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Hahn Axel (hahn) authoredHahn Axel (hahn) authored
check_dns_responsetime 4.28 KiB
#!/bin/bash
# ======================================================================
#
# Check DNS response time
# requirements:
# - netstat
#
# ----------------------------------------------------------------------
# 2020-06-17 v1.0 <axel.hahn@iml.unibe.ch>
# 2021-11-12 v1.1 <axel.hahn@iml.unibe.ch> check fqd instead of fixed value
# test tcp 53 first
# check result depends on 1st nameserver only
# 2022-10-24 v1.2 <axel.hahn@unibe.ch> shell fixes; remove pipe char in output
# 2023-07-27 v1.3 <axel.hahn@unibe.ch> shell fixes; add help page
# 2023-10-13 v1.4 <axel.hahn@unibe.ch> fix syntax error in export
# ======================================================================
. $( dirname $0 )/inc_pluginfunctions
export self_APPVERSION=1.4
tmpfile=/tmp/check_netstat_out_$$
infofile=/tmp/check_netstat_out_2_$$
myHost=$( hostname -f )
# set default / override from command line params
typeset -i iWarnLimit; iWarnLimit=$( ph.getValueWithParam 300 w "$@")
typeset -i iCriticalLimit; iCriticalLimit=$( ph.getValueWithParam 1000 c "$@")
rm -f $tmpfile $infofile 2>/dev/null
typeset -i iMax=0
typeset -i iTime=0
typeset -i iCounter=0
typeset -i iNotReachable=0
# show help
function showHelp(){
local _self; _self=$(basename $0)
cat <<EOF
$( ph.showImlHelpHeader )
Loop over all defined dns servers (in /etc/resolv.conf) and check
each:
- detect of port 53 is available (DNS service)
- 5x check time of a nslookup for current host (${myHost})
The a warning / critical response will be reached if the maximum time
of nslookup on the first dns server reaches a limit.
The critical response will be returned if the first of the
nameservers is not available.
An unknown response will be returned if the current hostname
(hostname -f) is no FQDN.
SYNTAX:
$_self [ -w VALUE -c VALUE -h ]
OPTIONS:
-w VALUE warning level (default: 300)
-c VALUE critical level (default: 1000)
-h or --help Show this help.
EOF
}
# ----------------------------------------------------------------------
# MAIN
# ----------------------------------------------------------------------
# --- check param -h
case "$1" in
"--help"|"-h")
showHelp
exit 0
;;
*)
esac
if ! echo $myHost | cut -f 3- -d "." | grep "\." >/dev/null; then
ph.setStatus unknown
ph.status "DNS check for [$myHost] - SKIP: hostname -f returned a FQDN with less than 2 dots"
ph.exit
fi
ph.require nslookup
for mydns in $(grep ^nameserver /etc/resolv.conf | awk '{ print $2 } ' )
do
iCounter=$iCounter+1
typeset -i iSrvMax=0
echo "" >>$infofile
echo "---------- $iCounter - $mydns " >>$infofile
# todo loop
if ! >/dev/tcp/${mydns}/53 >>$infofile 2>&1; then
iNotReachable=$iNotReachable+1
test $iCounter -eq 1 && ph.setStatus critical
echo "ERROR: ${mydns} is not reachable on tcp 53" >>$infofile
else
for i in $(seq 5)
do
(time nslookup ${myHost} $mydns) >$tmpfile 2>&1
iTime=$(cat $tmpfile | grep "^real.*m.*\..*s" | cut -f 2 -d "m" | sed "s#[\.s]##g" | sed "s#^0*##g" )
echo "$mydns #$i >>> $iTime ms" >>$infofile
test $iTime -ge $iWarnLimit && cat $tmpfile | grep -vE "^(real|user|sys)" >> $infofile
test $iTime -gt $iSrvMax && iSrvMax=$iTime
done
echo "max: $iSrvMax ms" >>$infofile
# --- set status
test $iCounter -eq 1 && ph.setStatusByLimit $iSrvMax $iWarnLimit $iCriticalLimit
label=${mydns//\./-}
ph.perfadd "response-$label" "${iSrvMax}"
test $iSrvMax -gt $iMax && iMax=$iSrvMax
fi
test $iCounter -eq 1 && (echo " ^"; echo " :"; echo " +--- 1st nameserver is relevant for total status of the check. Limits are warning=$iWarnLimit and critical=$iCriticalLimit") >>$infofile
echo "" >>$infofile
done
test $iNotReachable -eq 0 && ph.status "DNS check for $myHost - found maximum was $iMax ms - OK: all nameservers are reachable"
test $iNotReachable -ne 0 && ph.status "DNS check for $myHost - found maximum was $iMax ms - INFO: $iNotReachable of $iCounter nameservers not reachable"
cat $infofile
rm -f $tmpfile $infofile
ph.exit
# ----------------------------------------------------------------------