ASUS Merlin aka. asuswrt-merlin

By | April 12, 2015

Asuswrt-Merlin is actively developed, custom firmware built based on ASUS asuswrt -firmware mainly developed by Eric Sauvageau. Usually – and for a reason – I don’t get so hyped for custom firmware. Often custom firmware changes some functionalities to worse, breaks something or adds some major functionalities. This can cause problems and unexcpeted bugs. But with ASUS Merlin, the approach is different. It doesn’t make big changes to original firmware. It’s goal is to fix bugs, improve stability, add tweaks and add basic functionalities which are lacking from the original. In my opinion, this kind of approach with custom firmware we need to see more.

The GPL code makes possible that almost all of the source code and build tools can be downloaded and used to compile new build from the original ASUS firmware. However, some components are closed source. But since binary versions are provided by ASUS, they can be added to firmware just like in the stock firmware.

Fixes, optimizations and new functionalities

Here’s a list of some changes what ASUS Merlin currently offers:

  • Fixes and optimizations
  • User scripts and cron jobs
  • SNMP support
  • Turn off all leds of the router
  • Persistent JFFS partition
  • Edit configuration files of router services
  • NFS sharing via web gui
  • Acting as a WINS server, force acting as a master browser
  • SSHD support (hybrid drive, HDD and SSD combined)
  • CIFS support
  • Advanced OpenVPN client
  • Enchanced traffic monitoring (monthly and IP monitoring), and saving them to USB or JFFS partition

In the beginning of 2015, the following routers were supported (with U, R and W variants of all models, since they use same firmware):



This custom firmware is well thought off. It has it’s priorities well balanced, quote from Github:

Stability > performance > features

As there’s less changes to the code, there’s also less change of creating bugs.

The firmware was initially released in 2012, so ASUS Merlin has come a long way, and possibility of bugs is even smaller. And what’s even more impressive, the firmware is still kept up to date and updated. In the time of writing, previous update came about a week ago. There’s not so many custom firmware, which has been actively updated for a so long time to this day.

However before flashing, one should have a knowledge what he or she is doing. There’s always a possibility of bricking the router and possibly voiding the device warranty. Also if the router is used by a company, be aware of security regulations which can prevent using custom firmware in their devices. Although, sometimes custom firmware can be a better option. Updates can be provided faster, like in this example.

So there shouldn’t be need to worry that things break if you decide flash your router’s firmware to ASUS Merlin. There’s basically no downsides with it. Usually with custom firmware you don’t see this kind of quality provided.

Should you use ASUS Merlin?

So should you flash your router with ASUS Merlin? General rule applies: If you are happy with your current setup, think twice before bothering. You have a chance to mess up things and waste time. However, if you know what you are doing and want to try it for a reason or another, go ahead.

ASUS Merlin homesite:

Download latest ASUS Merlin firmware: