Saturday 23 January 2010

Adding local DNS entries to a Netgear DG834

There is a program running on your DG834 called dnsmasq, which is used to forward DNS requests to the appropriate servers. The program can optionally use one or more local hosts files, so if you are hosting a webserver at home, for example, you can add it to the hosts file, and any LAN requests will return the LAN ip address, rather than the internet one.

By default, at least on the DG834Gv5, the option to add your own entries is not enabled.

Log into your netgear with telnet.

With a web browser, connect to http://your-modem/setup.cgi?todo=debug
Telnet to your modem: telnet

Create a new hosts file with local addresses:

mkdir /var/etc
cp /etc/hosts /var/etc/hosts
echo "" >> /var/etc/hosts

To check it works, restart the DNS Masquerade program:

killall dnsmasq
dnsmasq -h -n -c 0 -N -i br0 -r /tmp/resolv.conf -u r -H /var/etc/hosts

Making things permanent:

Now, there is a problem making this permanent as the root filesystem is 100% full, but what you would need to do is:

Mount the root disk read/write: mount / -o rw,remount
Copy the hosts file over: cp /var/etc/hosts /etc/hosts


  1. It would appear that on DG834Gv4 dnsmasq is not even present; dnrd is used instead, that also uses the /etc/hosts file as dnsmasq.

    To check if it works use
    killall dnrd

    dnrd -a yourLANrouterAddress -m hosts -c off -b -s dnsServer1 -s dnsServer2
    or wathever command line your router is using as found by
    cat /proc/PIDofDNRD/cmdline

    where PIDofDNR can be found using ps | grep dnrd


  2. On my DG834Gv4 the mount command fails so I'm unable to make the change permanent:
    Cannot read /etc/fstab: No such file or directory.
    I could create a fstab file but have no idea what should go in it !

  3. RE:DG834Gv4 and DG834Gv3 for that matter,
    Create the absent file system table using:
    cat /proc/mounts > /etc/fstab

  4. mount / -o rw,remount

    mount: Mounting rootfs on / failed: Permission denied

    Any ideas ?

  5. Anonymous (7 June 2011 22:19), worked?

  6. I'm having the same problem as Anonymous (7 June 2011 22:19):

    # mount / -o rw,remount
    Cannot read /etc/fstab: No such file or directory
    # cat /proc/mounts > /etc/fstab
    # mount / -o rw,remount
    mount: Mounting rootfs on / failed: Permission denied
    # cat /etc/fstab
    rootfs / rootfs rw 0 0
    /dev/root / squashfs ro 0 0
    none /dev devfs rw 0 0
    /proc /proc proc rw,nodiratime 0 0
    ramfs /tmp ramfs rw 0 0

    Any help here is greatly appreciated.

  7. Thanks for the tutorial, it's working fine :)
    Is there any workaround for the full filesystem?
    Thanks again.