networking, tool (ping, originally contrived to match
submariners' term for the sound of a returned sonar pulse) A
program written in 1983 by Mike Muuss (who also wrote
TTCP)
used to test reachability of destinations by sending them one,
or repeated,
ICMP echo requests and waiting for replies.
Since ping works at the
IP level its server-side is often
and is thus the lowest level test of whether a remote host is
alive. Ping will often respond even when higher level,
TCP-based services cannot.
Sadly, Mike Muuss was killed in a road accident on 2000-11-20.
The term is also used as a verb: "Ping host X to see if it is
up."
The
Unix command "ping" can be used to do this and to
measure round-trip delays.
The funniest use of "ping" was described in January 1991 by
Steve Hayman on the
Usenet group comp.sys.next. He was
trying to isolate a faulty cable segment on a
TCP/IPrecording feature on the NeXT, he wrote a
script that
repeatedly invoked ping, listened for an echo, and played back
the recording on each returned
packet. This caused the
machine to repeat, over and over, "Ping ... ping ... ping ..."
as long as the network was up. He turned the volume to
maximum, ferreted through the building with one ear cocked,
and found a faulty tee connector in no time.
(2002-11-29)