Netgear Unbrick Utility
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Latest commit d4a72d6 Sep 11, 2018

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 and R6220, but is likely to work with many other Netgear routers as well.

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

Usage: nmrpflash [OPTIONS...]

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

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  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: 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. 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 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 ACK(0)/OACK."

The device did not respond to nmrpflash's TFTP upload request. By default, nmrpflash will assign to the target device, while adding 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, specify a free IP address, such as -a, 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, 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 ( Download the latest WinPcap Developer Pack and extract it into the root folder of the nmrpflash sources.