[asterisk-users] IAX port

Ishfaq Malik ish at pack-net.co.uk
Tue Feb 10 07:04:24 CST 2015

On 10 February 2015 at 12:55, jg <webaccounts173 at jgoettgens.de> wrote:

>> Some firewalls have a 'consistent NAT' option that needs to be enabled,
>> otherwise you get the symptoms described.
>>  While reading about NAT, I came across this web site:
> http://nattest.net.in.tum.de/
> The test tool looks at various NAT related properties and prints the
> results related to TCP/UDP binding properties, TCP/UDP hole punching, etc.
> In my case a very short value was reported for the UDP timeout, such that
> depending on the sequence of packets, the entry in the mapping table might
> already have been deleted. This could explain the random nature of my
> connection problem. Port predictability does not seem to be a problem.
> Does that make any sense?
> jg

UDP timeout being too short is another thing I've experience with firewalls
(admittedly limited and once removed experience). Actually, this one can be
a (mild) problem on Draytek routers and can be resolved by telnetting into
the router and using the portmaptime command.

Also, turn of stateful packet inspection if it is an option.


Ishfaq Malik
Department: VOIP Support
Company: Packnet Limited
t: +44 (0)845 004 4994
f: +44 (0)161 660 9825
e: ish at pack-net.co.uk
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