[asterisk-dev] synchronizing RTP

Klaus Darilion klaus.mailinglists at pernau.at
Mon Mar 8 09:46:36 CST 2010



Am 08.03.2010 14:47, schrieb Kevin P. Fleming:
...
> TDM network, not between two packet networks. If you are going use
> SIP/G.711 as your 'TDM' network, you'll have to force that endpoint to
> only generate packets every 20ms, so that it will appear to be a TDM
> endpoint. This is not a problem in the gateway application.

Is it that Asterisk always use the received RTP packets for timing?

That actually frightens me. For example if a service provider provides 
an Echotest extension and NAT=no (or the attacker spoofes its source IP 
addres). A malicious user calls the Echo() extensions and provides in 
the SDP the IP address of the DoS target. Then it sends 10000 RTP 
packets/s to Asterisk which echos the 10000 packets to the target, thus 
exploited for a reflector attack.

regards
klaus




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