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failsafe_mode_recovery

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So your router has become unresponsive and you have heard the horror stories of 'bricked' routers and are in panic mode. Relax my friend, I have flashed 100s of times and recovered unresponsive routers dozens of times. I have only complete destroyed 1 router in my sordid career. Chances are excellent that your router can be recovered. Below are a couple of tricks of the trade.

Failsafe recovery via ssh

This procedure assumes that:

  1. you had a good Gargoyle install on the router
  2. you messed up your settings and can no longer get to the Gargoyle Web interface

Open a terminal and:

  1. type ssh root@192.168.1.1
  2. provide your password
  3. at the Gargoyle prompt type firstboot
  4. wait until the command prompt returns
  5. power cycle the router.

The router which should now come up in its default Gargoyle configuration and you will be able to get started again.

Using Failsafe recover mode

If you cannot get the ping response from your router then try to get into OpenWRTs failsafe recovery mode. This procedure can recover your router if a configuration error on your part has made it impossible to access the router via the web interface or SSH.

The procedure assumes that you had a good Gargoyle install on the router and just messed up your settings.

If you cannot get to the Web interface of your router but you can get a command line prompt using SSH then you only need to do steps 8 & 9 below.

  1. Install Wireshark on your computer.
  2. Configure your computer with static IP 192.168.1.2
  3. Connect your computer to a LAN port on the router.
  4. Start Wireshark and monitor the LAN connection.
  5. Powerup your router, when wireshark shows the first packet from 192.168.1.1 immediately press and hold the reset button on the back of the router for three seconds.
  6. Router power LED should be flashing quickly. (Failsafe mode)
  7. From a command prompt on your computer “telnet 192.168.1.1”
  8. From the command prompt of the router “firstboot”
  9. Reboot your router which should now come up in its default Gargoyle configuration.

TFTP a new firmware image to your router

If you router's power LED is flashing fast it means you are stuck in boot mode. Configure your computer's ethernet port to a manual IP address of 192.168.1.2. Then 'ping 192.168.1.1' if you get a response it means your bootloader will most likely accept a new image so get the appropriate image for your router. For Broadcom routers you should get the “.bin” version rather than the “.trx” because the bootloader does not understand the “.trx” format. Then TFTP the image to your router and wait. The image transfers fast but it takes a few minutes for the bootloader to actually write the image you sent to flash. Cycling power during this period will result in having to start all over. When it is done it will reboot on its own.

Here is an example

  D:\My Documents\Downloads>ping 192.168.1.1
  Pinging 192.168.1.1 with 32 bytes of data:
  Reply from 192.168.1.1: bytes=32 time=1ms TTL=100
  Reply from 192.168.1.1: bytes=32 time<1ms TTL=100
  Ping statistics for 192.168.1.1:
  Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
  Approximate round trip times in milli-seconds:
  Minimum = 0ms, Maximum = 1ms, Average = 0ms
  D:\My Documents\Downloads>tftp -i 192.168.1.1 PUT gargoyle_1.4.1-wrt54g-squashfs.bin
  Transfer successful: 3346464 bytes in 6 seconds, 557744 bytes/s  

If you get this

  D:\My Documents\Downloads>tftp -i 192.168.1.1 PUT gargoyle_1.4.1-wrt54g-squashfs.trx
  Error on server : code pattern incorrect

It means your bootloader does not understand the format of your image file. Make sure you are using the correct one for your router and make sure you reboot before trying again. I have noticed that the bootloader will only accept one TFTP attempt per boot.

JTAG recovery method

If you cannot get either of the above to work for you then the next approach I use is the JTAG cable method. This method requires that you purchase a cable on Ebay for $5 and solder a JTAG connector onto the motherboard of your router. So you need to decide how much work you are willing to do for the cost of a new router. I am not going to go into the details of this method since so much go info is already written about it at http://wiki.openwrt.org/doc/hardware/port.jtag

failsafe_mode_recovery.1441029313.txt.gz · Last modified: 2015/08/31 13:55 by nworbnhoj