diff --git a/net/adblock/Makefile b/net/adblock/Makefile
index 28a7feeff..00abdf3a2 100644
--- a/net/adblock/Makefile
+++ b/net/adblock/Makefile
@@ -6,7 +6,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=adblock
-PKG_VERSION:=3.1.1
+PKG_VERSION:=3.4.0
 PKG_RELEASE:=1
 PKG_LICENSE:=GPL-3.0+
 PKG_MAINTAINER:=Dirk Brenken <dev@brenken.org>
@@ -17,6 +17,7 @@ define Package/adblock
 	SECTION:=net
 	CATEGORY:=Network
 	TITLE:=Powerful adblock script to block ad/abuse domains
+	DEPENDS:=+jshn +jsonfilter
 	PKGARCH:=all
 endef
 
@@ -53,6 +54,7 @@ define Package/adblock/install
 	$(INSTALL_CONF) ./files/adblock.conf $(1)/etc/config/adblock
 
 	$(INSTALL_DIR) $(1)/etc/adblock
+	$(INSTALL_CONF) ./files/adblock.notify $(1)/etc/adblock/
 	$(INSTALL_CONF) ./files/adblock.blacklist $(1)/etc/adblock/
 	$(INSTALL_CONF) ./files/adblock.whitelist $(1)/etc/adblock/
 endef
diff --git a/net/adblock/files/README.md b/net/adblock/files/README.md
index 6b373da52..7010c3eaf 100644
--- a/net/adblock/files/README.md
+++ b/net/adblock/files/README.md
@@ -43,8 +43,6 @@ A lot of people already use adblocker plugins within their desktop browsers, but
     * => regional blocklist for Romania, weekly updates, approx. 600 entries
     * [reg_ru](https://code.google.com/p/ruadlist)
     * => regional blocklist for Russia, weekly updates, approx. 2.000 entries
-    * [securemecca](http://www.securemecca.com)
-    * => infrequent updates, approx. 25.000 entries
     * [shallalist](http://www.shallalist.de) (categories "adv" "costtraps" "spyware" "tracker" "warez" enabled by default)
     * => daily updates, approx. 32.000 entries (a short description of all shallalist categories can be found [online](http://www.shallalist.de/categories.html))
     * [spam404](http://www.spam404.com)
@@ -76,6 +74,7 @@ A lot of people already use adblocker plugins within their desktop browsers, but
 * minimal status & error logging to syslog, enable debug logging to receive more output
 * procd based init system support (start/stop/restart/reload/suspend/resume/query/status)
 * procd network interface trigger support or classic time based startup
+* keep the dns cache intact after adblock processing (currently supported by unbound and named)
 * conditional dns backend restarts by old/new blocklist comparison with sha256sum (default) or md5sum
 * suspend & resume adblock actions temporarily without blocklist reloading
 * output comprehensive runtime information via LuCI or via 'status' init command
@@ -86,6 +85,7 @@ A lot of people already use adblocker plugins within their desktop browsers, but
 * optional: automatic blocklist backup & restore, they will be used in case of download errors or during startup in backup mode
 * optional: 'backup mode' to re-use blocklist backups during startup, get fresh lists only via reload or restart action
 * optional: 'whitelist mode' to block access to all domains except those explicitly listed in the whitelist file
+* optional: send notification emails in case of a processing error or if the overall domain count is &le; 0
 * optional: add new adblock sources on your own via uci config
 
 ## Prerequisites
@@ -133,18 +133,21 @@ A lot of people already use adblocker plugins within their desktop browsers, but
     * adb\_forcesrt => force overall sort on low memory devices with less than 64 MB RAM (default: '0', disabled)
     * adb\_backup_mode => do not automatically update blocklists during startup, use backups instead (default: '0', disabled)
     * adb\_whitelist_mode => block access to all domains except those explicitly listed in the whitelist file (default: '0', disabled)
+    * adb\_dnsflush => flush DNS cache after adblock processing, i.e. enable the old restart behavior (default: '0', disabled)
+    * adb\_notify => send notification emails in case of a processing error or if the overall domain count is &le; 0 (default: '0', disabled)
+    * adb\_notifycnt => Raise minimum domain count email notification trigger (default: '0')
 
 ## Examples
-**change default dns backend to 'unbound':**  
+**change default dns backend to 'unbound':**
 
-Adblock deposits the final blocklist 'adb_list.overall' in '/var/lib/unbound' where unbound can find them in its jail. If you use manual configuration for unbound, then just include the following line in your 'server' clause:
-<pre><code>
-  include: "/var/lib/unbound/adb_list.overall"
-</code></pre>
+Adblock deposits the final blocklist 'adb_list.overall' in '/var/lib/unbound' where unbound can find them in its jail.  
+To preserve the DNS cache after adblock processing you need to install 'unbound-control'.  
   
-**change default dns backend to 'named' (bind):**  
+**change default dns backend to 'named' (bind):**
 
-Adblock deposits the final blocklist 'adb_list.overall' in '/var/lib/bind'. To use the blocklist please modify '/etc/bind/named.conf':
+Adblock deposits the final blocklist 'adb_list.overall' in '/var/lib/bind'.  
+To preserve the DNS cache after adblock processing you need to install & configure 'bind-rdnc'.  
+To use the blocklist please modify '/etc/bind/named.conf':
 <pre><code>
 in the 'options' namespace add:
   response-policy { zone "rpz"; };
@@ -158,21 +161,45 @@ and at the end of the file add:
   };
 </code></pre>
   
-**change default dns backend to 'kresd':**  
+**change default dns backend to 'kresd':**
+
+The knot-resolver (kresd) is only available on Turris Omnia devices.  
+Adblock deposits the final blocklist 'adb_list.overall' in '/etc/kresd', no further configuration needed.
+  
+**change default dns backend to 'dnscrypt-proxy':**
 
-The knot-resolver (kresd) is only available on turris omnia devices. Adblock deposits the final blocklist 'adb_list.overall' in '/etc/kresd'. To use the blocklist please modify '/etc/config/resolver':
+The required 'blacklist' option of dnscrypt-proxy is not enabled by default, because the package will be compiled without plugins support.  
+Take a custom LEDE build with plugins support to use this feature. Adblock deposits the final blocklist 'adb_list.overall' in '/tmp'.  
+To use the blocklist please modify '/etc/config/dnscrypt-proxy' per instance:
 <pre><code>
-    list rpz_file '/etc/kresd/adb_list.overall'
+  list blacklist 'domains:/tmp/adb_list.overall'
 </code></pre>
   
-**change default dns backend to 'dnscrypt-proxy':**  
+**enable email notification via msmtp:**
 
-The required 'blacklist' option of dnscrypt-proxy is not enabled by default, because the package will be compiled without plugins support. Take a custom LEDE build with plugins support to use this feature. Adblock deposits the final blocklist 'adb_list.overall' in '/tmp'. To use the blocklist please modify '/etc/config/dnscrypt-proxy' per instance:
+To use the email notification you have to install & configure the package 'msmtp'.  
+Modify the file '/etc/msmtprc':
 <pre><code>
-  list blacklist 'domains:/tmp/adb_list.overall'
+[...]
+defaults
+auth            on
+tls             on
+tls_certcheck   off
+timeout         5
+syslog          LOG_MAIL
+[...]
+account         adb_notify
+host            smtp.gmail.com
+port            587
+from            dev.adblock@gmail.com
+user            dev.adblock
+password        xxx
 </code></pre>
+Edit the file '/etc/adblock/adblock.notify' and change at least the 'mail_receiver'.  
+Finally make this file executable via 'chmod' and test it directly. If no more errors come up you can comment 'mail_debug', too.
   
 **configuration for different download utilities:**
+
 <pre><code>
 wget (default):
   option adb_fetch '/usr/bin/wget'
@@ -192,24 +219,27 @@ curl:
 </code></pre>
   
 **receive adblock runtime information:**
+
 <pre><code>
 /etc/init.d/adblock status
 ::: adblock runtime information
   + adblock_status  : enabled
-  + adblock_version : 3.1.0
-  + overall_domains : 5117
+  + adblock_version : 3.4.0
+  + overall_domains : 5167 (normal/backup mode)
   + fetch_utility   : wget (built-in)
   + dns_backend     : kresd (/etc/kresd)
-  + last_rundate    : 03.11.2017 22:57:41
-  + system_release  : Turris Omnia, OpenWrt omnia 15.05/3.8.4
+  + last_rundate    : 27.12.2017 20:52:35
+  + system_release  : Turris Omnia, OpenWrt omnia 15.05/3.9.1
 </code></pre>
   
 **cronjob for a regular block list update (/etc/crontabs/root):**
+
 <pre><code>
 0 06 * * *    /etc/init.d/adblock reload
 </code></pre>
   
 **blacklist entry (/etc/adblock/adblock.blacklist):**
+
 <pre><code>
 ads.example.com
 
@@ -224,6 +254,7 @@ This entry does not block:
 </code></pre>
   
 **whitelist entry (/etc/adblock/adblock.whitelist):**
+
 <pre><code>
 here.com
 
@@ -236,7 +267,7 @@ This entry does not remove:
   www.adwhere.com
 </code></pre>
   
-**query the active blocklist for a certain (sub-)domain, e.g. for whitelisting:**  
+**query the active blocklist for a certain (sub-)domain, e.g. for whitelisting:**
 
 The query function checks against the submitted (sub-)domain and recurses automatically to the upper top level domain. For every (sub-)domain it returns the first ten relevant results.
 <pre><code>
@@ -255,7 +286,7 @@ The query function checks against the submitted (sub-)domain and recurses automa
   + www-google-analytics.l.google.com
 </code></pre>
   
-**add a new blocklist source:**  
+**add a new blocklist source:**
 
 1. the easy way ...  
 example: https://easylist-downloads.adblockplus.org/rolist+easylist.txt  
diff --git a/net/adblock/files/adblock.conf b/net/adblock/files/adblock.conf
index da2f6fe3b..960d7d923 100644
--- a/net/adblock/files/adblock.conf
+++ b/net/adblock/files/adblock.conf
@@ -126,12 +126,6 @@ config source 'reg_ru'
 	option adb_src_rset 'BEGIN{FS=\"[|^]\"}\$0~/^\|\|([[:alnum:]_-]+\.){1,}[[:alpha:]]+\^("\\\$third-party")?$/{print tolower(\$3)}'
 	option adb_src_desc 'focus on russian ads plus generic easylist additions, weekly updates, approx. 14.500 entries'
 
-config source 'securemecca'
-	option enabled '0'
-	option adb_src 'http://securemecca.com/Downloads/hosts.txt'
-	option adb_src_rset '\$0~/^127\.0\.0\.1[[:space:]]+([[:alnum:]_-]+\.){1,}[[:alpha:]]+([[:space:]]|$)/{print tolower(\$2)}'
-	option adb_src_desc 'broad blocklist, infrequent updates, approx. 13.700 entries'
-
 config source 'shalla'
 	option enabled '0'
 	option adb_src 'http://www.shallalist.de/Downloads/shallalist.tar.gz'
diff --git a/net/adblock/files/adblock.init b/net/adblock/files/adblock.init
index d49c6ea2d..b7b25f154 100755
--- a/net/adblock/files/adblock.init
+++ b/net/adblock/files/adblock.init
@@ -82,7 +82,7 @@ service_triggers()
 
     if [ "${trigger}" != "none" ] && [ "${trigger}" != "timed" ]
     then
-        PROCD_RELOAD_DELAY=$((${delay:=1} * 1000))
+        PROCD_RELOAD_DELAY=$((${delay:-1} * 1000))
         procd_add_interface_trigger "interface.*.up" "${trigger}" "${adb_init}" start
     fi
     procd_add_reload_trigger "adblock"
diff --git a/net/adblock/files/adblock.notify b/net/adblock/files/adblock.notify
new file mode 100644
index 000000000..3f8fc9723
--- /dev/null
+++ b/net/adblock/files/adblock.notify
@@ -0,0 +1,38 @@
+#!/bin/sh
+#
+# adblock send mail script for mstmp
+# written by Dirk Brenken (dev@brenken.org)
+# Please note: you have to install and configure the package 'mstmp' before using this script.
+
+# This is free software, licensed under the GNU General Public License v3.
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+LC_ALL=C
+PATH="/usr/sbin:/usr/bin:/sbin:/bin"
+mail_daemon="$(command -v sendmail)"
+mail_profile="adb_notify"
+mail_debug="--debug"
+mail_rc=0
+
+# mail header
+#
+mail_sender="no-reply@adblock"
+mail_receiver="!!!ChangeMe!!!"
+mail_topic="adblock notification"
+mail_head="From: ${mail_sender}\nTo: ${mail_receiver}\nSubject: ${mail_topic}\nReply-to: ${mail_sender}\n\n"
+
+# mail body
+#
+mail_text="adblock status, generated at $(date 2>&1)!"
+mail_text="${mail_text}\n++\n++ System Information ++\n++\n$(cat /etc/banner 2>&1)"
+mail_text="${mail_text}\n\n++\n++ Adblock Information ++\n++\n$(/etc/init.d/adblock status 2>&1)"
+
+# send mail
+#
+if [ -x "${mail_daemon}" ]
+then
+    printf "%b" "${mail_head}${mail_text}" | "${mail_daemon}" ${mail_debug} -a "${mail_profile}" "${mail_receiver}" 2>&1
+    mail_rc=${?}
+fi
+exit ${mail_rc}
diff --git a/net/adblock/files/adblock.sh b/net/adblock/files/adblock.sh
index 209fc00fe..7d2a35fe5 100755
--- a/net/adblock/files/adblock.sh
+++ b/net/adblock/files/adblock.sh
@@ -10,7 +10,7 @@
 #
 LC_ALL=C
 PATH="/usr/sbin:/usr/bin:/sbin:/bin"
-adb_ver="3.1.1"
+adb_ver="3.4.0"
 adb_sysver="unknown"
 adb_enabled=0
 adb_debug=0
@@ -18,22 +18,27 @@ adb_backup_mode=0
 adb_whitelist_mode=0
 adb_forcesrt=0
 adb_forcedns=0
+adb_notify=0
+adb_notifycnt=0
 adb_triggerdelay=0
 adb_backup=0
 adb_backupdir="/mnt"
-adb_fetch="/usr/bin/wget"
+adb_fetchutil="/usr/bin/wget"
 adb_fetchparm="--quiet --no-cache --no-cookies --max-redirect=0 --timeout=10 --no-check-certificate -O"
 adb_dns="dnsmasq"
 adb_dnsprefix="adb_list"
 adb_dnsfile="${adb_dnsprefix}.overall"
+adb_dnsflush=0
 adb_whitelist="/etc/adblock/adblock.whitelist"
 adb_rtfile="/tmp/adb_runtime.json"
-adb_hashsum="$(command -v sha256sum)"
-adb_action="${1:-"start"}"
+adb_hashutil="$(command -v sha256sum)"
+adb_hashold=""
+adb_hashnew=""
 adb_cnt=0
 adb_rc=0
+adb_action="${1:-"start"}"
 
-# f_envload: load adblock environment
+# load adblock environment
 #
 f_envload()
 {
@@ -54,6 +59,13 @@ f_envload()
         adb_sysver="${sys_model}, ${sys_desc}"
     fi
 
+    # check hash utility
+    #
+    if [ ! -x "${adb_hashutil}" ]
+    then
+        adb_hashutil="$(command -v md5sum)"
+    fi
+
     # source in system libraries
     #
     if [ -r "/lib/functions.sh" ] && [ -r "/usr/share/libubox/jshn.sh" ]
@@ -103,30 +115,35 @@ f_envload()
     config_load adblock
     config_foreach parse_config source
 
-    # set/check dns backend environment
+    # check dns backend
     #
     case "${adb_dns}" in
         dnsmasq)
+            adb_dnsinstance=0
             adb_dnsuser="${adb_dnsuser:-"dnsmasq"}"
-            adb_dnsdir="${adb_dnsdir:-"/tmp/dnsmasq.d"}"
-            adb_dnsformat="awk '{print \"local=/\"\$0\"/\"}'"
+            adb_dnsdir="${adb_dnsdir:-"/tmp"}"
+            adb_dnsheader=""
+            adb_dnsformat="awk '{print \"server=/\"\$0\"/\"}'"
             if [ ${adb_whitelist_mode} -eq 1 ]
             then
-                adb_dnsformat="awk '{print \"local=/\"\$0\"/#\"}'"
-                adb_dnsblock="local=/#/"
+                adb_dnsformat="awk '{print \"server=/\"\$0\"/#\"}'"
+                adb_dnsblock="server=/#/"
             fi
-            ;;
+        ;;
         unbound)
+            adb_dnsinstance=0
             adb_dnsuser="${adb_dnsuser:-"unbound"}"
             adb_dnsdir="${adb_dnsdir:-"/var/lib/unbound"}"
+            adb_dnsheader=""
             adb_dnsformat="awk '{print \"local-zone: \042\"\$0\"\042 static\"}'"
             if [ ${adb_whitelist_mode} -eq 1 ]
             then
                 adb_dnsformat="awk '{print \"local-zone: \042\"\$0\"\042 transparent\"}'"
                 adb_dnsblock="local-zone: \".\" static"
             fi
-            ;;
+        ;;
         named)
+            adb_dnsinstance=0
             adb_dnsuser="${adb_dnsuser:-"bind"}"
             adb_dnsdir="${adb_dnsdir:-"/var/lib/bind"}"
             adb_dnsheader="\$TTL 2h"$'\n'"@ IN SOA localhost. root.localhost. (1 6h 1h 1w 2h)"$'\n'"  IN NS localhost."
@@ -136,8 +153,9 @@ f_envload()
                 adb_dnsformat="awk '{print \"\"\$0\" CNAME rpz-passthru.\n*.\"\$0\" CNAME rpz-passthru.\"}'"
                 adb_dnsblock="* CNAME ."
             fi
-            ;;
+        ;;
         kresd)
+            adb_dnsinstance=0
             adb_dnsuser="${adb_dnsuser:-"root"}"
             adb_dnsdir="${adb_dnsdir:-"/etc/kresd"}"
             adb_dnsheader="\$TTL 2h"$'\n'"@ IN SOA localhost. root.localhost. (1 6h 1h 1w 2h)"$'\n'"  IN NS  localhost."
@@ -147,24 +165,22 @@ f_envload()
                 adb_dnsformat="awk '{print \"\"\$0\" CNAME rpz-passthru.\n*.\"\$0\" CNAME rpz-passthru.\"}'"
                 adb_dnsblock="* CNAME ."
             fi
-            ;;
+        ;;
         dnscrypt-proxy)
+            adb_dnsinstance=0
             adb_dnsuser="${adb_dnsuser:-"nobody"}"
             adb_dnsdir="${adb_dnsdir:-"/tmp"}"
+            adb_dnsheader=""
             adb_dnsformat="awk '{print \$0}'"
-            ;;
+        ;;
     esac
 
     # check adblock status
     #
     if [ ${adb_enabled} -eq 0 ]
     then
-        if [ -s "${adb_dnsdir}/${adb_dnsfile}" ]
-        then
-            f_rmdns
-            f_dnsrestart
-        fi
         f_extconf
+        f_rmdns
         f_jsnupdate
         f_log "info " "adblock is currently disabled, please set adb_enabled to '1' to use this service"
         exit 0
@@ -172,7 +188,7 @@ f_envload()
 
     if [ -d "${adb_dnsdir}" ] && [ ! -f "${adb_dnsdir}/${adb_dnsfile}" ]
     then
-        > "${adb_dnsdir}/${adb_dnsfile}"
+        printf '%s\n' "${adb_dnsheader}" > "${adb_dnsdir}/${adb_dnsfile}"
     fi
 
     case "${adb_action}" in
@@ -202,12 +218,14 @@ f_envload()
     fi
 }
 
-# f_envcheck: check/set environment prerequisites
+# check environment
 #
 f_envcheck()
 {
     local ssl_lib
 
+    f_log "info " "start adblock processing (${adb_action})"
+
     # check external uci config files
     #
     f_extconf
@@ -215,23 +233,23 @@ f_envcheck()
     # check fetch utility
     #
     ssl_lib="-"
-    if [ -x "${adb_fetch}" ]
+    if [ -x "${adb_fetchutil}" ]
     then
-        if [ "$(readlink -fn "${adb_fetch}")" = "/usr/bin/wget-nossl" ]
+        if [ "$(readlink -fn "${adb_fetchutil}")" = "/usr/bin/wget-nossl" ]
         then
             adb_fetchparm="--quiet --no-cache --no-cookies --max-redirect=0 --timeout=10 -O"
-        elif [ "$(readlink -fn "${adb_fetch}")" = "/bin/busybox" ] ||
-            ([ "$(readlink -fn "/bin/wget")" = "/bin/busybox" ] && [ "$(readlink -fn "${adb_fetch}")" != "/usr/bin/wget" ])
+        elif [ "$(readlink -fn "${adb_fetchutil}")" = "/bin/busybox" ] ||
+            ([ "$(readlink -fn "/bin/wget")" = "/bin/busybox" ] && [ "$(readlink -fn "${adb_fetchutil}")" != "/usr/bin/wget" ])
         then
-            adb_fetch="/bin/busybox"
+            adb_fetchutil="/bin/busybox"
             adb_fetchparm="-q -O"
         else
             ssl_lib="built-in"
         fi
     fi
-    if [ ! -x "${adb_fetch}" ] && [ "$(readlink -fn "/bin/wget")" = "/bin/uclient-fetch" ]
+    if [ ! -x "${adb_fetchutil}" ] && [ "$(readlink -fn "/bin/wget")" = "/bin/uclient-fetch" ]
     then
-        adb_fetch="/bin/uclient-fetch"
+        adb_fetchutil="/bin/uclient-fetch"
         if [ -f "/lib/libustream-ssl.so" ]
         then
             adb_fetchparm="-q --timeout=10 --no-check-certificate -O"
@@ -240,18 +258,11 @@ f_envcheck()
             adb_fetchparm="-q --timeout=10 -O"
         fi
     fi
-    if [ ! -x "${adb_fetch}" ] || [ -z "${adb_fetch}" ] || [ -z "${adb_fetchparm}" ]
+    if [ ! -x "${adb_fetchutil}" ] || [ -z "${adb_fetchutil}" ] || [ -z "${adb_fetchparm}" ]
     then
         f_log "error" "no download utility found, please install 'uclient-fetch' with 'libustream-mbedtls' or the full 'wget' package"
     fi
-    adb_fetchinfo="${adb_fetch##*/} (${ssl_lib})"
-
-    # check hashsum utility
-    #
-    if [ ! -x "${adb_hashsum}" ]
-    then
-        adb_hashsum="$(command -v md5sum)"
-    fi
+    adb_fetchinfo="${adb_fetchutil##*/} (${ssl_lib})"
 
     # initialize temp files and directories
     #
@@ -261,30 +272,119 @@ f_envcheck()
     > "${adb_tmpdir}/tmp.whitelist"
 }
 
-# f_extconf: set external config options
+# remove temporary files and directories
 #
-f_extconf()
+f_rmtemp()
 {
-    # kresd related options
-    #
-    if [ "${adb_dns}" = "kresd" ]
+    if [ -d "${adb_tmpdir}" ]
     then
-        if [ ${adb_enabled} -eq 1 ] && [ -z "$(uci -q get resolver.kresd.rpz_file | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
-        then
-            uci -q add_list resolver.kresd.rpz_file="${adb_dnsdir}/${adb_dnsfile}"
-        elif [ ${adb_enabled} -eq 0 ] && [ -n "$(uci -q get resolver.kresd.rpz_file | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
+        rm -f "${adb_tmpload}"
+        rm -f "${adb_tmpfile}"
+        rm -rf "${adb_tmpdir}"
+    fi
+}
+
+# remove dns related files and directories
+#
+f_rmdns()
+{
+    if [ -n "${adb_dns}" ]
+    then
+        f_hashcompare
+        printf '%s\n' "${adb_dnsheader}" > "${adb_dnsdir}/${adb_dnsfile}"
+        > "${adb_dnsdir}/.${adb_dnsfile}"
+        > "${adb_rtfile}"
+        rm -f "${adb_backupdir}/${adb_dnsprefix}"*.gz
+        f_hashcompare
+        if [ ${?} -eq 1 ]
         then
-            uci -q del_list resolver.kresd.rpz_file="${adb_dnsdir}/${adb_dnsfile}"
+            f_dnsrestart
         fi
-        if [ -n "$(uci -q changes resolver)" ]
+    fi
+}
+
+# commit uci changes
+#
+f_ucichange()
+{
+    local config="${1}"
+
+    if [ -n "$(uci -q changes "${config}")" ]
+    then
+        uci -q commit "${config}"
+        case "${config}" in
+            dhcp)
+                /etc/init.d/"${adb_dns}" reload >/dev/null 2>&1
+            ;;
+            firewall)
+                /etc/init.d/firewall reload >/dev/null 2>&1
+            ;;
+        esac
+    fi
+}
+
+# list/overall count
+#
+f_count()
+{
+    local mode="${1}"
+
+    adb_cnt=0
+    if [ -s "${adb_dnsdir}/${adb_dnsfile}" ] && ([ -z "${mode}" ] || [ "${mode}" = "format" ])
+    then
+        if [ "${adb_dns}" = "named" ] || [ "${adb_dns}" = "kresd" ]
         then
-            uci -q commit resolver
+            adb_cnt="$(( ( $(wc -l  2>/dev/null < "${adb_dnsdir}/${adb_dnsfile}") - $(printf "%s" "${adb_dnsheader}" | grep -c "^") ) / 2 ))"
+        else
+            adb_cnt="$(wc -l 2>/dev/null < "${adb_dnsdir}/${adb_dnsfile}")"
         fi
+    elif [ -s "${adb_tmpfile}" ]
+    then
+        adb_cnt="$(wc -l 2>/dev/null < "${adb_tmpfile}")"
     fi
+}
 
-    # firewall related options
-    #
-    if [ ${adb_enabled} -eq 1 ] && [ ${adb_forcedns} -eq 1 ] && [ -z "$(uci -q get firewall.adblock_dns)" ]
+# set external config options
+#
+f_extconf()
+{
+    local uci_config
+
+    case "${adb_dns}" in
+        dnsmasq)
+            uci_config="dhcp"
+            if [ ${adb_enabled} -eq 1 ] && [ -z "$(uci -q get dhcp.@dnsmasq[${adb_dnsinstance}].serversfile | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
+            then
+                uci -q set dhcp.@dnsmasq[${adb_dnsinstance}].serversfile="${adb_dnsdir}/${adb_dnsfile}"
+            elif [ ${adb_enabled} -eq 0 ] && [ -n "$(uci -q get dhcp.@dnsmasq[${adb_dnsinstance}].serversfile | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
+            then
+                uci -q delete dhcp.@dnsmasq[${adb_dnsinstance}].serversfile
+            fi
+        ;;
+        kresd)
+            uci_config="resolver"
+            if [ ${adb_enabled} -eq 1 ] && [ -z "$(uci -q get resolver.kresd.rpz_file | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
+            then
+                uci -q add_list resolver.kresd.rpz_file="${adb_dnsdir}/${adb_dnsfile}"
+            elif [ ${adb_enabled} -eq 0 ] && [ -n "$(uci -q get resolver.kresd.rpz_file | grep -Fo "${adb_dnsdir}/${adb_dnsfile}")" ]
+            then
+                uci -q del_list resolver.kresd.rpz_file="${adb_dnsdir}/${adb_dnsfile}"
+            fi
+# wait for upstream change
+#            if [ ${adb_enabled} -eq 1 ] && [ ${adb_dnsflush} -eq 0 ] && [ "$(uci -q get resolver.common.msg_keep_cache)" != "1" ]
+#            then
+#                uci -q set resolver.common.msg_keep_cache="1"
+#            elif [ ${adb_enabled} -eq 0 ] || ([ ${adb_dnsflush} -eq 1 ] && [ "$(uci -q get resolver.common.msg_keep_cache)" = "1" ])
+#            then
+#                uci -q delete resolver.common.msg_keep_cache
+#            fi
+        ;;
+    esac
+    f_ucichange "${uci_config}"
+
+    uci_config="firewall"
+    if [ ${adb_enabled} -eq 1 ] && [ ${adb_forcedns} -eq 1 ] && \
+       [ -z "$(uci -q get firewall.adblock_dns)" ] && [ $(/etc/init.d/firewall enabled; printf "%u" ${?}) -eq 0 ]
     then
         uci -q set firewall.adblock_dns="redirect"
         uci -q set firewall.adblock_dns.name="Adblock DNS"
@@ -297,117 +397,146 @@ f_extconf()
     then
         uci -q delete firewall.adblock_dns
     fi
-    if [ -n "$(uci -q changes firewall)" ]
-    then
-        uci -q commit firewall
-        if [ $(/etc/init.d/firewall enabled; printf "%u" ${?}) -eq 0 ]
-        then
-            /etc/init.d/firewall reload >/dev/null 2>&1
-        fi
-    fi
+    f_ucichange "${uci_config}"
 }
 
-# f_rmtemp: remove temporary files & directories
+# restart of the dns backend
 #
-f_rmtemp()
+f_dnsrestart()
 {
-    if [ -d "${adb_tmpdir}" ]
-    then
-        rm -f "${adb_tmpload}"
-        rm -f "${adb_tmpfile}"
-        rm -rf "${adb_tmpdir}"
-    fi
-}
+    local dns_up cache_util cache_rc out_rc=1 cnt=0
 
-# f_rmdns: remove dns related files & directories
-#
-f_rmdns()
-{
-    if [ -n "${adb_dns}" ]
+    if [ ${adb_dnsflush} -eq 0 ] && [ ${adb_enabled} -eq 1 ] && \
+       [ "${adb_rc}" -eq 0 ] && [ "${adb_action}" != "stop" ]
     then
-        > "${adb_dnsdir}/${adb_dnsfile}"
-        > "${adb_rtfile}"
-        rm -f "${adb_dnsdir}/.${adb_dnsfile}"
-        rm -f "${adb_backupdir}/${adb_dnsprefix}"*.gz
+        case "${adb_dns}" in
+            dnsmasq)
+                cache_util="n/a"
+                killall -q -HUP "${adb_dns}"
+                cache_rc=${?}
+            ;;
+            unbound)
+                cache_util="$(command -v unbound-control)"
+                if [ -x "${cache_util}" ] && [ -f "${adb_dnsdir}"/unbound.conf ]
+                then
+                    "${cache_util}" -c "${adb_dnsdir}"/unbound.conf dump_cache > "${adb_tmpdir}"/adb_cache.dump 2>/dev/null
+                fi
+                "/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
+            ;;
+            kresd)
+                cache_util="n/a"
+                "/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
+                cache_rc=${?}
+            ;;
+            named)
+                cache_util="$(command -v rndc)"
+                if [ -x "${cache_util}" ] && [ -f /etc/bind/rndc.conf ]
+                then
+                    "${cache_util}" -c /etc/bind/rndc.conf reload >/dev/null 2>&1
+                    cache_rc=${?}
+                else
+                    "/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
+                fi
+            ;;
+            *)
+                "/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
+            ;;
+        esac
+    else
+        "/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
     fi
-}
-
-# f_dnsrestart: restart the dns backend
-#
-f_dnsrestart()
-{
-    local dns_up cnt=0
 
-    "/etc/init.d/${adb_dns}" restart >/dev/null 2>&1
     while [ ${cnt} -le 10 ]
     do
         dns_up="$(ubus -S call service list "{\"name\":\"${adb_dns}\"}" | jsonfilter -l1 -e "@[\"${adb_dns}\"].instances.*.running")"
         if [ "${dns_up}" = "true" ]
         then
-            return 0
+            case "${adb_dns}" in
+                unbound)
+                    cache_util="$(command -v unbound-control)"
+                    if [ -x "${cache_util}" ] && [ -s "${adb_tmpdir}"/adb_cache.dump ]
+                    then
+                        while [ ${cnt} -le 10 ]
+                        do
+                            "${cache_util}" -c "${adb_dnsdir}"/unbound.conf load_cache < "${adb_tmpdir}"/adb_cache.dump >/dev/null 2>&1
+                            cache_rc=${?}
+                            if [ ${cache_rc} -eq 0 ]
+                            then
+                                break
+                            fi
+                            cnt=$((cnt+1))
+                            sleep 1
+                        done
+                    fi
+                ;;
+            esac
+            out_rc=0
+            break
         fi
         cnt=$((cnt+1))
         sleep 1
     done
-    return 1
+    f_log "debug" "cache_util: ${cache_util}, cache_rc: ${cache_rc}, cache_flush: ${adb_dnsflush}, count: ${cnt}, out_rc: ${out_rc}"
+    return ${out_rc}
 }
 
-# f_list: backup/restore/remove blocklists
+# backup/restore/remove blocklists
 #
 f_list()
 {
-    local mode="${1}" in_rc="${adb_rc}" cnt=0
+    local mode="${1}" in_rc="${adb_rc}"
 
     case "${mode}" in
         backup)
-            cnt="$(wc -l < "${adb_tmpfile}")"
             if [ ${adb_backup} -eq 1 ] && [ -d "${adb_backupdir}" ]
             then
-                gzip -cf "${adb_tmpfile}" > "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz"
+                gzip -cf "${adb_tmpfile}" > "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz" 2>/dev/null
                 adb_rc=${?}
             fi
-            ;;
+        ;;
         restore)
             if [ ${adb_backup} -eq 1 ] && [ -d "${adb_backupdir}" ] &&
                 [ -f "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz" ]
             then
-                gunzip -cf "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz" > "${adb_tmpfile}"
+                gunzip -cf "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz" > "${adb_tmpfile}" 2>/dev/null
                 adb_rc=${?}
             fi
-            ;;
+        ;;
         remove)
             if [ -d "${adb_backupdir}" ]
             then
                 rm -f "${adb_backupdir}/${adb_dnsprefix}.${src_name}.gz"
             fi
             adb_rc=${?}
-            ;;
+        ;;
         merge)
             if [ -s "${adb_tmpfile}" ]
             then
                 cat "${adb_tmpfile}" >> "${adb_tmpdir}/${adb_dnsfile}"
                 adb_rc=${?}
             fi
-            ;;
+        ;;
         format)
+            src_name="overall"
             if [ -s "${adb_tmpdir}/tmp.whitelist" ]
             then
                 grep -vf "${adb_tmpdir}/tmp.whitelist" "${adb_tmpdir}/${adb_dnsfile}" | eval "${adb_dnsformat}" > "${adb_dnsdir}/${adb_dnsfile}"
             else
                 eval "${adb_dnsformat}" "${adb_tmpdir}/${adb_dnsfile}" > "${adb_dnsdir}/${adb_dnsfile}"
             fi
-            if [ -n "${adb_dnsheader}" ]
+            if [ ${?} -eq 0 ] && [ -n "${adb_dnsheader}" ]
             then
                 printf '%s\n' "${adb_dnsheader}" | cat - "${adb_dnsdir}/${adb_dnsfile}" > "${adb_tmpdir}/${adb_dnsfile}"
                 cat "${adb_tmpdir}/${adb_dnsfile}" > "${adb_dnsdir}/${adb_dnsfile}"
             fi
             adb_rc=${?}
-            ;;
+        ;;
     esac
-    f_log "debug" "name: ${src_name}, mode: ${mode}, count: ${cnt}, in_rc: ${in_rc}, out_rc: ${adb_rc}"
+    f_count "${mode}"
+    f_log "debug" "name: ${src_name}, mode: ${mode}, count: ${adb_cnt}, in_rc: ${in_rc}, out_rc: ${adb_rc}"
 }
 
-# f_tldcompression: top level domain compression
+# top level domain compression
 #
 f_tldcompression()
 {
@@ -419,35 +548,64 @@ f_tldcompression()
     sort -u "${temp}" > "${source}"
 }
 
-# f_switch: suspend/resume adblock processing
+# blocklist hash compare
+#
+f_hashcompare()
+{
+    local hash out_rc=1
+
+    if [ -x "${adb_hashutil}" ] && [ -f "${adb_dnsdir}/${adb_dnsfile}" ]
+    then
+        hash="$(${adb_hashutil} "${adb_dnsdir}/${adb_dnsfile}" 2>/dev/null | awk '{print $1}')"
+        if [ -z "${adb_hashold}" ] && [ -n "${hash}" ]
+        then
+            adb_hashold="${hash}"
+        elif [ -z "${adb_hashnew}" ] && [ -n "${hash}" ]
+        then
+            adb_hashnew="${hash}"
+        fi
+        if [ -n "${adb_hashold}" ] && [ -n "${adb_hashnew}" ]
+        then
+            if [ "${adb_hashold}" = "${adb_hashnew}" ]
+            then
+                out_rc=0
+            fi
+            adb_hashold=""
+            adb_hashnew=""
+        fi
+    fi
+    f_log "debug" "hash_util: ${adb_hashutil}, hash: ${hash}, out_rc: ${out_rc}"
+    return ${out_rc}
+}
+
+# suspend/resume adblock processing
 #
 f_switch()
 {
-    local source target status mode="${1}"
+    local mode="${1}"
 
-    if [ -s "${adb_dnsdir}/${adb_dnsfile}" ] && [ "${mode}" = "suspend" ]
+    if [ ! -s "${adb_dnsdir}/.${adb_dnsfile}" ] && [ "${mode}" = "suspend" ]
     then
-        source="${adb_dnsdir}/${adb_dnsfile}"
-        target="${adb_dnsdir}/.${adb_dnsfile}"
-        status="suspended"
+        f_hashcompare
+        cat "${adb_dnsdir}/${adb_dnsfile}" > "${adb_dnsdir}/.${adb_dnsfile}"
+        printf '%s\n' "${adb_dnsheader}" > "${adb_dnsdir}/${adb_dnsfile}"
+        f_hashcompare
     elif [ -s "${adb_dnsdir}/.${adb_dnsfile}" ] && [ "${mode}" = "resume" ]
     then
-        source="${adb_dnsdir}/.${adb_dnsfile}"
-        target="${adb_dnsdir}/${adb_dnsfile}"
-        status="resumed"
+        f_hashcompare
+        cat "${adb_dnsdir}/.${adb_dnsfile}" > "${adb_dnsdir}/${adb_dnsfile}"
+        > "${adb_dnsdir}/.${adb_dnsfile}"
+        f_hashcompare
     fi
-    if [ -n "${status}" ]
+    if [ ${?} -eq 1 ]
     then
-        cat "${source}" > "${target}"
-        > "${source}"
-        chown "${adb_dnsuser}" "${target}" 2>/dev/null
         f_dnsrestart
         f_jsnupdate
-        f_log "info " "adblock processing ${status}"
+        f_log "info " "${mode} adblock processing"
     fi
 }
 
-# f_query: query blocklist for certain (sub-)domains
+# query blocklist for certain (sub-)domains
 #
 f_query()
 {
@@ -455,10 +613,7 @@ f_query()
     local domain="${1}"
     local tld="${domain#*.}"
 
-    if [ ! -s "${adb_dnsdir}/${adb_dnsfile}" ]
-    then
-         printf "%s\n" "::: no active blocklist found, please start / resume adblock first"
-    elif [ -z "${domain}" ] || [ "${domain}" = "${tld}" ]
+    if [ -z "${domain}" ] || [ "${domain}" = "${tld}" ]
     then
         printf "%s\n" "::: invalid domain input, please submit a single domain, e.g. 'doubleclick.net'"
     else
@@ -472,7 +627,7 @@ f_query()
             else
                 result="$(awk "/(^[^\*][[:alpha:]]*[\.]+${search}|^${search})/{i++;{printf(\"  + %s\n\",\$1)};if(i>9){exit}}" "${adb_dnsfile}")"
             fi
-            printf "%s\n" "::: max. ten results for domain '${domain}'"
+            printf "%s\n" "::: results for domain '${domain}' (max. 10)"
             printf "%s\n" "${result:-"  - no match"}"
             domain="${tld}"
             tld="${domain#*.}"
@@ -480,11 +635,11 @@ f_query()
     fi
 }
 
-# f_jsnupdate: update runtime information
+# update runtime information
 #
 f_jsnupdate()
 {
-    local status rundate="$(/bin/date "+%d.%m.%Y %H:%M:%S")"
+    local status mode="normal mode" rundate="$(/bin/date "+%d.%m.%Y %H:%M:%S")"
 
     if [ ${adb_rc} -gt 0 ]
     then
@@ -497,15 +652,15 @@ f_jsnupdate()
         status="paused"
     else
         status="enabled"
-        if [ -s "${adb_dnsdir}/${adb_dnsfile}" ]
-        then
-            if [ "${adb_dns}" = "named" ] || [ "${adb_dns}" = "kresd" ]
-            then
-                adb_cnt="$(( ( $(wc -l < "${adb_dnsdir}/${adb_dnsfile}") - $(printf "%s" "${adb_dnsheader}" | grep -c "^") ) / 2 ))"
-            else
-                adb_cnt="$(wc -l < "${adb_dnsdir}/${adb_dnsfile}")"
-            fi
-        fi
+        f_count
+    fi
+
+    if [ ${adb_backup_mode} -eq 1 ]
+    then
+        mode="normal/backup mode"
+    elif [ ${adb_whitelist_mode} -eq 1 ]
+    then
+        mode="whitelist mode"
     fi
 
     if [ -z "${adb_fetchinfo}" ] && [ -s "${adb_rtfile}" ]
@@ -519,16 +674,22 @@ f_jsnupdate()
     json_add_object "data"
     json_add_string "adblock_status" "${status}"
     json_add_string "adblock_version" "${adb_ver}"
-    json_add_string "overall_domains" "${adb_cnt}"
+    json_add_string "overall_domains" "${adb_cnt} (${mode})"
     json_add_string "fetch_utility" "${adb_fetchinfo}"
     json_add_string "dns_backend" "${adb_dns} (${adb_dnsdir})"
     json_add_string "last_rundate" "${rundate}"
     json_add_string "system_release" "${adb_sysver}"
     json_close_object
     json_dump > "${adb_rtfile}"
+
+    if [ ${adb_notify} -eq 1 ] && [ -x /etc/adblock/adblock.notify ] && ([ "${status}" = "error" ] || \
+        ([ "${status}" = "enabled" ] && [ ${adb_whitelist_mode} -eq 0 ] && [ ${adb_cnt} -le ${adb_notifycnt} ]))
+    then
+        (/etc/adblock/adblock.notify >/dev/null 2>&1) &
+    fi
 }
 
-# f_status: output runtime information
+# output runtime information
 #
 f_status()
 {
@@ -548,7 +709,7 @@ f_status()
     fi
 }
 
-# f_log: write to syslog, exit on error
+# write to syslog, exit on error
 #
 f_log()
 {
@@ -559,15 +720,11 @@ f_log()
         logger -t "adblock-[${adb_ver}] ${class}" "${log_msg}"
         if [ "${class}" = "error" ]
         then
-            logger -t "adblock-[${adb_ver}] ${class}" "Please check 'https://github.com/openwrt/packages/blob/master/net/adblock/files/README.md' (${adb_sysver})"
-            f_rmtemp
-            if [ -s "${adb_dnsdir}/${adb_dnsfile}" ]
-            then
-                f_rmdns
-                f_dnsrestart
-            fi
             adb_rc=1
+            f_rmdns
             f_jsnupdate
+            f_rmtemp
+            logger -t "adblock-[${adb_ver}] ${class}" "Please check 'https://github.com/openwrt/packages/blob/master/net/adblock/files/README.md' (${adb_sysver})"
             exit 1
         fi
     fi
@@ -577,11 +734,9 @@ f_log()
 #
 f_main()
 {
-    local src_name src_rset shalla_archive enabled url hash_old hash_new
-    local mem_total="$(awk '/^MemTotal/ {print int($2/1000)}' "/proc/meminfo")"
+    local src_name src_rset shalla_archive enabled url mem_total="$(awk '/^MemTotal/ {print int($2/1000)}' "/proc/meminfo")"
 
-    f_log "info " "start adblock processing ..."
-    f_log "debug" "action: ${adb_action}, dns: ${adb_dns}, fetch: ${adb_fetchinfo}, hashsum: ${adb_hashsum}, backup: ${adb_backup}, backup_mode: ${adb_backup_mode}, whitelist_mode: ${adb_whitelist_mode}, force_srt/_dns: ${adb_forcesrt}/${adb_forcedns}, mem_total: ${mem_total}"
+    f_log "debug" "dns: ${adb_dns}, fetch_util: ${adb_fetchinfo}, backup: ${adb_backup}, backup_mode: ${adb_backup_mode}, whitelist_mode: ${adb_whitelist_mode}, force_srt/_dns: ${adb_forcesrt}/${adb_forcedns}, mem_total: ${mem_total}"
     > "${adb_rtfile}"
     > "${adb_dnsdir}/.${adb_dnsfile}"
 
@@ -598,10 +753,11 @@ f_main()
         awk "${adb_whitelist_rset}" "${adb_whitelist}" > "${adb_tmpdir}/tmp.whitelist"
     fi
 
-    # whitelist mode
+    # whitelist mode processing
     #
     if [ ${adb_whitelist_mode} -eq 1 ] && [ "${adb_dns}" != "dnscrypt-proxy" ]
     then
+        f_hashcompare
         f_tldcompression "${adb_tmpdir}/tmp.whitelist"
         eval "${adb_dnsformat}" "${adb_tmpdir}/tmp.whitelist" > "${adb_dnsdir}/${adb_dnsfile}"
         printf '%s\n' "${adb_dnsblock}" >> "${adb_dnsdir}/${adb_dnsfile}"
@@ -610,7 +766,11 @@ f_main()
             printf '%s\n' "${adb_dnsheader}" | cat - "${adb_dnsdir}/${adb_dnsfile}" > "${adb_tmpdir}/${adb_dnsfile}"
             cat "${adb_tmpdir}/${adb_dnsfile}" > "${adb_dnsdir}/${adb_dnsfile}"
         fi
-        f_dnsrestart
+        f_hashcompare
+        if [ ${?} -eq 1 ]
+        then
+            f_dnsrestart
+        fi
         if [ ${?} -eq 0 ]
         then
             f_jsnupdate "${adb_cnt}"
@@ -618,10 +778,11 @@ f_main()
         else
             f_log "error" "dns backend restart with active whitelist failed"
         fi
+        f_rmtemp
         return
     fi
 
-    # normal & backup mode
+    # normal & backup mode processing
     #
     for src_name in ${adb_sources}
     do
@@ -634,7 +795,7 @@ f_main()
 
         # basic pre-checks
         #
-        f_log "debug" "name: ${src_name}, enabled: ${enabled}, url: ${url}, rset: ${src_rset}"
+        f_log "debug" "name: ${src_name}, enabled: ${enabled}"
         if [ "${enabled}" != "1" ] || [ -z "${url}" ] || [ -z "${src_rset}" ]
         then
             f_list remove
@@ -662,7 +823,7 @@ f_main()
         elif [ "${src_name}" = "shalla" ]
         then
             shalla_archive="${adb_tmpdir}/shallalist.tar.gz"
-            "${adb_fetch}" ${adb_fetchparm} "${shalla_archive}" "${url}" 2>/dev/null
+            "${adb_fetchutil}" ${adb_fetchparm} "${shalla_archive}" "${url}" 2>/dev/null
             adb_rc=${?}
             if [ ${adb_rc} -eq 0 ]
             then
@@ -679,11 +840,11 @@ f_main()
             rm -f "${shalla_archive}"
             rm -rf "${adb_tmpdir}/BL"
         else
-            "${adb_fetch}" ${adb_fetchparm} "${adb_tmpload}" "${url}" 2>/dev/null
+            "${adb_fetchutil}" ${adb_fetchparm} "${adb_tmpload}" "${url}" 2>/dev/null
             adb_rc=${?}
         fi
 
-        # check download result and prepare list output (incl. tld compression, list backup & restore)
+        # check download result and prepare list output
         #
         if [ ${adb_rc} -eq 0 ] && [ -s "${adb_tmpload}" ]
         then
@@ -716,12 +877,9 @@ f_main()
         fi
     done
 
-    # hash preparation, whitelist removal and overall sort
+    # overall sort and conditional dns restart
     #
-    if [ -x "${adb_hashsum}" ] && [ -f "${adb_dnsdir}/${adb_dnsfile}" ]
-    then
-        hash_old="$(${adb_hashsum} "${adb_dnsdir}/${adb_dnsfile}" 2>/dev/null | awk '{print $1}')"
-    fi
+    f_hashcompare
     if [ -s "${adb_tmpdir}/${adb_dnsfile}" ]
     then
         if [ ${mem_total} -ge 64 ] || [ ${adb_forcesrt} -eq 1 ]
@@ -733,15 +891,9 @@ f_main()
         > "${adb_dnsdir}/${adb_dnsfile}"
     fi
     chown "${adb_dnsuser}" "${adb_dnsdir}/${adb_dnsfile}" 2>/dev/null
-    f_rmtemp
 
-    # conditional restart of the dns backend and runtime information export
-    #
-    if [ -x "${adb_hashsum}" ] && [ -f "${adb_dnsdir}/${adb_dnsfile}" ]
-    then
-        hash_new="$(${adb_hashsum} "${adb_dnsdir}/${adb_dnsfile}" 2>/dev/null | awk '{print $1}')"
-    fi
-    if [ -z "${hash_old}" ] || [ -z "${hash_new}" ] || [ "${hash_old}" != "${hash_new}" ]
+    f_hashcompare
+    if [ ${?} -eq 1 ]
     then
         f_dnsrestart
     fi
@@ -752,6 +904,7 @@ f_main()
     else
         f_log "error" "dns backend restart with active blocklist failed"
     fi
+    f_rmtemp
 }
 
 # handle different adblock actions
@@ -759,31 +912,28 @@ f_main()
 f_envload
 case "${adb_action}" in
     stop)
-        f_rmtemp
         f_rmdns
-        f_dnsrestart
-        ;;
+    ;;
     restart)
-        f_rmtemp
-        f_rmdns
         f_envcheck
+        f_rmdns
         f_main
-        ;;
+    ;;
     suspend)
         f_switch suspend
-        ;;
+    ;;
     resume)
         f_switch resume
-        ;;
+    ;;
     query)
         f_query "${2}"
-        ;;
+    ;;
     status)
         f_status
-        ;;
+    ;;
     *)
         f_envcheck
         f_main
-        ;;
+    ;;
 esac
 exit 0