One embodiment is directed to a technique for in-band signaling of time stamp information where a kernel driver executing in kernel space modifies a received timing message (for example, a Precision Time Protocol (PTP) Delay Request message) to include timing information associated with the time the timing message was received by a network interface. This is done so that an application running in the user space can obtain the timing information from the modified timing message and reconstruct a timestamp for the received timing message (for example, a PTP T4 timestamp) for use in implementing at least a part of a packet-based synchronization protocol (for example, the PTP).