ctf-eth-env

An ethereum node environment for CTF challenges.

The solution is to use Nginx as a reverse proxy and set up the whitelist of Ethereum RPC methods by using njs for access control to the upstream Ethereum POA nodes, and thus implement an anti-plagiarism server-side environment.

Background

It is unfair that some CTF blockchain challenge players can cheat by searching back the blockchain history, where all the transactions of those who have solved the challenges are recorded. These dishonest players can solve the challenges simply by replaying the transactions. The root cause of this problem is that all data in the permissionless blockchain is public and everyone can fetch it by querying the specified RPC methods.

So the idea of this project is to disable several RPC methods (e.g. eth_getBlockByHash, eth_getBlockByNumber) of an Ethereum POA node and then use it as the challenge server-side environment. In this way, players on the client side have no longer any access to the transaction IDs of others.

Install

git clone https://github.com/chainflag/ctf-eth-env.git
cd ctf-eth-env

Usage

Create a sealer account

docker run -it --rm  -v `pwd`/config:/root/.ethereum ethereum/client-go account new
echo "your keystore password" > `pwd`/config/password.txt

Generate genesis config

$ go get github.com/ethereum/go-ethereum/cmd/puppeth # or download Geth & Tools from https://geth.ethereum.org/downloads/
$ puppeth
Please specify a network name to administer (no spaces, hyphens or capital letters please)
> genesis

What would you like to do? (default = stats)
 1. Show network stats
 2. Configure new genesis
 3. Track new remote server
 4. Deploy network components
> 2

What would you like to do? (default = create)
 1. Create new genesis from scratch
 2. Import already existing genesis
> 1

Which consensus engine to use? (default = clique)
 1. Ethash - proof-of-work
 2. Clique - proof-of-authority
> 2

How many seconds should blocks take? (default = 15)
> 5

Which accounts are allowed to seal? (mandatory at least one)
> 0x # Enter the account address created in the previous step

Which accounts should be pre-funded? (advisable at least one)
> 0x # Enter the account address created in the previous step

Should the precompile-addresses (0x1 .. 0xff) be pre-funded with 1 wei? (advisable yes)
> no

Specify your chain/network ID if you want an explicit one (default = random)
>

What would you like to do? (default = stats)
 1. Show network stats
 2. Manage existing genesis
 3. Track new remote server
 4. Deploy network components
> 2

 1. Modify existing configurations
 2. Export genesis configurations
 3. Remove genesis configuration
> 2

Which folder to save the genesis specs into? (default = current)
  Will create genesis.json, genesis-aleth.json, genesis-harmony.json, genesis-parity.json
> config

Run Geth with proxy

docker-compose up -d

Related Project

• eth-faucet
• eth-challenge-base

Contributing

PRs accepted.

License

The MIT License (MIT)