asterisk users - Nov 2004 - SIP via Wireless Ethernet Bridge and Double NAT

Just moved into a new place and it'll take 2-3 weeks for my SDSL to be
installed.

 

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.

 

I tried port forwarding 5060:5061 and 10000:20000 from the Netgear to the
Belkin and then to the Cisco, but no luck. It could be the double NAT, or
one of them isn't properly NAT'ing in order for VOIP to work. I believe
it
could be the Netgear, as I think I've used the Cisco behind the Belkin in
the past without a problem. Either that, or maybe UDP doesn't work across
wireless links so well. My only other thing to try is to put a 5 port switch
between the LinkSys WAP54g and the Belkin and plug my Cisco ATA 186 and my
Belkin into it. This way the Cisco ATA 186 is only behind the Netgear NAT,
not behind the Belkin NAT. 

 

 

Cable Modem <-Ethernet-> Netgear Wireless Router <-----802.11----->
LinkSys
WAP54G <-Ethernet-> 5 Port Switch <-Ethernet-> Belkin Router

 
<-Ethernet-> Cisco ATA186

 

 

Anyways, just wanted to see if anybody has tried something as exotic or
similar? Anybody had problems with Netgear or Belkin NAT devices? Or
Wireless links? 

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On Mon, 2004-11-01 at 15:37, Paul Rodan wrote:
> 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.
I've seen this situation, it's probably slightly different to how you
describe, although has the same effect.

AFAIK when you send the register, the asterisk sends back a hash so you
can encode the password. If the client doesn't get the reply it will
just try again without the password. You need to see what's going on at
the ATA end of the network to see if the packets are coming back.

Can you tcpdump at any point along the way? If not then set the
'nprintf' host on your ATA and see if that sends any useful info about
what is happening. If you don't have the nprintf server software from
cisco then you can just use netcat:
 nc -l -u -p 9001

It sounds as though it'll take you more than 2 weeks to fix, might as
well wait for the SDSL ;)

Adam.

I've tried double NAT and it doesn't work.  Your only chance is to run
everything behind the Netgear bridged.  Even then, if you are using
wireless bridges, you will need to make sure the arp entries do not fall
out of the bridge(s) due to lack of activity.  One way to do this is to
make sure they are re-registering often.  I'm sure there are other ways to
deal with this, but that is what worked for me.

Bruce Komito
High Sierra Networks, Inc.
www.servers-r-us.com
(775) 236-5815


On Mon, 1 Nov 2004, Paul Rodan wrote:
> Just moved into a new place and it'll take 2-3 weeks for my SDSL to be
> installed.
>
>
>
> 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.
>
>
>
> I tried port forwarding 5060:5061 and 10000:20000 from the Netgear to the
> Belkin and then to the Cisco, but no luck. It could be the double NAT, or
> one of them isn't properly NAT'ing in order for VOIP to work. I
believe it
> could be the Netgear, as I think I've used the Cisco behind the Belkin
in
> the past without a problem. Either that, or maybe UDP doesn't work
across
> wireless links so well. My only other thing to try is to put a 5 port
switch
> between the LinkSys WAP54g and the Belkin and plug my Cisco ATA 186 and my
> Belkin into it. This way the Cisco ATA 186 is only behind the Netgear NAT,
> not behind the Belkin NAT.
>
>
>
>
>
> Cable Modem <-Ethernet-> Netgear Wireless Router
<-----802.11-----> LinkSys
> WAP54G <-Ethernet-> 5 Port Switch <-Ethernet-> Belkin Router
>
>
> <-Ethernet-> Cisco ATA186
>
>
>
>
>
> Anyways, just wanted to see if anybody has tried something as exotic or
> similar? Anybody had problems with Netgear or Belkin NAT devices? Or
> Wireless links?
>
>
>
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> 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