1 changed files with 142 additions and 0 deletions
@ -0,0 +1,142 @@
|
||||
--- |
||||
title: OpenWrt on the DG834Gv4 modem router |
||||
tags: [openwrt, modem, router, backdoor] |
||||
updated: 2018-04-19 18:00 |
||||
description: Installing OpenWrt on the DG834Gv4 modem router |
||||
--- |
||||
|
||||
# Overview |
||||
|
||||
 |
||||
|
||||
The [DG834Gv4](https://wikidevi.com/wiki/Netgear_DG834Gv4) is an old |
||||
*Netgear* WiFi modem/router and has been my first wireless access |
||||
point. Years have passed and this hardware shows signs |
||||
of its age. It is compliant to |
||||
[802.11 b/g](https://en.wikipedia.org/wiki/IEEE_802.11#802.11g) only and |
||||
has 100 Mbps ethernet ports . |
||||
Also, when using it as a DSL modem, it sometimes disconnects |
||||
because of the heat it generates. It was time to decommission it. |
||||
|
||||
In the meantime someone discovered a *nice* |
||||
[backdoor](https://github.com/elvanderb/TCP-32764) |
||||
[feature](https://wikidevi.com/wiki/TCP-32764) in a series of |
||||
modem/routers, including the DG834Gv4. One more reason not to use it *as-is*. |
||||
|
||||
*After the router collected some dust*, I evaluated some options such as |
||||
installing OpenWrt or the [DGTeam](http://www.dgteam-mirror.talktalk.net/Home.html) firmwares. |
||||
I went with the DGTeam firmware at first because it had modem support. This |
||||
meant I could use it as a spare modem. |
||||
|
||||
A few weeks ago, however, I tried installing OpenWrt and it wasn't so straight |
||||
forward as I thought. |
||||
|
||||
# Steps |
||||
|
||||
- [Follow the instuctions reported on the wiki](https://openwrt.org/toh/netgear/dg834g.v4?s[]=dg834gv4) |
||||
but instead of getting Chaos Calamer get |
||||
[Attitude Adjustment](https://archive.openwrt.org/attitude_adjustment/12.09/brcm63xx/generic/openwrt-96348GW-10-generic-squashfs-cfe.bin). |
||||
Use `nftp.c` to flash the image on it. This will work even of you brick the |
||||
router. |
||||
|
||||
The reason to select such an old image is because of the insufficient free |
||||
RAM available once the important services start up. Even with Attitude |
||||
Adjustment you'll run out of memory easily. I also tried using older versions |
||||
of OpenWrt without success. |
||||
|
||||
- Go to [http://192.168.1.1](http://192.168.1.1) and change the root password via the *LuCI* web interface. |
||||
This will also enable the SSH daemon. |
||||
|
||||
- Login via SSH (`ssh root@192.168.1.1`) and run the following to remove |
||||
the web interface. |
||||
|
||||
/etc/init.d/uhttpd stop |
||||
/etc/init.d/uhttpd disable |
||||
# repeat the following until no more packages are removed. |
||||
opkg remove --autoremove luci* |
||||
|
||||
## Network and device configuration |
||||
|
||||
- Time configure the network interfaces with `vi`: |
||||
|
||||
```shell |
||||
root@OpenWrt:~# cat /etc/config/wireless |
||||
config wifi-device radio0 |
||||
option type 'mac80211' |
||||
option macaddr '<router_s MAC address here>' |
||||
option hwmode '11g' |
||||
option channel '<channel>' |
||||
option country '<region>' |
||||
option txpower '20' |
||||
|
||||
# REMOVE THIS LINE TO ENABLE WIFI: |
||||
option disabled '0' |
||||
|
||||
config wifi-iface |
||||
option device 'radio0' |
||||
option network 'lan' |
||||
option mode 'ap' |
||||
option encryption 'psk2+aes' |
||||
option key '<your key here>' |
||||
option ssid '<your SSID here>' |
||||
|
||||
root@OpenWrt:~# cat /etc/config/network |
||||
|
||||
config interface 'loopback' |
||||
option ifname 'lo' |
||||
option proto 'static' |
||||
option ipaddr '127.0.0.1' |
||||
option netmask '255.0.0.0' |
||||
|
||||
config interface 'lan' |
||||
option ifname 'eth0' |
||||
option type 'bridge' |
||||
option proto 'static' |
||||
option ipaddr '<router_s address>' |
||||
option netmask '<router_s netmask>' |
||||
``` |
||||
|
||||
- If you want to use the router as a switch/repeater, this will disable the |
||||
DHCP server: |
||||
|
||||
```shell |
||||
/etc/init.d/dnsmasq stop |
||||
/etc/init.d/dnsmasq disable |
||||
``` |
||||
|
||||
|
||||
# Problems |
||||
|
||||
There is not enough memory to install anything even after killing several |
||||
processes. |
||||
|
||||
route add default gateway 192.168.1.1 netmask 0.0.0.0 metric 0 |
||||
echo "nameserver 8.8.8.8" > /etc/resolv.conf |
||||
|
||||
root@OpenWrt:~# opkg install sshfs |
||||
Installing sshfs (2.2-1) to root... |
||||
Downloading http://downloads.openwrt.org/attitude_adjustment/12.09/brcm63xx/generic/packages/sshfs_2.2-1_brcm63xx.ipk. |
||||
Collected errors: |
||||
* gz_open: fork: Cannot allocate memory. |
||||
* opkg_install_pkg: Failed to unpack control files from /tmp/opkg-Ry3bvT/sshfs_2.2-1_brcm63xx.ipk. |
||||
* opkg_install_cmd: Cannot install package sshfs. |
||||
|
||||
For some reason, WiFi seems less powerful (as in range) than it should be. |
||||
This is quite disappointing. |
||||
|
||||
|
||||
# Alternatives |
||||
|
||||
It would be interesting to patch the original Netgear/SerComm firmware by |
||||
removing the `scfgmgr` file and a line in a shell script that is launched at boot. |
||||
|
||||
You need a 32 bit GNU/Linux distribution with the appropriate development |
||||
libraries and only then you'll be able to run the software that rebuilds the |
||||
image. Unfortunately there is only a text file describing generic instructions |
||||
so it takes quite some time to track down all the necessary libraries and to have |
||||
a working environment. Maybe another time... |
||||
|
||||
# Applications using OpenWrt |
||||
|
||||
I ended up using it for this: |
||||
[openwrt-leds-as-notification](https://github.com/frnmst/openwrt-leds-as-notification) |
||||
Loading…
Reference in new issue