Gordon Henderson wrote:
On Thu, 25 Jan 2007, Yuan LIU wrote:
Thanks for this information. Does this mean two IAX boxes can talk
behind their respective NAT's (without any server sitting in voice
path)? I'm imagining this:
Asterisk1 <--> NAT1 --- { Internet } --- NAT2 <--> Asterisk2
Using IAX, yes. It's quite straightforward to do. You do need to open
the IAX port on each NAT device though - this may be called
port-forwarding, depending on the hardware or its configuration
interface. Essentially, you port-forward port 4569 from the outside to
the IP address of the asterisk box on the inside on both sides.
Then have a look at:
http://astrecipes.net/index.php?n=204
To get you going.
Is this the concept of STUN? Does this also create latency (by adding
an additional leg in the route), packet loss, even jitter?
STUN doesn't intercept the data. It gives the client device hints as to
how best to traverse the local NAT firewall.
IAX uses a single port for both commands and data. SIP uses more than
one and thats when it gets hard as it's easy for a NAT router to track a
single data stream, but tracking multiple is hard. I have noticed newer
routers offering SIP NAT traversal though (and the later linux kernels
claim to be able to do it) I guess, like handling FTP (which also uses
multiple ports) they are inspecting the SIP packet contents to try to
work out the RTP ports it's going to use and do the right thing.
I did have issues with a Juniper router recently though - the owner
claimed it has SIP traversal but it didn't work, but when we turned it
off and used old fashioned port forwarding it "just worked" ...
My experience with SIP ALG implemented in several routers/modems/NAT
box/fillintheblanks....is not exactly good :-)
I saw many cases where the messing around done by the middlebox break
either authentication+integrity or even the voice path.
I've not tried the SIP ALG in the iptables modules, but, not sure how
much better would be :-)..
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
asterisk-users mailing list
To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-users
