[asterisk-dev] Re: Asterisk servers as UDP amplifier

[Wolfgang S. Rupprecht]

John Todd <jtodd at loligo.com> writes:
> Next: How do you eliminate amplification attacks via INVITE, or SUBSCRIBE?

Move to sip over tcp and only run rtp over a udp transport?  TCP is
nice in that you really do need to get a reply to the opening 3-way
handshake before the communication channel is deemed open by the OS.
It is darn hard for some attacker to guess the random values (like the
randomized ISN) if they want to spoof someone else's address.

-wolfgang
-- 
Wolfgang S. Rupprecht                http://www.wsrcc.com/wolfgang/
Direct SIP URL Dialing: http://www.wsrcc.com/wolfgang/phonedirectory.html