  BGP is the protocol that keeps Internet connected. Operators use it by
announcing Address Prefixes (APs), namely IP address blocks, that they own or
that they agree to serve as transit for. BGP enables ISPs to devise complex
policies to control what AP announcements to accept (import policy), the route
selection, and what AP to announce and to whom (export policy). In addition,
BGP is also used to coarse traffic engineering for incoming traffic via the
prepend mechanism.
  However, there are no wide-spread good tools for managing BGP and much of the
complex configuration is done by home-brewed scripts or simply by manually
configuring router with bare-bone terminal interface. This process generates
many configuration mistakes.
  In this study, we examine typos that propagates in BGP announcements and can
be found in many of the public databases. We classify them and quantify their
presence, and surprisingly found tens of ASNs and hundreds of APs affected by
typos on any given time. In addition, we suggest a simple algorithm that can
detect (and clean) most of them with almost no false positives.
