fping
send ICMP ECHO_REQUEST packets to network hosts
see also :
netstat - ping - ifconfig
Synopsis
fping [
options ] [ systems... ]
add an example, a script, a trick and tips
examples
The following perl script will check a list of hosts and send
mail if any are unreachable. It uses the open2 function which
allows a program to be opened for reading and writing. fping does
not start pinging the list of systems until it reads EOF, which
it gets after INPUT is closed. Sure the open2 usage is not needed
in this example, but it’s a good open2 example none the less.
#!/usr/bin/perl
require ’open2.pl’;
$MAILTO = "root";
$pid = &open2("OUTPUT","INPUT","/usr/local/bin/fping -u");
@check=("slapshot","foo","foobar");
foreach(@check) { print INPUT "$_\n"; }
close(INPUT);
@output=<OUTPUT>;
if ($#output != -1) {
chop($date=’date’);
open(MAIL,"|mail -s ’unreachable systems’ $MAILTO");
print MAIL "\nThe following systems are unreachable as of:
$date\n\n";
print MAIL @output;
close MAIL;
}
Another good example is when you want to perform an action only
on hosts that are currently reachable.
#!/usr/bin/perl
$hosts_to_backup = ’cat /etc/hosts.backup | fping -a’;
foreach $host (split(/\n/,$hosts_to_backup)) {
# do it
}
description
fping is
a program like ping(8) which uses the Internet
Control Message Protocol (ICMP) echo request to determine if
a target host is responding. fping differs from ping
in that you can specify any number of targets on the command
line, or specify a file containing the lists of targets to
ping. Instead of sending to one target until it times out or
replies, fping will send out a ping packet and move
on to the next target in a round-robin fashion.
In the default
mode, if a target replies, it is noted and removed from the
list of targets to check; if a target does not respond
within a certain time limit and/or retry limit it is
designated as unreachable. fping also supports
sending a specified number of pings to a target, or looping
indefinitely (as in ping ).
Unlike ping,
fping is meant to be used in scripts, so its output is
designed to be easy to parse.
options
-a
Show systems that are alive.
-A
Display targets by address rather than DNS name.
-bn
Number of bytes of ping data to send. The minimum size
(normally 12) allows room for the data that fping
needs to do its work (sequence number, timestamp). The
reported received data size includes the IP header (normally
20 bytes) and ICMP header (8 bytes), so the minimum total
size is 40 bytes. Default is 56, as in ping. Maximum
is the theoretical maximum IP datagram size (64K), though
most systems limit this to a smaller, system-dependent
number.
-Bn
In the default mode, fping sends several requests
to a target before giving up, waiting longer for a reply on
each successive request. This parameter is the value by
which the wait time is multiplied on each successive
request; it must be entered as a floating-point number
(x.y). The default is 1.5.
-c
Number of request packets to send to each target. In
this mode, a line is displayed for each received response
(this can suppressed with -q or -Q). Also,
statistics about responses for each target are displayed
when all requests have been sent (or when interrupted).
-C
Similar to -c, but the per-target statistics are
displayed in a format designed for automated response-time
statistics gathering. For example:
% fping
-C 5 -q somehost
somehost : 91.7
37.0 29.2 - 36.8
shows the
response time in milliseconds for each of the five requests,
with the "-" indicating that no response was
received to the fourth request.
-d
Use DNS to lookup address of
return ping packet. This allows you to give fping a list of
IP addresses as input and print hostnames in the output.
-e
Show elapsed (round-trip) time of packets.
-f
Read list of targets from a file. This option can only
be used by the root user. Regular users should pipe in the
file via stdin:
% fping <
targets_file
-g
Generate a target list from a
supplied IP netmask, or a starting and ending IP. Specify
the netmask or start/end in the targets portion of the
command line. If a network with netmask is given, the
network and broadcast addresses will be excluded.
ex. To ping the
network 192.168.1.0/24, the specified command line could
look like either:
fping -g
192.168.1.0/24
or
fping -g
192.168.1.1 192.168.1.254
-h
Print usage message.
-in
The minimum amount of time (in milliseconds) between
sending a ping packet to any target (default is 25).
-l
Loop sending packets to each target indefinitely. Can be
interrupted with Ctrl-C; statistics about responses for each
target are then displayed.
-m
Send pings to each of a target host’s multiple
interfaces.
-n
Same as -d.
-p
In looping or counting modes (-l, -c, or
-C), this parameter sets the time in milliseconds that
fping waits between successive packets to an
individual target. Default is 1000.
-q
Quiet. Don’t show per-target results, just set
final exit status.
-Qn
Like -q, but show summary results every n
seconds.
-rn
Retry limit (default 3). This is the number of times an
attempt at pinging a target will be made, not including the
first try.
-s
Print cumulative statistics upon exit.
-Saddr
Set source address.
-Iif
Set the interface (requires SO_BINDTODEVICE support)
-tn
Initial target timeout in milliseconds (default 500). In
the default mode, this is the amount of time that
fping waits for a response to its first request.
Successive timeouts are multiplied by the backoff
factor.
-Tn
Ignored (for compatibility with fping 2.4).
-u
Show targets that are unreachable.
-Tn
Set the typ of service flag (TOS). n can be
either decimal or hexadecimal (0xh) format.
-v
Print fping version information.
-Hn
Set the IP TTL field (time to live hops).
diagnostics
Exit status is 0 if all the hosts are reachable, 1 if some hosts
were unreachable, 2 if any IP addresses were not found, 3 for
invalid command line arguments, and 4 for a system call failure.
restrictions
If certain options are used (i.e, a low value for -i and -t, and
a high value for -r) it is possible to flood the network. This
program must be installed as setuid root in order to open up a
raw socket, or must be run by root. In order to stop mere mortals
from hosing the network (when fping is installed setuid root) ,
normal users can’t specify the following:
-i n where n < 10 msec
-r n where n > 20
-t n where n < 250 msec
bugs
Ha! If we knew
of any we would have fixed them!
see also
netstat ,
ping , ifconfig (8c)
authors
Roland J.
Schemers III, Stanford University, concept and versions 1.x
RL "Bob" Morgan, Stanford University, versions 2.x
David Papp, versions 2.3x and up,
David Schweikert, versions 3.0 and up
fping website: http://www.fping.org