[SR-Users] nat_keepalive() and fix_contact() are incompatible - SOLVED

[David]

Hello,

I was using add_path() to add the path, in this case it was the wrong 
method.

To anyone who runs into the same problem as me, the solution is that the 
proxy doing nat should have add_path_received() instead of add_path() 
and the proxy should also have the parameter modparam("path", 
"use_received", 1). Also, loose_route() has to be called even if there 
is no to tag so that the incoming requests are routed to the phone.

With this the keep alives are sent every 20 seconds, so that's good. 
Trouble is, the state file is not being written. I will see if I can 
figure out why and post back my results.

David

On 13-05-23 04:04 AM, Daniel-Constantin Mierla wrote:
> Hello,
>
> if you have registrar behind a proxy, then you have to use path module.
>
> Cheers,
> Daniel
>
> On 5/22/13 3:17 PM, David wrote:
>> Hello,
>>
>> fix_nated_register() doesn't seem to apply in this case because my 
>> NAT proxy is seperate from my usrloc proxy. I guess I forgot that 
>> information in my first email. Sorry.
>>
>> I tried using add_contact_alias, but it does the same thing.
>>
>> Is there an example somewhere of how to use the nat keep alive option 
>> on a server that does NAT before t_relaying it to another server that 
>> has usrloc on it?
>>
>> Thanks,
>>
>> David
>>
>> On 13-05-22 04:06 AM, Klaus Darilion wrote:
>>>
>>>
>>> On 21.05.2013 18:37, David wrote:
>>>> Hello,
>>>>
>>>> So I want to setup a Kamailio SIP Proxy(  version 4 ) that will do NAT
>>>> signalling handling. With the help of nat_traversal and path modules.
>>>>
>>>> Attached is my kamailio.cfg file.
>>>>
>>>> My problem is I want to do keep alive on users who are behind NAT, 
>>>> so I
>>>> called nat_keepalive();. The script will work fine, but as soon as I
>>>> enable either add_contact_alias() or fix_contact(), the keep alive
>>>> doesn't activate.
>>>>
>>>> I modified nat_traversal.c to identify the issue and found that it is
>>>> comparing the contact header from the request and the reply to find 
>>>> the
>>>> expiration. Trouble is, the request contact header was taken from 
>>>> before
>>>> I called fix_contact() and the reply header has the contact from after
>>>> the fix_contact() call. So my traces show that on the return trip the
>>>> callback is called, I bet the stack trace looks like this :
>>>>
>>>> 1. Some method in tm
>>>> 2. __tm_reply_in() defined at nat_traversal.c:1358
>>>> 3. get_register_expire called from nat_traversal.c:1377 and defined at
>>>> nat_traversal.c:878
>>>> 4. STR_MATCH_STR called from nat_traversal.c:937 and defined at
>>>> nat_traversal.c:77
>>>>
>>>> STR_MATCH_STR returns false because the headers are different.
>>>>
>>>> I added
>>>>
>>>>                else
>>>>                          {
>>>>                                  LM_ERR("failed to match because 
>>>> request
>>>> %s is not reply %s", contact->uri.s, r_contact->uri.s ) ;
>>>>                          }
>>>>
>>>> to the code and see :
>>>>
>>>> May 21 12:18:52 kamailio-dev-nat /usr/sbin/kamailio[30163]: ERROR:
>>>> nat_traversal [nat_traversal.c:946]: failed to match because request
>>>> sip:username at mytld#015#012#015#012 is not reply
>>>> sip:username at myip:59080>;expires=60;received="sip:64.18.189.196:5060"#015#012Server: 
>>>>
>>>> CenseredUA 5.2-rc1#015#012Content-Length: 0#015#012#015
>>>>
>>>> So as you can see the original Contact header has the server's domain
>>>> name and the response has the IP address that set by fix_contact().
>>>
>>> Even if you do not call fix_contact I fail to see how the URIs 
>>> should match, as the contact URI in the response has the "expires" 
>>> parameter and therefore the string comparison should fail.
>>>
>>>> So I think that nat_keepalive() should not be comparing the Contact 
>>>> from
>>>> the original request but using the contact header from the modified
>>>> request.
>>>
>>> That would be a solution. Another solution would be to use 
>>> fix_nated_register() for REGISTER and add_contact_alias() for other 
>>> requests (from nathelper module)
>>>
>>> regards
>>> Klaus
>>>
>>>
>>>>
>>>> Any ideas what to do next ?
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
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>>>> list
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>>>>
>>
>>
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