I would like to understand the basics of Ethereum and i would like to clone it and make my own local currency based on Ethereum to experiment at most its capabilities. Is there anyone that can give me some good hints on this point? I have good skills with Bitcoin related forks and i cloned a lot of different coins for education purposes in the last years.

I'm just wondering about how in example generate a new genesis hash for a an Eth fork. Anyone?

Thanks anyone in advance for the many infos you can help me to gather.

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    Consider making the answer as accepted, you can do it by checking the tick sign under votes.
    – niksmac
    Commented Mar 25, 2016 at 1:12

2 Answers 2


You should actually read Building Ethereum

Once you have installed a client, you need to download the python script that generates the Genesis file. It’s called ‘mk_genesis_block.py’, and can be downloaded here.

You will then be able to generate the Genesis block by running:

python mk_genesis_block.py --extradata hash_for_#1028201_goes_here > genesis_block.json

Read Final Steps - by Stephan Tual

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    Many thanks for your addressment. I actually know how to build ethereum on both linux and mac os, just looking at more details on how to customise also the chain settings such blocktime, gas cost, fees, block rewards, etc. I will look at your links now, but if you have also other infos to share about it let me know! Thank for your efforts again.
    – Kranio23
    Commented Mar 12, 2016 at 14:50
  • In example i would like also to change the name, cause in details i would like to apply my fork for my game server where i play with my firends. So we would like to use smart contracts to do votes etc, but we would like to have everything customised for our game...everything it will remain internal to server so that's why i want to customise as much as ican to play with it.
    – Kranio23
    Commented Mar 12, 2016 at 15:12
  • Damn i just tried using that script and i got banned from Blockchain.info!!! What the heck is happened there? I launched the command exactly as you written there: python mk_genesis_block.py --extradata here_i_have_set_random_eth_block_hash > genesis_block.json
    – Kranio23
    Commented Mar 12, 2016 at 16:24
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    There is no way that could happen because of this. That python script is not contacting the website in any way..
    – niksmac
    Commented Mar 13, 2016 at 1:33
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    Actually, it queries Blockchain.info for pre-sale statistics, according to the blog Commented Aug 23, 2016 at 15:10

If you are using Geth as client, you can refer to the official documentation on private networks:


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