This is some old code, based off of the hashcash algorithm, that prototypes protecting DNS servers using a proof of work (also UDP). <a href="https:&#x2F;&#x2F;github.com&#x2F;jevinskie&#x2F;SlothNS&#x2F;blob&#x2F;master&#x2F;pow&#x2F;pow.c#L58-L116" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;jevinskie&#x2F;SlothNS&#x2F;blob&#x2F;master&#x2F;pow&#x2F;pow.c#L...</a>