[OpenSIPS-Users] Several questions on nat_traversal

Julian Santer julian.santer at rolmail.net
Wed Dec 23 15:37:56 CET 2015

Hi guys,

we are using the nat_traversal module and nat_keepalive().
Now we got some problems with a specific kind of installation.
The UAC is a AVM Fritz!Box (different models) with current firmware as ip client behind NAT (fibre router).
We send each 56 seconds a keepalive OPTIONS. After some time, the Fritz!Box blocks our SIP traffic.
We spoke with AVM and they told us, that the OPTIONS are not formatted as they expect. It's missing the username in the TO header.
And as we send every 56 seconds a package there is mechanism to detect and prevent DOS attacks.

1) AVM asked us to increase the interval. It's possible to set a dynamic keepalive_interval per user?
I don't want do increase the interval for all users. Maybe we got some problems with other scenarios.

2) nat_keepalive sends OPTIONS. In this options the TO header looks like: sip:IP:PORT
Is there a possibility to add the username in the TO header?
AVM said, if we sent OPTIONS with username, the DOS mechanism should not be triggered anymore.

Best regards and merry christmas,
Julian Santer
Raiffeisen OnLine

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