[SR-Users] nathelper: ping options over tcp

[Daniel-Constantin Mierla]

Hello,

if it happens also between INVITE and 200ok or between 200ok and the
ACK, then very likely sending the OPTIONS will not help. Probably the
far end routers have a broken implementation of NAT.

Is this happening only for a specific group of users, or happens
randomly for different users?

Cheers,
Daniel


On 05.04.17 14:25, Abdoul Osséni wrote:
> Hello,
>
> Thanks for this feedback.
>
> Here the description of the issue I am trying to solve.
>
> I use already tcp_keepalive.
>
> Call flow is:
> UACs --> Nat device --> Kamailio
>
> Transport protocol is TLS.
>
> Kamailio sends TCPs keepalive (tcp_keepalive option) to the softphone
> located behind the nat devices in order to prevent disconnection due
> to network inactivity.
> In most cases I have the expected behavior, I do not have any problems.
>
> I think somes NAT devices don't properly handle TCPs keepalive because
> they close the connection after TCP keepalives.
> I have always this issue with NAT devices using VSS-Monitoring protocol.
>
> A network capture shows:
> - Kamailio sends a tcp keepalive 
> - The NAT device sends a tck keepalive ACK to Kamailio with a new
> filed : vss-monitoring
> Frame 70: 62 bytes on wire (496 bits), 62 bytes captured (496 bits)
> Linux cooked capture
> Internet Protocol Version 4, Src: x.x.x.x, Dst: x.x.x.x
> Transmission Control Protocol, Src Port: 13178, Dst Port: 443, Seq:
> 2752, Ack: 6214, Len: 0
> *VSS-Monitoring ethernet trailer, Source Port: 0*
> *Src Port: 0*
>
> - Kamailio received then a TCP from the NAT device that notifies the
> closure of the connection.
>
> Frame 73: 87 bytes on wire (696 bits), 87 bytes captured (696 bits)
> Linux cooked capture
> Internet Protocol Version 4, Src: x.x.x.x, Dst: x.x.x.x
> Transmission Control Protocol, Src Port: 13178, Dst Port: 443, Seq:
> 3436, Ack: 6214, Len: 31
> Secure Sockets Layer
>     TLSv1.2 Record Layer: Alert (Level: Warning, Description: Close
> Notify)
>         Content Type: Alert (21)
>         Version: TLS 1.2 (0x0303)
>         Length: 26
>         Alert Message
>             Level: Warning (1)
>             Description: Close Notify (0)
> - After a FIN ACK sent to Kamailio by the NAT device, a new tcp
> three-way handshake is made again.
>
> Sometimes, I have this issue during the connection establishment that
> cause a problem of sending or receiving SIP messages (for examples 200
> OK and ACK).
>
>
> The advantage of the SIP ping options is a bidirectional traffic
> through NAT. I think in this case, my issue will be solved.
>
> Regards
> Abdoul OSSENI
>
> 2017-04-05 12:48 GMT+02:00 Daniel-Constantin Mierla <miconda at gmail.com
> <mailto:miconda at gmail.com>>:
>
>     Hello,
>
>     nathelper module does ping OPTIONS only for UDP.
>
>     For tcp/tls, there is transport layer keepalive:
>
>       -
>     https://www.kamailio.org/wiki/cookbooks/5.0.x/core#tcp_keepalive
>     <https://www.kamailio.org/wiki/cookbooks/5.0.x/core#tcp_keepalive>
>
>     What is the problem you are trying to solve with this? Maybe there
>     are some other options for it.
>
>     Cheers,
>     Daniel
>
>     On 31.03.17 13:03, Abdoul Osséni wrote:
>>     Hi,
>>
>>     Is it possible to send ping OPTIONS over tcp or tls?
>>
>>     If yes, could you me how?
>>
>>     Regards
>>     Abdoul.
>>
>>
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>
>     -- 
>     Daniel-Constantin Mierla
>     www.twitter.com/miconda <http://www.twitter.com/miconda> -- www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
>     Kamailio Advanced Training - May 22-24 (USA) - www.asipto.com <http://www.asipto.com>
>     Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com <http://www.kamailioworld.com>
>
-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - May 22-24 (USA) - www.asipto.com
Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com
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