Feature request: support ICMP type 13/14 timestamps

[moeller0]

Sometimes for debugging it is helpful to get an idea about one way delays (or even just changes in one way delays). However the amount of servers willing to serve precise time (e.g. NTP servers) is quite low, not well distributed over the internet and often only willing to reply at low packet rates. However quite a number of publicly reachable servers are willing to respond to ICMP timestamps requests with the appropriate response. It would be excellent if fping could grow the capability to use ICMP timestamps instead of ICMP (caveat, ICMP over IPv6 tends not to support ICMP timestamps, but with large parts of the internet being IPv4 that still keeps ICMP timestamps relevant).

[lynxthecat]

I would like to second this request. In addition to the excellent reasons provided above, I think this would serve to yet further increase the attractiveness of fping set against the other existing ping utilities which either: offer it but are buggy (e.g. nping); offer it but are no longer maintained (e.g. hping3); or do not even offer it (e.g. iputils-ping). ICMP type 13 requests remain a powerful tool for ascertaining not only RTT, but also its constituent one way delays between the client and the server.