Ok, the title is a little misleading. You build a serial cable and use it to manually adjust the firewall, then you can SSH in over ethernet (or wireless? It’s not explicitly stated).
Jauszi from Hungary appears to have sucessfully obtained SSH access to his El Cheapo and gives us the steps necessary to do it. Jauszi, please forgive me for quoting your entire blog entry below, but it is -technical-instruction, and not journalistic reporting, so I thought it was reasonable to do so. I’d like to keep a copy of these instructions here as a mirror, if you don’t mind.
Folks, please check out his blog first at this point, in case he has updated it or made corrections:http://jauzsi.hu/2006/10/13/inside-of-the-fonera
$5 for a wireless AP is no big money, however in this case you get a completely closed box with no telnet or ssh. No known bugs in web interface, firmware upgrades are digitally signed. So what do we do?
Of course we open it up! (2 screws at the front under the rubber pads)
Inside you’ll find pinouts for a serial connector
Connect a ttl level shifter (aka max232, etc).
Serial pinouts for the Fonera:
VCC (3.3V) red
For the colorblinds:
. . . . r
. w o . b
# mv /etc/init.d/dropbear /etc/init.d/S50dropbear
# vi /etc/firewall.user
Uncomment the two lines at the SSH section, so it will look like this:
iptables -t nat -A prerouting_rule -i $WAN -p tcp dport 22 -j ACCEPT
iptables -A input_rule -i $WAN -p tcp dport 22 -j ACCEPT
Now you can reboot or type these: