DynDNS updates with TSIG and /etc/ppp/ip-up.local but without NetworkManager

ip-up.local

#!/bin/bash
#
# adapted from
# NetworkManager dispatcher script to update dyndns via TSIG using nsupdate
# http://centos5.pcfe.net/wordpress/2011/09/dyndns-updates-with-tsig-and-networkmanager-dispatcher/
# http://www.pcfe.net/octopress/blog/2011/09/13/dyndns-updates-with-tsig-and-networkmanager-dispatcher/
# pcfe, 2012-09-07
#
# adaptation of http://messinet.com/trac/browser/networkmanager-nsupdate-gss-tsig/20-nsupdate-gss-tsig
# read https://www.dyndns.com/account/settings/tsig.html
# and https://www.dyndns.com/support/kb/ddns_updates_and_tsig.html
# pcfe, 2011-09-13
#

# set -x

# http://www.tldp.org/HOWTO/PPP-HOWTO/x1455.html
# When the ppp link comes up, this script is called with the following
# parameters
#       $1      the interface name used by pppd (e.g. ppp3)
#       $2      the tty device name
#       $3      the tty device speed
#       $4      the local IP address for the interface
#       $5      the remote IP address
#       $6      the parameter specified by the 'ipparam' option to pppd
#

#
# Function definitions
#

# Invoke nsupdate 
# (vars defined below)
updateRRs() {
  (echo "server update.dyndns.com"
   echo "zone ${ZONE}"
   echo "key ${KEY_NAME} ${KEY_HMAC}"
   echo "update add ${HOST}.${ZONE} ${TTL} A ${ADDR}"
   echo "send"
  ) | nsupdate -t 60 || exit 1
}

#
# Start working...
#

# Set the host name & ttl
ADDR=`/sbin/ifconfig $1 | grep "inet addr:" | awk '{print $2}' | awk -F ":" '{print $2}'`
#ADDR=`/sbin/ifconfig $1 | grep "inet " | awk '{print $2}'`
# short TTL so we have the new address shortly after ADSL came up
TTL=60
# the DynDNS hostname and zone you want to update, e.g. myserver.mydomain.net
HOST="myserver"
ZONE="mydomain.net"
# get the next two values from https://www.dyndns.com/account/settings/tsig.html
KEY_NAME="MyKeyName"
KEY_HMAC="MyKeyHMAC"
# Proceed only if called for ppp  interface
if [[ "$1" ==  ppp* ]]
then
  # logger "Called as $0 $@."
  logger updating DNS to point at $4
  updateRRs
else
  logger "Not called for ppp interface. Exiting."
  exit 1
fi

exit 0