nmrpflash - Netgear Unbrick Utility

nmrpflash uses Netgear's NMRP protocol to flash a new firmware image to a compatible device. It has been successfully used on a Netgear EX2700, DNG3700v2, R6220, R7000, D7000, WNR3500, R6400 and R6800, but is likely to be compatible with many other Netgear devices.

Prebuilt binaries for Linux, OS X macOS and Windows are available here (Npcap is required on Windows).

Usage: nmrpflash [OPTIONS...]

Options (-i, and -f or -c are mandatory):
 -a <ipaddr>     IP address to assign to target device
 -A <ipaddr>     IP address to assign to selected interface
 -B              Blind mode (don't wait for response packets)
 -c <command>    Command to run before (or instead of) TFTP upload
 -f <firmware>   Firmware file
 -F <filename>   Remote filename to use during TFTP upload
 -i <interface>  Network interface directly connected to device
 -m <mac>        MAC address of target device (xx:xx:xx:xx:xx:xx)
 -M <netmask>    Subnet mask to assign to target device
 -t <timeout>    Timeout (in milliseconds) for NMRP packets
 -T <timeout>    Time (seconds) to wait after successfull TFTP upload
 -p <port>       Port to use for TFTP upload
 -R <region>     Set device region (NA, WW, GR, PR, RU, BZ, IN, KO, JP)
 -v              Be verbose
 -V              Print version and exit
 -L              List network interfaces
 -h              Show this screen

Using nmrpflash

Your Netgear router must be connected to your network using an Ethernet cable. The device running nmrpflash must be connected to the same network, using either Wi-Fi or Ethernet.

All available network interfaces can be listed using

# nmrpflash -L
eth0      192.168.1.2  f2:11:a1:02:03:b1

Once you've determined the interface to use, we can flash the image. Firmware images can usually be downloaded directly from Netgear. Power on your device immediately after starting nmrpflash.

# nmrpflash -i eth0 -f EX2700-V1.0.1.8.img
Advertising NMRP server on eth0 ... /
Received configuration request from a4:2b:8c:00:00:01.
Sending configuration: 10.164.183.252/24
Received upload request: filename 'firmware'.
Uploading EX2700-V1.0.1.8.img ...
Upload successful.
Waiting for remote to respond.
Remote finished. Closing connection.
Reboot your device now.

Common issues

In any case, run nmrpflash with -vvv before filing a bug report. Also, try connecting your Netgear router directly to the computer running nmrpflash.

"Error while loading shared libraries: ..." (Linux)

You must install your Linux distribution's libpcap and libnl-3 packages (exact names will vary depending on your distribution).

"The program can't start because wpcap.dll is missing" (Windows)

Install Npcap. For nmrpflash versions prior to 0.9.14, install Npcap with "WinPcap Compatibility" enabled.

Version 0.9.13 is the last version to support Windows XP.

"No suitable network interfaces found."

Make sure the network interface is up (wireless interfaces are not supported). On Windows, try restarting the WinPcap service (commands must be run as administrator):

C:\> net stop npf
C:\> net start npf

"No response after 60 seconds. Bailing out."

The router did not respond. Always run nmrpflash in the following manner:

• Turn off the router.
• Run nmrpflash.
• Turn on the router.

If that still doesn't work, you can try "blind mode", which can be invoked using -B. Note that you also have to specify your router's mac address using -m xx:xx:xx:xx:xx:xx. Also beware that in this mode, careful timing between running nmrpflash and turning on the router may be required!

It's also possible that your device does not support the NMRP protocol.

"Timeout while waiting for ACK(0)/OACK."

The device did not respond to nmrpflash's TFTP upload request. By default, nmrpflash will assign 10.164.183.252 to the target device, while adding 10.164.183.253 to the network interface specified by the -i flag. You can use -a to change the IP address assigned to the target (e.g. if your network is 192.168.1.0/24, specify a free IP address, such as -a 192.168.1.252), and -A to change the IP address used for the network interface.

This error message could also indicate a bug in the TFTP code; try using an external tftp client (busybox in this example), by specifying the -c flag instead of the -f flag:

# nmrpflash -i eth0 -c 'busybox tftp -p -l EX2700-V1.0.1.8.img $IP'

The environment variable IP is set by nmrpflash (other environment variables are: MAC, PORT, NETMASK).

"Timeout while waiting for CLOSE_REQ."

After a successful file upload, nmrpflash waits for up to 5 minutes for an answer from your device. You can increase this by specifying a longer timeout using -T switch (argument is in seconds).

It's entirely possible that the image was flashed successfully, but the operation took longer than 5 minutes.

"Address X/Y cannot be used on interface Z."

nmrpflash refuses to use an IP address / subnet mask combination that would make the remote device unreachable from the device running nmrpflash. For example, if the IP address of your computer is 192.168.0.1/255.255.255.0, assigning 192.168.2.1/255.255.255.0 to the router makes no sense, because the TFTP upload will fail.

"IP address of X has changed. Please assign a static IP to the interface."

This can happen if the network interface in question automatically detects that the network cable has been connected, and your computer tries to reconfigure that interface (NetworkManager on Linux does this for example) - this can usually be disabled.

An alternative would be to add -c 'ifconfig <interface> <ip>' to the command line, for example:

# nmrpflash -i eth0 -a 192.168.1.1 -f firmware.bin -c 'ifconfig eth0 192.168.1.2'

This will execute the command specified by -c prior to starting the TFTP upload (in this case setting the IP address to 192.168.1.2).

"Received keep-alive request."

This usually means that flashing is in progress. On some devices, you may get a few hundred keep-alive requests before it eventually finishes!

"TFTP block rollover. Upload might fail!"

By default, file transfers using TFTP are limited to 65535 * 512 bytes (almost 32 MiB). Uploading files exceeding this limit might fail, depending on the device.

Building and installing

Linux, Mac OS X, BSDs

$ make && sudo make install

Windows

The repository includes a DevCpp project file (nmrpflash.dev). Download the latest Npcap SDK and extract it into the root folder of the nmrpflash sources.