20 Aug
2018
20 Aug
'18
5:23 p.m.
For what it's worth, we've set up a network/system where Asterisk resides
completely on a private network with Kamailio acting as an edge proxy.
RTPEngine is necessary as well to help the media through to the private
network, but that's probably not surprising. It is completely doable,
although the suggestions below about simply restricting Asterisk on a
public network to the locations of the Kamailio proxies also works quite
well.
Matching inbound requests in Asterisk to only the pool of Kamailio proxies
can be done in a variety of fashions - IP address matching being the
simplest. You will obviously need to think carefully about how Asterisk
handles its outbound calling. If Kamailio is going to act as your
registrar, then you will need to find some way to expose the registered
contacts to Asterisk - we chose this route, and wrote a small REST sidecar
to Kamailio for that purpose. If Asterisk is going to act as your
registrar, you will need to fork the REGISTER requests to all of the
Asterisk instances. Additionally, for INVITE requests being initiated by
Asterisk, you will want to force those to flow through your edge proxies.
This can be done using Asterisk's outbound_proxy setting on the AOR object
in pjsip.conf.
On Mon, Aug 20, 2018 at 6:23 AM Kevin Olbrich <ko(a)sv01.de> wrote:
Hi Henning,
I browsed the files but was unable to find one using Kamailio as SBC
without exposing the Asterisk core.
Most examples indeed expose the node and let media flow directly (
https://www.kamailio.org/events/2017-KamailioWorld/Day1/08-David.Casem-Buil…
- interesting solution with e/iBGP which we would also be able to deploy).
There was just a single presentation that I was able to locate that had
the proxy only on the edge:
https://www.kamailio.org/events/2017-KamailioWorld/Day2/15-Sebasitan.Damm-A…
At least it looks like they are located behind the SBC.
After the research my impression is, that co-locating the B2BUA with the
Edge-Proxy and firewall-ing it, seems best practice.
We will try to add some security by bridge-firewalling and BGP.
If anyone has a hint for a presentation with high-security edge-proxy, I
would appreciate it. Thank you.
Kind regards,
Kevin
Am Do., 16. Aug. 2018 um 19:12 Uhr schrieb Henning Westerholt <
hw(a)kamailio.org>gt;:
--
Matthew Jordan
Digium, Inc. | CTO
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org
Am Donnerstag, 16. August 2018, 11:57:03 CEST
schrieb Kevin Olbrich:
_______________________________________________
Kamailio (SER) - Users Mailing List
sr-users(a)lists.kamailio.org
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I am working successfully with Kamailio in my lab
setup where Kamailio
is
the SBC for Asterisk.
The network layout is looking like this:
SIP-Phone <== PUBLIC NET ==> Kamailio (SBC) <== PRIVATE NET ==> Asterisk
<== PUBLIC NET ==> Carrier
Each public network is reachable from the internet and has a local
firewall
with IP whitelists.
The internal SIP transactions are UDP-only but for external phones I
would
like to also listen for TCP/TLS.
For this layout to work with rtpproxy (before we move on to RTPengine),
we
have to enable mhomed in Kamailio.
We also have some routing issues with packets leaving with the wrong IP
via
rtpproxy (when call between carrier and external
phone needs to be
bridged).
Most examples show that Asterisk is deployed on the same network as the
external interface of Kamailio (-> Asterisk exposed to the public
network).
In our tests, this works much better but I have
great security concerns
because this Asterisk instance itself does not need to be reachable from
external.
How do other users deploy Kamailio in front of Asterisk or similar as
SBC
to secure internals?
There is lot of docs for Kamailio's config but IMHO less for the setup
as
DMZ (SBC) proxy.
Hello Kevin,
this is indeed a common setup to protect asterisk and to have also much
greater flexibility with regards to balancing and/or SIP message
adaptions.
To get some ideas, have a look to the last years conferences available
here:
https://www.kamailio.org/events/
There should be some talks about using Kamailio to in front of asterisk,
the
talk name is usually in the file name.
I think even on this year cluecon Fred Posner did a talk about Kamailio
as
Edge Proxy, and also on astricon there were some talks about this
scenario if
I remember correctly.
You should also find in the Kamailio World or FOSDEM talks a lot of
information about this scenario. You find all the talks available from
Kamailio World in our youtube channel:
https://www.youtube.com/kamailioworld
Best regards,
Henning
--
Henning Westerholt
https://skalatan.de/blog/