Dealing with Corrupt Opegear Firmware

It was inevitable. Now that I'm proudly compiling my own cellular router firmware, I'm also becoming familiar with the process of recovering from corrupt firmware.

I'm using an Ubuntu VM (described in the previous post) running in my MacBook for recovery purposes.

The Opengear instructions for recovering from bad firmware suggest that holding down the reset button is required, but I find that my router attempts to load firmware from the network no matter what. Maybe that's because I've wiped out my configuration? <- Update: yes, this seems to be the case. I haven't nailed it down exactly, but my router doesn't try to netboot every time.

Here's how I'm using that Ubuntu VM:

Required Packages
sudo apt-get install -y tftpd-hpa dhcp3-server

Recovery Software Image

cd /var/lib/tftpboot

sudo wget ftp://ftp.opengear.com/release/recovery/ACM500x_Recovery.flash

Configure DHCP Service

sudo cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.orig

cat > /tmp/foo << EOF

option domain-name "opengear-recovery.com";

option subnet-mask 255.255.255.0;

subnet 192.168.0.0 netmask 255.255.255.0 {

  range 192.168.0.200 192.168.0.253;

}

host myopengear {

  hardware ethernet 00:13:C6:xx:xx:xx;

  fixed-address 192.168.0.10;

  filename "ACM500x_Recovery.flash";

}

EOF

sudo mv /tmp/foo /etc/dhcp/dhcpd.conf

Configure Static IP

It's rare that my MacBook Ethernet cable is plugged in, so my VMs are typically run in NAT mode. For this task, I'll need to run the VM in bridged mode with a fixed IP.

cat > /tmp/foo << EOF

auto lo

iface lo inet loopback

autoeth0

iface eth0 inet static

        address 192.168.0.100

        netmask 255.255.255.0

EOF

sudo mv /tmp/foo /etc/network/interfaces.static

sudo cp /etc/network/interfaces /etc/network/interfaces.dhcp

Switch to Bridged Mode

At this point, I switch the VM's network adapter from NAT to bridged mode using the Virtual Machine->Network Adapter pulldown menu in VMware Fusion.

In Parallels it's Virtual Machine ->Configure->Hardware->Network->Type

Now run the following to complete the change in the VM:

sudo ln -s /etc/network/interfaces.static /etc/network/interfaces

sudo pkill dhclient3

sudo /etc/init.d/network restart

sudo service isc-dhcp-server stop

sudo service isc-dhcp-server start

Recover!

At this point, I power on the Opengear router while holding down it reset button with a pin. A few seconds later the router collects an IP address via BOOTP, and then the firmware via TFTP.

Hit the The router will be running a web service on port 80. Use that to replace the firmware.

Switch back to NAT mode

Before changing back to NAT mode in the hypervisor, do:

sudo ln -s /etc/network/interfaces.dhcp /etc/network/interfaces

sudo service isc-dhcp-server stop

sudo /etc/init.d/network restart