28 May
2020
28 May
'20
6:58 p.m.
Welcome!
Btw, would anyone find it useful to be able to add also SRV records in
the cache via modparam? I did it for A/AAAA records, but should be easy
to extend for SRV...
Cheers,
Daniel
On 28.05.20 17:01, Alex Balashov wrote:
Thank you for this, Daniel!
On 5/28/20 3:51 AM, Daniel-Constantin Mierla wrote:
--
Daniel-Constantin Mierla -- www.asipto.com
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Funding: https://www.paypal.me/dcmierla
For the records, I added a modparam to corex
module which allows
adding A/AAAA records in the internal dns cache at startup. It could
be useful in this case as alternative for /etc/hostname entries, but
also at least for some testing scenarios to avoid updating records on
dns server, which may take time to propagate.
*
https://www.kamailio.org/docs/modules/devel/modules/corex.html#corex.p.dns_…
During runtime, there are rpc commands to add/remove records in the
dns cache.
Cheers,
Daniel
On 20.05.20 20:56, Daniel-Constantin Mierla wrote:
--
Alex Balashov | Principal | Evariste Systems LLC
Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
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Hello,
having use_dns_cache=no is not that bad if you have a local dns
cache application pointed by /etc/resolv.conf, provided that you do
not need srv based load balancing.
Not being the developer of dns resolving part in kamailio and the
dns cache, I investigated a bit and practically the /etc/hosts is
the pre-dns way of associating domains to ip addresses, without ttl
and other attributes specific to dns records. That seems the reason
the libc dns related functions do not use it implicitly, thus also
not reflected inside kamailio dns caching.
Now, you can add records to kamailio dns cache via rpc commands,
which can be done also from config using jsonrpc_exec() from
jsonrpcs module (e.g., using event_route[htable:mod-init] before sip
traffic is handled). The command should be liked:
kamctl rpc dns.add_a domain ttl ipaddr flags
The flags can be 1 to add it as a bad record (blacklisted domain) or
2 to add it as permanent record (do not expire). You can use
dns.add_aaaa for ipv6.
Actually I am now thinking to add the possibility to add to dns
cache via modparam of ipops module, to make it easier overall.
Cheers,
Daniel
On 20.05.20 19:35, George Diamantopoulos wrote:
--
Daniel-Constantin Mierla --www.asipto.com
www.twitter.com/miconda --www.linkedin.com/in/miconda
Funding:https://www.paypal.me/dcmierla
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Hello all,
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.
George
On Tue, 19 May 2020 at 19:44, Daniel-Constantin Mierla
<miconda(a)gmail.com <mailto:miconda@gmail.com>> wrote:
A quick follow up as I found quite interesting that nowadays
*BSDs allow
specifying order of lookup in resolv.conf to include the hosts
file, but
that doesn't seem to be in Linux:
* https://man.openbsd.org/resolv.conf.5#lookup
Cheers,
Daniel
On 19.05.20 17:48, Daniel-Constantin Mierla wrote:
> Hello,
>
> worth to clarify that Kamailio doesn't implement a dns resolver
from
> scratch, it still uses the functions from libc. It only does
caching and
> try to use cashing records first.
>
> By default, the following dns functions are used internally
when the
> cache doesn't have the record already -- they are set in the
dns_func
> structure:
>
> struct dns_func_t dns_func = {
> res_init,
> res_search,
> gethostbyname,
> #ifdef HAVE_GETHOSTBYNAME2
> gethostbyname2
> #else
> NULL
> #endif
> };
>
> So practically by leveraging res_init()/res_search() is
relying on
> /etc/resolv.conf to do DNS queries, which is not using the
/etc/hosts
> (iirc). For more see:
>
> * https://linux.die.net/man/3/res_search
>
> Cheers,
> Daniel
>
> On 19.05.20 17:23, Alex Balashov wrote:
>> You are correct that Kamailio does not use the libc resolver /
>> libresolv, but rather its own resolver, which ignores
/etc/hosts.
>>
>> -- Alex
>>
>> On 5/19/20 10:42 AM, George Diamantopoulos wrote:
>>> Hello all,
>>>
>>> I've come across this today when trying to setup DMQ
replication:
>>>
>>> root@sbcpub0-stage-lhe0-cn1:/root# systemctl restart kamailio
>>> root@sbcpub0-stage-lhe0-cn1:/root# kamcmd dmq.list_nodes
>>> {
>>> host: 172.30.154.189
>>> port: 5090
>>> resolved_ip: 172.30.154.189
>>> status: active
>>> last_notification: 0
>>> local: 1
>>> }
>>> root@sbcpub0-stage-lhe0-cn1:/root# getent hosts
>>> dmq-ng.services.domain.com
<http://dmq-ng.services.domain.com>
<http://dmq-ng.services.domain.com>
>>> 172.30.154.189 dmq-ng.services.domain.com
<http://dmq-ng.services.domain.com>
>>> <http://dmq-ng.services.domain.com>
>>> 172.17.130.13 dmq-ng.services.domain.com
<http://dmq-ng.services.domain.com>
>>> <http://dmq-ng.services.domain.com>
>>>
>>> root@sbcpub0-stage-lhe0-cn1:/root# grep dmq-ng /etc/kamailio/*
>>> /etc/kamailio/kamailio-module-params.cfg:modparam("dmq",
>>> "notification_address",
"sip:dmq-ng.services.domain.com:5090
<http://dmq-ng.services.domain.com:5090>
>>> <http://dmq-ng.services.domain.com:5090>")
>>>
>>> In another case, where the resolving IPs for the DMQ service
hostname
>>> were listed as A records in DNS, this worked as expected.
>>> In this case, the second host of the DMQ group is not
listed in
>>> dmq.list_nodes, despite its being set in /etc/hosts, as shown
by the
>>> getent command.
>>>
>>> Doesn't kamailio use nss for hostname resolution? Am I missing
>>> something else? Thanks!
>>>
>>> BR,
>>> George
>>>
>>>
>>> _______________________________________________
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<mailto:sr-users@lists.kamailio.org>
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>>>
>> --
>> Alex Balashov | Principal | Evariste Systems LLC
>>
>> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
>> Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
>>
>> _______________________________________________
>> Kamailio (SER) - Users Mailing List
>> sr-users(a)lists.kamailio.org
<mailto:sr-users@lists.kamailio.org>
>> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
> --
> Daniel-Constantin Mierla -- www.asipto.com
<http://www.asipto.com>
> www.twitter.com/miconda <http://www.twitter.com/miconda> --
www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
> Funding: https://www.paypal.me/dcmierla
>
-- Daniel-Constantin Mierla -- www.asipto.com
<http://www.asipto.com>
www.twitter.com/miconda <http://www.twitter.com/miconda> --
www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
Funding: https://www.paypal.me/dcmierla
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_______________________________________________
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--
Daniel-Constantin Mierla --www.asipto.com
www.twitter.com/miconda --www.linkedin.com/in/miconda
Funding:https://www.paypal.me/dcmierla