Asuswrt is the name of the firmware developed by Asus for use in all their recent routers. It was originally based on Tomato, and got extensively modified by Asus over the years as they added their own features to it.

Asuswrt-Merlin is an alternative, custom version of that firmware. Developped by Eric Sauvageau, its primary goals are to enhance upon the existing firmware without bringing any radical changes, and to fix some of the known issues and limitations, while maintaining the same level of performance as the original firmware. This means Asuswrt-Merlin retains full support for NAT acceleration (sometimes referred to as "hardware acceleration"), enhanced NTFS performance (through the proprietary drivers used by Asus from either Paragon or Tuxera), and the Asus exclusive features such as AiCloud or the TrendMicro-powered AiProtection. New feature addition is very low on the list of priorities in this project.

Asuswrt-merlin officially supports the following router models:

  • RT-N66U
  • RT-AC66U
  • RT-AC56U
  • RT-AC68U
  • RT-AC68P (same firmware as RT-AC68U)
  • RT-AC87
  • RT-AC3200

Further models and download link:

Asuswrt-Merlin retains all the features of the original stock Asus firmware. In addition, the following features have been added/enhanced:

System:

  • Based on the 3.0.0.4.378_4980 source release from Asus
  • Various bugfixes
  • Performance optimizations to CPU-bound services such as OpenVPN
  • Some components were updated to their latest versions, for improved stability and security
  • Persistent JFFS partition
  • User scripts that run on specific events
  • Cron jobs
  • Customized config files for router services
  • LED control - put your Dark Knight in Stealth Mode by turning off all LEDs
  • Entware easy setup script (a modern alternative to Optware)
  • SNMP support

Disk sharing:

  • Optionally use shorter share names (folder name only)
  • Disk spindown after user-configurable inactivity timeout
  • NFS exporting of USB drives

Networking:

  • Act as a SMB Master Browser
  • Act as a WINS server
  • Advanced SSHD support
  • Allows tweaking TCP/UDP connection tracking timeouts
  • CIFS client support (for mounting remote SMB share on the router)
  • User-defined options for WAN DHCP queries (required by some ISPs)
  • Advanced OpenVPN client and server, based on code originally written by Keith Moyer for Tomato and reused with his permission. (all models except RT-N16)
  • Netfilter ipset module, for efficient blacklist implementation
  • Site survey page (under Wireless)
  • Configurable lowest/highest allowed UPNP ports
  • IPSec kernel support (N16/N66/AC66)
  • DNS-based Filtering, can be applied globally or per client
  • Custom DDNS (through a user script)
  • Advanced NAT loopback (as an alternative to the default one)
  • TOR support, individual client control
  • Policy routing for the OpenVPN client (based on source or destination IPs), sometimes referred to as "selective routing")

Web interface:

  • Optionally save traffic stats to disk (USB or JFFS partition)
  • Enhanced traffic monitoring: added monthly, as well as per IP monitoring
  • Name field on the DHCP reservation list and Wireless ACL list
  • System info summary page
  • Wireless client IP, hostname, rate and rssi on the Wireless Log page
  • Wifi icon reports the state of both radios
  • Display the Ethernet port states
  • The various MAC/IP selection pulldowns will also display hostnames when possible instead of just NetBIOS names
  • Advanced Wireless client list display, including automated refresh

A few features that first debuted in Asuswrt-Merlin have since been integrated/enabled in the official firmware:

  • HTTPS configuration interface
  • Turning WPS button into a radio on/off toggle
  • Clicking on the MAC address of an unidentified client will do a lookup in the OUI database.
  • WakeOnLan web interface (with user-entered preset targets)
  • Display active/tracked network connections
  • VPN Status page
  • DualWAN and Repeater mode (while it was still under development by Asus)
  • Basic OpenVPN (client and server) support
  • Configurable IPv6 firewall
  • Improved compatibility with 3TB+ and Advanced Format HDDs
  • SSHD

Previous versions:

2015-12-30