[Freeswitch-users] Question regarding continuous SIP trace with Freeswitch

Gregor Maier freeswitch13 at mailbox.org
Tue Nov 9 05:49:35 UTC 2021

Hello David!

On 09.11.21 at 00:19 David Villasmil wrote:
> Then why not just run tcpdump filtering for the signaling port and rotate
> every N bytes or Mb or whatever? And then simply pushing those files
> somewhere you can later use them?
> Maybe I misunderstood something

Yes. See my initial post: SIP (and RTP) is TLS'd and I don't have any certificate 
because the VoIP provider owns it.

> If what you want is to go at some on-demand time to trace, then just do it
> like that.

That's exactly what I'm doing with Asterisk. Asterisk is able to write pcap files. 
Therefore no problem.

Just out of curiosity, I tested the actual Homer version (with Asterisk). But I 
gave up, because:

- correlation does work only partly (maybe an Asterisk problem)
- correlation of ongoing calls doesn't work (~5 minutes e.g. and much more)
- for me, the basic list of result is highly confusing (single call legs
   aren't correlated. Even Invite and answer 401 isn't correlated)
- registers aren't correlated
- search for something like CID's doesn't work reliably (it's working 2 or 3 times
   - afterwards no more - tested w/ FF and Chromium - I wasn't able to search for 2
   CIDs at the same time)
- The GUI makes the browser going crazy (-> one CPU is used 100% after some time)

sngrep is able to correlate single call legs over hours *out of the box* - why 
can't homer do the same? I don't think, a result list based on single methods is a 
good solution - or did I miss something? This could be very possible, because I 
wasn't able to find any reliable and complete and actual documentation.

If sngrep could safe regular pcap files based on HEP data, sngrep would be the way 
to go - unfortunately, sngrep writes broken pcap files if the input data stream is 
HEP. That's a known missing feature at this time. Even sngrep itself can't read 
those pcap files any more.


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