If you are only connecting to specified SIP providers, then you could specify those endpoints at the firewall level, which would help.
> Date: Thu, 14 Jun 2012 10:27:50 +0800
> From: ocset@the800group.com
> To: freeswitch-users@lists.freeswitch.org
> Subject: [Freeswitch-users] Brute-force attack
>
> Hi
>
> I have deployed Freeswiitch on windows 7 and since there is no fail2ban
> on windows, I was wondering what the real risk is with opening it up to
> the internet. If I was to ensure that all users and passwords were
> extremely difficult to guess (passwords like "2$53E_d7?^2!3s$"), what
> are the risks that I am exposing myself to? Is there a type of DoS for
> voip where hackers can just flood my system with requests simply to be
> malicious?
>
> There are VB windows scripts available that emulate what fail2ban does
> on Linux but I was just wondering whether I really need to implement
> this level of security if I can control the password complexity in
> Freeswitch.
>
> Thanks
> O