Netgear Unbrick Utility


nmrpflash - Netgear Unbrick Utility

This program uses Netgear's [NMRP protocol] (http://www.chubb.wattle.id.au/PeterChubb/nmrp.html) to flash a new firmware image to a compatible device. This utility has been successfully used on a Netgear EX2700 and DNG3700v2, but is likely to work with many other Netgear routers as well.

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

Usage: nmrpflash [OPTIONS...]

Options (-a, -i and -f and/or -c are mandatory):
 -a <ipaddr>     IP address to assign to target device
 -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 regular messages
 -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

Connect your Netgear router to your computer using a network cable. Assign a static IP address to the network adapter that's plugged into the Netgear router.

For this example, we'll assume that your network interface is eth0. First, we have to assign a static IP address to our network interface. In this example, we'll use All available network interfaces can be listed using

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

Now we can flash the image. The argument for the -a option needs to be a free IP address from the same subnet as the one used by your network interface; we'll use Firmware images can usually be downloaded directly from Netgear. For details on how to do this, see here. Power on your device immediately after starting nmrpflash.

# nmrpflash -i eth0 -a -f EX2700-V1.0.1.8.img
Advertising NMRP server on eth0 ... /
Received configuration request from a4:2b:8c:00:00:01.
Sending configuration: ip, mask
Received upload request: filename 'firmware'.
Uploading EX2700-V1.0.1.8.img ... OK
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.

"Error while loading shared libraries: libpcap.so.0.8" (Linux)

You must install your Linux distribution's libpcap package. In openSUSE or Ubuntu for example, install libpcap0.8. Other distros will have a similarily named package.

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

Install WinPcap.

"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. Try rebooting the device and run nmrpflash again. You could also try running nmrpflash with -m and specify your router's MAC address. It's also possible that your device does not support the NMRP protocol.

"Timeout while waiting for initial reply."

The device did not respond to nmrpflash's TFTP upload request. This could 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 -a -c "busybox tftp -p -l EX2700-V1.0.1.8.img"

"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, assigning 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 -f firmware.bin -c 'ifconfig eth0'

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

Building and installing

Linux, Mac OS X, BSDs
$ make && sudo make install

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

Obtaining firmware images

Firmware images can be downloaded directly from Netgear's FTP servers. For the Netgear EX2700 for example, download ftp://updates1.netgear.com/ex2700/ww/fileinfo.txt. At the top there should be an entry like this:


The download link for the latest firmware image for this device is thus: ftp://updates1.netgear.com/ex2700/ww/EX2700-V1.0.1.8.img. Substitute ex2700 for your device (wndr4300, wndr3700, r6100, etc.). If neccessary, substitute ww (world-wide) for a specific region.

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