1.5 Prerequisites/Preconditions

The Remote Programs Extensions for Remote Desktop Protocol has the assumption to operate in a fully operational RDP connection. A fully operational RDP connection is a connection that has passed the Connection Finalization phase, as specified in [MS-RDPBCGR] section 1.3.1.1.

The RAIL server endpoint expects that the Channel PDU Header ([MS-RDPBCGR] section 2.2.6.1.1) is visible for all data that flows over the RAIL virtual channel (sections 1.3.1 and 2.2.2). To ensure that this condition is met, the CHANNEL_FLAG_SHOW_PROTOCOL (0x00000010) flag has to be set in the flags field of the Channel PDU Header.