On Tuesday 13 December 2005 12:16, Shuchit Velkar wrote: > So can anyone using unlimitel tell me what kind of NAT'ing issues to > expect with IAX2 and SIP and is the workaround as simple opening up a > port to the voip adaptor. > Also, what security implications does this have, ie. can the voip > adaptor be hacked since it is exposed on the Internet ?
If you port forward udp/4569 to your Asterisk box, you won't have ANY NAT issues with IAX2. SIP has NAT issues because it uses dynamic port allocation for the media streams, and any NATting firewall that doesn't recognize the SDP will end up not passing the audio in one direction or the other (or both). You can get around this by getting your firewall to forward the ten thousand (by default) UDP ports that you could end up having media on to your Asterisk box. Other options include trying to restrict the ports used, but many phones are hideously broken and just don't listen to the suggested port ranges anyway. Another option is to use a SIP proxy outside of NAT and it will fix this up pretty handily as well. The voip specific dd-wrt firmware for the WRT series of routers has SER (a SIP proxy) so you can generally get it to Just Work with that. That's the whirlwind explanation -- if there are any specific areas you've still got questions about, just let me know and I'll try to explain it. :-) -A.
