fping 3 README
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fping is a program to send ICMP echo probes to network hosts, similar to ping,
but much better performing when pinging multiple hosts. fping has a long long
story: Roland Schemers did publish a first version of it in 1992 and it has
established itself since then as a standard tool.
Current maintainer:
David Schweikert <david@schweikert.ch>
Website:
http://www.fping.org
Original author: Roland Schemers (schemers@stanford.edu)
Previous maintainer: RL "Bob" Morgan (morgan@stanford.edu)
IPv6 Support: Jeroen Massar (jeroen@unfix.org / jeroen@ipng.nl)
to enable IPV6 compile with -DIPV6
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Original README (from 1992!)
fping - A tool to quickly ping N number of hosts to determine
their reachability.
Roland J. Schemers III - Stanford University
schemers@Stanford.EDU
fping is a ping(1) like program which uses the Internet Control
Message Protocol (ICMP) echo request to determine if a host is
up. fping is different from ping in that you can specify any
number of hosts on the command line, or specify a file containing
the lists of hosts to ping. Instead of trying one host until it
timeouts or replies, fping will send out a ping packet and move
on to the next host in a round-robin fashion. If a host replies,
it is noted and removed from the list of hosts to check. If a host
does not respond within a certain time limit and/or retry limit it
will be considered unreachable.
Site
Stanford University has a large TCP/IP network with over 16,000
assigned IP addresses and over 100 IP subnets.
Problem and Issues
With a large a number of IP addresses in use, its becomes more and
more time consuming to check on which IP addresses are actively
in use, and which critical machines (routers, bridges, servers, etc)
are reachable. One example is we have a program which goes through
all of our routers arp caches looking for IP addresses that are in
use. After finding a list of IP addresses that aren't in any arp
caches fping can then be used to see if these IP addresses really
aren't being used, or are just behind the routers. Checking 2500
hosts (99% of which are unreachable) via ping can take hours.
fping was written to solve the problem of pinging N number of hosts
in an efficient manner. By sending out pings in a round-robin fashion
and checking on responses as they come in at random, a large number of
hosts can be checked at once.
Unlike ping, fping is meant to be used in scripts and its
output is easy to parse.
