Add use of /etc/default config file
--- a/pam_cas_expire
+++ b/pam_cas_expire
@@ -36,6 +36,8 @@
     shift
 done
 
+[ -e "/etc/default/pam_cas_expire.conf" ] && . "/etc/default/pam_cas_expire.conf"
+
 [ -n "$expireConfO" ] && expireConf="$expireConfO"
 [ -e "$expireConf" ] && . "$expireConf"
 
