tstamp_allow_data

file: /proc/sys/net/core/tstamp_allow_data
variable: net.core.tstamp_allow_data
Official reference

Allow processes to receive tx timestamps looped together with the original packet contents. If disabled, transmit timestamp requests from unprivileged processes are dropped unless socket option SOF_TIMESTAMPING_OPT_TSONLY is set. Default: 1 (on)

source