diff --git a/miniupnpd/netfilter/iptables_init.sh b/miniupnpd/netfilter/iptables_init.sh
index 0b064c9..bf64340 100755
--- a/miniupnpd/netfilter/iptables_init.sh
+++ b/miniupnpd/netfilter/iptables_init.sh
@@ -1,10 +1,13 @@
 #! /bin/sh
 # $Id: iptables_init.sh,v 1.5 2011/05/16 12:11:37 nanard Exp $
-IPTABLES=/sbin/iptables
+IPTABLES="`which iptables`" || exit 1
+IP="`which ip`" || exit 1
 
 #change this parameters :
-EXTIF=eth0
-EXTIP="`LC_ALL=C /sbin/ifconfig $EXTIF | grep 'inet ' | awk '{print $2}' | sed -e 's/.*://'`"
+#EXTIF=eth0
+EXTIF="`LC_ALL=C $IP -4 route | grep 'default' | sed -e 's/.*dev[[:space:]]*//' -e 's/[[:space:]].*//'`" || exit 1
+EXTIP="`LC_ALL=C $IP -4 addr show $EXTIF | awk '/inet/ { print $2 }' | cut -d "/" -f 1`"
+
 echo "External IP = $EXTIP"
 
 #adding the MINIUPNPD chain for nat
diff --git a/miniupnpd/netfilter/iptables_init_and_clean.sh b/miniupnpd/netfilter/iptables_init_and_clean.sh
index 16f27d6..1783383 100755
--- a/miniupnpd/netfilter/iptables_init_and_clean.sh
+++ b/miniupnpd/netfilter/iptables_init_and_clean.sh
@@ -3,11 +3,15 @@
 # Improved Miniupnpd iptables init script.
 # Checks for state of filter before doing anything..
 
-EXTIF=eth0
-IPTABLES=/sbin/iptables
-EXTIP="`LC_ALL=C /sbin/ifconfig $EXTIF | grep 'inet ' | awk '{print $2}' | sed -e 's/.*://'`"
-NDIRTY="`LC_ALL=C /sbin/iptables -t nat -L -n | grep 'MINIUPNPD' | awk '{printf $1}'`"
-FDIRTY="`LC_ALL=C /sbin/iptables -t filter -L -n | grep 'MINIUPNPD' | awk '{printf $1}'`"
+IPTABLES="`which iptables`" || exit 1
+IP="`which ip`" || exit 1
+
+#EXTIF=eth0
+EXTIF="`LC_ALL=C $IP -4 route | grep 'default' | sed -e 's/.*dev[[:space:]]*//' -e 's/[[:space:]].*//'`" || exit 1
+EXTIP="`LC_ALL=C $IP -4 addr show $EXTIF | awk '/inet/ { print $2 }' | cut -d "/" -f 1`"
+
+NDIRTY="`LC_ALL=C $IPTABLES -t nat -L -n | awk '/MINIUPNPD/ {printf $1}'`"
+FDIRTY="`LC_ALL=C $IPTABLES -t filter -L -n | awk '/MINIUPNPD/ {printf $1}'`"
 echo "External IP = $EXTIP"
 
 if [[ $NDIRTY = "MINIUPNPDChain" ]]; then
diff --git a/miniupnpd/netfilter/iptables_removeall.sh b/miniupnpd/netfilter/iptables_removeall.sh
index df8f282..5e10d0b 100755
--- a/miniupnpd/netfilter/iptables_removeall.sh
+++ b/miniupnpd/netfilter/iptables_removeall.sh
@@ -1,10 +1,12 @@
 #! /bin/sh
 # $Id: iptables_removeall.sh,v 1.5 2011/05/16 12:11:37 nanard Exp $
-IPTABLES=/sbin/iptables
+IPTABLES="`which iptables`" || exit 1
+IP="`which ip`" || exit 1
 
 #change this parameters :
-EXTIF=eth0
-EXTIP="`LC_ALL=C /sbin/ifconfig $EXTIF | grep 'inet ' | awk '{print $2}' | sed -e 's/.*://'`"
+#EXTIF=eth0
+EXTIF="`LC_ALL=C $IP -4 route | grep 'default' | sed -e 's/.*dev[[:space:]]*//' -e 's/[[:space:]].*//'`" || exit 1
+EXTIP="`LC_ALL=C $IP -4 addr show $EXTIF | awk '/inet/ { print $2 }' | cut -d "/" -f 1`"
 
 #removing the MINIUPNPD chain for nat
 $IPTABLES -t nat -F MINIUPNPD