diff --git a/4-public-ip.sh b/4-public-ip.sh
index 8347d17..1538e1e 100755
--- a/4-public-ip.sh
+++ b/4-public-ip.sh
@@ -1,8 +1,8 @@
 #!/bin/bash
 
-# does not always work, when you have an IPv6 connection
-#dig +short A myip.opendns.com @resolver1.opendns.com
+# works consistently if you specify the -4 to force IPv4
+dig -4 +short A myip.opendns.com @resolver1.opendns.com
 
-curl https://ipinfo.io/ip
-echo ""
+#curl --fail --silent --show-error https://ipinfo.io/ip
+#echo ""
 
diff --git a/6-public-ip.sh b/6-public-ip.sh
index 9584d55..9bd7b32 100755
--- a/6-public-ip.sh
+++ b/6-public-ip.sh
@@ -1,4 +1,5 @@
 #!/bin/bash
 
-dig +short AAAA myip.opendns.com @resolver1.opendns.com
+# works consistently if you specify the -6 to force IPv6
+dig -6 +short AAAA myip.opendns.com @resolver1.opendns.com
 
diff --git a/dynv6.sh b/dynv6.sh
new file mode 100755
index 0000000..7dfa1b0
--- /dev/null
+++ b/dynv6.sh
@@ -0,0 +1,85 @@
+#!/bin/sh
+
+hostname=$1
+device=$2
+
+file4="$HOME/.dynv6.addr4"
+file6="$HOME/.dynv6.addr6"
+
+[ -e $file4 ] && old4=`cat $file4`
+[ -e $file6 ] && old6=`cat $file6`
+
+# ensure we have required information
+if [ -z "$hostname" -o -z "$token" ]; then
+    echo "Usage: token=<your-authentication-token> [netmask=64] $0 your-name.dynv6.net [device]"
+    exit 1
+fi
+
+# [device] would be something like "eth0" or "wlan0"
+if [ -n "$device" ]; then
+    device="dev $device"
+fi
+
+# what command should we use to call the API
+if [ -e /usr/bin/curl ]; then
+    bin="curl -fsS"
+elif [ -e /usr/bin/wget ]; then
+    bin="wget -O-"
+else
+    echo "neither curl nor wget found"
+    exit 1
+fi
+
+# what command should we use to determine IPv4
+if [ -e /usr/bin/dig ]; then
+    lookup4="dig -4 +short A myip.opendns.com @resolver1.opendns.com"
+else
+    lookup4="$bin https://ipinfo.io/ip"
+fi
+
+# lookup IPv4
+ipv4=`$lookup4`
+if [ -z "$ipv4" ]; then
+    echo "failed to lookup IPv4 address, continuing with 'auto'"
+    ipv4="auto"
+fi
+
+# calculate IPv6
+address6=$(ip -6 addr list scope global $device | grep -v " fd" | sed -n 's/.*inet6 \([0-9a-f:]\+\).*/\1/p' | head -n 1)
+
+if [ -z "$address6" ]; then
+    echo "no IPv6 address found"
+    exit 1
+fi
+
+if [ -z "$netmask" ]; then
+    netmask="128"
+fi
+
+ipv6="$address6/$netmask"
+
+# update IPv4, if changed
+if [ "$old4" = "$ipv4" ]; then
+    echo "IPv4 address unchanged"
+else
+    echo -n "Updating IPv4: "
+    $bin "https://ipv4.dynv6.com/api/update?hostname=$hostname&ipv4=$ipv4&token=$token"
+    echo ""
+
+    # save current address
+    echo $ipv4 > $file4
+fi
+
+# update IPv6, if changed
+if [ "$old6" = "$ipv6" ]; then
+    echo "IPv6 address unchanged"
+else
+    # send addresses to dynv6
+    echo -n "Updating IPv6: "
+    $bin "https://ipv6.dynv6.com/api/update?hostname=$hostname&ipv6=$ipv6&token=$token"
+    echo ""
+
+    # save current address
+    echo $ipv6 > $file6
+fi
+