ppp(8) and inbound IP connections

Eric van Gyzen eric at vangyzen.net
Tue May 7 19:33:58 UTC 2013


On 05/07/2013 14:24, Matthias Apitz wrote:
> El día Tuesday, May 07, 2013 a las 02:17:33PM -0500, Eric van Gyzen escribió:
>
>>> Ofc, the provider must NAT somehow my local addr behind some routable
>>> valid IP addr, in our case 82.113.99.104; without this nothing would
>>> come back, even when the 1st SYN was from my side; the question is, why
>>> they do not manage the NAT table so any SYN to 82.113.99.104 is sent to
>>> my ppp link;
>>>
>>> or if they do send it, and my ppp config is wrong?
>> Most likely, multiple customers' local addresses are NATed to the same
>> routable address, so the router can't know which customer to chose for a
>> new incoming connection.  De-NATing of incoming packets for existing
>> sessions is done via per-connection state-tracking, which of course
>> doesn't exist for a new incoming connection.
> That is my understanding as well, but why they claim that they do
> support incoming connections?

Miscommunication, perhaps?

Eric


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