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#! /bin/bash
###
# Nagios plugin skeleton
# http://nagiosplug.sourceforge.net/developer-guidelines.html
#
# Check dns resolution of the hostname spacified agains the current ip.
#
# @AUTHOR: Patrik Dufresne (http://patrikdufresne.com)
# Copyright 2012 Patrik Dufresne
# Last modified 2012-11-02
# Please send all comments, suggestions, bugs and patches to (info AT patrikdufresne DOT com)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
###
# You should provide a meaningful VERSION
VERSION=0.1
# Who can be contacted about this?
AUTHOR="Patrik Dufresne"
# Name what is being checked to be printed out next to OK/WARNING/CRITICAL/UNKNOWN
SERVICE="DYNDNS"
# Replacement for the exit function, will cleanup any tempfiles or such
# before exiting.
function cleanup {
exit $1
}
declare -rx PROGNAME=${0##*/}
declare -rx PROGPATH=${0%/*}/
if [ -r "${PROGPATH}utils.sh" ] ; then
source "${PROGPATH}utils.sh"
else
echo "Can't find utils.sh. This plugin needs to be run from the same directory as utils.sh which is most likely something like /usr/lib/nagios/plugins or /usr/lib64/nagios/plugins"
printf "Currently being run from %s\n" "$PROGPATH"
# Since we couldn't define STATE_UNKNOWN since reading utils.sh
# failed, we use 3 here but everywhere else after this use cleanup $STATE
cleanup 3
fi
# Set STATE to UNKNOWN as soon as we can (right after reading in util.sh
# where the STATES are defined)
STATE=$STATE_UNKNOWN
# make sure that any external commands are installed, in the PATH and
# executable. The following example is stupid because of course date is
# installed but it's the only command this trivial check really uses
CURL=/usr/bin/curl
if [ ! -x "$CURL" ] ; then
echo "The utility $CURL is not installed. Exiting."
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cleanup $STATE_UNKNOWN
fi
HOST=/usr/bin/host
if [ ! -x "$HOST" ] ; then
echo "The utility host is not installed. Exiting."
cleanup $STATE_UNKNOWN
fi
# provide a quick one liner of how to use the program
function usage {
printf " %s %s for Nagios - Usage %s -H <dns name> \
[-t timeout] [-v [-v [-v]]]\n" "$PROGNAME" "$VERSION" "$PROGNAME"
cleanup $STATE_UNKNOWN
}
# provide detailed explanations of the command line syntax
function longhelp {
# put your long help here
printf "%s plugin version %s for Nagios by %s
-h, --help Display this message.
-H, --hostname Define the dns name to verify.
-t, --timeout=sec Set script timeout in seconds.
-v, --verbose Up the verbosity level by one.
--verbosity=val Set the verbosity level to val.
-V, --version Print version information.
" "$PROGNAME" "$VERSION" "$AUTHOR"
cleanup $STATE_UNKNOWN
}
if [ $# -eq 0 ] ; then
usage
fi
# use getopt, trust me on this one. It's the easiest way
getopt -T
if [ $? -ne 4 ] ; then
printf "%s: getopt is in compatibility mode.\n" "$SCRIPT"
cleanup $STATE_UNKNOWN
fi
# Tell it which switches and longswitches you'll take and place a trailing
# colon (:) on the ones take arguments. Nagios guidelines require you to
# use all the ones specified below with the exception of --verbosity which I've
# added to circumvent the awkward -v -v -v syntax. Getopt takes care of
# positional parameters and errors for missing expected arguments so we can
# shift later without checking
RESULT=`getopt --name "$SCRIPT" --options "-h,-V,-v,-t:,-H:" --longoptions "help,version,verbose,verbosity:,timeout:,hostname:" -- "$@"`
# make the result of getopt your new argument list ($@)
eval set -- "$RESULT"
declare WARNING
declare CRITICAL
# all scripts should have a mechanism to terminate themselves if they are
# running for too long. Scripts you might think of as innocuous could end
# up waiting forever on I/O, especially if a disk is failing
declare -i TIMELIMIT=15
# Nagios defines behavior for VERBOSITY 0 (default) through 3
declare -i VERBOSITY=0
while [ $# -gt 0 ] ; do
case "$1" in
-h | --help)
longhelp;;
-V | --version)
print_revision "$PROGNAME" "$VERSION"
cleanup $STATE;;
-v | --verbose)
VERBOSITY=$(($VERBOSITY + 1));;
--verbosity)
shift
VERBOSITY=$1;;
-t | --timeout)
shift
TIMELIMIT=$1;;
-H | --hostname)
shift
HOSTNAME=$1;;
--)
shift
break;;
*)
echo "Option $1 not supported. Ignored." >&2;;
esac
shift
done
#Verbosity level Type of output
#0 Single line, minimal output. Summary
#1 Single line, additional information (eg list processes that fail)
#2 Multi line, configuration debug output (eg ps command used)
#3 Lots of detail for plugin problem diagnosis
if [ $VERBOSITY -gt 2 ] ; then
shopt -o -s xtrace
fi
# what needs to happen in the event of a timeout
function timeout {
echo "UNKNOWN - script timed out after $TIMELIMIT seconds."
cleanup $STATE_UNKNOWN
}
# since we've processed the options which potentially set the timeout limit,
# we can setup a timeout trap now
trap timeout USR1
# what we're doing here sending a USR1 signal back to this process which
# we just set a trap to catch and run the timeout function the syntax of
# this is important and very odd - if you know of a better way to do this,
# please email me what we're doing is starting another process in the
# background that sleeps for TIMELIMIT seconds and then uses pgrep when
# it 'wakes up' to see if a process with our number, name and user exists,
# only then will the USR1 signal be sent we have to use pgrep so that we
# don't sent a USR1 signal to just any program. The only risk we run with
# this is sending USR1 to another instance of this script that just happens
# to get assigned the same process ID it should be reasonable to assume
# that your Nagios check interval is greater than the specified timeout
# still, if you havea better idea...
( sleep $TIMELIMIT; if [ `pgrep -U $USER -f "$SCRIPT" | grep -c ^$$$` -gt 0 ] ; then kill -USR1 $$ ; fi; ) </dev/null &>/dev/null &
# Check that sensor is provided
if [ -z "$HOSTNAME" ] ; then
usage
fi
# Get the hostname value
DYNDNS_IP=$($CURL --max-time $TIMELIMIT checkip.dyndns.org 2>&1)
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IP_STATE=$?
if [ $? -eq 0 ]
then
DYNDNS_IP=`expr "$DYNDNS_IP" : '^.*<body>Current IP Address: \([0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\)</body>.*$'`
IP_STATE=$?
fi
HOSTNAME_IP=`$HOST "$HOSTNAME"`
HOST_SATE=$?
if [ $? -eq 0 ]
then
HOSTNAME_IP=`expr "$HOSTNAME_IP" : '.* has address \([0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\)$'`
HOST_SATE=$?
fi
# Once we're done doing work that could take any real time, we can end the
# trap because from here on out it's just comparisons and string
# concatenation
trap - USR1
# Check the state
if [ $IP_STATE -ne 0 ] ; then
STATE=$STATE_UNKNOWN
OUT="Cannot parse result from checkip.dyndns.org"
else
if [ $HOST_SATE -ne 0 ] ; then
STATE=$STATE_CRITICAL
OUT="Could not resolve hostname $HOSTNAME"
else
if [ "$HOSTNAME_IP" == "$DYNDNS_IP" ] ; then
STATE=$STATE_OK
OUT="hostname resolved to $HOSTNAME_IP"
else
STATE=$STATE_CRITICAL
OUT="hostname resolution doesn't matches : $HOSTNAME_IP <> $DYNDNS_IP"
fi
fi
fi
case $STATE in
$STATE_OK)
printf "%s OK - %s\n" "$SERVICE" "$OUT";;
$STATE_WARNING)
printf "%s WARNING - %s\n" "$SERVICE" "$OUT";;
$STATE_CRITICAL)
printf "%s CRITICAL - %s\n" "$SERVICE" "$OUT";;
$STATE_UNKNOWN)
printf "%s UNKNOWN - %s\n" "$SERVICE" "$OUT";;
esac
cleanup $STATE