4. Using OpenWrt

4.1. Using OpenWrt for the first time

If you got till here you are allready pretty far for now. If the upload of the firmeware has been running without interruption and your router reboots you can try to log in with telnet.Once booted, you should be able to telnet into the router using the last address it was configured for.

Connected to
Escape character is '^]'.

BusyBox v1.00 (2004.12.24-03:19+0000) Built-in shell (ash)
Enter 'help' for a list of built-in commands.

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M

The firmware itself is designed to occupy as little space as possible while still providing a reasonably friendly commandline interface. With no packages installed, the firmware will simply configure the network interfaces, setup a basic NAT/firewall and load the telnet server and dnsmasq (a combination dns forwarder and dhcp server).

NoteWhy no telnet password?

Telnet is an insecure protocol with no encryption, we try to make a point of this insecurity by not enabling a password. If you're in an enviornment that requires password protection we suggest installing the dropbear ssh server.

NoteWhat if I can't get in?

The problem is caused when the jffs2 partition (see below) is detected but unusable, either the result of previous OpenWrt installation or occasionally just caused by a brand new router. Simply boot into Failsafe (see ) and run firstboot to reformat the jffs2 partition.

4.2. Firstboot / jffs2.

The OpenWrt firmware contains two pieces, a kernel and a readonly filesystem embeded in the firmare known as squashfs. The job of the firstboot script is to make a secondary, writable jffs2 filesystem out of the free space in flash.

When OpenWrt boots it will check for the existance of a jffs2 partition and attempt to boot from that, otherwise it will boot from the squashfs filesystem. The lack of a jffs2 partition will automatically trigger the firstboot script which will run in the background, creating a jffs2 filesystem and populating it with symbolic links to the squashfs filesystem (which is now remounted to the /rom directory). The effect of this is that the root filesystem will suddenly appear to be writable shortly after bootup, this can be verified with the mount command:

$ mount

/dev/mtdblock/4 on / type jffs2 (rw)


If you do not see this line you may need to run firstboot manually (just type "firstboot"). The firstboot script can also be used to erase all changes to the jffs2 partition, particularly useful when upgrading from previous OpenWrt versions with different filesystem layouts.

4.3. Editing Files.

The use of symlinks by the firstboot script saves space on the jffs2 partition, but it does have some interesting side effects such as edititing files. Since all files are by default symlinks to a readonly filesystem, you will not be able to edit files directly -- you'll get a readonly error if you try. Instead you have to delete the symlink and copy the file to the jffs2 partition to be able to edit it.

$ rm /etc/ipkg.conf
$ cp /rom/etc/ipkg.conf /etc/ipkg.conf
$ vim /etc/ipkg.conf

4.4. ipkg

The ipkg utility is a lightweight package manager used to download and install OpenWrt packages from the internet. (Linux users familiar with apt-get will recognise the similarities)

Table 4.

ipkg updateDownload a list of packages available
ipkg listView the list of packages
ipkg install dropbearInstall the dropbear package
ipkg remove dropbearRemove the dropbear package

More options can be found via ipkg --help.

Additional packages can be found through Nico's package tracker; these packages can be installed using ipkg install http://example.com/package.ipkg or by adding the the source repository to your /etc/ipkg.conf.