On Mon, 6 Feb 2006, Paco Orozco wrote:

Hola Paco,

I Cc: to the list.

...

You can see here that the NAT device is changing the source port from 5060 to 10145, which is the port used by Openser to send the reply. Openser is doing fine while your NAT device is doing wrong because it keeps the external rewriten source port when sending the packet to the internal side of the NAT (see the second line of the above tcpdump trace).

You are right, I was confused because I thought that Openser was answer me wrong.

...

Which NAT device/router are you using?. Are you forwarding ports from the external to the internal side at the NAT device?.

My NAT device is a 3Com Office Connect 812. A typical ADSL router. I haven't got any forwarding ports external to internal?

How can i solve this?

Upgrade the firmware of the router. That model is already known because the NAT management problems for UDP packets. With the last firmware version the problem should be fixed.

Saludos JesusR.

------------------------------- Jesus Rodriguez VozTelecom Sistemas, S.L. jesusr@voztele.com http://www.voztele.com Tel. 902360305 -------------------------------