Asterisk IP updater & SIP blocker

astipupdate script, detects public ip and sip peer ip change , blocks unwanted sip traffic.
script start parameter will permit sip traffic only for trusted hosts via iptables,
can also update them with updatepeer parameter if ip changes.
updatepublic parameter reloads asterisk on public ip change (in case you have too long register intervals).
copy this script to /etc/init.d and activate it with update-rc.d astipupdate defaults
enable in cron like: */5 * * * * root /etc/init.d/astipupdate updateboth &> /dev/null

Now includes also an ddnsupdater which uses a simple wget to update if host cmd detects a change.