fail2ban is 1 option. <div><a href="http://wiki.freeswitch.org/wiki/Fail2ban">http://wiki.freeswitch.org/wiki/Fail2ban</a></div><div><br></div><div><a href="http://wiki.freeswitch.org/wiki/Fail2ban"></a>after X # of failed attempts it will be auto added to the firewall.</div>

<div><br></div><div>Restricting the external ports to only trusted hosts can be an option as well if you don&#39;t have any incoming sip calls from unknown sources.</div>