Wednesday, August 08, 2007

Netgear DG834GT Hacking

Some time back I have replace my ADSL modem provided by BSNL with Netgear DG834GT There are several reasons for this
  • BSNL provided Huawei SmartX MT880 is a poor performer
  • Has got a laptop which needs wireless access which MT880 does not provide
DG834GT is a good performer however it suffers from poor firmware provided by the Netgear. The firmaware is based on opensource software so it provides opportunity to hack around things yourself to fix problems improves performance.

Bracco has done excellent job with providing ADSL parameters control interface with a stable older firmware version V1.01.32 (which he calls Ubergt) which was not officially release by Netgear Support.

I have been using this firmware for some time now and able tune to extract very good speeds from my DataOne connection. BSNL making all home plans to up to 2Mbps I could reach maximum download rate of 260 KBPS (Kilo Bytes Per Second).

Recently Netgear has release new firmware V1.02.09 which claims improved ADSL line stability and performance, which also been confirmed by several users in various forums.

I have been playing with V1.02.04 firmware source for some time but couldn't make much use of it as it seems to be broke (Linux kernel image never gets compiled properly). With new release out and people saying stability improved I wanted to see whether the new source is any good. I tried to build the kernel and re-created the image which seems to work fine. Now I wanted to do few things which are planed for long time
  1. Enable Squashfs with LZMA compression as root file system - Currently Netgear firmware uses only Cramfs with ZLIB compression and Squashfs is superior to Cramfs in performance & Compressed size. This should give more room on the Flash to put more useful applications.
  2. Fix a bug I found for my time zone GMT +5.30, i.e time is always off with this time zone setting.
  3. Modify the DynDNS client to support SSL to communicate with OpenDNS and other services which require SSL, probably by replacing the existing old client ez-ipupdate with ndyndns (I have not evaluated it yet).
  4. More things to come!
As a first step I wanted to import Bracco's changes to this firmware (I believe Bracco is already working on that with more improvements) and then try to putting latest version of Squashfs with only ZLIB compression (i.e Squashfs 3.2-r2) . This experiment has been successful and I have the new firamware and its source (patch) for you to try out. Currently I am using this firmware and max download rate reached with this is 350KBPS (Kilo Bytes Per Second), with a good server (ex: it hovers around 230-270KBPS.

  • DG834GT_V1.02.09_squash3.2_ubergt.img
    • Base is V1.02.09 firmware
    • Only English web interface
    • Includes Ubergt changes
    • Uses Squashfs 3.2r2 for the root filesystem (with ZLIB compression)
    • Usual DISCLAIMERS apply i.e use it on your own risk
  • DG834GT_V1.02.09_squash3.2_ubergt_src.tar.bz2
    • Source i.e tools, rootfs folder & kernel patch
    • Instructions are present in the file README-SQUASH-UBERGT
    • Usual DISCLAIMERS apply i.e use it on your own risk
  • Next to follow
    • Squashfs 3.2r2 with LZMA compression
If you have any comments, feedback etc. please do let me know.

Update 8/24/2007:
As nick (see comments) observed the UberGT settings are not taking effect after reboot also, I could find the reason I will be releasing the updated firmware soon.

Update 8/26/2007:
Updated firmware is available now which fixes UberGT mod issue.

Update 10/4/2008:
Check New Releases here

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At 8/11/2007 3:25 AM, Anonymous Anonymous said...

Cool - more firmware hacking - AFAIK there's only you and Bracco doing this - I'll give this a whirl and let you know how I get on!

At 8/11/2007 3:52 AM, Anonymous nickb834 said...

It looks like something is broken in this firmware, namely the UberGT modifications. Changing the Target SNR / Trellis / Seamless Rate / BitSwap has no effect. The line doesn't drop and resynch like it should. A manual reboot doesn't seem to make use of the adjusted settings. It looks like the Uber GT mods aren't applied correctly to this version of firmware.

At 8/15/2007 9:29 PM, Anonymous Anonymous said...

great work ..
how about ability to set wifi power levels
and a few of the mods that are found on the linksys routers

At 8/17/2007 1:49 PM, Blogger Kabeer Ahmed said...

Well I am still watching your blog my friend. Hope things are fine with you.

It is good to see you on the blogs again. Take care.

At 8/17/2007 6:25 PM, Blogger Kabeer Ahmed said...

Nice to see you back Subhash!

At 8/19/2007 4:59 PM, Blogger Subhash Chandra said...

Hi nick,
They seem to work on my end however I will check and verify the things.

I need one more help from you or any one from UberGT forums. I am unable to register with the forums to communicate with the guys there. I tried registering with 2 different email ids however the activation mail never reached me. Please ask the forum admin to send me activation mail for my account (id: yschandra).

At 8/19/2007 11:31 PM, Anonymous mariog said...


Do you think Is possible to extract and integrate the WOL from

P.S. I've forwarded your message to Bracco.


At 8/20/2007 11:58 AM, Blogger Subhash Chandra said...


Thanks for the help, Surely I will have a look at WOL as I also need it. First I need to verify the nicks observation of UberGT mods are not working correctly then I will have a look. You can watch this blog for updates.

At 8/24/2007 11:04 PM, Anonymous Anonymous said...

I really hope you get the UberGT mods working with the new firmware, i await the new firmware with great anticipation.

Keep up the good work :-)

At 9/03/2007 4:20 AM, Blogger Nick said...

Hi Subhash,

I've tried the new version you compiled and I seem to have a new problem. My ADSL line fails to connect, it doesn't even try to analyse the channels / bits:

adslctl reports this:

# adslctl info
adslctl: ADSL driver and PHY status
Status: IdleRetrain Reason: 0

All other functions of the router still work (WiFi, Switch, Ethernet ports, Web gui) I'll try a power cycle and failing that go back to UberGT.

I'll let you know how I get on - hopefully it won't take two weeks this time :-)

At 9/04/2007 3:26 PM, Anonymous nick said...

Hi again, I've had to revert to the UberGT version by bracco (1.05 beta3) as there was some weird stuff going on, my adsl intermittently refused to do anything and just sat idle. And also the UberGT settings (SRA, Trellis etc) didn't seem to apply.
If you can help me with some tests / commands to run I can provide feedback and results to help you track down what's happening.

At 7/04/2008 12:40 PM, Blogger Paveen said...

Please help me. How can I hack password from Netgear DG834GT, if I never knew its password? And default password has been changed.

At 7/04/2008 6:58 PM, Blogger Subhash Chandra said...


Follow the instruction given here

If this does not work then try this

1) Type this URL in browser
Then a page will come up saying debug enabled

2) Now telnet to the router from windows cmd shell
i.e telnet

3) Now you should a unix shell, here type

nvram show

this will show lot of information some where it has your login id "admin" and its password. Note it down and try from web interface

At 9/28/2008 8:28 PM, Anonymous Anonymous said...

I'm having Sky Netgear Modem DG834GT (Firmware v1.03.87) which I was using while in UK. Now I'm in bangalore and have taken BSNL broadband connection.
I tried many ways as suggested in various forums to configure without any success :(

Could you please help in this regard?

My email is

Many Thanks

At 9/30/2008 8:43 AM, Blogger Subhash Chandra said...

Pls use for questions, it will be easy for me to track and answer


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