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Topic: Messed around with Netgear DG834GT

The content of this topic has been archived on 27 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.

Post #1
e-san
15 Feb 2018, 21:09

Hi friends!

I'm many-years Linux user and it is not my first Opened router. It was never easy, but at least once succeed.

So, I have Netgear DG834GT router and started to mess around with it. Based on really good written howto (wiki.openwrt.org/toh/netgear/dg834gt) I've uploaded Backfire (downloads.openwrt.org/backfire/10.03.1/brcm63xx/openwrt-DG834GT_DG834PN-squashfs-cfe.bin) onto.

Everything went ok - it booted up and I was able to do some changes in config etc. But... When router was offline (nothing connected to eth1 aka WAN) I was able to connect to LuCI. When i put ethernet cable to WAN, i got "external" IP and was unable to connect to the web interface (internet works).
Didn't want to annoy about asking such a trivial question I started to messing around. Tried to change some stuff about DHCP, do this (wiki.openwrt.org/toh/netgear/dg834gt#assigning_a_wan_port_with_dhcp) and finally upgrade to Barrier Breaker...

As stated in the wiki:

Barrier Breaker 14.07 appears to work too.

Yeah, it works... barely... The web interface is almost useless*, so I decided to downgrade. Through the Web interface, it was impossible (Bad gateway, too long response...).

*changing root's password was a pain!

Failsafe failed - triggering "reset button" enters router into failsafe (blinking LEDs), but I was unable to connect.

So I tried over ssh.

Here (techtrickszone.com/2017/05/02/openwrt-firmware-upgradation-with-ssh-command-with-piture/) is information to use WinSCP - I know scp and I'm Linux user - let's check if it works - yeah! it works.

So i copied the previous image to /tmp.

Stall.

Scp stalled or I was unable to log in over ssh. Tried (askubuntu.com/questions/82984/why-does-scp-get-stalled-how-do-i-resolve-it#82988)

scp -l 512 openwrt-DG834GT_DG834PN-squashfs-cfe.bin root@192.168.1.1:/tmp

and it didn't help a lot...
I made conclusion - it is because out of ram. So I found this (wiki.openwrt.org/doc/howto/generic.sysupgrade)

One has actually 752+6636 KiB of free memory available.

quickest and safest way to free up, some RAM is to delete the opkg packages file:

rm -r /tmp/opkg-lists/

drop caches:

sync && echo 3 > /proc/sys/vm/drop_caches

prevent wireless drivers to be loaded at next boot and then reboot:

rm /etc/modules.d/*80211*
rm /etc/modules.d/*ath9k*
rm /etc/modules.d/b43*
reboot

The wireless drivers, usually take up quite some amount of RAM and are not required (unless you are connected via wireless of course ;-)), so an easy way to free up some RAM is to delete the symlinks in etc/modules.d so these are not loaded into memory at the next reboot.

After doing so I was able to scp image and start sysupgrade:

mtd -r writer /tmp/image

- didn't work.

sysupgrade -v /tmp/filename-of-downloaded-sysupgrade.bin

- hung once. I've tried again and left it over the night (but disconnected) - we'll see tomorrow wink

What can I do if it fails? If not, how to solve the first problem - being unable to connect to web interface after connecting WAN.

P.S. I'm able to solder RS - no problem for me - if it is necessary.

(Last edited by e-san on 15 Feb 2018, 21:10)

Post #2
tmo26
16 Feb 2018, 08:04
e-san wrote:

What can I do if it fails?

Buy a new router with sufficient RAM. Seriously.

Post #3
e-san
16 Feb 2018, 10:39

It seems to be bricked now wink

I found somewhere info to: 

root@OpenWrt:/tmp# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00010000 00002000 "CFE"
mtd1: 0011ff00 00010000 "kernel"
mtd2: 002c0000 00010000 "rootfs"
mtd3: 000a0000 00010000 "rootfs_data"
mtd4: 00010000 00010000 "nvram"
mtd5: 003e0000 00010000 "linux"
root@OpenWrt:/tmp# mtd write openwrt-DG834GT_DG834PN-squashfs-cfe.bin linux
Unlocking linux ...

Writing from openwrt-DG834GT_DG834PN-squashfs-cfe.bin to linux ...  [w]Connection to 192.168.1.1 closed by remote host.
Connection to 192.168.1.1 closed.

Whoops!

Post #4
ninjaef
16 Feb 2018, 10:51

how are you connecting to luci (web interface) , IP address or hostname, and what values are you using?

BTW, that router is shit:
Broadcom BCM6348 (256 MHz) - duh!
4 Mb (Macronix MX29LV320BTC-70G) - got to be joking
16 Mb (Winbond W9812G2DH-7) - come on , really

I mean you are asking for trouble trying to run custom firmware on that pile of garbage

(Last edited by ninjaef on 16 Feb 2018, 10:53)

Post #5
e-san
16 Feb 2018, 12:53
tmo26 wrote:

Buy a new router with sufficient RAM. Seriously.

Rubbish! Where's the fun?!
Seriously - I bought it just to play with it wink

CFE method helped. (wiki.openwrt.org/toh/netgear/dg834gt#tftp_and_serial_port_method)

I'm now on Backfire again.
But still i do not know how to make it not-transparent.

Post #6
mk24
16 Feb 2018, 18:49

This was originally a DSL modem/router so it doesn't have a dedicated "WAN" ethernet port, as it was expecting the Internet to be connected by DSL.  Since there is no open-source driver, the DSL modem function is not supported by OpenWrt though, thus it won't be possible to connect anything to the DSL port. 

You will need to set up VLANs in the switch and on the CPU port to make one of the four Ethernet ports a WAN port.  The default configuration probably has them all switched together as a LAN.

How to do that on Backfire is something that no one here will remember.  You're dealing with antique software, and hardware.

The discussion might have continued from here.