It is a good idea to print out these instructions before proceeding,
especially if you’re flashing the firmware in your sole router. If your
router has already been flashed with CeroWrt firmware, so you can
proceed to Step 1 (“Configuring and Installing the Router”) below.
Step 0. Flashing the router
Please see the CeroWrt flashing instructions for how to
install the current CeroWrt build on your
bismark:WNDR3700v2 or WNDR3800 Router from your platform of
choice (Windows, OS X, Linux).
Step 1. Configuring and Installing the Router
Power on your router. The router should boot in under
two minutes. It takes a lot longer the first time after flashing
(sometimes six or seven minutes) as it has to fully check flash
for errors. The router itself comes up on 172.30.42.1. The router
serves IP addresses on 172.30.42.0/27 networks by default. (see
Connect to your router. Plug in a laptop or computer to one of
the 4 LAN ports on the router, and refresh your laptop/computer’s
DHCP IP address. Alternatively, connect via wireless by setting your
SSID to “CEROwrt” (no SSID password) or “CEROwrt5”. Your machine
should get an IP address from the 172.30.42.0/27 subnet in the first
case, other networks in the second and third.
Configure your router’s default password. In your web browser,
go to the router configuration screen at https://172.30.42.1:81 (see
also why 81?). (You can ignore the
warning generated by the self-signed certificate.) The default
username is ‘root’, the password is ‘Beatthebloat’. Go to the
System/Administration screen and enter in a new password for
the router. Write this password down somewhere. The login will
be “root”, and the password that you set should be
something difficult. Note you can also just go to gw.home.lan for
most things, once DNS is up.
Secure your wireless interfaces Go to the Network->Wireless
configuration page, and change the SSIDs of the various interfaces
to suit your liking. (See also FAQ) Enable WPA2
encryption on the LAN interfaces, and if you wish your guest
interfaces to be secured, do the same there, too. Choose unique
passwords for the LAN and guest interfaces.
Set your country. If you are not in the US, please set your
country for both radios to the correct country in order to ensure
SAVE and APPLY. At the bottom part of the Web interface, save
and apply the changes (these are two distinct steps).
Reboot the router. You will need to reboot the router for SSH
and the Internet to come up. Reboot and connect the WAN interface to
the Internet (i.e., to your DSL or Cable modem). Wait a few minutes,
and refresh your laptop/computer’s DHCP address.
Important Configuration Notes:
The wireless interfaces default to the United States regulatory
wireless spectrum by default. If you’re outside the US, you should
set your country immediately to stay within your local regulations.
The wireless interfaces are also configured as open
(no password) by default. Change the SSID and/or passwords from the
web GUI, or see the Automated Configuration of CeroWrt page.
If you are configuring an interior router rather than your primary
router, the directions Setting up an interior gateway router will be helpful. CeroWrt comes with mesh networking
capability using the Babel protocol.
Step 2. Fine-tuning your SQM Settings
By default, the CeroWrt Router is configured to work pretty well at
virtually all WAN link speeds. You can do even better by
Setting up SQM in the
Step 3. That’s It!
You should now be on the Internet using the latest and greatest code
from the CeroWrt Project, the
Bufferbloat project, and
We hope that your experience will be exceptional. Please send us your
feedback and comments by registering on the
wiki and posting to the
list. You can also file bugs and feature requests in our Bug
Additional steps for configuring your CeroWrt router
If this is going to be a one-time installation of CeroWrt, using the Web
GUI is not very difficult. However, if you’re tracking the recent builds
closely, you may have a list of settings that you wish to modify after
updating the firmware. The Automated Configuration of CeroWrt page allows you to put your parameters into a file and
perform them repeatably and all at once. The script lets you:
Update the root password
Set the time zone
Enable SNMP for traffic monitoring and measurements
Enable NetFlow export for traffic analysis
Enable mDNS/ZeroConf on the ge00 (WAN) interface
Change default IP addresses and subnets for interfaces
We really don’t recommend you change the default network numbering unless you know what you are doing. Seriously. Don’t
mess with it.
But: If you wish to use other default IP address ranges… we recommend
against using 192.168.0.1 and 192.168.1.1 for historical reasons.
(They’re used by so many other vendors that you’re likely to run into
Go to the Network screen on the router and change to suit. By default,
the secured interfaces come up on the 172.30.42.1⁄27, 172.30.42.65⁄27,
172.30.42.97⁄27 addresses, and the guest networks come up on
172.30.42.129⁄27 and 172.30.42.161⁄27 - the mesh network is disabled by
default. You will also need to change the firewall rules, the
/etc/xinetd.conf file and many files below /etc/chroot/named/etc/bind/
Instead of using the web GUI, it is FAR easier to change these by
editing the relevant files directly on the router. As an alternative,
since we have DNS, just use gw.home.lan and don’t worry about the IP
addresses…. (have we scared you enough yet?) If you must change the
addresses or DNS, the Automated Configuration of CeroWrt
script simplifies the process.
Important: If you change the default IP address, your router’s web
interface will change at this point to be whatever-you-chose:81 after
doing a save and apply. You should probably reboot the router; you will
also need to change the address in the url in your browser accordingly.