[asterisk-users] Why is this happening?

[Brian Candler]

On Wed, Oct 18, 2006 at 09:11:15AM -0400, Matt wrote:
> >In the case of you example the IAX2 registration came in from the source
> >port on the far device of 1207.
> >
> >Connections don't just move between ports.
> 
> I understand all this.  However, here is my question.
> 
> MY on 4569  OTHER SIDE 1027.
> 
> Is both the incoming and outgoing traffic on OTHER SIDE going in and
> out of 1027?

Packets from the other side to you will have
   source IP         x.x.x.x
   source port       1027
   destination IP    y.y.y.y
   destination port  4569

Packets from you to the other side will have
   source IP         y.y.y.y
   source port       4569
   destination IP    x.x.x.x
   destination port  1027

If there is NAT in between, then the packets may have their source and/or
destination address and/or port changed by the time they reach the other
side. This depends on how the NAT is set up, and which device is on the
"inside" of the NAT and which is on the "outside".