[Freeswitch-users] To Proxy Media or Not

Kristian Kielhofner kris at kriskinc.com
Wed Mar 9 20:02:14 MSK 2011

If your intention is to *strictly* hide topology proxy media will
rewrite the IP address in the SDP but that's about it.  Technically
that counts as "topology hiding".  Other SDP parameters, however, will
pass through and leak various bits of information about the endpoints
behind the SBC:

- Codec support
- Payload types
- Other "random" various SDP parameters

Most real SBCs will rewrite the entire SDP (as FS does by default).

Another thing to consider - the vast majority of FS users do not use
proxy media (and most that do use it incorrectly).  This leaves you
open to the possibility that you'll experience strange edge case bugs
using a media mode different from the majority of the rest of the FS
user base.

On Wed, Mar 9, 2011 at 10:52 AM, Max Clark <max.clark at gmail.com> wrote:
> Hello,
> I have a couple of FreeSWITCH boxes functioning as SBCs on our
> network. We need them to:
> - Route Calls
> - Function as B2BUAs for call logging
> - Hide topology from the endpoints
> They do not need to:
> - Intercept/play audio
> - Manipulate the SDP
> - Transcode
> - Process anything other than SIP
> So these machines have been running with Proxy Media enabled in the
> dialplan. Is the the proper/recommended way of configuring for our
> environment/needs? Is the minimal gain of resources by not processing
> the RTP worth it?
> Thanks,
> Max

Kristian Kielhofner

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