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I'm on OS X 10.7 and just found out, the

ping -s 10 host

does not work as expected. Its output does not contain the round trip time:

PING host (IP): 10 data bytes
18 bytes from IP: icmp_seq=0 ttl=248
18 bytes from IP: icmp_seq=1 ttl=248
^C
--- host ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss

It works if -s's value is 16 and above. I also experienced this on Linux, but with a smaller value. I read man ping, but it does not mention a restriction.

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1 Answer 1

up vote 3 down vote accepted

With packet sizes that small, there's not enough room in the packet to hold the timestamp.

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This can't really be the answer, as: 1) The RTT could also be derived from the ICMP identifier, and 2) I tested that even size 8 contains a timestamp, but the ping command does not show the RTT though –  Max Ried Feb 17 '12 at 10:48
    
That timestamp is not accurate enough to display a meaningful RTT measurement. And while the RTT could be derived from the ICMP identifier, it isn't. –  David Schwartz Feb 17 '12 at 10:58
    
Thanks, I just had a look at busybox source. It's a shame, I look into patching it. –  Max Ried Feb 17 '12 at 11:01

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