<div dir="ltr"><div>Hello all,</div><div><br></div><div>Thank you for your enlightening answers. I ended up creating DNS entries anyway, so it's all good now. use_dns_cache=no sounded a little scary :-).<br></div><div><br></div><div>BR.</div><div>George<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, 19 May 2020 at 19:44, Daniel-Constantin Mierla <<a href="mailto:miconda@gmail.com">miconda@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">A quick follow up as I found quite interesting that nowadays *BSDs allow<br>
specifying order of lookup in resolv.conf to include the hosts file, but<br>
that doesn't seem to be in Linux:<br>
<br>
* <a href="https://man.openbsd.org/resolv.conf.5#lookup" rel="noreferrer" target="_blank">https://man.openbsd.org/resolv.conf.5#lookup</a><br>
<br>
Cheers,<br>
Daniel<br>
<br>
<br>
On 19.05.20 17:48, Daniel-Constantin Mierla wrote:<br>
> Hello,<br>
><br>
> worth to clarify that Kamailio doesn't implement a dns resolver from<br>
> scratch, it still uses the functions from libc. It only does caching and<br>
> try to use cashing records first.<br>
><br>
> By default, the following dns functions are used internally when the<br>
> cache doesn't have the record already -- they are set in the dns_func<br>
> structure:<br>
><br>
> struct dns_func_t dns_func = {<br>
> res_init,<br>
> res_search,<br>
> gethostbyname,<br>
> #ifdef HAVE_GETHOSTBYNAME2<br>
> gethostbyname2<br>
> #else<br>
> NULL<br>
> #endif<br>
> };<br>
><br>
> So practically by leveraging res_init()/res_search() is relying on<br>
> /etc/resolv.conf to do DNS queries, which is not using the /etc/hosts<br>
> (iirc). For more see:<br>
><br>
> * <a href="https://linux.die.net/man/3/res_search" rel="noreferrer" target="_blank">https://linux.die.net/man/3/res_search</a><br>
><br>
> Cheers,<br>
> Daniel<br>
><br>
> On 19.05.20 17:23, Alex Balashov wrote:<br>
>> You are correct that Kamailio does not use the libc resolver /<br>
>> libresolv, but rather its own resolver, which ignores /etc/hosts.<br>
>><br>
>> -- Alex<br>
>><br>
>> On 5/19/20 10:42 AM, George Diamantopoulos wrote:<br>
>>> Hello all,<br>
>>><br>
>>> I've come across this today when trying to setup DMQ replication:<br>
>>><br>
>>> root@sbcpub0-stage-lhe0-cn1:/root# systemctl restart kamailio<br>
>>> root@sbcpub0-stage-lhe0-cn1:/root# kamcmd dmq.list_nodes<br>
>>> {<br>
>>> host: 172.30.154.189<br>
>>> port: 5090<br>
>>> resolved_ip: 172.30.154.189<br>
>>> status: active<br>
>>> last_notification: 0<br>
>>> local: 1<br>
>>> }<br>
>>> root@sbcpub0-stage-lhe0-cn1:/root# getent hosts<br>
>>> <a href="http://dmq-ng.services.domain.com" rel="noreferrer" target="_blank">dmq-ng.services.domain.com</a> <<a href="http://dmq-ng.services.domain.com" rel="noreferrer" target="_blank">http://dmq-ng.services.domain.com</a>><br>
>>> 172.30.154.189 <a href="http://dmq-ng.services.domain.com" rel="noreferrer" target="_blank">dmq-ng.services.domain.com</a><br>
>>> <<a href="http://dmq-ng.services.domain.com" rel="noreferrer" target="_blank">http://dmq-ng.services.domain.com</a>><br>
>>> 172.17.130.13 <a href="http://dmq-ng.services.domain.com" rel="noreferrer" target="_blank">dmq-ng.services.domain.com</a><br>
>>> <<a href="http://dmq-ng.services.domain.com" rel="noreferrer" target="_blank">http://dmq-ng.services.domain.com</a>><br>
>>><br>
>>> root@sbcpub0-stage-lhe0-cn1:/root# grep dmq-ng /etc/kamailio/*<br>
>>> /etc/kamailio/kamailio-module-params.cfg:modparam("dmq",<br>
>>> "notification_address", "sip:<a href="http://dmq-ng.services.domain.com:5090" rel="noreferrer" target="_blank">dmq-ng.services.domain.com:5090</a><br>
>>> <<a href="http://dmq-ng.services.domain.com:5090" rel="noreferrer" target="_blank">http://dmq-ng.services.domain.com:5090</a>>")<br>
>>><br>
>>> In another case, where the resolving IPs for the DMQ service hostname<br>
>>> were listed as A records in DNS, this worked as expected.<br>
>>> In this case, the second host of the DMQ group is not listed in<br>
>>> dmq.list_nodes, despite its being set in /etc/hosts, as shown by the<br>
>>> getent command.<br>
>>><br>
>>> Doesn't kamailio use nss for hostname resolution? Am I missing<br>
>>> something else? Thanks!<br>
>>><br>
>>> BR,<br>
>>> George<br>
>>><br>
>>><br>
>>> _______________________________________________<br>
>>> Kamailio (SER) - Users Mailing List<br>
>>> <a href="mailto:sr-users@lists.kamailio.org" target="_blank">sr-users@lists.kamailio.org</a><br>
>>> <a href="https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users" rel="noreferrer" target="_blank">https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users</a><br>
>>><br>
>> -- <br>
>> Alex Balashov | Principal | Evariste Systems LLC<br>
>><br>
>> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)<br>
>> Web: <a href="http://www.evaristesys.com/" rel="noreferrer" target="_blank">http://www.evaristesys.com/</a>, <a href="http://www.csrpswitch.com/" rel="noreferrer" target="_blank">http://www.csrpswitch.com/</a><br>
>><br>
>> _______________________________________________<br>
>> Kamailio (SER) - Users Mailing List<br>
>> <a href="mailto:sr-users@lists.kamailio.org" target="_blank">sr-users@lists.kamailio.org</a><br>
>> <a href="https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users" rel="noreferrer" target="_blank">https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users</a><br>
> -- <br>
> Daniel-Constantin Mierla -- <a href="http://www.asipto.com" rel="noreferrer" target="_blank">www.asipto.com</a><br>
> <a href="http://www.twitter.com/miconda" rel="noreferrer" target="_blank">www.twitter.com/miconda</a> -- <a href="http://www.linkedin.com/in/miconda" rel="noreferrer" target="_blank">www.linkedin.com/in/miconda</a><br>
> Funding: <a href="https://www.paypal.me/dcmierla" rel="noreferrer" target="_blank">https://www.paypal.me/dcmierla</a><br>
><br>
-- <br>
Daniel-Constantin Mierla -- <a href="http://www.asipto.com" rel="noreferrer" target="_blank">www.asipto.com</a><br>
<a href="http://www.twitter.com/miconda" rel="noreferrer" target="_blank">www.twitter.com/miconda</a> -- <a href="http://www.linkedin.com/in/miconda" rel="noreferrer" target="_blank">www.linkedin.com/in/miconda</a><br>
Funding: <a href="https://www.paypal.me/dcmierla" rel="noreferrer" target="_blank">https://www.paypal.me/dcmierla</a><br>
<br>
<br>
_______________________________________________<br>
Kamailio (SER) - Users Mailing List<br>
<a href="mailto:sr-users@lists.kamailio.org" target="_blank">sr-users@lists.kamailio.org</a><br>
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</blockquote></div></div>