Possible to run AirVPN on cascaded router with fixed DNS...

[d3miGod 0]

My ISP requires using their residential gateway (rg - modem/router combo) which does not allow you to change the DNS settings. I have a Netgear R8000 X6 Nighthawk running DD-WRT cascaded from the RG. Can I run AirVPN in this configuration without issue? If I change the DNS on the X6 to AirVPN DNS settings will I lose internet connectivity as this router gets internet through the rg? If this works, will I leak DNS?

 

Thanks in advance.

[tamikyle 4]

Yes, it should be fine.

 

What you'll need to do is hook up your Nighthawk to one of the LAN ports of your ISP-provided router. Then make sure you configure the Nighthawk to do something called "masquerading", also called "NAT". This will make your Nighthawk replace the "source" IP address on all packets it receives with its own IP address, so the ISP router can happily pretend that the Nighthawk is just one device. Doing NAT this way is usually the default setting on most router firmware these days, so you should be good out-of-the-box.

 

As for how the DNS stuff will work, here's a quick sketch of how it ought to go, assuming you set it up right:

 

- Computers connected to your Nighthawk will have all their traffic routed through the VPN.

- When a computer wants to connect to a new domain, it will query the Nighthawk for the IP address (the Nighthawk is a "local DNS server").

- If the Nighthawk doesn't know where to find the domain, then it asks AirVPN's DNS (through the same tunnel that regular traffic is routed through).

- While the VPN tunnel is all set up, the ISP router will only see encrypted packets going to/from your chosen AirVPN server, nothing else.

- The only time you'll use your ISP's DNS is when opening the connection to AirVPN in the first place: your Nighthawk will do one DNS query for "airvpn.org", and then you'll use that address to build the tunnel, through which all future DNS queries will be routed.

 

Hope this clears it up for you. Just follow the normal instructions, and it should work out fine. If anything doesn't work right, come back here and ask for more help.

 

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Edit: on the off chance that AirVPN's internal DNS doesn't have an entry for a domain, then your router may fall back to querying the upstream router (i.e. your ISP's router). Then you will indeed be leaking DNS queries. To prevent this, consider providing your Nighthawk with a backup DNS server, like 8.8.8.8 (Google), or one of the many OpenNIC DNS servers. I'm not too familiar with DD-WRT, but your two goals should be:

 

1. Prevent your router from ever using your ISP router as a DNS server.

2. Provide an alternative DNS server, just in case 10.4.0.1 doesn't have what you're looking for.

Edited ... by tamikyle

[d3miGod 0]

Thanks for the detailed reply. I definitely appreciate it. And just for clarification, I should not need to mirror my primary router's DNS settings for internet to "pass-through" to the cascaded router, correct? The instructions that I've received to setup the cascaded router all say to match the DNS of the primary router which, of course, I don't want to do. This should be easy enough for me to test, however, I'm not currently home so if anyone has an answer...

[tamikyle 4]

You are correct: do not mirror the primary router's DNS settings. Your ISP would suggest to do this simply so that your router has a DNS server at all -- since you'll be using AirVPN's DNS, there is no need to use your ISP's.