From Telecomix Crypto Munitions Bureau
BGP is short for Border Gateway Protocol. The BGP protocol is used between internet service providers (ISPs) to exchange information about each others networks. BGP is essentially what makes internet tick.
 Open software
 Darknets running BGP
BGP informs all other BGP nodes about how they are connected, in detail. It is thus possible to get a map of the network by joining it and setting up your own BGP router within it. This is not a security breach, but a feature. Because of this feature, TCMB has discontinued its research of BGP. It might be a better idea to use RIP or some other crappy and old routing protocol to hide the fine details of the network configuration.