This is a DDNS updater for the freedns.afraid.org service. It updates the DNS entries for two separate connected IP networks (for example, if you have work and personal ADSL) by amending the routing on the box. Note, you'll still need proper routing once it's inside your network!

ddns-update-multi-source

#! /bin/sh
# Authored by Jon Spriggs (jon@sprig.gs) on 2015-03-10
# Based on the DDNS script at afraid.org
#!/bin/bash

# ALTERNATE ROUTE
# This is the path for the second DDNS update to take
NEW_ROUTE=192.168.1.1

# TUNNELBROKER.NET CONFIGURATION
# USERNAME: This is the username you log into tunnelbroker.net with
TBN_USERNAME=""
# PASSWORD: This is the per-tunnel authenticator, found on the "Advanced" tab as "Update Key"
TBN_PASSWORD=""
# TUNNELID: This is the tunnel ID, found on the "IPv6 Tunnel" tab as "Tunnel ID"
TBN_TUNNELID=""

# FREEDNS.AFRAID.ORG CONFIGURATION
# Get this from the "Direct URL" link on http://freedns.afraid.org/dynamic/
FEO_URL_1="http://freedns.afraid.org/dynamic/update.php?<HOSTID>"
# This is the host name it refers to (or an alias of your choice) - just used for logs
FEO_Name_1="DDNS-Name-1"
# Get this from the "Direct URL" link on http://freedns.afraid.org/dynamic/
FEO_URL_2="http://freedns.afraid.org/dynamic/update.php?<HOSTID>"
# This is the host name it refers to (or an alias of your choice) - just used for logs
FEO_Name_2="DDNS-Name-2"

####################################### VARIABLE MAPPING
# This URL found here: https://forums.he.net/index.php?topic=1994.0
TBN_URL="https://ipv4.tunnelbroker.net/nic/update?username=${TBN_USERNAME}&password=${TBN_PASSWORD}&hostname=${TBN_TUNNELID}"
# Used in log files and updates
TBN_Name="Tunnel-${TBN_TUNNELID}"

############################## SCRIPT PROPER STARTS HERE
############################## DO NOT TOUCH BELOW THIS LINE!
VERBOSE=0

# Enable or disable limited debugging
if [ -n "$1" ]; then
  case $1 in
    verbose|--verbose|-v)VERBOSE=1;;
  esac
fi

# Resolve the DNS name for freedns.afraid.org
FREEDNS="`host freedns.afraid.org | cut -d " " -f4`"
if [ "$VERBOSE" != "0" ]; then echo "Resolved freedns.afraid.org to $FREEDNS"; fi

if [ -z "$FREEDNS" ]; then
  echo "Failed to identify the gateway address for FreeDNS.Afraid.org - try again later"
  exit
fi

# Update first name
# - Add route
ip -f inet route add $FREEDNS via $NEW_ROUTE
cp /etc/hosts /etc/hosts.ddnsmigrate
echo "$FREEDNS freedns.afraid.org" >> /etc/hosts
if [ "$VERBOSE" != "0" ]; then echo "Added the host route and hosts file entry for freedns.afraid.org"; fi

# - Then update record
if [ "$VERBOSE" != "0" ]
then
  RUNTIME="`date`"
  echo "Performing wget against freedns for $FEO_Name_1"
  OUTPUT="`wget -q -O - $FEO_URL_1`"
  echo "$OUTPUT"
  echo -n "$RUNTIME -  $OUTPUT" | grep -v "has not changed" >> "/tmp/ddns_${FEO_Name_1}.log" 2>&1
else
  (echo -n `date` -  && wget -q -O - "$FEO_URL_1") | grep -v "has not changed" >> "/tmp/ddns_${FEO_Name_1}.log" 2>&1
fi

# Remove route
ip -f inet route del $FREEDNS
mv /etc/hosts.ddnsmigrate /etc/hosts

# Update second name
if [ "$VERBOSE" != "0" ]
then
  RUNTIME="`date`"
  echo "Performing wget against freedns for $FEO_Name_2"
  OUTPUT="`wget -q -O - $FEO_URL_2`"
  echo "$OUTPUT"
  echo -n "$RUNTIME -  $OUTPUT" | grep -v "has not changed" >> "/tmp/ddns_${FEO_Name_2}.log" 2>&1
else
  (echo -n `date` -  && wget -q -O - "$FEO_URL_2") | grep -v "has not changed" >> "/tmp/ddns_${FEO_Name_2}.log" 2>&1
fi

# Update HE TunnelBroker.net
if [ "$VERBOSE" != "0" ]
then
  RUNTIME="`date`"
  echo "Performing wget against tunnelbroker for $TBN_Name"
  OUTPUT="`wget -q -O - $TBN_URL`"
  echo "$OUTPUT"
  echo -n "$RUNTIME -  $OUTPUT" | grep -v "nochg" >> "/tmp/ddns_${TBN_Name}.log" 2>&1
else
  (echo -n `date` -  && wget -q -O - "$TBN_URL") | grep -v "nochg" >> "/tmp/ddns_${TBN_Name}.log" 2>&1
fi

exit 0

Note, this doesn't work on IPv6 networks. Working to revise it.