[Asterisk-Users] SIP via Wireless Ethernet Bridge and Double NAT

[Stewart Nelson]

> Anyways, found an unsecured wireless network going through my new townhouse
> at 30% strength. Found the owner and they said I could share it for a couple
> of weeks.

> They have a Netgear, 108mbs 802.11 b/g. So I took a LinkSys WAP54g and put
> it in Ethernet bridge mode, it took the signal and converted it to Ethernet
> for me. I then plugged it into my Belkin 4 Wireless Router w/ 4 port switch.
> So now I'm redistributing the connection in my townhouse. I plugged a Cisco
> ATA-186 into the Belkin, but it's having problems registering with the
> Asterisk server. I figured the double NAT was messing it up.  I'm getting
> less than 1% packet loss to the internet, so the link is strong.

> Cable Modem <-Ethernet-> Netgear Wireless Router <-----802.11-----> LinkSys
> WAP54G <-Ethernet-> Belkin Router <-Ethernet-> Cisco ATA186.

> I keep seeing sip registration failed requests on Asterisk. I checked and
> double checked the passwords, its fine. I believe it's that the device gets
> the UDP packets through to the Asterisk server fine, with the authentication
> information or whatever; but when the Asterisk server tries to respond via
> UDP, it doesn't make it through. So it fails.

You can eliminate the double NAT by disabling the DHCP server on the Belkin,
changing its LAN IP to not conflict with anything on your neighbor's LAN,
and plugging the WAP54G into a LAN port on the Belkin.  Leave the Belkin's
WAN port unconnected.  The Belkin should now be acting as a switch and
wireless access point; it won't be doing any routing.  Your computers, if
set up for automatic addressing, will get them by DHCP from the Netgear.
You may want to give the ATA a static address so you can forward ports to
it on the Netgear.  That address, of course, should be in the subnet of
your neighbor's LAN, but outside of the range assigned by DHCP.

Make sure that your neighbor's kids won't be hacking into your system ;)

Good luck,

Stewart