Redirect DNS requests with OpenWrt

Nikolai Kim asked:

I’ve brought a wireless router to my office, because there’s no free network socket near my place. Every normal computer that is connected via Ethernet cable normally gets an IP and DNS server addresses from the enterprise router by DHCP.

Our organization has some internal addresses that have their own URIs that are resolved by the local DNS server. Now I can access them by IP address, but not URI, as “the host is unknown”.

In the DHCP and DNS section of LuCI (OpenWrt’s webinterface) under the option DNS Forwardings I specified the addresses of enterprise DNS servers (they are static), but with no success.

How can I make OpenWrt forward all DNS requests that it can’t resolve itself, to these enterprise servers, or just all DNS traffic to that servers?

My answer:


Don’t bother with DNS forwarding, or with OpenWrt’s internal DNS server, just serve the existing DNS servers to your DHCP clients directly. You can do this by setting DHCP option 6, which will be formatted in the web interface like:

6,192.168.32.35,192.168.48.35

You can access the relevant part of the web interface in LuCI by going through Network –> Interfaces –> LAN –> Scroll down to bottom –> “Advanced Settings” tab:

LuCI DHCP configuration

I also have to remind you to do this only with the explicit knowledge and approval of your company’s network admin, IT department, etc.


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