#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>
+
+PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"
+export PATH
+PROGNAME=`basename $0`

[mathias, 2018/05/30 08:12:00]

What if $0 contains white-space characters?

+PROGPATH=`echo $0 | sed -e 's,[\\/][^\\/][^\\/]*$,,'`

[mathias, 2018/05/30 08:12:00]

Isn't there a regular POSIX or Linux command for that? It should not require a
regular expression in the script just to get the directory name.

+
+#. $PROGPATH/utils.sh

[mathias, 2018/05/30 08:12:00]

Please avoid "commented-out" lines that do no serve a purpose, e.g. in
documentation.

+
+CURRENT_DATE=`date +%y%m%d`
+HOST=$2
+PORT=$4
+CRITICAL=$6
+WARNING=$8

[mathias, 2018/05/30 08:12:00]

What if any of $2, $4, $6, $8 contain white-space characters?

+
+DAY=`echo | openssl s_client -connect "$HOST":$PORT 2>/dev/null | openssl x509 -noout -enddate 2>/dev/null | awk '{print $2}'`

[mathias, 2018/05/30 08:12:00]

There should be a better way to send non-input to the `openssl` command other
than pipe-lining an `echo`. You could use input redirection from /dev/null, for
example. See https://www.tutorialspoint.com/unix/unix-io-redirections.htm for an
introduction.

+
+if [ ! $DAY ]

[mathias, 2018/05/30 08:11:59]

Since you `-connect` to `$HOST:$PORT` multiple times during the script, why do
you have error handling logic only for the first attempt?

+then
+  echo "UNKNOWN - Could not connect to $HOST via port $PORT"
+  exit $STATE_UNKNOWN
+fi
+
+MONTH=`echo | openssl s_client -connect "$HOST":$PORT 2>/dev/null | openssl x509 -noout -enddate | awk '{print $1}' | cut -c 10-`
+YEAR=`echo | openssl s_client -connect "$HOST":$PORT 2>/dev/null | openssl x509 -noout -enddate | awk '{print $4}'`
+
+case $MONTH in
+
+  "Jan")
+    MONTH="01"
+    ;;
+  "Feb")
+    MONTH="02"
+    ;;
+  "Mar")
+    MONTH="03"
+    ;;
+  "Apr")
+    MONTH="04"
+    ;;
+  "May")
+    MONTH="05"
+    ;;
+  "Jun")
+    MONTH="06"
+    ;;
+  "Jul")
+    MONTH="07"
+    ;;
+  "Aug")
+    MONTH="08"
+    ;;
+  "Sep")
+    MONTH="09"
+    ;;
+  "Oct")
+    MONTH="10"
+    ;;
+  "Nov")
+    MONTH="11"
+    ;;
+  "Dec")
+    MONTH="12"
+    ;;
+  "*")
+    echo "An error occured"
+    exit 1
+    ;;
+esac
+
+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`
+
+if [ $DIFF -le $CRITICAL ]
+then
+  echo "CRITICAL - $HOST: SSL certificate has been expired!"
+  exit $STATE_CRITICAL

[mathias, 2018/05/30 08:11:59]

Where are the $STATE_{CRITICAL,WARNING,OK,UNKNOWN} variables defined?

+elif [ $DIFF -le $WARNING ] && [ $DIFF -gt $CRITICAL ]

[mathias, 2018/05/30 08:12:00]

You already know at this point that $DIFF is greater than $CRITICAL because you
already determined above that $DIFF is not less than or equal $CRITICAL.

+then
+  echo "WARNING - $HOST: SSL certificate will be expired in $DIFF days!"
+  exit $STATE_WARNING
+elif [ $DIFF -gt $WARNING ]
+then
+  echo "OK - $HOST: SSL certificate will be expired in $DIFF days"
+  exit $STATE_OK
+else
+  echo "UNKNOWN - $HOST: Could not retrieve data"
+  exit $STATE_UNKNOWN
+fi