Whitepaper titled Protocol Hopping Covert Channels – Protocol Hopping Covert Channels (PHCC) are a way to realize covert channels that switch between different protocols while a covert channel is established. PHCCs even can use a randomized protocol order and a mixed packet order to transfer packets what makes them hard to detect.
You can download it from the following link: https://packetstormsecurity.com/files/download/60881/protocolhopping.txt
Source: https://packetstormsecurity.com/files/60881/protocolhopping.txt.html