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<title>OpenWrt - Important Knowledge</title>
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<h1>OpenWrt - Important Knowledge</h1>
<p>
2011-02-19<br />
by Gernot WALZL
</p>
<p>
OpenWrt (<a href="http://openwrt.org/">http://openwrt.org/</a>)
is a custom GNU/Linux based firmware for network routers.
</p>
<h2>Enable boot_wait</h2>
<p>
After flashing a custom linux firmware, it is <b>HIGHLY RECOMMENDED</b>
to enable boot_wait.
</p>
<pre>
root@OpenWrt:~# nvram set boot_wait=on
root@OpenWrt:~# nvram get boot_wait # just to confirm, should respond "on"
root@OpenWrt:~# nvram commit # takes a few seconds to complete
</pre>
<p>
In case of an emergency, you should be able to easily recover a broken device
via it's bootloader using TFTP to flash another firmware image.
</p>
<h2>Recover a broken device</h2>
<p>
The bootloader always sets 192.168.1.1 as the devices IP Address.
</p>
<ol>
<li>Remove power cord of the WRT device.</li>
<li>Run TFTP on a computer inside the LAN.<br />
The network device of this computer has to be configured to reach 192.168.1.1.
The WRT device will accept correct binary (*.bin) images only.
<pre>
$ tftp 192.168.1.1
tftp> binary
tftp> rexmt 1
tftp> timeout 60
tftp> trace
tftp> put openwrt-wrt54g-squashfs.bin
</pre>
</li>
<li>Plug in power cord. It will take approximately 5 minutes until
the new firmware is flashed.</li>
</ol>
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