[Serusers] Ser + Windows NAT

SIP sip at arcdiv.com
Tue Jun 12 20:46:59 CEST 2007

We've also had serious problems with boxes behind Windows as a NATted 
gateway. It does some very funky thing with the way it handles ports. It 
doesn't seem to want to keep open ports for return communications after 
an outgoing communication.

For instance, when I send data out port 3510, awaiting a response, it 
immediately closes the port. It's incredibly, frustratingly non-standard 


Thomas Britis wrote:
> Hi all,
> 	I'm getting a problem when a user behind a windows gateway (NATed 
> client) connects to my ser box.
> 	I think this was already discussed here but I didn't find anything on 
> the logs.
> 	The problem is with the '407 Proxy Authentication Required' signal that 
> never reaches the client.
> 	Here is the scenario:
> 1- The user sends the INVITE from a higher port to the SIP server.
> It looks like this:
> User:63040 -> SER:5060
> 2- SER responds with a 407 Proxy Authentication Required on the client's 
> local sip port:
> SER:5060 -> User:5060
> 	At this point, I think windows drops the package because it don't refer 
> to any entry at the NAT table, but I'm not sure about that.
> 	I want to know if there's a solution to this 'problem'.
> 	Thank you all.

More information about the Serusers mailing list