[Freeswitch-users] VoIP IP DSLAMs

David Ponzone david.ponzone at ipeva.fr
Sun Jun 19 11:33:25 MSD 2011

Let's say a weird way to do NAT.
To make it short, the algorithm to compute the external source port of a connection was statically computed from source IP and source port (no randomization of any kind).
So basically, if you had a packet coming from internal IP:port and one coming from internal IP+1:port-1, both were using the same outside port....
You can imagine the result of that with RTP and its systematic RTCP flow using the same port+1.
We had no to number the IP Phones using consecutive IP addresses...

The issue is I had trouble to convince the support that was very wrong.

David Ponzone  Direction Technique
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Le 18/06/2011 à 18:31, shouldbe q931 a écrit :

> 2011/6/18 David Ponzone <david.ponzone at ipeva.fr>:
>> I found bugs in the NAT layer of the Vigor 2820 that I prefer not to tell
>> you about....
> Is this a security issue, or a breaks protocol x issue ?
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