast mode

Flashbots default RPC can be slow because it guarantees no reverts. If you prioritize speed over revert protection (e.g. for minting NFTs), use the fast endpoint: https://rpc.flashbots.net/fast

Summary

Privacy is not optional in 2026. It is the baseline for security. Whether you are trading Uniswap manually or running an automated bot, check your RPC endpoint. If it says "Infura", you are the prey. Change it today.