[Freeswitch-users] Update DNS SRV records

Tue Jun 18 07:05:15 UTC 2019

Hi,

slowly it becomes annoying. Since a few days I need to reload the gateway
profile twice a day to refresh the SRV records. I found out that my SIP
Provider "Deutsche Telekom" updated their Documentation of their SIP Trunk.

Perhaps interesting for others. Here is the updated PDF
https://geschaeftskunden.telekom.de/blobCache/umn/uti/457678_1548405575000/blobBinary/SIP-Trunk-Technische-Unterlage.ps

The document also includes a section on DNS and SRV. Can someone tell me if
I can make changes in the configuration based on the following information
so that the SRV records are updated correctly?

Best regards,

############

Domain and IP address recognition and resolution on the SIP trunk interface
is performed via DNS servers.

In the registration mode, the IP address, transport and port of the server
are determined according to RFC 3263 and SIPConnect 2.0 16.1 "Locating SIP
Servers".

According to RFC 3263, the SIP-PBX performs a NAPTR query for the domain
names:
- reg.sip-trunk.telekom.de.
- stat.sip-trunk.telekom.de

and receives the records with the protocols supported by the domain name
(in case of a SIP trunk usage of the TLS via TCP and TCP protocol depending
on whether the client uses TLS or not).

Since the protocol has been determined, an IP address and port must also be
determined, as described in RFC 3263, Chapter 5, and an SRV query is sent
to the record returned by the NAPTR. Finally, the client performs an
A-Record lookup on these records to obtain the IP addresses of the servers.
The destination node selection is the SIP-PBX behavior (SIPconnect 2.0,
Chapter 17.1 for Register Mode and Chapter 16.1 for Static Mode).

A lookup to these domain names is not possible. Therefore a lookup with
some tools (e.g. nslookup under some Windows versions) does not lead to
success, because these only make an A-Record query by default!
The correct query order is therefore
- NAPTR on reg.sip-trunk.telekom.de
- SRV to a record of the NAPTR response
- A to a record of the SRV response

Success also leads:
- SRV on reg.sip-trunk.telekom.de

- A to a record of the SRV response

Does not lead to success:
- A on reg.sip-trunk.telekom.de

Attention: With many PBXs, setting the port (e.g. to 5060) leads to a
behavior in which only the A record is queried, which then fails. A
NAPTR/SRV query is only performed if the port is set to "0". (The
background is that the SRV query provides the port, i.e. the port cannot be
set to a fixed value in advance).

############

Am Di., 7. Mai 2019 um 13:42 Uhr schrieb Paul Muaddib <
paul.muaddib83 at gmail.com>:

> How can I check the TTL of the SRV register?
>
> Am Di., 7. Mai 2019 um 12:36 Uhr schrieb Raúl Alexis Betancor Santana <
> rbetancor at gmail.com>:
>
>> The only way you have is to tell FS to "reload" that provider gw profile.
>>
>> You should check the TTL of that provider SRV registers as may be a
>> problem on their end, not updating them correctly.
>>
>> On Tue, May 7, 2019 at 10:25 AM Paul Muaddib <paul.muaddib83 at gmail.com>
>> wrote:
>>
>>> Hi Lawrence,
>>>
>>> I think that you want to know how to tell your fS to re-lookup the SRV
>>>> records for that gateway's domain while running, as the SRV records in that
>>>> provider's DNS changes regularly.
>>>>
>>>> I can't help on the details of fS's DNS lookup code, but is that the
>>>> actual problem you have and so the question you want to ask?
>>>>
>>>
>>> Yes, that is my problem.
>>>
>>> Am Di., 7. Mai 2019 um 00:07 Uhr schrieb Lawrence Conroy <
>>> lconroy at insensate.co.uk>:
>>>
>>>> Hi
>>>>  They may do; they may not. It's hard to tell when the question is that
>>>> confusing.
>>>>
>>>> 1. IIUC, fS doesn't update local DNS records at all.
>>>> (it could, but you'd need to write something external to do the DNS
>>>> update).
>>>>
>>>> 2. you talk of not being able to call OUT.
>>>> That's good, as it means there is no need to update your domain's DNS
>>>> records.
>>>>
>>>> I assume that what you mean is that your provider changes its SRV
>>>> records every couple of days.
>>>> You have a gateway entry in your fS config for that provider.
>>>> That gateway spec has a defined domain name for the server.
>>>> I think that you want to know how to tell your fS to re-lookup the SRV
>>>> records for that gateway's domain while running, as the SRV records in that
>>>> provider's DNS changes regularly.
>>>>
>>>> I can't help on the details of fS's DNS lookup code, but is that the
>>>> actual problem you have and so the question you want to ask?
>>>>
>>>> br,
>>>>   Lawrence
>>>>
>>>>
>>>> On 6 May 2019, at 21:04, Paul Muaddib <paul.muaddib83 at gmail.com> wrote:
>>>>
>>>> > Really nobody with the same problem?
>>>> >
>>>> > Am Do., 2. Mai 2019 um 11:23 Uhr schrieb Paul Muaddib <
>>>> paul.muaddib83 at gmail.com>:
>>>> > Hi,
>>>> >
>>>> > how can I tell freeswitch to update the SRV records or is there a way
>>>> to force the update without restarting. My provider keeps changing the
>>>> entries after a few days and if I don't restart freeswitch I can not call
>>>> out anymore (403)
>>>> >
>>>> > Best regards
>>>> >
>>>> _________________________________________________________________________
>>>> >
>>>> > The FreeSWITCH project is sponsored by SignalWire
>>>> https://signalwire.com
>>>> > Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>>>> services.
>>>> > Build your next product on our scalable cloud platform.
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>>>> >
>>>> > Professional FreeSWITCH Services
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>>>> >
>>>> > Official FreeSWITCH Sites
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>>>>
>>>>
>>>>
>>>> _________________________________________________________________________
>>>>
>>>> The FreeSWITCH project is sponsored by SignalWire
>>>> https://signalwire.com
>>>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>>>> services.
>>>> Build your next product on our scalable cloud platform.
>>>>
>>>> Join our online community to chat in real time
>>>> https://signalwire.community
>>>>
>>>> Professional FreeSWITCH Services
>>>> sales at freeswitch.com
>>>> https://freeswitch.com
>>>>
>>>> Official FreeSWITCH Sites
>>>> https://freeswitch.com/oss
>>>> https://freeswitch.org/confluence
>>>> https://cluecon.com
>>>>
>>>> FreeSWITCH-users mailing list
>>>> FreeSWITCH-users at lists.freeswitch.org
>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>> UNSUBSCRIBE:
>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>> https://freeswitch.com
>>>
>>> _________________________________________________________________________
>>>
>>> The FreeSWITCH project is sponsored by SignalWire https://signalwire.com
>>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>>> services.
>>> Build your next product on our scalable cloud platform.
>>>
>>> Join our online community to chat in real time
>>> https://signalwire.community
>>>
>>> Professional FreeSWITCH Services
>>> sales at freeswitch.com
>>> https://freeswitch.com
>>>
>>> Official FreeSWITCH Sites
>>> https://freeswitch.com/oss
>>> https://freeswitch.org/confluence
>>> https://cluecon.com
>>>
>>> FreeSWITCH-users mailing list
>>> FreeSWITCH-users at lists.freeswitch.org
>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>>> https://freeswitch.com
>>
>> _________________________________________________________________________
>>
>> The FreeSWITCH project is sponsored by SignalWire https://signalwire.com
>> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN
>> services.
>> Build your next product on our scalable cloud platform.
>>
>> Join our online community to chat in real time
>> https://signalwire.community
>>
>> Professional FreeSWITCH Services
>> sales at freeswitch.com
>> https://freeswitch.com
>>
>> Official FreeSWITCH Sites
>> https://freeswitch.com/oss
>> https://freeswitch.org/confluence
>> https://cluecon.com
>>
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>> https://freeswitch.com
>
>
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