[SR-Users] nathelper: ping options over tcp

[Abdoul Osséni]

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>:

> 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
> 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 Mierlawww.twitter.com/miconda -- www.linkedin.com/in/miconda
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>
>
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