Editing Ping (networking utility) (section)

==History==
[[File:Cmd-ping.png|thumb|DOS version of ping]]
The ping utility was written by [[Mike Muuss]] in December 1983 during his employment at the [[Ballistic Research Laboratory]], now the [[US Army Research Laboratory]]. A remark by [[David L. Mills|David Mills]] on using ICMP echo packets for IP network diagnosis and measurements prompted Muuss to create the utility to troubleshoot network problems.<ref name="ping" /> The author named it after the sound that [[sonar]] makes since its methodology is analogous to sonar's echolocation.<ref name="ping">{{cite web
| author = Mike Muuss
| author-link = Mike Muuss
| title=The Story of the PING Program
| url=https://ftp.arl.army.mil/~mike/ping.html
| archive-url = https://web.archive.org/web/20191025013201/https://ftp.arl.army.mil/~mike/ping.html
| publisher = U.S. Army Research Laboratory
| archive-date = 25 October 2019
| url-status = live
| access-date = 8 September 2010
| quote = My original impetus for writing PING for 4.2a BSD UNIX came from an offhand remark in July 1983 by Dr. Dave Mills ... I named it after the sound that a sonar makes, inspired by the whole principle of echo-location ... From my point of view PING is not an acronym standing for Packet InterNet Grouper, it's a sonar analogy. However, I've heard second-hand that Dave Mills offered this expansion of the name, so perhaps we're both right.
}}</ref><ref>{{cite book
|last=Salus
|first=Peter
|author-link=Peter Salus
|title=A Quarter Century of UNIX
|publisher=[[Addison-Wesley]]
|year=1994
|isbn=978-0-201-54777-1
}}</ref> The [[backronym]] Packet InterNet Groper for PING has been used for over 30 years. Muuss says that, from his point of view, PING was not intended as an acronym but he has acknowledged Mills' expansion of the name.<ref name="ping" /><ref name="davidmills">{{cite IETF
| title = Internet Delay Experiments
| rfc = 889
| last1 = Mills
| first1 = D.L.
| author-link1 = David L. Mills
| date = December 1983
| publisher = [[IETF]]
| access-date = 26 November 2019
}}</ref> The first released version was [[public domain software]]; all subsequent versions have been licensed under the [[BSD license]]. Ping was first included in [[4.3BSD]].<ref>{{Cite web|url=http://www.manpagez.com/man/8/ping/|title=man page ping section 8|website=www.manpagez.com}}</ref> The [[FreeDOS]] version was developed by Erick Engelke and is licensed under the [[GPL]].<ref>{{Cite web|url=http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.2/repos/pkg-html/ping.html|title=ibiblio.org FreeDOS Package -- ping (Networking)|website=www.ibiblio.org}}</ref> Tim Crawford developed the [[ReactOS]] version. It is licensed under the [[MIT License]].<ref>{{Cite web|url=https://github.com/reactos/reactos|title=GitHub - reactos/reactos: A free Windows-compatible Operating System.|date=8 August 2019|via=GitHub}}</ref>

Any host must process ICMP echo requests and issue echo replies in return.{{Ref RFC|1122|quote=Every host MUST implement an ICMP Echo server function that receives Echo Requests and sends corresponding Echo Replies.}}