We describe the goals of the IETF's Intrusion Detection Working Group (IDWG) and the requirements for a transport protocol to communicate among intrusion detection systems. We then describe the design and implementation of IAP, the first attempt at such a protocol. After a discussion of IAP's limitations, we discuss BEEP, a new IETF general framework for application protocols. We then describe the Intrusion Detection Exchange Protocol (IDXP), a transport protocol designed and implemented within the BEEP framework that fulfills the IDWG requirements for its transport protocol. We conclude by discussing probable future directions for this ongoing effort.