user73029: I have experienced 51% attack after launching a new altcoin last month. 
While i mined only 100 blocks using coin-cli generate 1, i noticed somebody already mined 2000 blocks within minutes attacking my network. I was running 2 nodes (without wallet) and 1 node (with wallet installed) in Ubuntu server.

Why would the attacker target new cryptocurrencies? Is he after coins? 
What changes in the code i have to implement to prevent the 51% attack?

My altcoin is based on scrypt (litecoin), Block generation time is 10 minutes/hour, Coin maturity 100 blocks, with parameters almost same as bitcoin.

user12983: 
Why would the attacker target new cryptocurrencies?

Why not? He has the same reasons as you to create blocks

What changes in the code i have to implement to prevent the 51% attack?

Disable decentralization. Allow mining from one pubkey/address only :)

73029: <p>I have experienced 51% attack after launching a new altcoin last month. </p>

<p>While i mined only 100 blocks using <code>coin-cli generate 1</code>, i noticed somebody already mined 2000 blocks within minutes attacking my network. I was running 2 nodes (without wallet) and 1 node (with wallet installed) in Ubuntu server.</p>

<ul>
<li>Why would the attacker target new cryptocurrencies? Is he after coins? </li>
<li>What changes in the code i have to implement to prevent the 51% attack?</li>
</ul>

<p>My altcoin is based on scrypt (litecoin), Block generation time is 10 minutes/hour, Coin maturity 100 blocks, with parameters almost same as bitcoin.</p>
 12983: <blockquote>
  <p>Why would the attacker target new cryptocurrencies?</p>
</blockquote>

<p>Why not? He has the same reasons as you to create blocks</p>

<blockquote>
  <p>What changes in the code i have to implement to prevent the 51% attack?</p>
</blockquote>

<p>Disable decentralization. Allow mining from one pubkey/address only :)</p>
