--- /dev/null
+#!/bin/bash
+
+# Checks if a given cert on disk will expire soon
+
+# Copyright 2009, 2012 Peter Palfrader
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+set -u
+set -e
+
+# warn if expires within 2 weeks, critical if within a day or already is expired
+warn=1209600
+crit=86400
+
+while [ "$#" -ge 2 ]; do
+ case "$1" in
+ -c)
+ shift
+ crit="$1"
+ ;;
+ -w)
+ shift
+ warn="$1"
+ ;;
+ *)
+ break
+ ;;
+ esac
+ shift
+done
+
+if [ "$#" != 1 ]; then
+ echo "Usage: $0 [-w <seconds>] [-c <seconds>] <crlfile>" >&2
+ exit 3
+fi
+
+crl="$1"
+
+if ! [ -r "$crl" ] ; then
+ echo "CRL file ($crl) does not exist or is not readable" >&2
+ exit 3
+fi
+
+expires="$(openssl crl -nextupdate -noout < "$crl" | cut -d = -f 2)"
+expsec="$(date -d "$expires" +%s)"
+now="$(date +%s)"
+delta="$(( $expsec - $now ))"
+
+if [ "$delta" -gt "$warn" ] ; then
+ echo "OK: next update expected $expires"
+ exit 0
+fi
+if [ "$delta" -gt "$crit" ] ; then
+ echo "WARN: next update expected $expires"
+ exit 1
+fi
+echo "CRITICAL: next update expected $expires"
+exit 2