Circumference is a server-client-style implementation to supplement the WebAuth Diameter subprotocol, complete with an extensible Diameter server and base library. Diameter is a peer-to-peer authentication protocol (RFC 6733).
This project is a C++ library which allows incorporating DKIM into an existing MTA or other application. It provides full support for signing, verifying, and SSP. It is compliant with RFC 4871.
A Simple Middlebox Configuration Protocol (RFC 4540) implementation for Linux.
SIMCO is a signaling protocol that can be used by applications (such as SIP B2BUAs) to dynamically control firewalls and Network Address Translators (NATs).