In computer networking, Semaphore Flag Signaling System (SFSS) is a humorous proposal to carry Internet Protocol (IP) traffic by semaphores. Semaphore Flag Signaling System was initially described in RFC 4824, an April Fools' Day RFC issued by the Internet Engineering Task Force edited by J. Hofmueller, et al. and released on April Fools' Day 2007. It is one of several April 1 RFCs.