Flashing TP-Link WR841N router with DD-WRT

[soldar]

OK, slowly making progress. I fitted a pull-up resistor as shown and now the modem receives data from the laptop.


Now, after I start up the router I get the same wall of text as before and then I hit enter and "help"and this is what I get:

Code: [Select]

BusyBox v1.22.1 (2015-01-19 11:49:24 CET) built-in shell (ash)
Enter 'help' for a list of built-in commands.

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 BARRIER BREAKER (Barrier Breaker, r44049)
 -----------------------------------------------------
  * 1/2 oz Galliano         Pour all ingredients into
  * 4 oz cold Coffee        an irish coffee mug filled
  * 1 1/2 oz Dark Rum       with crushed ice. Stir.
  * 2 tsp. Creme de Cacao
 -----------------------------------------------------
root@OpenWrt:/# help
Built-in commands:
------------------
        . : [ [[ alias bg break cd chdir command continue echo eval exec
        exit export false fg getopts hash help history jobs kill let
        local printf pwd read readonly return set shift source test times
        trap true type ulimit umask unalias unset wait

root@OpenWrt:/#
So it seems I am logged into OpenWRT.
Now what?

[soldar]

Stuck again.  I found out I can stop the booting into Openwrt by typing "tpl" when it says "Autobooting in 1 seconds". It is impossible to type it in fast enough but I can paste it just in time.

So I can avoid booting into Openwrt and stay in uboot (I guess).  And then I have the following commands:

Code: [Select]


U-Boot 1.1.4 (Build from LSDK-9.5.3.16 at Oct 13 2014 - 17:01:20)
hb> help
?       - alias for 'help'
boot    - boot default, i.e., run 'bootcmd'
bootd   - boot default, i.e., run 'bootcmd'
bootm   - boot application image from memory
cp      - memory copy
erase   - erase FLASH memory
help    - print online help
md      - memory display
mm      - memory modify (auto-incrementing)
mtest   - simple RAM test
mw      - memory write (fill)
nm      - memory modify (constant address)
ping    - send ICMP ECHO_REQUEST to network host
printenv- print environment variables
progmac - Set ethernet MAC addresses
reset   - Perform RESET of the CPU
run     - run commands in an environment variable
setenv  - set environment variables
tftpboot- boot image via network using TFTP protocol
version - print monitor version
hb>
I tried ping and it gets a response via the Ethernet port.

But I still have no idea how to change the firmware.

[Black Phoenix]

You have to load the image of the firmware now via TFTP:

tftpboot- boot image via network using TFTP protocol

You need to have a PC with a TFTP Server enable and in that server you have the file that is the image to load.

Then by selecting the TFTP option above, you put the IP of the TFTP server and the file should be downloaded to the Router and installed.

[soldar]

This exercise has been extremely frustrating but after many hours of trial and error I managed to load successfully Openwrt V15.  I am very surprised I did not brick the router in the process because I did it wrong over 20 times until I succeeded. 

After many hours of trying I found this video https://www.youtube.com/watch?v=RtqVKNfuxWM?t=0 (over an hour long!) and following the instructions I managed to load Openwrt V15 which I now have running on the router and I am playing with it. I suppose if I want to flash the router with a new OS I can do it from there and not go through the entire rigamarole again.

The instructions are complex and prone to making mistakes. I could not find anywhere a detailed explanation of the syntax of tftpboot and it was very frustrating.

tftpboot 0x80000000 openwrt-15.05.1-ar71xx-generic-tl-wr841n-v9-squashfs-factory.bin

erase 0x9f020000 +0x3c0000

cp.b 0x80000000 0x9f020000 3c0000

reset

Anyway, all's well that ends well.

I will now spend some time learning a bit about Openwrt and see what I can do with it.  I would like to block some IP addresses and another thing I'd like is a VPN but I do not think I have seen any VPN configuration in the menus.

After some playing it can replace another router I have, a TPLink WR340G, with all the menus and interface in Chinese. Maybe that can be the next flashee.