DNS timeouts when adapter is behind router.

Posts: 2 · New Forum Member Joined: Nov 21, 2005 Posts: 2

If you havn't updated your router lately you may not know this is a problem yet. DNS was recently patched to respond on a random udp port. The problem is Vonage adapters need to have ports 10000-20000 udp forwarded to them. A decent portion of DNS upd packets meant for the other machines on the LAN get dumped to the Vonage adapter resulting in DNS timeouts for the computers on the LAN. This is only an issue if your Vonage adapter lies behind your router. Tech support says to connect the Vonage adapter directly to the modem. Does anyone else here think this is unacceptable? I personally need to be able to route traffic for several services with only one NAT hop. Id imagine there are actually several services that cant jump two virtual ip's.

Additionally, some people connect to the internet with a modem/router combination unit. If you have such a device you WILL loose udp packets meant for other machines if you forward 10k-20k udp to the Vonage adapter. I think many people with DSL lines use a device like this. Also, several cable companies use a device that provides routing/modem in one unit. You will receive a DNS timeout about 15% of the time with any of these configurations.

For those who don't understand a dns timeout.... When you open your internet browser and type www.google.com. Your machine sends a request to the dns server saying "what is the address associated with www.google.com?" The dns server responds to you via a random port (possibly between 10000-20000 which Vonage uses) saying "the address is 199.199.199.199" your computer then connects to that particular address. When you get a screen that says something like "Address not found" you have run into this problem. As more DNS servers are patched more and more of you will run into this issue... that is unless you connect your Vonage adapter DIRECTLY to the internet as in your adapter has a "real" ip address. You may even find that Vonage adapter/router appliances have the same problem.

Posts: 350 · Vonage Forum Evangelist Joined: Dec 04, 2005 Posts: 350

You should not need to forward UDP 10000-20000. The upstream router just needs to not explicitly block them.

Posts: 881 · Vonage Forum Evangelist Joined: Nov 05, 2005 Posts: 881

There is a flaw with dns name servers where if you're not protected it could allow a hacker to take over the internet and forward users to impostor sites. To find out if the DNS server you use is susceptible to this flaw, head over to http://www.doxpara.com and run the DNS Checker. If you find that you are vulnerable to this flaw, you can use opendns servers. For more information on opendns, go to http://www.opendns.com

exigent, if your DNS servers are safe from this flaw there is no need to put your Vonage adapter ahead of your primary router. My Vonage adapter (V-Portal) is behind my primary router (WRT54GL) and all is well.