From The Core Issue: A look at what it takes to defend your Bitcoin node against the myriad of threats from the wider internet.
Over 50 years after the first inter-networked message, peer-to-peer networks remain rare beasts in the jungle of the Internet. Bitcoin’s ability to provide an open monetary system depends on its peer-to-peer architecture, and across its attack surface it is the networking layer–how peers discover and connect to each other–that is the most vulnerable. There are two main places problems can occur: Bitcoin’s own peering protocol, and the Internet protocols that Bitcoin’s protocol depends on. In this light Core has a dual mandate to prevent Denial of Service (DOS) vectors that can be abused between nodes, and enable nodes to communicate safely in the wider adversarial environment that is the Internet.
“Governments are good at cutting off the heads of a centrally controlled networks like Napster, but pure P2P networks like Gnutella and Tor seem to be holding their own.”
– Satoshi, Nov 7, 2008 [1]
The P2P protocol encompasses how nodes exchange messages about transactions, blocks, and other peers. This exchange of information is required before any transaction or consensus validation can occur, and is therefore a primary concern.
