[asterisk-users] configure SRTP port range?
hw at gc-24.de
Sat Feb 23 10:53:13 CST 2019
On 2/23/19 5:39 PM, Joshua C. Colp wrote:
> On Sat, Feb 23, 2019, at 12:17 PM, hw wrote:
>>> Any source to UDP ports X to Y (10000 to 20000 by default) allow.
>> Are you saying that the ports specified in rtp.conf ('rtpstart' and
>> 'rtpend') specify with ports asterisk uses regardless whether RTP or
>> SRTP is being used? Is that why you speak of "media" (ports)?
>> (That would have been and would answer my original question: Where to
>> specify the SRTP ports?)
Maybe a hint like "these ports are used for SRTP as well" in the default
rtp.conf would clarify this. (I was actually looking for an srtp.conf
to begin with ...)
>>> What you can't do is limit the rule based on the source of media, except for circumstances where you know for sure the source.
>>> Note that RTP ports in Asterisk aren't open all the time and only listen when a call is using it, and they also learn the source of media - blocking out other sources.
>> After opening the ports specified in rtp.conf, both RTP and SRTP were
>> working in the test calls I made. But:
>> How do clients know which media ports to use? Is asterisk telling them
>> I. e., can I (basically) rely on the clients to use the media ports in
>> rtp.conf, or did I just get lucky that by chance the clients happened to
>> use these ports when I made the test calls?
> It's exchanged as part of call setup using SDP. SDP specifies where media should be sent, the codecs that can be used, and also controls hold/unhold. Each side provides SDP which is parsed, interpreted, negotiated, and used.
Thank you very much! So I got this to work; next step would be to try
it with clients from outside the local network ... :)
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