diff --git a/scripts/_common.sh b/scripts/_common.sh
index 901985c..687315f 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -8,6 +8,31 @@
 # PERSONAL HELPERS
 #=================================================
 
+configure_network_interface_dnsmasq(){
+# used to put the network interface in a dedicated dnsmasq config
+
+    ipv4_interface=$(echo "$(ip -4 route get 1.2.3.4 2> /dev/null)" | head -n1 | grep -oP '(?<=dev )\w+' || true)
+    ipv6_interface=$(echo "$(ip -6 route get ::1.2.3.4 2> /dev/null)" | head -n1 | grep -oP '(?<=dev )\w+' || true)
+
+    if [ -z "$ipv4_interface" ] && [ -z "$ipv6_interface" ]; then
+            ynh_die --message="Impossible to find the main network interface, please report this issue."
+    elif [ "$ipv4_interface" != "$ipv6_interface" ]; then
+            if [ -z "$ipv4_interface" ]; then
+                    echo -e "bind-interfaces\nexcept-interface=$ipv6_interface" > "/etc/dnsmasq.d/$app"
+            elif [ -z "$ipv6_interface" ]; then
+                    echo -e "bind-interfaces\nexcept-interface=$ipv4_interface" > "/etc/dnsmasq.d/$app"
+            else
+                    echo -e "bind-interfaces\nexcept-interface=$ipv4_interface, $ipv6_interface" > "/etc/dnsmasq.d/$app"
+            fi
+    else
+            echo -e "bind-interfaces\nexcept-interface=$ipv4_interface" > "/etc/dnsmasq.d/$app"
+    fi
+
+    systemctl restart dnsmasq
+
+    ynh_store_file_checksum --file="/etc/dnsmasq.d/$app"
+}
+
 is_public_ip(){
 # used to discriminate publics IPs over privates IPs
 # private IPv4 start with: 10.; 169.; 172. or 192.168.
diff --git a/scripts/install b/scripts/install
index faf9a6a..ff98f43 100644
--- a/scripts/install
+++ b/scripts/install
@@ -77,27 +77,8 @@ usermod -a -G ssl-cert "$app"
 #=================================================
 ynh_script_progression --message="Adding a configuration file..." --weight=1
 
-# echo the ip route command to prevent a crash if the server doesn't have any ipv4/6
-ipv4_interface=$(echo "$(ip -4 route get 1.2.3.4 2> /dev/null)" | head -n1 | grep -oP '(?<=dev )\w+' || true)
-ipv6_interface=$(echo "$(ip -6 route get ::1.2.3.4 2> /dev/null)" | head -n1 | grep -oP '(?<=dev )\w+' || true)
-
-if [ -z "$ipv4_interface" ] && [ -z "$ipv6_interface" ]; then
-    ynh_die --message="Impossible to find the main network interface, please report this issue."
-elif [ "$ipv4_interface" != "$ipv6_interface" ]; then
-    if [ -z "$ipv4_interface" ]; then
-        echo -e "bind-interface\nexcept-interface=$ipv6_interface" > "/etc/dnsmasq.d/$app"
-    elif [ -z "$ipv6_interface" ]; then
-        echo -e "bind-interfaces\nexcept-interface=$ipv4_interface" > "/etc/dnsmasq.d/$app"
-    else
-        echo -e "bind-interfaces\nexcept-interface=$ipv4_interface, $ipv6_interface" > "/etc/dnsmasq.d/$app"
-    fi
-else
-    echo -e "bind-interfaces\nexcept-interface=$ipv4_interface" > "/etc/dnsmasq.d/$app"
-fi
-
-systemctl restart dnsmasq
-
-ynh_store_file_checksum --file="/etc/dnsmasq.d/$app"
+# put the network interface in a dedicated dnsmasq config
+configure_network_interface_dnsmasq
 
 # get IPv4 for the AGH config file
 ipv4_addr=$(process_ips "$(ip -4 route get 1.2.3.4 2> /dev/null | head -n1 | head -n1)")
diff --git a/scripts/restore b/scripts/restore
index d028225..2909ab7 100644
--- a/scripts/restore
+++ b/scripts/restore
@@ -41,9 +41,12 @@ ynh_script_progression --message="Restoring the app main directory..." --weight=
 
 ynh_restore_file --origin_path="$install_dir"
 
-# we need to update IP adresses in case the backup is restored in a different
+# we need to refresh IP adresses in case the backup is restored in a different
 # environment, else AGH will try to bind port 53 on non-existent IPs and crash
 
+# put the network interface in a dedicated dnsmasq config
+configure_network_interface_dnsmasq
+
 # get IPv4 for the AGH config file
 ipv4_addr=$(process_ips "$(ip -4 route get 1.2.3.4 2> /dev/null | head -n1 | head -n1)")
 
diff --git a/scripts/upgrade b/scripts/upgrade
index 915c4ab..4532929 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -126,26 +126,8 @@ usermod -a -G ssl-cert "$app"
 #=================================================
 ynh_script_progression --message="Updating a configuration file..." --weight=1
 
-ipv4_interface=$(echo "$(ip -4 route get 1.2.3.4 2> /dev/null)" | head -n1 | grep -oP '(?<=dev )\w+' || true)
-ipv6_interface=$(echo "$(ip -6 route get ::1.2.3.4 2> /dev/null)" | head -n1 | grep -oP '(?<=dev )\w+' || true)
-
-if [ -z "$ipv4_interface" ] && [ -z "$ipv6_interface" ]; then
-		ynh_die --message="Impossible to find the main network interface, please report this issue."
-elif [ "$ipv4_interface" != "$ipv6_interface" ]; then
-		if [ -z "$ipv4_interface" ]; then
-				echo -e "bind-interfaces\nexcept-interface=$ipv6_interface" > "/etc/dnsmasq.d/$app"
-		elif [ -z "$ipv6_interface" ]; then
-				echo -e "bind-interfaces\nexcept-interface=$ipv4_interface" > "/etc/dnsmasq.d/$app"
-		else
-				echo -e "bind-interfaces\nexcept-interface=$ipv4_interface, $ipv6_interface" > "/etc/dnsmasq.d/$app"
-		fi
-else
-		echo -e "bind-interfaces\nexcept-interface=$ipv4_interface" > "/etc/dnsmasq.d/$app"
-fi
-
-systemctl restart dnsmasq
-
-ynh_store_file_checksum --file="/etc/dnsmasq.d/$app"
+# put the network interface in a dedicated dnsmasq config
+configure_network_interface_dnsmasq
 
 # get IPv4 for the AGH config file
 ipv4_addr=$(process_ips "$(ip -4 route get 1.2.3.4 2> /dev/null | head -n1 | head -n1)")