How to change DNS in DHCP on the BBox2

If you are like me and have a Bbox2 from Belgacom, chances are you’d like to change the DNS server the router is suggesting to connecting clients through DHCP.

Unfortunately, Belgacom has lobotomised the OpenWRT version they are using on their internet modems to the point where it’s not possible to configure certain ( from my point of view ) basic things. At least not directly!

On their web interface they seem to give you the possibility to change the DNS server, but you’ll soon realise that the cake is a lie.

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Even if you change the Primary DNS Server to something else, it’ll still serve you the IP address of the router itself.

You might be wondering why one should change that in the first place since everything pretty much works.

Here is a shameless excerpt from Steve Gibson’s Podcast, Security Now at http://www.grc.com/sn/sn-226.txt who talks about the subject:

The problem is that, if you remoted your DNS to the router, now it's sort of your proxy. 
And so your computers all just get one DNS address, meaning the router, and are at the mercy of the router doing the right thing. 
It's certainly possible for a smart router to be doing a good job with DNS resolution and be passing that back to the clients that are using it to provide that service. 
But the fact that we've seen flaky router operation, and in fact the DNS benchmark has revealed that some routers are much slower than going direct. 
That is, the router is actually a speed problem for that.
So just from a point of view of network performance, it’s often a good idea to let your router not handle DNS on your behalf.
Without further ado, here are the steps you need to take to change the DNS server address served by your Bbox2 through DHCP.
  1. Connect to your Bbox2 using telnet (example: telnet 192.168.1.1)
  2. Login with admin and password BGCVDSL2 (since 15/11/2012 the default password is the serial number of your bbox2)
  3. To see the currently served DNS address: rg_conf_print /dev/br0/dhcps/dns/0/ (output example:  (0(192.168.1.1))
  4. Change the address like so: rg_conf_set /dev/br0/dhcps/dns/0/ 8.8.8.8
  5. Save the configuration by issuing the command: save

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Reconnect to your network and check to see that the router gave you the DNS address you wanted through DHCP.

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How to Bridge the Lan ports of your Belgacom BBox2

People in Belgium who are Belgacom clients which provides them with an Internet connection, usually get a modem/router as part of the package to connect to the internet.

New clients will get a Router, more commonly refered to as “BBox2”, which is needed to be able to connect to Belgacom’s VDSL2 network.

BBox2

Although most average consumers won’t have any need to modify it (other than changing the default access password, Wireless ID and encryption key), some people like myself would like to have the device just handle the modem part of the connection (simply handling the transmission) while using their own network equipment to handle all the routing operations.

The modification I’ll show is called “Bridging”, meaning, we are going to configure the Lan ports of the BBox2 to simply transmit anything that passes without making certain routing assumptions.

Other services like Belgacom TV and I-Talk will continue to work.

Please be aware that I don’t have information about the following:

  • How to reach the configuration page of the BBox2 after the modifications (I think you’ll have to reset the device to it’s factory default settings to be able to access it again)
  • Does the second Lan port work? (I believe that port works as a HUB, though I didn’t bothered checking it out)

That said, you’ll need to do the following:

  • Disable the Router’s capability to perform  Wan PPPoE
  • Set the Lan ports as bridges
  • (Not tested) Disable the wireless on the Router (I disabled it because I want my own equipment to handle the wireless)

With no further ado, here’s how it’s done:

  1. Connect to your BBox2, the ip address is probably the default 192.168.1.1
  2. Go to Advanced Settings and then select Network Interfaces
  3. Select Wan PPPoE, then Disable, and then OK
  4. Then, Settings > Underlying Connection, select Lan Bridge

Now you can use your own Router to perform the authentication to access the internet and handle all the connections.