[Gambas-user] UDP hole punching

[Brian G]

Yes Dimitris!
--
Thanks
Brian G Tuesday, 01 June 2021, 05:32PM -07:00 from Dimitris Anogiatis  dosida at gmail.com :

>Brian G,
>
>A silly question. So in essence is hole punching just basically using an external server S to connect two clients A and B without doing port forwarding on each other's router?
>On Tue, Jun 1, 2021 at 5:28 PM Brian G < brian at westwoodsvcs.com> wrote:
>>I thought the nat took care of that..
>>
>>Flow:
>>
>>A and B each begin a UDP conversation with S; the NAT devices NA and NB create UDP translation states and assign temporary external port numbers EPA and EPB.
>>
>>S examines the UDP packets to get the source port used by NA and NB (the external NAT ports EPA and EPB).
>>
>>S passes EIPA:EPA to B and EIPB:EPB to A.
>>
>>A sends a packet to EIPB:EPB.
>>
>>NA examines A's packet and creates the following tuple in its translation table: (Source-IP-A, EPA, EIPB, EPB).
>>
>>B sends a packet to EIPA:EPA.
>>
>>NB examines B's packet and creates the following tuple in its translation table: (Source-IP-B, EPB, EIPA, EPA).
>>
>>Depending on the state of NA's translation table when B's first packet arrives 
>>   (i.e. whether the tuple (Source-IP-A, EPA, EIPB, EPB) has been created by the time of arrival of B's first packet),
>>   B's first packet is dropped (no entry in translation table) or passed (entry in translation table has been made).
>>
>>Depending on the state of NB's translation table when A's first packet arrives
>>   (i.e. whether the tuple (Source-IP-B, EPB, EIPA, EPA) has been created by the time of arrival of A's first packet),
>>   A's first packet is dropped (no entry in translation table) or passed (entry in translation table has been made).
>>
>>At worst, the second packet from A reaches B; at worst the second packet from B reaches A. 
>>   Holes have been "punched" in the NAT and both hosts can directly communicate.
>>
>>
>>From this it looks like your app get a message from S the go between containing the ip and port and then creates an outbound connection to the other host
>>looks like you just need to read s's message and create a new udp connection to B.
>>
>>Maybe I am just miss reading or don't get what you are doing.
>>
>>Do you have a sample program?
>>
>>"Failure is the key to success; 
>> each mistake teaches us something"  .. Morihei Ueshiba
>>Brian G
>>
>>----- On Jun 1, 2021, at 10:43 AM, Mayost Sharon  sharon at 455.co.il wrote:
>>
> Hello to you
>
> Can it be done:
> UDP hole punching
> Through:
> gb.net
>
> I understand that I need to change:
> UdpSocket.SourceHost and UdpSocket.SourcePort
> And they are for reading only
> They cannot be changed
>
> Is there another way to perform: UDP hole punching
>
> Thank you
>
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>>
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