[asterisk-users] IAX port

[Ishfaq Malik]

On 10 February 2015 at 09:02, jg <webaccounts173 at jgoettgens.de> wrote:

>
>
>>
>> I get an occasional similar problem, we have Mikrotik firewalls and from
>> tcpdump monitoring on the asterisk boxes I can see that the firewall
>> (unbidden) has changed the IAX port. Usually a firewall reset and sometimes
>> PBX reset combination fixes it.
>>
>> Its odd as its only one direction, occurs rarely and with no obvious
>> driver. So IAX is happy in one direction but not the other. And I can see
>> packets in the unhappy point arriving on the wrong port.
>>
>> I couldn't fix it without kicking the router/firewall so I would say its
>> a router problem in the Destination NAT process.
>>
>> Cheers Duncan
>>
>>
>>> Port is changed when NAT is applied from LAN to WAN.
>>> While UDP session is maintained as ESTABLISHED, that port should not
>>> change.
>>>
>>> If your peer changes constantly of session port could be UDP session
>>> is too short in NAT table on routers.
>>> You can try setting qualify=1000 (which is in ms. Default is 2000),
>>> and see if peer keeps same port.
>>>
>>> Regards.
>>>
>>>  voip-info.org also has an entry about general NAT related issues,
> which could be relevant here
>
> I do not seem to have problems with Netgear firewalls, but other firewalls
> show this effect. So far it happened only on a single side, such that calls
> work from the other side. I already checked the open ports with
> nc/ncat/netcat as UDP sender and receiver on the other end. The ports are
> open, even when the arbitrary ports are used by Asterisk.
>
> I'll need to read a bit more and evaluate my pcap traces and possibly ask
> the router vendors.
>
> Thank you for your efforts.
>
> jg
>
>
>
>
>
Some firewalls have a 'consistent NAT' option that needs to be enabled,
otherwise you get the symptoms described.



-- 

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
w: http://www.pack-net.co.uk

Registered Address: PACKNET LIMITED, Duplex 2, Ducie House
37 Ducie Street
Manchester, M1 2JW
COMPANY REG NO. 04920552
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.digium.com/pipermail/asterisk-users/attachments/20150210/24e4d1de/attachment.html>