iputils-clockdiff 3:20180629-2ubuntu2 (amd64 binary) in ubuntu disco

 Clockdiff computes the difference between the time of the machine on
 which it is called and the time of other network-accessible machines.
 The time differences measured by clockdiff are obtained using a
 sequence of ICMP TSTAMP messages which are returned to the sender by
 the IP module in the remote machine.