Packet InterNet Groper

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

implemented entirely within the operating system kernel

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/IP

Ethernet hooked up to a NeXT machine. Using the sound

recording 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.

See also ACK, ENQ, traceroute, spray.

The Story of the Ping Program.

Unix manual page: ping(8).

(2002-11-29)