#3298 - SSL monitoring script for icinga

check_ssl_cert.sh

 #!/bin/sh
 
-# Icinga plugin that checks how many days are left until SSL certificate expires
-# Usage: <PluginDir>/check_ssl_cert -H <HOSTNAME> -P <PORT> -c <CRITICAL> -w <WARNING>
+# Icinga plugin that checks how many days are left
+# until SSL certificate expires.
+# Usage:
+# $PLUGIN_DIR/check_ssl_cert.sh -H $HOST -P $PORT -c $CRITICAL -w $WARNING
 
-PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"
+get_ssl_expiry_date() {
+  openssl s_client -connect "$1:$2" </dev/null 2>/dev/null \
+  | openssl x509 -noout -enddate 2>/dev/null
+}
 
 CURRENT_DATE=`date +%y%m%d`
 HOST="$2"
 PORT="$4"
 CRITICAL="$6"
 WARNING="$8"
 STATE_OK=0
 STATE_WARNING=1
 STATE_CRITICAL=2
 STATE_UNKNOWN=3
+OUTPUT=`get_ssl_expiry_date "$HOST" "$PORT"`
 
-OUTPUT=`openssl s_client -connect "$HOST":"$PORT" </dev/null 2>/dev/null | openssl x509 -noout -enddate 2>/dev/null`

[mathias, 2018/06/05 16:24:19]

Please place this in a function() and invoke it to assign the output, e.g.
OUTPUT=`function_name "$HOST" "$PORT"`.

-
-if [ ! "$OUTPUT" ]
+if [ -z "$OUTPUT" ]
 then
   echo "UNKNOWN - Could not connect to $HOST via port $PORT"
   exit "$STATE_UNKNOWN"
 fi
 
-DAY=`echo "$OUTPUT" | awk '{print $2}'`
+DAY=`echo "$OUTPUT" | awk '{printf "02d", $2}'`
 MONTH=`echo "$OUTPUT" | awk '{print $1}' | cut -c 10-`
 YEAR=`echo "$OUTPUT" | awk '{print $4}'`
 
 case "$MONTH" in
 
   "Jan")
     MONTH="01"
     ;;
   "Feb")
     MONTH="02"
@@ skipping 27 matching lines @@
     ;;
   "Dec")
     MONTH="12"
     ;;
   "*")
     echo "An error occured"
     exit 1
     ;;
 esac
 
-EXPIRY_DATE_IN_SEC=`date -d "$YEAR""$MONTH""$DAY" +%s`

[mathias, 2018/06/05 16:24:19]

You can use "$YEAR$MONTH$DAY" or, even better, "${YEAR}${MONTH}${DAY}" here --
there's no need for the additional quotes.

+EXPIRY_DATE_IN_SEC=`date -d "${YEAR}${MONTH}${DAY}" +%s`
 CURRENT_DATE_IN_SEC=`date -d "$CURRENT_DATE" +%s`
-DIFF=`expr "$EXPIRY_DATE_IN_SEC" - "$CURRENT_DATE_IN_SEC"`
-DIFF=`expr "$DIFF" / 86400`
+DIFFERENCE=`expr \( "$EXPIRY_DATE_IN_SEC" - "$CURRENT_DATE_IN_SEC" \) / 86400`
 
-if [ "$DIFF" -le "$CRITICAL" ]
+if [ "$DIFFERENCE" -le "$CRITICAL" ]
 then
   echo "CRITICAL - $HOST: SSL certificate has been expired!"
   exit "$STATE_CRITICAL"
-elif [ "$DIFF" -le "$WARNING" ]
+elif [ "$DIFFERENCE" -le "$WARNING" ]
 then
-  echo "WARNING - $HOST: SSL certificate will be expired in $DIFF days!"
+  echo "WARNING - $HOST: SSL certificate will be expired in $DIFFERENCE days!"
   exit "$STATE_WARNING"
-elif [ "$DIFF" -gt "$WARNING" ]
+elif [ "$DIFFERENCE" -gt "$WARNING" ]
 then
-  echo "OK - $HOST: SSL certificate will be expired in $DIFF days"
+  echo "OK - $HOST: SSL certificate will be expired in $DIFFERENCE days"
   exit "$STATE_OK"
 else
   echo "UNKNOWN - $HOST: Could not retrieve data"
   exit "$STATE_UNKNOWN"
 fi