The subject disclosure is directed towards a technology by which computing devices such as a phone and a personal computer may reliably communicate internet protocol (IP)-based network data to one another via an unreliable point-to-point data transfer mechanism such as a USB connection. To this end, each computing device includes a bi-directional proxy component (e.g., a proxy and reliable transfer tunnel), that processes network data into packets for transmission over the point-to-point connection, and processes received packets into internet protocol (IP)-based network data for a network connection. Also described are an acknowledgement and sequence number-based mechanism that ensures reliable point-to-point data transfers, and a flow control mechanism that prevents a recipient from receiving more data than it can handle until ready.