Source: Sybil attack on Wikipedia

Sybil attacks are also called sock puppetry

Creating a large number of pseudonymous identities and uses them to gain a disproportionately large influence (e.g. control of >50% nodes allows you to ‘override’ the consensus)

3E’s of Preventing Sybil Attacks

  1. Entry Cost
  2. Existence Cost
  3. Exit Penalty

See also: fault tolerance