[SIPForum-discussion] Change of contact field when behind NAT

[rahul sankanur]

Hi Vijay ,
Thank you for the reply..

I see that when I connect 2 devices behind the same NAT and enable STUN in
both , I cannot get media through the mapped ports..Is this behavior proper
??

I see that the router is not routing the media to the other device (present
in same NAT) through the public side NAT... But both the devices do send
media but CAN't RECEIVE any..

I have tried it with 3 routers and find that all the routers are NOT
forwarding the packets to the other device.....

Is it a behaviour of Router NOT to route packets within the same NAT
through mapped ports???


Thanks and Regards,
Rahul Sankanur



On Thu, Oct 17, 2013 at 12:04 PM, Vijay Swami
<Vijay.Swami at matrixcomsec.com>wrote:

> Hi Rahul,****
>
> ** **
>
> It seems that one of the router is giving symmetric behavior. Please check
> the mapped port for which STUN query is made and the actual mapped port
> while sending RTP.****
>
> If both are same then there is no symmetric behavior of router and some
> other issue is there but if they are not same then Router is giving
> symmetric behavior and it will not work with STUN. ****
>
> STUN do not work with Symmetric NAT.****
>
> ** **
>
> *Regards,*
>
> *Vijay Swami* ****
>
> ** **
>
> *From:* discussion-bounces at sipforum.org [mailto:
> discussion-bounces at sipforum.org] *On Behalf Of *rahul sankanur
> *Sent:* Friday, October 11, 2013 3:01 PM
> *To:* discussion at sipforum.org
>
> *Subject:* Re: [SIPForum-discussion] Change of contact field when behind
> NAT****
>
> ** **
>
> Hi all, ****
>
> ** **
>
> Mohit and Vijay ,thank you very much for the information....****
>
> ** **
>
> I have a Belkin and a Dlink router..I have been seeing something very
> strange in both...****
>
> I have two devices behind NAT and STUN is enabled in both ..Therefore in
> their SDPs, the devices will be their respective mapped IP and ports..****
>
> But i see that the both the routers are NOT forwarding the media packets
> to the other side..Both the end devices send to the  mapped IP and mapped
> ports though...I get ICMP packets sometimes with destination port
> unreachable (but media STUN keepalive is ON).****
>
> ** **
>
> But when one device is inside NAT and other is outside , router is
> forwarding properly...****
>
> ** **
>
> So is there any other specific setting to be done in the routers or both
> the routers' routing tables are flawed???****
>
> ** **
>
> This problem arises only when 2 devices are in same NAT and media is
> flowing through the mapped port of the routers....****
>
> ** **
>
> ** **
>
> Thanks and regards,****
>
> Rahul Sankanur****
>
> ** **
>
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