Prevent tag length from being used for active probing
On some transports it may be possible to use the fixed tag length to probe a transport endpoint to determine whether it's likely to be accepting BTP traffic: the endpoint will always accept (tag length - 1) random bytes but close the transport connection after (tag length) bytes.
It may be possible to address this by picking a random number for each incoming transport connection and reading that many bytes before deciding whether to accept the connection. The number could be anywhere between (tag length) and (tag length + stream header length). The number could be drawn from a distribution supplied by the TAP profile, allowing the distribution to be tailored to the transport.