Testing Connectivity with fping and send mail if any hosts are unreachable

by on November 21, 2007 · 7 comments· LAST UPDATED November 21, 2007

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fping is one my favorite network profiling / scripting tool. It uses the Internet Control Message Protocol (ICMP) echo request to determine if a target host is responding or not.

Unlike ping , fping is meant to be used in scripts, so its output is designed to be easy to parse.

You can easily write perl / shell script to check a list of hosts and send mail if any are unreachable.

fping command example

Just type the following command to see if we can reach to router:
$ fping router
Output:

router is alive

You can read list of targets (hosts / servers) from a file. The -f option can only be used by the root user. Regular users should pipe in the file via
I/O redirectors (stdin). For example read all host names from ~/.ping.conf file
$ fping < ~/.ping.conf

You can also netmask to ping the entire network i.e generate a target list from a supplied IP netmask. For example, ping the class C 192.168.1.x:
$ fping -g 192.168.1.0/24
or
$ fping -g 192.168.1.0 192.168.1.255

Sample shell script to send email if host is down

#!/bin/bash
HOSTS="router sun printer laptop sony-laptop xbox backup-server"
DLIST=""
for h in $HOSTS
do
  fping -u $h >& /dev/null
  if [ $? -ne 0 ]; then
          echo ${h} host is down send email
          # mail -s "Host ${h} down" admin@you.com </dev/null
  fi
done

Another good example is when you want to perform an action only on hosts that are currently reachable.

#!/usr/bin/perl
$myHosts = ‘cat /etc/hosts.backup | fping -a‘;
foreach $host (split(/\n/,$myHosts)) {
        # take action or call other function
}
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{ 7 comments… read them below or add one }

1 Rishi kapur November 26, 2007 at 8:31 am

It’s good tool but it is not in-built in redhat.
[root@server1 scripts]# fping
-bash: fping: command not found
[

from where can I download.

Reply

2 nixCraft November 26, 2007 at 9:09 am

@Rishi, Download FPING RHEL / CentOS / Fedora Package -
http://dag.wieers.com/rpm/packages/fping/

Reply

3 Ren January 3, 2008 at 8:36 pm

Show us an example of your ping.conf file contents.

Reply

4 nixCraft January 3, 2008 at 8:53 pm

cat ping.conf

router
nas
moon
sun
oldbox
dell-laptop
sony-laptop
xbox360
wireless-router
ps3
emb1
emb2
opendns.com
myisp.com

Reply

5 Steely April 4, 2012 at 5:26 pm

Hi Vivek,
First of all, thank you for all of the great nix guides which you have posted. I use them all the time.

So I am a somewhat new network admin and I am administering some Fedora 16 boxes. I really like your script here, so I have put it on my testing server (which I use for testing new scripts and software before putting them on the important servers). When I run the script myself, it works perfectly. However, when I run it from crontab, it sends the error emails even though all the hosts I have put into the script are definitely up.

Is there something about crontab which makes this script work differently?

Thanks

Reply

6 nixCraft April 5, 2012 at 5:58 am

Set the full path to binaries i.e. fping command. Also, check your cron log file in /var/log directory.

Reply

7 Steely April 5, 2012 at 4:37 pm

Vivek,
Using the full path for fping did the trick. Thank you!

Reply

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