[Galene] Re: udp-port range and subsequent "turn" use of ports outside that range

[Dirk-Willem van Gulik <dirkx@webweaving.org>]

> On 15 Feb 2024, at 19:09, Juliusz Chroboczek <jch@irif.fr> wrote:
> 
>> The situation is slightly more odd.  With galene ran as:
>> 
>> /usr/local/bin/galene -static /usr/local/share/galene \
>> .... \
>> -turn OUTSIDEIP:SRCPORT \
>> -udp-range 18100-19100
> 
>> I would expect to only see UDP traffic going out that originates from
>> OUTSIDEIP.
> 
> I don't see why.  The above configuration only specifies that the TURN
> server is advertised on OUTSIDEIP.  It says nothing about the addresses
> that are advertised for direct (non-TURN) traffic.
> 
> So in the above configuration, Galene will advertise:
> 
>  - all local addresses with ports 18100-19100 ;
>  - arbitrary STUN-ed addresses ;
>  - TURN addresses on OUTSIDEIP:SRCPORT.
> 
>> 1) I had not expected to see OUTSIDEIP_2 in this list at all.
> 
> That's a STUNed address.
> 
>> 2) I had not expected source UDP ports such as 11247 in below list.
> 
> If you seen port 11247 inside the NAT, then it's suprising.  Seeing port
> 11247 outside the NAT might happen if the NAT remapped a port in udp-range
> to a different value.
> 
>> With the attempts to reach 10.11.0.240 a case where perhaps some RFC1918
>> optimisation can be applied.
> 
> That's normal behaviour, the first point in the enumeration above.
> 
> Please be patient, I'm up to my ears in other stuff right now, but I'm
> really interested in understanding the behaviour you've pointed out.

No worries - feel free to ignore this completely - I'll see if I can get a more decent test case using some logging inside the sturn/ice code.

Dw.