| Ping Overview |
The Ping utility is essentially a system administrator's tool that is used to
see if a computer is operating and also to see if network connections are
intact. Ping uses the Internet Control Message Protocol (ICMP) Echo function
which is detailed in RFC 792.
A small packet is sent through the network to a particular IP address. This
packet contains 64 bytes - 56 data bytes and 8 bytes of protocol reader
information. The computer that sent the packet then waits (or 'listens') for a
return packet. If the connections are good and the target computer is up, a good
return packet will be received. PING can also tell the user the number of hops
that lie between two computers and the amount of time it takes for a packet to
make the complete trip. Additionaly, an administrator can use Ping to test out
name resolution. If the packet bounces back when sent to the IP address but not
when sent to the name, then the system is having a problem matching the name to
the IP address. As mentioned previously, Ping has also evloved from a
noun/acronym into a verb, for example: "Ping server X to see if it is up" The
time it takes for the packet to get to the target computer and back again is
known as the round trip time. If this takes an extended period of time, it is
indicative that something may be wrong. (Sources: Netlingo site, Windows NT Help
Menu, Connected: An Internet Encyclopedia site, Brown Computer Solutions site,
Guide to Practical Linux by Mark G. Sobell, FreeBSD Ping Manpage)
If you are looking for an even more detailed explanation of Ping and also how
to use it in detecting network problems, goto Heavy Ping Detail. Here is a
sample ping packet decode
Ping was created by Mike Muuss (pronounced "moose") of the Army Research
Labortory in Decmeber of 1983 in about a day in response to network difficulties
he encountered. To read the full story of the Ping program, click The History of
Ping. To learn more about the brilliant inventor of Ping, clink the Inventor of
Ping. It is worthy to note that Ping is a part of all Linux distributions,
FreeBSD, NetBSD, OpenBSD, Solaris, all Unix variants and Windows
95/98/NT/2000/XP operating systems - making the program pretty much distributed
all over the planet. This is fantastic accomplishment on Mike's part by any
standard.
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