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SIP ALG

jwshome
Posts: 9
 Member Since:
2008-07-31
Submitted by jwshome on Mon, 09/01/2008 - 6:48am.

Hi, I'm new to Trixbox and noticed my router (Actiontec that comes with Verizon FIOS) has an advanced setting called SIP ALG. It is currently disabled, but based on what I've read I'm guessing that if I enable it I won't have to forward any ports and the router will handle all NAT traversal issues for SIP calls. Is this correct? If so - how do I tell the router which local machine is the Trixbox? There's no setting for that (or does the router figure that out by querying the different devices on the LAN?).

‹ TB 2.6.1 Done Searching.... Need help ›

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Kbedford
Posts: 187
 Member Since:
2008-06-12
If you want to receive calls
Mon, 09/01/2008 - 6:54am

If you want to receive calls you will still need port forwards. Also according to

http://www.voip-info.org/wiki/view/Routers+SIP+ALG

You should leave it disabled because it might break the SIP traffic all together.


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VoicePulse
Posts: 135
 Member Since:
2006-06-01
It is almost guaranteed that
Mon, 09/01/2008 - 6:55am

It is almost guaranteed that turning on whatever SIP application layer gateway your home-level router has will break your ability to make phone calls. The most common scenario our support people see is that you'll be able to register, but unable to make calls. That is why we recommend that customers turn off any SIP ALG on their routers, unless it is a high-end router with excellent support.

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jwshome
Posts: 9
 Member Since:
2008-07-31
Excellent, thanks for the
Mon, 09/01/2008 - 7:09am

Excellent, thanks for the very quick feedback. I will simply do the port forwarding.

May I ask a related question - I understand that I may not need to forward all of the 10000 ports in the 10-20 range, depending on the volume of calls I plan to make. is that correct, and if so is there an algorithm for determining how many ports to open up?


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stechnique
Posts: 733
 Member Since:
2008-02-21
The RTP ports you need to
Mon, 09/01/2008 - 9:26am

The RTP ports you need to forward depend solely on your SIP provider.
Your local RTP settings will determine the port range on which trixbox SENDS RTP traffic, this is the setting that you can limit. If your SIP provider sends RTP traffic over 10K-20K, you have to choice to forward all of them to your trixbox, because there is no way to control which ports your provider will use.


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jwshome
Posts: 9
 Member Since:
2008-07-31
Got it, thanks very much.
Mon, 09/01/2008 - 1:12pm

Got it, thanks very much.


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16again
Posts: 370
 Member Since:
2007-03-04
RTP packets have both source
Tue, 09/02/2008 - 12:23am

RTP packets have both source and destination ports.
For outgoing packets, destination port is set external (provider, extern device...) and can be anything in 1024....65535 range

For outgoing packets, source ports is set by asterisk rtp.conf
The default range (10.000 20.000) can be altered in rtp.conf

Set up firewall to only filter on ports set by asterisk


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